PHD PROGRAM: “DENTAL MATERIALS AND CLINICAL APPLICATIONS” · · 2010-03-02PHD PROGRAM: “DENTAL MATERIALS AND CLINICAL APPLICATIONS ... pulpal pathology or pulpal death, partial

1

UNIVERSITY OF SIENA SCHOOL OF DENTAL MEDICINE PHD PROGRAM: “DENTAL MATERIALS AND CLINICAL APPLICATIONS” Ph D THESIS OF: Andrea Fabianelli TITLE: A STUDY INTO THE SIGNIFICANCE OF TRACING MICROLEAKAGE BY COLOR DIE INFILTRATION December 18th, 2004

2

Policlinico “le Scotte” Siena Italy Committee: Promoter Prof. Marco Ferrari Co-Promoter Prof. Carel L Davidson Prof. Piero Balleri Prof. Egidio Bertelli Prof. Franklin R Tay Prof. Manuel Toledano TITLE: A STUDY INTO THE SIGNIFICANCE OF TRACING MICROLEAKAGE BY COLOR DIE INFILTRATION CANDIDATE Andrea Fabianelli

December 18th, 2004

3

CONTENTS

Chapter 1 Page 4

Introduction

Chapter 2 Page 21

Efficacy of self-etching primer on sealing margins

of Class II restorations.

Chapter 3 Page 38

In vitro evaluation of wall-to-wall adaptation of self-adhesive resin

cement used for luting gold and ceramic inlays.

Chapter 4 Page 61

Sealing ability of packable resin composites in class II restorations.

Chapter 5 Page 78

Marginal integrity of ceramic inlays luted with a self-curing resin

system.

Chapter 6 Page 97

Influence of tissue characteristics at margins on leakage of Class II

indirect porcelain restorations.

Chapter 7 Page 127

A clinical trial of Empress II porcelain inlays luted to vital

abutments with the self-light-curing adhesive system Excite DSC

and MultiLink.

Chapter 8 Page 147 Leakage and SEM evaluation of in vitro Class V cavities restored

with diverse materials.

Chapter 9 Page 168 General Discussion

Chapter 10 Page 172 Summary and Conclusions

Chapter 11 Page 206 References

Acknowledgments Page 228

Curriculum Vitae Page 230 Publications and abstracts Page 231

4

Chapter 1

Introduction

One of the major requirements of a tooth restoration is protection of the

exposed dentin against bacteria and their toxins (Bränström M et al, 1978).

The interface between restoration and dental substrate is an area of clinical

concern that can result in secondary decay, marginal discoloration, and

pulpits (Bränström M & Vojinovic O; 1976) For that reason, perfect sealing

should be the plan of each clinical performance (Eakle WS & Ito RK, 1990).

In other words: leakage should be prevented.

However, due to inconsistent physical properties between tooth structure

and restorative materials, perfect adaptation is hard to be accomplished.

Clinically, absence of secure adaptation cannot always be detected.

Eventual hidden leakage is usually denoted by microleakage. Microleakage

may be defined as the clinically undetectable passage of bacteria, fluids,

molecules or ions between a cavity wall and the restorative material applied

to it (Kidd EAM, 1976).

One of the most desirable properties that an ideal restorative material should

have is a perfect and complete seal of the restoration’s margin. In fact the

absence of space between dental substrates and restorative materials can

prevent restoration failure and most of the current literature focuses on

elimination of leakage, which is one of the major factors determining the long

term success of restorations. Clinical experiences that are associated to

leakage are staining around the margins of restorations, post-operative

sensitivity, secondary caries, restoration failure, pulpal pathology or pulpal

death, partial or total loss of restoration (Eick JD & Welch FH,1986; Krejci I &

Lutz F,1991).

5

Marginal staining can lead to aesthetic breakdown and consequently to the

need to replace the restoration. The penetration of bacteria and the

presence of a gap can have as early consequence sensitivity when chewing

or when exposed to thermal stimuli. Then secondary decay may occur

(Moreira Jr G et al, 1999). It has to be emphasised that every plaque

retention site is a possible location for secondary decay (Cagidiaco MC et al,

1996). The multiplication of bacteria in the crevice around the filling is

facilitated as they can be acquired in a short time from the oral environment,

tooth surface or smear layer. Subsequently the bacteria and toxic products

are able to diffuse through dentinal troubles and cause pulpal inflammation

(Skogendal O & Erikensen HM,1976).

Fluids along the interface may create hydrolytic breakdown of adhesive resin

and collagen within hybrid layer thereby compromising the stability of resin-

dentin adhesive interface (Finger WJ et al, 1994).

Microleakage of a restoration may vary over time. Resin-based composites in

association with dental adhesives are believed to loose sealing ability over

time, permitting microleakage (Lundin SA & Noren JG, 1991).

On the other side, materials such as amalgam are believed to seal

restoration margins through formation of corrosion products over time (Ben-

Amar A et al, 1995).

Furthermore new marginal gaps may develop during the service life of

restoration due to thermally or mechanically induced stresses (Hakimeh S et

al, 2000).

In addition it has been demonstrated that modern dental adhesives have a

positive influence on preventing leakage that lasts only 6 months and

became in influent after one year of storage (Moore DS et al, 1995).

6

Causes for microleakage

Leakage is related to several factors, such as dimensional changes of

materials due to shrinkage of materials’ polymerisation, thermal contraction,

absorption of water, mechanical stress and also dimensional changes in

tooth structures (Staninec M et al, 1986).

The polymerisation shrinkage of a resin-based composite can create

contraction forces that may disrupt the bond to cavity walls, with marginal

failure and subsequent microleakage (Davidson CL et al, 1984). Modern

composites undergo volumetric contractions ranging between 2.6% to 4.8 %.

(Lösche GM, 1999) and even if modern dentin bonding agents exhibit bond

strengths to dentin higher than 20 MPa (Eick JD et al, 1997), exceeding then

the contraction stress generated by polymerisation stress (13-17 MPa), total

contraction forces may win the adhesive strength to substrates, leading to

open margins.

Also the shape of the cavity can challenge the adaptation: in fact the C-

factor of cavities is firmly related to occurrence of microleakage, especially if

filled with composite and dental adhesive (Davidson CL, 1986; Douvitsas G,

1991; Hakimeh S et al, 2000).

One of the weakest links of Class II composite restorations is leakage at the

gingival margin of proximal boxes. The latter is due to the absence of

enamel at gingival margins implying a less stable and uniform cementum-

dentin substrate for bonding (Carvalho RM et al, 1996). This is sustained by

Cagidiaco et al. who experimentally demonstrated the presence of an outer

layer, partially formed by cementum, of 150-200 microns located below the

cementum enamel junction, that does not allow micro retentions for adhesive

materials (Cagidiaco MC et al, 1995).

Also the orientation of dentinal tubules can negatively affect the quality of

hybridization and thus favor leakage in resin-based restorations placed in

deep inter-proximal boxes (Schubach P et al, 1997).

7

On the other hand it has also been reported that enamel micro-fractures

occurred along the margins in many restorations, immediately after

polymerization of resin composite bonded to etched enamel (Han L et al,

1990).

Furthermore the coefficient of thermal expansion of resin-based composites

differs substantially from that of tooth structure (Yazici AR et al, 2003).

The coefficient of thermal expansion of composite (25 to 60 ppm°C-1) is

several times larger than that of enamel (11,4 ppm°C-1) and dentin ( 8

ppm°C-1)(McCabe JF & Walls AW 1998).

This physical property is also appointed to be responsible of microleakage in

resin-based restorations (Feilzer AJ et al, 1988).

Last but not least, micro-movements of the restoration along the cavity walls

as a result of non-matching moduli of elasticity can contribute to failure of the

mechanical bond and following microleakage (Lundin SA & Noren JG, 1991).

Restricting microleakage

Given that we have to work with the available materials, many attempts to

reduce microleakage are performed by clinicians during restorative

procedures involving application of combinations of different materials, direct

or indirect techniques, different curing strategies etc.

Relying on curing techniques as a means to prevent leakage is controversial:

many authors claimed that incremental placement and curing can generate

less leakage (Cooley R & Barkmeirer W, 1991; Crim GA & Chapman KW,

1986) while other researchers found that both bulk and incremental

techniques have the same substantial leakage at the gingival margin (Coli P

& Brånnstrøm M, 1993; Affleck MS et al, 1999).

The use of a relatively thick layer of a viscous bonding agent, resilient lining

cements and low modulus restorative materials have been advocated to

absorb volumetric changes associated with polymerisation (Kemp-Scholte

CM & Davidson CL, 1990). In the line of applying flexible linings (Davidson

8

CL, 1994) it was in 1996 proposed to minimize polymerisation contraction of

resin-based composites by using flowable composites for restoring Class V

cavities. These restorative materials are micro-hybrid resins which are 60-

70% filled by weight with filler particles ranging in size from 0.7-1.0 micro-

meters. Such composites exhibit a substantially lower modulus of elasticity

that enables increased elastic deformation to flex and absorb polymerization

shrinkage stress (Unterbrink GL & Liebenberg WH, 1999). Moreover the

composition gives to this material a coefficient of thermal expansion similar

to that of tooth structures (Chuang SF et al, 2001).

Undeniably, this operative protocol is able to reduce microleakage, as

reported in literature (Leevailoj C et al, 2001) and reduce stress of 18-50 %

(Kemp-Sholte CM & Davidson CL,1990).

Still this technique could not completely prevent microleakage (Belli S et al,

2001).

Another approach to reduce leakage in Class II restorations is the adaptation

of a slow self curing composite on gingival margin located on cementum as

first step, and then the layering of a photo-cured hybrid composite. Indeed, it

could be demonstrated that light cured resins developed more

polymerisation stresses than chemical cure resins (FusayamaT,1992;

Davidson-Kaban SS et al, 1997).

Also this strategy does not seem to solve the problem completely (Van

Dijken J & Horsted P, 1998).

Another approach is to apply indirect restorations, where eventual bulk

polymerization shrinkage can partly be tackled. Still the luting cement has to

polymerize in situ and will put the seal of the margins at damage. Cement

layer thickness plays a role in stress development (Ausiello P et al, 2002).

To date it is almost impossible to obtain an indirect restoration that perfectly

fits the cavity.

Clinically acceptable margins in metallic restorations have been reported to

be 50 up to 70 microns (Löfstrom LH & Barakat MM, 1989), while for ceramic

9

restorations the gap ranges from 50 to 300 microns (Audenino G et al,

1999).

Certain indirect restorative techniques with soft alloys or gold foil direct

restorations may improve marginal adaptation by burnishing margins

towards dental tissues, thus reducing leakage.

Then there is the need to get a perfect seal with the use of a sealing/luting

agent: In case of wide space between inlays and cavities a thick layer of

viscous resin cements may be the optimum to get sealed margins (Hahn et

al, 2001).

Inlays adhesively luted with resin cements have a small volume of luting

composite that can reduce stress formation caused from polymerisation

shrinkage. (Lutz F et al, 1991), and showing less marginal micro-fracture on

enamel than direct restorations (Iida K et al, 2003), but on the other hand,

the narrower the luting space, the more is the stress occurs (Davidson CL &

De Gee AJ, 1984). In addition this stress is increased by an unfavourable C-

factor, very high in cavities prepared for inlays (Feilzer AJ et al, 1987).

Given the experience that prevention of gap formation is hardly to be

achieved, antibacterial effects of the restoration can be an important

additional safeguard, because the inactivation of bacteria means a direct

strategy to minimize the risk of secondary decay (Imazato S, 2003).

The composites as we have now at our disposition have little or no bacterio-

static or bactericidal effects against oral bacteria. Silica-based filler and resin

monomers such ad TEGDMA, Bis-GMA and UDMA are not antibacterial

against S. Mutans (Kawai K, 1988).

This lack of antibacterial properties means no inhibitory effect against plaque

accumulation that can occur in leakage sites. Indeed it has been

demonstrated that more bacteria accumulation is seen on composites when

compared with other restorative materials (Skjörland KKR, 1973). What is

more, a study demonstrated that composites even promote caries (Kawai K

& Tsuchitani Y, 2000).

10

Glass-ionomer cements exhibit a moderate anti-bacterial effect, in addition

to the presence of fluoride-releasing components that seem to prevent

premature demineralisation and thus protection against secondary caries

(Herrera M et al, 2000). The positive effect of zinc is still a neglected area in

dental literature. Furthermore fluoride releasing materials, such glass-

ionomer and silicate cements, can affect bacterial metabolism with different

mechanisms (Marquis RE, 1995).

In amalgam and other metallic restorations, the presence of metal ions such

as silver or copper can present antibacterial activity (Duguid R, 1983).

Mercury has a long story as an antimicrobial agent effective against

eukaryotic and prokaryotic organisms, even if the basis of this activity is not

well established (Dixit V et al, 2004). In leakage tests, fresh amalgam

restorations usually show total involvement of the cavity’s wall (McCurdy CR,

1974). However it is reported in previous studies that the initial poor seal of

fresh amalgams improves with aging due to the deposition of corrosion

products at the cavity-restoration interface. Indeed it is often reported that

patients only complain about eventual post-operative sensitivity during the

first week after placement, where after the pain disappears. Whether this

effect can be attributed to improved sealing is questionable as it has been

documented that up to 2 years may be required to reduce leakage almost

completely around amalgam restorations (Andrews JT et al, 1980).

It’s reported in literature that over time, water sorption can cause gap

reduction by hygroscopic expansion of resin-based composites (Thonemann

BM et al, 1997). It has to be stressed that it is not seem too realistic to rely

on this mechanism to solve the problem of leakage.

Measuring microleakage

Microleakage usually has been evaluated with in vitro models. A number of

techniques including bacteria-, chemical or radioactive tracer molecules

infiltration are available. Colour dye penetration studies are the most

11

employed tests. Since continuously many new materials are brought on the

market short time laboratory assessments are required because clinical

evaluations are expensive and time consuming and require ethical approval,

in vitro studies such as leakage tests can provide important information on

possible clinical performance of new restorative materials (Mota CS et al,

2003). These are methods of screening dental materials and determining the

eventual presence of microleakage, with the theoretical ability to transfer the

findings in vivo (Roulet JF, 1994).

Microleakage tests are very common in literature (Raskin et al, 2001), even

if these studies have given often contradictory results and were performed

in different procedures and without standardization. Nonetheless it is

reported that microleakage tests may be reliable parameters to predict in

vivo performance (Söderholm KLM, 1991).

Data based on the aetiology of decay lead to the conclusion that every site

of plaque retention has the possibility to be the location of secondary decay

(Olgart L et al, 1974; Cagidiaco MC et al, 1996). The problem with in vitro

studies is, amongst others, that the number of samples is limited to a few. In

literature one finds studies based on ten- twelve cavities for each group

(Hormati AA & Chan KC, 1980; Bauer JG & Henson JL, 1985). Statistical

analysis can only be based on the less powerful ones (Norman GR &

Streiner DL, 1999).

To some extend the oral environment can be mimicked by water storage and

thermo-cycling of the samples. The use of thermo-cycling as simulation of

clinical aging is quite common artificial aging technique. There are

disagreeing opinions about the influence of thermo-cycling on microleakage:

some authors report the absolute absence of any influence of thermo-cycling

on microleakage (Doerr CL et al, 1996), while others show increase of

microleakage at the cementum-dentin-restoration interface after thermal

stressing (Yap AUJ, 1997).

In these studies methylene blue was employed as tracer to evaluate the

degree of infiltration. The small particle size and the permeability of dentinal

12

tubules may lead to overestimate the relevance of this infiltration (Gale MS &

Darvell BW, 1999). The area of methylene blue is calculated to be around

0,52 nm2 , smaller than average bacteria. As bacteria have a diameter of

0,3-1,5 µm or larger, this technique cannot distinguish between too narrow

and sufficiently wide gaps to allow bacteria passage. An interesting finding

was that the use of methylene blue tracer leads to higher leakage scores

than other microscope evaluations (Almeida JB et al 2003). Few data are

available on crevice dimensions: Cooley and Barkmeier founded gaps of 10

microns around Vitrebond restorations (Cooley RL & Barkmeier WW, 1991).

The dwelling time of specimen in methylene blue seems to have no

influence on microleakage scores (Hilton TJ, 1998).

Often the evaluation of penetration scores is done on one or more cuts and

optical microscope observation. This evaluation method may be less

sensitive than three-dimensional evaluation (Gale MS et al, 1994), however

it is reported that also the use of several (eg. three) sections of one tooth

may avoid under-estimation of in vitro microleakage (Raskin A et al, 2003).

This mainly qualitative and to some extend quantitative method of evaluation

is a useful tool to show the pattern of dye penetration and can indicate

where the penetration occurs (Alani AH & Toh CG, 1997).

Based on above discussed measuring methodology it was concluded that

thus far no adhesive restorative technique is available that guarantees a

reliable marginal adaptation when margins are located in cementum-dentin

(Davidson CL & Feilzer AJ, 1997; Van Meerbeek B et al,1998).

Although the contribution of leakage to restoration failure remains

controversial (Camps J et al, 2000; Mior IA & Toffenetti F, 2000), leakage

studies are being carried out at most dental material laboratories.

So it was and is done at our facilities in order to obtain a preliminary idea

about one of the main qualities of a new material or combination of

materials: the potential to seal the cavity. However throughout the present

study, where next to only laboratory studies were carried out, also clinical

assessment of some of the materials was established, not seldom good

13

clinical performance was observed, whilst the in vitro leakage studies

predicted disappointing clinical results.

In the following chapters reports are presented of our initial experimental

findings, whilst in chapter 7 the meant discrepancy between the in vitro

methylene blue leakage findings and the in vivo appreciations will be

discussed. In addition to that some conclusions will be posed in chapter 9.

14

References

Affleck MS, Denehy GE, Vargas MA. Microleakage with incremental vs bulk

placement utilizing condensable composites. J Dent Res 1999; 78: 155.

Alani AH, Toh CG. Detection of microleakage around dental restorations: a

review. Op Dent 1997; 22: 173-185.

Almeida JB, Platt JA, Oshida Y, Moore BK, Cochran MA, Eckert GJ. Three

different methods to evaluate microleakage of packable composites in class

II restorations. Op Dent 2003; 28: 453-460.

Andrews JT, Hembree JH Jr. Marginal leakage of amalgam alloys with high

content of copper: a laboratory study. Oper Dent 1980; 5: 7-10.

Audenino G, Bresciano ME, Bassi F, Carossa S. In vitro evaluation of fit of

adhesively luted ceramic inlays. Int J Prosth 1999; 12: 342-347.

Ausiello P, Apicella A, Davidson CL. Effect of adhesive layer properties on

stress distribution in composite restorations--a 3D finite element analysis.

Dent Mater 2002 (18): 295-3003).

Bauer JG, Henson JL. Microleakage of direct filling materials in class V

restorations using thermal cycling. Quintessence Int 1985; 11: 765-769.

Belli S, Inokoshi S, Ozer F, Pereira PNR, Ogata M, Tagami J. The effect of

additional enamel etching and a flowable composite to the interfacial

integrity of class II adhesive composite restorations. Op Dent 2001; 26: 70-

75.

Ben-Amar A, Cardash HS, Judes H. The sealing of the tooth-amalgam

interface by corrosion products. J Oral Rehabil 1995; 22: 101-104.

Brännström M, Vojinovic O. Response of dental pulp to invasion of bacteria

round three filling materials. J Dent Child 1976; 43: 15-21.

Brännström M, Nordenvall KJ. Bacterial penetration, pulpal reaction and the

inner surface of enamel bond, composite fillings in etched and un etched

cavities. J Dent Res 1978; 57: 3-10.

15

Cagidiaco MC, Vichi A, Ferrari M. SEM evaluation of outside dentin-

cementum layer at cervical margins of Class II restorations. CED-IADR

Congress, Lubliana, September 1995.

Cagidiaco MC, Ferrari M, Garberoglio M. Dentin contamination protection

after mechanical preparation for veneering. Am J Dent 1996; 9: 57-60.

Camps J, Dejou J, Remusat M, About I. Factors influencing pulpal response

to cavity restoration. Dent Mat 2000; 16: 432-444.

Carvalho RM, Pereira JC, Yoshiyama M, Pashley DH. A review of

polymerisation contraction: the influence of stress development versus

stress relief. Op Dent 1996; 21(1): 17-24.

Chuang SF, Liu JK, Chao CC, Liao FP, Chen YH. Effect of flowable

composite lining and operator experience on microleakage and internal

voids in Class II composite restorations. J Prosthet Dent 2001; 85(2): 177-

183.

Coli P, Brannstrom M. The marginal adaptation of four different bonding

agents in Class II composite resin restorations applied in bulk or in two

increments. Quintessence Int 1993; 24: 583-591.

Cooley R, Barkmeirer W. Dental shear bond strength, microleakage and

contraction gap of visible light- polymerised liner/bases. Quintessence Int

1991; 22: 467-474.

Crim GA, Chapman KW. Effect of placement techniques on microleakage of

a dentin bonded composite resin. Quintessence Int 1986; 17: 21-24.

Davidson CL, De Gee AJ, Feilzer A. The competition between the composite

dentin bond strength and the polymerisation contraction stress. J Dent Res

1984; 63(12) :1396-1399.

Davidson CL, De Gee AJ,. Relaxation of polymerisation contraction stresses

by flown in dental composites. J Dent Res 1984; 63: 146-148.

Davidson CL. Resisting the curing contraction with adhesive composites. J

Prosthet Dent 1986; 55(4):446-447.

16

Davidson CL. Glass Ionomer Bases Under Posterior Composites. In: Glass

Ionomers: The Next Generation. Proc. of the 2nd Int. Symp. on Glass

Ionomers. Ed.: P.R. Hunt, Philadelphia PA, USA. June 1994; p. 175-179

Davidson CL, Feilzer AJ. Polymerisation shrinkage and polymerisation

shrinkage stress in polymer based restoratives. J Dent 1997; 25:435-440.

Davidson-Kaban SS; Davidson CL; Feilzer AJ; de Gee AJ; Erdilek N The

effect of curing light variations on bulk curing and wall-to-wall quality of two

types and various shades of resin composites. Dent Mater 1997; 13:344-52.

Dixit V, Bini E, Drozda M, Blum P. Mercury inactivates transcription and the

generalized transcription factor TFB in the archaeon Sulfolobus solfataricus.

Antimic Ag Chem 2004; 48 (6): 1993-1999.

Doerr CL, Hilton TJ, Hermesch CB. Effect of thermocycling on the

microleakage of conventional and resin modified glass ionomer. Am J Dent

1996; 9: 19-21.

Douvitsas G. Effect of cavity design on gap formation in Class II in

composite resin restorations. J Prosthet Dent 1991; 65: 475-479.

Duguid R. Copper-inhibition of the growth of oral streptococci and

actinomyces. Biomat 1983; 4(3):225-227.

Eakle WS, Ito RK. Effect of insertion technique on microleakage in mesio-

occlusodistal composite resin restoration. Quintessence Int 1990; 21: 369-

374.

Eick JD , Welch FH. Polymerisation shrinkage of posterior composite resins

and its possible influence on post operative sensitivity. Quintessence int

1986; 17 (2):103-111.

Eick JD, Gwinnett AJ, Pashley DH, Robinson SJ. Current concepts on

adhesion to dentin. Critical Reviews of Oral Biology and Medicine 1997;

8(3): 306-335.

Feilzer AJ, De Gee J, Davidson CL. Setting stress in composite resin in

relation to configuration of restoration. J Dent Res 1987; 66: 1636- 1639.

Feilzer AJ, de Gee AJ, Davidson CL. Curing contraction of composites and

glass-ionomer cements. J Prosthet Dent 1988; 59(3): 297-300.

17

Finger WJ, Inoue M, Asmussen E. Effect of wettability of adhesive resins on

bonding to dentin. Am J Dent 1994; 7: 35-38.

FusayamaT. Indicationfor self-cured and light-cured adhesive composite

resins. J Prosth Dent 1992; 67: 46-51.

Gale MS, Darvell BW, Cheung GSP. Three-dimensional reconstruction of

microleakage pattern using a sequential grinding technique. J Dent 1994;

22: 370-375.

Gale MS, Darvell BW. Thermal cycling procedures for laboratory testing of

dental restorations. J Dent 1999;27:105-108.

Hahn P, Attin T, Grofke M, Hellwig E. Influence of resin cement viscosity on

microleakage of ceramic inlays. Dent Mat 2001; 17: 191-196.

Hakimeh S, Vaidyanathan J, Houpt ML, Vaidyanathan TK, Von Hagen S.

Microleakage of compomer Class V restorations: effect of load cycling,

thermal cycling and cavity shape differences. J Prosthet Dent 2000; 83: 194-

203.

Han L, Okamoto A, Iwaku M. The effect of various clinical factors on

marginal enamel micro-cracks produced around composite restorations.

Dent Mat 1990; 11: 26-37.

Herrera M, Castillo A, Bravo M, Lièbana J, Carrion P. Antibacterial activity of

resin adhesive, glass ionomer and resin-modified glass ionomer cements

and a compomer in contact with dentin caries samples. Op Dent 2000; 25:

265-269.

Hilton TJ. Can modern restorative procedures and materials reliably seal

cavities? In vitro investigations. Dent Mat Transactions 1998; 12: 21-71.

Hormati AA, Chan KC. Marginal leakage of compacted gold, composite

resin, and high copper amalgam restorations. J Prosthet Dent 1980; 44 (4):

418-422.

Kawai K. Effect of eluate from composite resin on Gtase and growth of

Streptococcus Mutans. Jpn J Conserv Dent 1988; 31: 322-351.

18

Kawai K, Tsuchitani Y. Effects of resin composite components on

glucosyltransferase of cariogenic bacterium. J Biomed Mat Res 2000;51:

123-127.

Kemp-Sholte CM, Davidson CL. Marginal integrity related to bond strength

and strain capacity of composite resin restorative systems. J Prosthet Dent

1990; 64: 658-664.

Kidd EAM. Microleakage: a review. J Dent 1976; 4:199-205.

Krejci I, Lutz F. Marginal adaptation of class V restorations using different

restorative techniques. J Dent 1991; 19: 24-32.

Iida K, Inokoshi S, Kurosaki N. Interfacial gaps following ceramic inlay

cementation vs direct composites. Op Dent 2003; 28: 445-452.

Imazato S. Antibacterial properties of resin composites and bonding

systems. Dent Mat 2003; 19: 449-457.

Leevailoj C, Cochran MA, Matis BA, Moore BK, Platt JA. Microleakage of

posterior packable resin composites with and without flowable liners. Op

Dent 2001; 26(3): 302-307.

Löfstrom LH, Barakat MM. Scanning electron microscopic evaluation of

clinically cemented cast gold restorations. J Prosth Dent 1989;61:664-669

Lösche GM. Marginal adaptation of Class II composite fillings:guided

polymerisation vs reduced light intensity. J Adhes Dent 1999; 1(1): 31-39.

Lundin SA, Noren JG. Marginal leakage in occlusally loaded, etched, Class

II composite resin restorations. Acta Odontol Scand 1991; 49: 247-254.

Lutz F, Krejci I, Barbakow F. Quality and durability of marginal adaptation in

bonded composite restorations. Dent Mater 1991; 7: 107-113.

Marquis RE. Antimicrobial actions of fluoride for oral bacteria. Can J

Microbiol 1995; 41(11): 955-964.

McCabe JF, Walls AW. Properties used to characterize materials. Applied

Dental Materials. 8th ed Oxford: Blackwell Science; 1998: 4-28.

McCurdy CR. A comparison of in vivo and in vitro microleakage of dental

restorations. JADA 1974; 88(3):592-602.

19

Mior IA, Toffenetti F. Secondary caries:a literature review with case reports.

Quint Int 2000; 31: 165-179.

Moore DS, Johnson WW, Kaplan I. A comparison of amalgam microleakage

with a 4-META liner and copal varnish. Int J Prosthodont 1995; 8: 461-466.

Moreira Jr G, Sobrinho APR, Nicoli JR, Bambirra EA, Farinas LM, Carvalho

MAR, Vieira EC. Evaluation of microbial infiltration in restored cavities- an

alternative method. J End 1999; 25:605-608.

Mota CS, Demarco FF, Camacho GB, Powers JM. Microleakage in ceramic

inlays luted with different resin cements. J Adhes Dent 2003; 5: 63-70.

Norman GR, Streiner DL. PDQ statistics. BC Decker inc. Hamilton 1999.

Olgart L, Brännstöm M, Johnson G. Invasion of bacteria into dentinal

tubules: Experiments in vivo and in vitro.Acta Odontol Scand 1974; 32: 61-

70.

Raskin A D’Hoore W, Gonthier S, Degrange M, Dejou J. Reliability of in vitro

microleakage test: a literature review.J Adhesiv Dent 2001; 3: 295-308.

Raskin A, Tassery H, D’Hoore W, Gonthier S, Vreven J, Degrange M, Déjou

J. Influence of the number of section on reliability of in vitro microleakage

evaluations. Am J Dent 2003;16(3):207-210.

Roulet JF. Marginal integrity: clinical significance. J Dent 1994; 22: 9-12.

Schubach P, Krejci I, Lutz F. Dentin bonding: effect of tubule orientation on

hybrid layer formation. Eur J Oral Sci 1997:105: 344-352.

Skjörland KKR. Plaque accumulation on different dental filling materials.

Scand J Dent Res 1973; 81: 538-542.

Skogendal O, Erikensen HM. Effect of composite resin restorations in

monkey’s teeth with experimentally induced pulpitis. Scand J Dent Res

1976; 84(5): 297-303.

Söderholm KLM. Correlation of in vivo and in vitro performance of adhesive

restorative matherials. Dent Mater 1991; 7:74-83.

Staninec M, Mochizuki A, Tanizaki K, Jukuda K, Tsuchitani Y. Interfacial

space, marginal leakage and enamel cracks around composite resins. Op

Dent 1986; 11: 14-24.

20

Thonemann BM, Federlin M, Schmalz G. SEM analysis of marginal

expansionand gap formation in Class II composite restorations. Dent Mater

1997; 13: 192-197.

Unterbrink GL, Liebenberg WH. Flowable resin composites as filled

adhesives; literature review and clinical recommendations. Quintessence Int

1999; 30(4): 249-257.

Van Dijken J, Horsted P. Directed polymerisation shrinkage in Class II

cavities in vivo. J Dent Res 1998; 77: 1326.

Van Meerbeek B, Perdigao J, Lambrechts P,Vanherle G. The clinical

performances of adhesives. J Dent 1998; 26: 1-20.

Yap AUJ. Effects of storage, thermal and load cycling on a new reinforced

glass ionomer cement. J Oral Rehabil 1997; 25: 40-44.

Yazici AR, Baseren M, Dayangaç B. The effect of flowable resin composite

on microleakage in Class V cavities. Op Dent 2003; 28: 42-46.

21

Chapter 2

Efficacy of self-etching primer on sealing margins of Class II restorations.

ABSTRACT: Purpose: To evaluate sealing ability of different types of

restorative-adhesive combinations and to correlate etch patterns with

leakage scores. Materials and Methods: 56 molars were selected and

divided randomly in four groups of 14 specimens each. A standardized

adhesive Class II preparation with the cervical margin placed 1 mm below

the CEJ and an occlusal reduction of 2 mm was performed. No bevels were

utilized in the preparation. Four combinations of bonding system/restorative

material were tested. Group 1: Excite (EX) in combination with Tetric Ceram

(TC) as control; Group 2: Prompt-L-Pop (PP1) applied for 15 seconds in

combination with TC; Group 3: Etch and Prime 3.0 in combination with

Definite restorative material (EP); Group 4: Prompt-L-Pop (PP2) applied for

30 seconds in combination with TC. The bonding systems (Groups 1, 2 and

3) and all restorative materials were used following strictly manufacturers’

instructions. The resin composite was applied following an incremental

technique. Ten specimens of each group were processed for leakage test.

The specimens were sectioned with a diamond saw in three different areas

in mesial-distal direction. Two different operators evaluated the sections

blindly for scoring leakage at cervical and occlusal margins. The highest

score for the sections of each tooth area was selected for scoring and further

statistical analysis. The results of the staining measurements were

statistically evaluated using the Kruskal-Wallis non-parametric analysis of

variance with Bonferroni alpha protection. The level of statistical significance

22

was defined as P< 0.05. The remaining four specimens of each group were

kept in a 37% HCl solution for 48 hours to dissolve the dental structures and

to observe the resin replica of the cavities by SEM. Results: EX showed

less dye penetration at occlusal margins than the other three groups, while

no statistically significant differences were found at the dentin margin. The

SEM observations showed rougher and more uniform enamel etch pattern

when phosphoric acid (EX) was applied than that obtained with self-etching

adhesive systems. Resin tags and adhesive lateral branches were noted in

all groups at the dentin site.

Conclusions: The sealing ability of self-etching priming bonding systems at

the enamel margins was less effective than that obtained using phosphoric

acid bonding systems.

23

Introduction

Patients’ demand for tooth colored restorations rather than amalgam

restorations is increasing day by day (Federation Dentaire Internationale,

1995). Resin-based composite materials are the most common alternative to

amalgam. Resin-based composites have been used for many years but only

recently exhibit improved wear resistance (Hickel R et al, 2000). In fact, the

average annual wear of new composites seems to be equal to that of

amalgam (Roulet JF, 1997). One of the main problems of resin restorations

is microleakage (Eakle WS & Ito RK, 1990). Leakage can be due to the

polymerization shrinkage of resin material that creates a gap between cavity

walls and restoration (Tjan AH et al, 1992). It has become apparent that

even with the development of adhesives that can produce adhesion to dentin

comparable to the adhesion attainable to enamel, leakage cannot be

prevented routinely (Eakle WS & Ito RK, 1990; Tjan AH et al, 1992). Thus,

alterations in the bonding systems and resin-based composites must be

achieved to minimize the deleterious effects of polymerization shrinkage of

the resin material, gap formation and consequent leakage; this will ultimately

make the material easier to use and less sensitive to technical parameters.

Recently, dentin adhesives have been developed with hydrophilic groups

and high wettability: good results on sealing margins of Class II restorations

were achieved (Duncalf WV & Wilson NH, 2000). These newer adhesives

can penetrate into a chemically conditioned dentin and create a mechanical

interlocking based on the formation of a hybrid layer and resin tags

penetrating into opened dentin tubules (Tay FR et al, 1996; Sano H et al,

1998).

Past generations of traditional dental adhesives utilized three steps:

decalcification, infiltration and polymerisation. Acid etching dentin removes

the smear layer and demineralises slightly the underlying dentin, exposing

collagen fibrils. Optimal hybrid layer formation requires the diffusion of a

mixture of hydrophilic resin monomers into the exposed collagen fibrils until

24

undemineralized dentin subsurface is reached (Tay FR et al, 1996;

Nakabayashi N & Pashley DH, 1998).

However, clinical steps of bonding procedures might be technique-sensitive

and lead to ineffective bonding if the operator is not experienced (Sano H et

al, 1998; Peschke A et al, 2000).

In order to simplify handling properties, reduce working time and avoid the

collapse of collagen fibrils, self-etching primers were proposed (Watanabe I

et al, 1994). These bonding systems create a continuum between tooth and

resin by the simultaneous demineralisation and resin penetration of dentin

substrate with acidic molecules that can be polymerised in situ (Watanabe I

et al, 1994) .

This study evaluated the sealing ability of different self-etching adhesives,

correlated etch patterns with leakage scores, and tested the null hypothesis

that there is no difference in the ability of different adhesive systems to seal

Class II restorations.

Materials and Methods

Fifty-six posterior teeth were selected. The teeth were divided randomly in

four groups of 14 specimens each. Extracted human posterior teeth which

had been stored in 1% chloramine between 1-3 months were selected. A

standardized adhesive Class II preparation was made in the mesial and

occlusal surface of each tooth (Fig. 1). The cervical margin of the

interproximal box was placed 1 mm below the cementum-enamel junction, in

cementum-dentin. The cavities had an occlusal reduction of 2 mm. The

bucco-lingual width of the proximal boxes was 4 mm, the occlusal width 3

mm and the depth of the pulpal and axial walls 2 mm. A tolerance of 0.3 mm

was used to include preparations in the test. A butt-joint margin preparation

was made at the cervical margin of all samples. The preparations were not

bevelled.

25

The dimensions of prepared cavities were measured with a Boley gauge.

Three combinations of bonding system and restorative material were tested

according to the manufacturer’s instructions, while a fourth group was used

by increasing the application time of one self-etching adhesive (Table 1).

Group 1: Excitea (EX) in combination with Tetric Cerama (TC) as control;

Group 2: Prompt-L-Pop self etching-priming adhesive systemb (PP1) in

combination with TC;

Group 3: Etch and Prime 3.0c in combination with Definitec restorative

material (EP);

Group 4: Prompt-L-Popb (PP2) in combination with TC. The application time

(etching step) was increased to 30 seconds instead of 15 seconds as

recommended by the manufacturer.

The bonding systems and restorative materials were used following

manufacturers’ instructions, except for Group 4. The composites were

applied using an incremental technique. Ten specimens of each group were

randomly selected and processed for the leakage test.

Leakage test After protecting apical foraminas and roots with nail varnish the specimens

were immersed in a dye solution (2% methylene blue) for 24 hours subjected

to 500 cycles of a thermal cycling test with a dwell time of 20 seconds

between 5°C and 55°C.

After the specimens were embedded in acrylic resin, they were sectioned

with a diamond saw (Isometd) in three different sites in a mesio-distal

direction (Fig. 2). The first section was positioned in the middle of the

restoration, while the two others were along the lingual and buccal proximal

walls along the interface between the restoration and the cavity wall.

The sections were evaluated blindly by two different operators for leakage

scores at cervical and occlusal margins and for the presence of voids and

porosities by a stereomicroscope. The highest score for the sections of each

tooth area was selected for scoring and statistical analysis. In case of

26

discrepancy between the two operators, the highest score was selected and

evaluated.

The depth of cervical staining was measured according to the following

parameters: 0= no penetration; 1= leakage not exceeding the middle of

gingival wall; 2= penetration exceeding the middle of gingival wall; 3=

penetration up to the axial wall; 4= penetration up to the axial cervical wall

or into dentin tubules. The extent of occlusal leakage was registered as

depth of dye penetration according to the following scores: 0= no

penetration; 1= leakage not deeper than the enamel-dentin junction; 2=

leakage deeper than the enamel-dentin junction; 3= leakage along the

occlusal and/or axial lateral walls. The results of the staining measurements

were statistically evaluated using the Kruskal-Wallis non-parametric ANOVA

with Bonferroni alpha protection. The level of statistical significance was

defined at P< 0.05.

The remaining four specimens of each group were kept 48 hours in a 37%

HCl solution to completely dissolve the dental structures and to observe the

resin replica of the cavities with a scanning electron microscopee (SEM).

After rinsing extensively with water, the specimens were gently air dried,

sputter-coated with goldf and observed with a SEM at different

magnifications, in order to evaluate the extent and the morphology of etched

dental substrates in three different enamel areas (occlusal, axial and close to

CEJ) and the resin tags formed (Fig. 3).

Results

Leakage test Excite (Group 1) revealed less dye penetration occlusally than the other

groups. Statistical analysis of the scores recorded at occlusal margins

showed significant differences among Group 1 and the other three groups.

In Group 1, 90% of the specimens showed a perfect seal occlusally (Table

2), while only 10-20% of specimens of Groups 2, 3 and 4 showed no

27

leakage. Statistical analysis of the scores recorded at cervical margins did

not show any statistical difference among the four groups (Table 3).

SEM observations

The SEM observation showed rougher and more uniform enamel etch

patterns when phosphoric acid was applied than when self-etching

adhesives were used. At the occlusal site, the enamel prisms were cut along

their long axis and samples etched with phosphoric acid (Group 1) showed a

deeper and more uniform etched pattern than the others groups (Figs. 4,5).

Similarly, the etched pattern at the axial site and close to CEJ was more

uniform and deeper in Group 1 than in the other groups (Figs. 6-9). Resin

tags and adhesive lateral branches were reported in all groups at the dentin

site (Figs. 10-13). The morphology of resin tags and adhesive lateral

branches was similar in all groups.

Discussion

The technique used in this study is a common procedure used for evaluating

sealing ability of bonding/resin composite restorations, allowing observation

of dye that penetrates into gaps between dental substrates and

restorations(Rigsby DF et al, 1990; Ferrari M et al, 1999).

A perfect seal is more difficult to achieve for axial margins(Hilton TJ et al,

1997; Hilton TJ & Ferracane JL, 1998). The sectioning procedure in this

study was selected also for evaluating the leakage at axial walls of cavities

and correlating leakage data with microscopic observations.

Self-etching adhesives which do not require rinsing and perform

simultaneously as primer and adhesive are a simplified approach to

adhesive techniques. The use of self-etching systems does not seem to

produce significant morphological changes in the enamel substrate, while

the dentin substrate was effectively treated by the tested materials.

28

Excitea (Group 1) showed less dye penetration at the occlusal margins than

the other three adhesives. When phosphoric acid in combination with Excitea

bonding system was used on cut enamel, the SEM observation of this area

showed rougher and more uniform etch pattern than that obtained withn self-

etching systems (Figs. 4-7).

The leakage score found at cervical margins is in accordance with others

(Thonemann B et al, 1999; Tung FF et al, 2000). Gap-free restorations are

possible to achieve only when margins of small Class II cavities were

located in enamel (Opdam NJM et al, 1998) and shrinkage stress is

counteracted by bonding to etched enamel (Ferrari M & Davidson CL, 1996).

A reason for the high percentage of leakage at the cervical margin noted in

this study might be the presence of an outer layer partially formed by

cementum of 150-200 µm at the cervical margins placed below the CEJ

(Cagidiaco MC et al, 1996). This outer layer is a hypo-mineralised hyper-

organic substrate that, even if etched, does not allow microretention for

adhesive material. Although the hybridisation of the cementum was

demonstrated (Ferrari M et al, 1997), the absence of resin tags in the first

150-200 µm from the cervical margins probably decreases the quality of the

bonding and the durability of adhesion at the cervical margin.

A recent workshop on posterior resin-based composites concluded that the

“quest continues for a more wear-resistant, biologically compatible, and

aesthetic restoration with no marginal leakage” (ADA Council on Scientific

Affairs, 1998). Also, further research in the areas of reducing polymerisation

shrinkage and contact wear, improving bonding and placement techniques,

and developing alternative matrix resins and polymerisation initiators were

encouraged.

Different types of sandwich techniques were evaluated and flowable

composites, glass-ionomer cements or compomer might be placed at the

cervical margin, as first layer of a Class II restoration in order to improve the

seal of the restorations (Ferrari M, 1999; Hilton TJ, 2002b). These materials

should act as stress absorbing layers, reducing the polymerisation

29

contraction stress (Ferrari M, 1999; Hilton TJ, 2002a). However, recent

studies( Labella R et al, 1999; Miguez PA et al, 2001) showed that placement

of a flowable resin-based composite as gingival increment in boxes results in

a moderate to severe leakage. Combinations of different materials and

layering procedures with self-etching systems are in progress in order to

evaluate if the sealing ability of Class II restorations can be improved

(Beznos C, 2001; Chuang SF et al, 2001) .

From this study the following conclusion can be drawn: when gingival

margins are placed below the CEJ, the tested material combinations

performed equally well, while adhesive systems including etching with

phosphoric acid sealed enamel margins significantly better than self-etching

primers and self-etching priming bonding agents.

The results of this study rejected the null hypothesis that was tested.

Different adhesive systems can affect the sealing ability of Class II

restorations.

a. Vivadent, Schaan, Liechtenstein.

b. 3M/ESPE, Seefeld, Germany.

c. Degussa, Hanau, Germany.

d. Buehler, Lake Bluff, IL, USA.

e. Philips Co, Eidhoven, The Netherlands.

f. Edwards Ltd, London, UK.

30

References

ADA Council on Scientific Affairs/ADA Council on Dental Benefit Programs.

Statement on posterior resin-based composites. J Am Dent Assoc 1998;

129: 1627-1628.

Beznos C. Microleakage at the cervical margin of composite Class II cavities

with different restorative techniques. Oper Dent 2001; 26: 60-69.


cementum layer at cervical margins of Class II restorations. J Dent Res

1996; 75: 1220 (Abstr 28).

Chuang SF, Liu JK, Jin YT. Microleakage and internal voids in Class II

composite restorations with flowable composite linings. Oper Dent 2001; 26:

193-200.

Duncalf WV, Wilson NH. A comparison of the marginal and internal

adaptation of amalgam and resin composite restorations in small to

moderate-sized Class II preparations of conventional design. Quintessence

Int 2000; 31: 347-352.

Eakle WS, Ito RK. Effects of insertion technique on microleakage in mesio-

occluso-distal composite resin restorations. Quintessence Int 1990; 21: 369-

374.

Federation Dentaire Internationale, World Health Organization, World Dental

Federation, Consensus statement on dental amalgam . FDI World 1995 : 9-

10.

Ferrari M, Davidson CL. Sealing performance of Scotchbond Multi-Purpose-

Z100 in class II restorations. Am J Dent 1996; 9: 145-149.

Ferrari M, Cagidiaco MC, Davidson CL. Resistance of cementum in Class II

and V cavities to penetration by an adhesive system. Dent Mater 1997; 13:

152-162.

31

Ferrari M. Advances in glass-ionomer cements. In: Davidson CL, Mjör IA.

Glass-ionomer cements. Berlin: Quintessence 1999: 137-148.

Ferrari M, Mason PN, Fabianelli A, et al. Influence of tissue characteristics at

margins on leakage of Class II indirect porcelain restorations. Am J Dent

1999; 12: 134-142.

Frankenberger R, Kramer N, Petschelt A. Technique sensitivity of dentin

bonding: Effect of application mistakes on bond strength and marginal

adaptation. Oper Dent 2001;4: 324-330.

Hickel R, Manhart J, García-Godoy F. Clinical results and new developments

of direct posterior restorations. Am J Dent 2000; 13: 41D-54D.

Hilton TJ, Schwartz RS, Ferracane JL. Microleakage of four Class II resin

composite insertion techniques at intraoral temperature. Quintessence Int

1997; 28: 135-144.

Hilton TJ, Ferracane JL. Cavity preparation factors and microleakage of

class II composite restorations filled at intraoral temperatures. Am J Dent

1998; 11: 123-130.


cavities? In vitro investigations. Part 1.Am J Dent 2002;15:198-210.



Kanca J. Resin bonding to wet substrate. I: Bonding to dentin. Quintessence

Int 1992; 23: 39-41.

Labella R, Lambrechts P, Van Meerbeek B, et al. Polymerization shrinkage

and elasticity of flowable composites and filled adhesives. Dent Mat 1999;

15: 128-137.

Miguez PA, Pereira PNR, Suh IB et al. Gap formation and bond strength of

composites lined with flowable resin. J Dent Res 2001; 80 (Sp. Issue abstr.

n. 1270)194.

Nakabayashi N, Pashley DH. Hybridization of hard dental tissues. Berlin:

Quintessence, 1998; 20-30.

32

Opdam NJM, Roeters JJM, Burgersdijk RCW. Microleakage of Class II box-

type composite restorations. Am J Dent 1998; 11: 160-164.

Peschke A, Blunck U, Roulet JF. Influence of incorrect application of a

water-based adhesive system on the marginal adaptation of Class V

restorations. Am J Dent 2000; 13:239-243.

Rigsby DF, Retief DH, Russell CM, et al. Marginal leakage and marginal gap

dimension of three dentinal bonding system. Am J Dent 1990; 3: 289-294.

Roulet JF. Benefits and disadvantages of tooth-colored alternatives to

amalgama. J Dent 1997; 25: 459-473.

Sano H, Kanemura N, Burrow MF, et al. Effect of operator variability on

dentin adhesion: Students vs. dentists. Dent Mater 1998; 17: 51-58.

Tay FR, Gwinnett AJ, Wei SH. Micromorphological spectrum from overdrying

to overwetting acid-conditioned dentin in water-free, acetone based, single

bottle primer/adhesives. Dent Mater 1996; 12: 236-244.

Thonemann B, Federlin M, Shmalz G, et al. Total bonding vs selective

bonding: adaptation of Class 2 composite restoration. Oper Dent 1999; 24:

261-271.

Tjan AH, Bergh BH, Lidner C. Effect of various incremental techniques on

the marginal adaptation of class II restoration. J Prosthet Dent 1992; 67: 62-

66.

Tung FF, Estafan D, Scherer W. Microleakage of a condensable resin

composite: An in vitro investigation. Quintessence Int 2000; 31: 430-434.

Watanabe I, Nakabayashi N, Pashley DH. Bonding to ground dentin by a

phenyl-P self-etching primer. J Dent Res 1994; 73: 1212-1220.

33

Table 1. Bonding procedures. ______________________________________________________________________________________________

______

Group Bonding system Clinical steps ______________________________________________________________________________________________

______

1 Excite a,b,e,f

2 Prompt-L-Pop c,e,f

3 Etch and Prime 3.0 c,d,e,f*

4 Prompt-L-Pop - applied

for 30 seconds c,e,f ______________________________________________________________________________________________

______

a. Dentin and enamel conditioning with phosphoric acid

b. Primer-adhesive application

c. Self-etching primer application

d. Bonding application

e. Air blowing

f. Light curing

34

Table 2. Leakage scores recorded at occlusal margin. ______________________________________________________________________________________________

______

0 1 2 3 4 ______________________________________________________________________________________________

______

Group 1a 9 1 0 0 0

Group 2b 2 2 3 3 0

Group 3b 1 1 2 1 5

Group 4b 2 3 2 2 1 ______________________________________________________________________________________________

______

Groups with the same letter did not show any statistical significant

difference.

Table 3. Leakage scores recorded at cervical margin. ______________________________________________________________________________________________

______

0 1 2 3 4 ______________________________________________________________________________________________

______

Group 1a 5 1 3 1 0

Group 2 a 6 2 1 0 1

Group 3 a 7 1 0 0 2

Group 4 a 7 1 1 0 1 ______________________________________________________________________________________________

______

Groups with the same letter did not show any statistical significant

difference.

35

Legends to illustrations

Fig. 1. Microphotograph showing a sample at low magnification (SEM x97). The numbers

indicate the area where higher magnifications were taken.

36

Fig. 2. A microphotograph showing the etched pattern at occlusal enamel (area 1 of Fig. 3). The

sample was treated with phosphoric acid (Group 1). The prisms are cut parallely to prisms’

direction and the etch pattern is uniform and deep (SEM x1010).

Fig. 3. Microphotograph showing the etched pattern at axial-occlusal enamel (area 1 of Fig. 3)

of Group 1 sample. The prisms are mainly cut obliquely and the etch pattern is uniform and

rough (SEM x1010).

Figs. 4,5. Microphotographs showing the etched pattern at cervical enamel (area 1 of Fig. 3).

The sample was treated with phosphoric acid (Group 1). The prisms are cut in the less

favourable direction: obliquely (6.) or mainly parallel to their long axis (7.). The etch pattern is

less deep than those observed in Figs. 4 and 5, but rougher and deeper than those noted in

Figs. 7-9 (Groups 2-4) (SEM x1010).

37

Figs. 6,7. The etch pattern at axial site of Groups 2 and 3 samples are less uniform and deep

than Group 1 sample (Fig. 6,7). Figs. 8 and 9 represent the less uniform and milder patterns

found in Groups 2-4 samples.

Figs. 8,9. The two microphotographs show resin tags and adhesive lateral branches formed

using bonding systems of Group 2-4. Uniform resin tag formation (SEM x1010) can be seen.

Fig. 10. The microphotograph shows resin tags and adhesive lateral branches formed when

dentin was treated with the bonding system of Group 1 (SEM x600).

38

Chapter 3

In vitro evaluation of wall-to-wall adaptation of self-adhesive resin cement used for luting gold and ceramic inlays.

Abstract: Purpose: This in vitro study evaluated the wall-to-wall adaptation

of a new self-adhesive resin-based cement (RelyX Unicem), in comparison

with that of other cements when luting gold and porcelain inlays in

standardized Class II cavities in extracted teeth. Materials and Methods: In

each experimental Group (n=10) a different combination of inlay and luting

material was tested. Group 1: Porcelain Empress II (EII) and RelyX Unicem

(U); Group 2: EII and resin-based cement Variolink II in combination with

primer and bonding Excite DSC; Group 3: Gold inlays (G) and U; Group 4: G

and Harvard zinc-oxy-phosphate cement; Group 4: G and glass-ionomer

cement Fuji Cem. After storage and thermo-cycling, microleakage test was

carried out and dye penetration scoring was performed at the occlusal and

cervical margins of each inlay. The differences in microleakage score were

tested for statistical significance first comparing all Groups, then pooling

together the Groups for inlay material (Kruskal-Wallis Non-Parametric

ANOVA and Mann-Whitney U test, p<0.05). SEM observations of the tooth-

cement-restoration interfaces were also performed in each Group. Results:

Harvard cement had the highest microleakage. The sealing ability exhibited

by RelyX Unicem was satisfactory with both gold and porcelain inlays, and

comparable respectively to that of Fuji Cem and Variolink II. Conclusion:

RelyX Unicem achieved an adequate seal on both enamel and dentin when

used to lute in vitro gold and porcelain inlays.

39

Introduction Notwithstanding the great popularity of resin-based composite restorations

some serious shortcomings of these materials have to be reckoned with.

Disadvantages of the material are polymerization shrinkage, limited color

stability and limited strength, eventually leading to leakage, decreasing

esthetics and premature fracture under stress (Mjör IA, 1992). These

undesirable deficiencies are less likely to occur with indirect porcelain or

gold restorations, which therefore are to be preferred above all for large

restorations, particularly when cuspal coverage is required. A weak link with

indirect restorations is eventual debonding of the luting cement. Moreover,

for the weaker sorts of porcelain, the lute has to guarantee a strong and

reliable bond between the tooth structure and the inlay (Davidson CL, 2001).

Ceramic inlays gain in mechanical characteristics if luted with resin cements

in combination with hydrofluoric acid and silane treatment as introduced by

Horn (Horn , 1983). Adhesives have the potential of eliminating surface flaws

(Sindel J et al,1999; Van Noort R, 2002). Besides luting material and

technique, also substrate conditions represent a critical factor in the quality

of a durable wall-to-wall integrity. As a result of its morphologic variability,

the properties of the organic component, and the changing conditions of

humidity, dentin is the least predictable and undependable substrate for

bonding (Pashley DH et al, 1997; Griffiths BM et al, 1999). To promote

proper adaptation to moist dentin, hydrophilic bi-functional monomers like

HEMA are incorporated in the adhesive (Inoue S et al, 2000). Several

materials are available for luting inlays. Among resin cements, a self-cure,

light-cure or dual-cure material can be chosen, and a simple, quick, and

straightforward handling of the material is usually the practitioner’s desire. In

line with the common trend toward “simplified” application techniques, a new

self-adhesive, single-step universal resin cement, RelyX Unicem (3M ESPE,

Seefeld, Germany)., has recently been introduced The purpose of this study

was to evaluate the wall-to-wall adaptation expressed in sealing ability of

40

RelyX Unicem when used for luting gold and porcelain inlays, in comparison

with cements that have traditionally been used for this purpose. The quality

of the marginal seal achieved with the materials on trial was assessed in

vitro through a microleakage test and scanning electron microscopic

observations of the tooth-cement-restoration interfaces after thermo-cycling.


Fifty extracted sound molars were collected for the study. The selected teeth

were hand-scaled, cleaned with slurry of pumice, and stored in distilled

water at room temperature until use in the experiment. The samples were

randomly divided into five Groups of ten specimens each. In each Group a

different combination of inlay and luting material was tested. Standardized

mesio-occlusal Class II cavities were prepared under copious water spray,

with diamond burs in a high-speed handpiece (Fig. 1). On the occlusal

surface of the teeth, the preparation was 3 mm wide bucco-lingually and 2

mm deep. The proximal box of the cavity had a bucco-lingual width of 4mm

and a depth of 2 mm; also the pulpal wall was 2 mm, and the cervical

margins were placed 1mm below the cementum-enamel junction. The

dimensions of the prepared cavities were checked with a Boley gauge. A

±0.3 mm tolerance in the measurements was considered acceptable for

including the specimen in the trial. Butt margins were created in cavities

meant to receive porcelain inlays (Groups 1 and 2), whereas on the teeth to

be restored with gold inlays (Groups 3-5), a 0.5 mm bevel was added at the

preparation margins. Impressions were then taken with a polyether

impression material (Impregum, 3M ESPE, Seefeld, Germany) and sent to

the laboratory. After impression taking the specimens were stored in distilled

water.

In Group 1, Empress II (Ivoclar-Vivadent, Schaan, Liechtenstein) inlays were

cemented with resin-based cement RelyX Unicem (3M ESPE, Seefeld,

Germany). In Group 2 Empress II inlays were cemented with resin-based

41

cement Excite DSC (Ivoclar-Vivadent, Schaan, Liechtenstein) in combination

with bonding system Variolink II (Ivoclar-Vivadent, Schaan, Liechtenstein)

after acid-etching for 20’’and water spray. In Groups 3 through 5 gold inlays

were cemented respectively with RelyX Unicem, Harvard zinc-oxy-

phosphate cement (De Trey, Dentsply, Konstanz, Germany), and glass-

ionomer cement Fuji Cem (GC, Tokyo, Japan). Each luting material was

handled strictly following manufacturer’s instructions (Table I). The inner

surfaces of ceramic inlays were etched with hydrofluoric acid 9,6 %

(Ultradent, South Jordan, UT), rinsed and silanated with Monobond S

(Ivoclar-Vivadent, Schaan, Liechtenstein). Inner surfaces of gold inlay were

only cleaned with gentle sandblasting.

Microleakage evaluation Once the restorations were completed, the specimens’ roots were coated

with two layers of nail varnish up to 2 mm from the cervical margin of the

restoration. After a 24-hour immersion in a 2% methylene blue solution and

submitted to 500 thermo-cyclings, each with a dwell time of 20 s. at 5 and 55 oC. Subsequently, each tooth was embedded in acrylic resin and sectioned

longitudinally with a low-speed diamond saw (Leitz 1600, Munich, Germany)

at three different levels in the mesio-distal direction (Fig. 2). The first cut was

positioned in the middle of the restoration, and the other ones along the

lingual and buccal lateral walls, approximately at the interface between the

restoration and the cavity wall.

The degree of occlusal leakage was quantified according to the following

parameters: 0 = no penetration; 1 = leakage no deeper than the enamel-

dentin junction; 2 = leakage deeper than the enamel-dentin junction; 3 =

leakage along the occlusal and/or axial lateral walls; 4 = leakage into

dentinal tubules (Fig. 3a). Dye penetration at the cervical margin of the

cavity was quantified according to the following score method: 0 = no

penetration; 1 = leakage not exceeding the middle of the cervical wall; 2 =

penetration past the middle of the cervical wall; 3 = penetration to the axial

42

wall; 4 = penetration to and along the axial wall and into the dentinal tubules

(Fig. 3b).

Two operators observed the sections separately by means of an optical

microscope at 20 magnifications (Bausch&Lomb, Rochester, NY, USA). In

case of a disagreement between the two investigators on the score assigned

to a certain specimen, the worst (higher) score was chosen for the statistical

analysis.

Statistical analysis The results of the staining measurements were statistically evaluated using

Kruskal-Wallis Non-Parametric ANOVA by ranks with Bonferroni alpha

protection. The Tukey test was applied for multiple comparisons. All of the

statistical tests were run by the Winks 4.62 software (Texasoft, Cedar Hill,

Texas, USA), setting the level of significance at p<0.05.

SEM evaluation After scoring the specimens for dye penetration, in each Group one section

per tooth was chosen at random to be observed with the scanning electron

microscope (Philips 515, Philips, Eindhoven, Netherlands). The purpose of

the SEM analysis was to assess the integrity and continuity of the tooth-

cement-restoration interfaces, as well as to visualize the structural uniformity

of the cement layer. Specimen preparation for SEM involved a gentle

decalcification with a 37% phosphoric acid solution for 10 s., followed by de-

proteinization with a 2% sodium hypochlorite solution for 1 min. Finally, the

specimens were mounted on an aluminum stub with a colloid silver paint,

and sputter coated with gold-palladium (Edward’s Coater S105B, London,

England).

43

Results Leakage observations Frequency of recording and median value of the microleakage scores for the

different combinations of inlay and luting materials are given in Table III. The

mean ranks of the microleakage scores for each Group are plotted in

Graph1.

When comparing all of the combinations on trial (Graph 1), it appeared that

the Harvard zinc phosphate cement had the worst microleakage score. In

general, RelyX Unicem and Fuji Cem gave a better seal than Variolink II and

Harvard.

The difference in microleakage between Harvard and RelyX Unicem in gold

inlays was statistically significant (p<0.001). Also the difference between

Harvard at the cervical margin and Fuji Cem at the occlusal margin was

statistically significant (p<0.001, Graph 2).

In the comparison among the materials used to lute Empress II inlays

(Graph 2), it is evident that RelyX Unicem performed better than Variolink II

at both the occlusal and the cervical margin. However, the difference was

statistically significant only between occlusal margin with RelyX Unicem and

cervical margin with Variolink II (p=0.03).

As regards using Unicem with Gold or Empress inlays, the results were not

significantly different (p>0.05) at the occlusal as well as at the cervical

margin (Graphs 1-3).

Microscopic observations As expected, the typical features of adhesion, such as the formation of a

hybrid layer at the interface between luting material and dental substrate,

were absent from the SEM views of specimens cemented with Harvard (Fig.

4a). On the other hand, a good adaptation between cement and dental

substrate was visible in the specimens luted with Fuji Cem (Fig. 4b). Also

44

RelyX Unicem was able to establish a good coupling with the dental

substrate. However, voids were often visible within the cement layer (Fig.

4c). In any case, the quality of the seal created by the self-adhesive resin

cement was comparable to that achieved following a standard adhesive

procedure in inlays luted with Variolink II. This appeared from the SEM

observation of specimens restored with porcelain inlays (Fig. 5 a,b).

Discussion Literature is scarce on gold inlay leakage studies. Long-lasting clinical

service is in general expected from gold restorations (Smales RJ &

Hawthorne WS et al, 1996). The fact that these restorations are usually

realized in selective and compliant patients, with a good motivation for oral

hygiene may have an influence on the results of a clinical trial (Mjör IA,

1992). For many years, zinc-oxy-phosphate cements have been the favorite

lute to cement gold inlays and evidence has been presented of the

satisfactory long performance of such restorations (Mjör IA, 1992; Yamashita

J et al, 2000). Once again, factors such as patient selection, oral hygiene,

dimensional matching of the materials involved are likely to play a role in

determining the clinical success of these restorations. Despite this,

restorations luted with this material exhibited in the present study a high

degree of microleakage (Graphs 1, 2). A tentative explanation might be the

generally accepted absence of adhesion. Although the hardening of oxy-

phosphate cements is preceded by the etching action of the cements’ liquid,

no evidence could be found of a form of hybridization at the interface. Grip of

oxy-phosphate cements is merely based on macro-retention and the cements’ excellent dimensional stability (De Gee, A.J, 2004). Inlays luted

with adhesive techniques showed better sealing ability in the laboratory. In

vivo however, these restorations have sometimes failed to produce

satisfactory results, especially when margins were located below the

cementum-enamel junction (Özturk N, & Aykent F, 2003). Some aspects of

45

the luting procedure with resin cements need to be considered. On one

hand, a thin layer of cement would be desirable in order to reduce the stress

generated by the material on curing whilst on the other hand, the smaller the

space available for the polymerizing cement, the higher the stress developed

(Davidson CL, 2001). Accuracy of fit (thicker cement layers) might be less

with ceramic than with gold inlays. Low viscosity of the lute is a prerequisite

for proper seating, thus favoring the achievement of a good marginal seal

(Hahn P et al, 2001). All cements employed in this study showed

comparable, satisfactory flow characteristics with both gold and Empress

inlays. Even with adequate wetting and flow characteristics, it has to be

emphasized that luting with an adhesive techniques is an operator-sensitive

procedure because extreme care has to be given to the condition of the

substrates. With respect to the latter, new resin cements have been

introduced to satisfy the demand for an easy-handling, “user-friendly”

material. Rely-X Unicem is a self-etch, dual-curable resin composite cement,

designed for cementation of crowns, inlays, and fiber posts luting. As a result

of new chemistry (Table III), it is claimed by the manufacturer that this

cement does not require any substrate pretreatment or adhesive application.

As far as the materials’ bond strength is concerned, the data so far collected

are not consistent. In some studies acceptable levels of bond strength have

been reported on both dental substrates (Hecht R et al, 2002) and

restorative materials (Piwowarczyk A et al, 2002). However, these findings

are not confirmed by the results of micro-tensile tests measuring the bond

strength of RelyX Unicem on enamel and dentin (Goracci C et al, 2003).

Strength might be a determining factor in preservation of the sealing ability.

In this part of the study, no mechanical fatiguing of the samples was

considered and thus physical factors other than adaptation and dimensional

stability during thermo-cycling can be used to clarify different sealing ability

of the various luting cements. The fact that Rely-X Unicem is a hydrophilic

resin system, might explain the relatively good sealing. Hydrophilicity will

allow water uptake after setting, which may account for swelling of the

46

material. This seems a positive feature, but it has to be realized that at the

same time, water uptake can accelerate premature degradation of the

cement (El Zohairy AA et al, 2004).

The present microscopic study revealed, as in previous investigations

(Goracci C et al, 2003), that RelyX Unicem is capable of a noticeable

coupling with the dental substrate. However, the formed hybrid layer was

fairly thin. This may explain for the asymmetry between effective sealing

ability and relatively poor bonding potential of this new material. Also, voids

within the cement layer (Fig. 4c) have regularly been observed. These

porosities may result from incomplete mixing of powder and liquid during

vibrating a capsule that contains the two components.

In conclusion, RelyX Unicem showed improved sealing properties to both

enamel and dentin, when used for luting gold and porcelain inlays. With gold

inlays, this resin cement performed significantly better than the zinc

phosphate and comparably to the glass-ionomer cement. In specimens

restored with porcelain inlays, no statistically significant differences in micro-

leakage were found when the restorations were cemented with the new self-

adhesive resin cement, as compared with a standard adhesive procedure

(Excite DSC and Variolink II). Over other adhesive cements, the latter

material offers the advantage of easy handling and, by consequence, of a

reduction in chair-time. The real value of the new cement, both in quality of

persisting adhesion and sealing as well as true reduction of chair time still

has to be established in long-term fatigue studies and clinical trials. Such

studies are under way.

Moreover, the meaning of leakage in restorative dentistry has to be

(re)considered. Laboratory studies seldom show perfect sealing, whilst the

majority of restorations are functioning in an apparently acceptable way. For

sure, leakage should be minimized to prevent post-operative sensitivity and

eventual recurrent caries, but “one leakage is not necessarily the other

leakage”. Here the chemical composition of the luting material may play a

47

significant role e.g. in defending bacteria. In this respect, release of metal

ions and fluorides will play an important role that deserves intensive study.

48

References Davidson CL. Luting Cement, the Stronghold or the Weak Link in Ceramic

Restorations. Advanced Engineering Materials 2001, 3, 10: 763-767).

De Gee, A.J. personal communications, 2004).

El Mowafi OM, Benmergui C, Levinton C. Meta- analysis on long-term

clinical performance of posterior composite restorations. J Dent 1994; 22:

33-43.

El Zohairy AA, De Gee AJ, Hassan FM, Feilzer AJ. The effect of adhesives

with various degrees of hydrophilicity on resin ceramic bond durability. Dent

Mater, 2004 in press.

Feilzer AJ, De Gee AJ, Davidson CL. Increased wall-to wall curing

contraction in thin bonded resin layers. J Dent Res 1989 ; 68 : 48-50.

Ferrari M, Mason PN, Fabianelli A, Cagidiaco MC, Kugel G, Davidson CL.

Influence of tissue characteristics at margins on leakage of class II in direct

porcelain restorations. Am J Dent 1999; 12: 134-142.

Goracci C, Ferrari M, Grandini S, Monticelli F, Tay FR. Bonding of a self-

adhesive resin cement to dental hard tissues. J Adhes Dent 2003 (in press).

Griffiths BM, Watson TF, Sherriff M. The influence of dentine bonding

systems and their handling characteristics on the morphology and micro

permeability of the dentine-adhesive interface. J Dent 1999; 27: 63-71.

Hahn P, Attin T, Grofke M, Hellwig E. Influence of resin cement viscosity on

microleakage of ceramic inlays.Dent Mater 2001; 17: 191-196.

Hecht R, Ludstek M, Raia G. Tensile bond strength of first self adhesive

resin based dental material. J Dent Res 2002; 81: A-75.

Hickel R,. Manhart J. Longevity of dental restorations in posterior teeth and

reasons for failure. J Adhesive Dent 2001; 3:45-64.

Horn HR. Porcelain laminate veneers bonded to etched enamel.

Dent Clin North Am. 1983 Oct;27(4):671-84.

49

Inoue S, Van Meerbeek B, Vargas M, Yoshig’da Y, Lambrechts P, Vanherle

G. Advanced adhesive dentistry, 3rd Int Kuraray Symposium, Como, Italy

2000.

Lutz F, Krejici I, Barbakow F. Quality and durability of marginal adaptation in


Mjör IA. Long term cost of restorative therapy using different materials.

Scand J Dent Res 1992; 100: 60-65.

Özturk N, Aykent F. Dentin bond strengths of two ceramic inlay systems

after cementation with three different techniques and one bonding system. J

Prosthet dent 2003; 89: 275-281.

Pashley DH, Sano H, Ciucchi B, Yoshiyama M, Carvalho RM. Adhesion

testing of dentin bonding agents: a review. Dent Mater 1995; 11: 117-125.

Piwowarczyk A, Berge HX, Lauer H-Ch, Soresen JA. Shear bond strength of

cements at zirconium and lithium di-silicate ceramics. J Dent Res 2002; 81:

A-401.

Roulet JF Benefits and disadvantages of tooth-colored alternatives to

amalgam. J Dent 1997; 25:459-473.

Sindel J, Frankenberger R, Kramer N, Petschelt A. Crack formation of all

ceramic crowns dependent on different core build-up and luting materials. J

Dent 1999; 27: 175)

Sjögren G, Molin M, van Dijken JWV. A 5-year clinical evaluation of ceramic

inlays cemented with dual-cured or chemically cured resin composite luting

agent. Acta Odontol Scand 1998; 56: 263-267.

Smales RJ, Hawthorne WS. Long-term survival and cost-effectiveness of

five dental restorative materials used in various classes of cavity

preparations. Int Dent J 1996; 46: 126-130.

Van Meerbeek B. Perdigao J, Lambrechts P, Vanherle G. The clinical

performance of adhesives. J Dent 1998; 26: 1-20.

Van Noort R. Introduction to dental materials. Mosby pub 2002: 267)

50

Yamashita J, Takakuda K, Shiozawa I, Nagasawa M, Miyairi H. Fatigue

behavior of the zinc-phosphate cement layer. Int J Prosthodont 2000; 13:

321-326.

51


Fig.1. The standardized Class II cavity prepared for the inlay restoration

Fig. 2. After immersion in a dye solution, each tooth was embedded in acrylic resin and

longitudinally sectioned at three different levels in the mesio-distal direction.

52

Fig. 3a

Fig 3 b

Fig. 3 (a) Dye penetration scores at the occlusal margin. (b) Dye penetration scores at the

cervical margin.

53

Fig. 4a

Fig. 4b

54

Fig. 4c

Fig. 4. SEM images of the tooth-cement-restoration interfaces in gold inlays (D=dentin,

C=cement, G=gold): (a) In specimens luted with Harvard cement, no sign of adhesion could be

detected (X231, bar 0.1 mm). (b) Fuji Cem showed a good adaptation on the dental substrate

(X1620, bar 10 micron). (c) A good coupling was visible also between RelyX Unicem and the

dental substrate. However, voids were often present within the cement layer (X186, bar 0.1

mm).

55

Fig. 5a

Fig. 5b

Fig. 5 SEM images of the tooth-cement-restoration interfaces in porcelain inlays (D=dentin,

C=cement, P=porcelain). The quality of the seal created by the self-adhesive resin cement

RelyX Unicem (a, X710, bar 0.1 mm) was comparable to that achieved following a standard

adhesive procedure in inlays luted with Variolink II (b, X372, bar 0.1 mm).

56

Table I: handling of the luting materials

Preparation of the substrate Material

conditionin

g

priming bondin

g

Handling of the luting material

RelyX

Unicem

Batch

143250

Mix powder and liquid in a

vibrator; light-cure for 20

seconds

Variolink II

Batch

558952bn

37% H3PO4

20’’

+

water rinse

Excite

Mix paste A and paste B; light-

cure for 20 seconds

Fuji Cem

Batch

200310151

Mix paste A and paste B

Harvard Batch

212230201

7

Mix powder and liquid

Table IIa : Chemical composition of the self-adhesive resin cement RelyX Unicem.

Powder Liquid

Radiopaque fluoro-aluminosilicate

glass

Micro-encapsulated potassium per-

sulfate and ascorbic acid catalyst

system

Aqueous solution of a poly-

carboxylic acid modified with

pendant methacrylate Group HEMA

Tartaric acid

57

Table IIb: chemical composition of Variolink II.

BisGMA, UDMA,TEGDMA

silicon dioxide,

self-cure initiators,

light-cure initiators

stabilizers

pigments

Table III: Frequency and median value of the microleakage scores for the different

combinations of inlay and luting materials.

Scores frequency

Material Margin 0 1 2 3 4 Median

occlusa 9 1 0 Gold+Unicem

cervical 6 1 1 2 0

occlusa 5 3 1 1 0.5 Gold+Fuji Cem

cervical 2 1 4 1 2 2

occlusa 9 1 3 Gold+Harvard

cervical 10 4

occlusa 2 2 1 5 3 Empress+VariolinkII

cervical 2 2 6 4

occlusa 8 1 1 0 Empress+Unicem

cervical 4 1 1 3 1 1.5

58

Graph 1. Mean rank of score for the different tested combinations of dental substrate, luting

material, and inlay material. In the legend the suffix “O” stands for occlusal margin, “C” for

cervical margin. Columns underlined by the same segment represent statistically similar

subgroups. 21

,95 30

,75

34,8 38

,75

45,7 53

,5 61,3 64

,6

67,1

5

86,5

0

10

20

30

40

50

60

70

80

90

100

mea

n ra

nk o

f the

sco

res

GoldUnicemO EmpressUnicemO GoldFujiOGoldUnicemC EmpressUnicemC GoldFujiCEmpressVariolinkO EmpressVariolinkO GoldHarvardGoldHarvardC

59

Graph 2. Mean rank of scores for the materials used to lute gold inlays. In the legend the suffix “O” stands

for occlusal margin, “C” for cervical margin. Columns underlined by the same segment represent

statistically similar subgroups.

12,9 20

,55

23,2

32,0

5 41,3

53

0

10

20

30

40

50

60

mea

n ra

nk o

f sco

res

UnicemO FujiO UnicemC

FujiC HarvardO HarvardC

60

Graph 3. Mean rank of scores for the materials used to lute porcelain inlays. In the legend the

suffix “O” stands for occlusal margin, “C” for cervical margin. Columns underlined by the same

segment represent statistically similar subgroups.

12,7

5

18,6

24,7

5

25,9

0

5

10

15

20

25

30

mea

n ra

nk o

f sco

res

UnicemO UnicemCVariolinkO VariolinkC

61

Chapter 4

Sealing ability of packable resin composites in class II restorations.

Abstract: Purpose: To evaluate in Class II restorations the marginal

adaptation of ten packable composite resins in combination with the

proprietary adhesive system.

Materials and Methods: Standard Class II cavities were prepared in 100

extracted molars. The sample was randomly divided into ten Groups. In each

Group one specific packable composite was tested, in association with its

own adhesive: Groups: 1) Scotchbond1/FiltekP60 2) Etch&Prime3.0/Definit

3) Prime & Bond 2.1/SureFil 4) Excite/Tetric Condensable 5) Gluma/Solitaire

6) Kerr Bonding/Prodigy Condensable 7) One-step/Pyramid 8)

Tenure/Virtuoso 9) Syntac/Cavex Packable 10) Excite/Tetric flow/Tetric

Ceram. The restored teeth were sectioned at three levels in the mesio-distal

direction and processed for the microleakage test. On each section the

degree of dye penetration along the margins of the restoration was

assessed, and the differences in the leakage given by the ten materials at either the occlusal or the cervical margin were evaluated for statistical

significance. A statistical analysis was also conducted to assess the

significance of the differences between the scores recorded at the occlusal

margin and those measured at the cervical margin of the restoration. Results and Conclusions: Microleakage was significantly higher at the

cervical than at the occlusal margin of the restorations. The application of a

thin layer of a flowable composite at the cervical margin, as a liner

underneath the packable composite enhanced the marginal adaptation of

the restoration. The use of a self-etching primer to condition the dental

substrate resulted at the occlusal margin in a higher microleakage than

when phosphoric acid was applied.

62

Introduction

Patients’ demand for tooth colored restorations in the place of amalgam

restorations is constantly increasing (FDI World 1995). Composite resins are

the materials clinicians most commonly turn to as an alternative to amalgam

in Class II restorations. Highly filled composite resins, with a wear resistance

comparable to that of amalgam(Leinefelder KF, 1995 and 1997), especially

meant for posterior restorations have lately been developed. The viscosity of

these composites is so high, in comparison with other resin-based materials,

that they require an application technique similar to that of amalgam. Hence

the name “packable”, by which this class of resin composites has been

called (Leinefelder KF et al, 1999).

The availability of a material with an handling similar to that of amalgam has

appeared to be a decisive factor in convincing many practitioners to move

from amalgam to direct composites also for posterior restorations. However,

packable composites have not yet given proof of mechanical properties far

superior to conventional composites (Manhart J et al, 2000). In addition,

some further light should be shed on the polymerization stress of these

highly-filled resins, which is a factor of crucial importance clinically, as it can

directly affect the quality of marginal seal in the restoration (Eakle WS & Ito

RK, 1990). Recently it has been reported (Chen et al, 2001) that packable

composites develop a quite high contraction stress in the early stages of

curing. This stress, if transmitted to the adhesive interface, can become

responsible for the failure of the bond, followed by the opening of a gap

between cavity walls and restoration, through which microleakage can occur

(Eakle WS & Ito RK, 1990; Tjan AH ,1992). It has been shown that even with

the latest generation adhesive systems, able to achieve on dentin levels of

bond strength similar to those reached on enamel, microleakage can not be

completely eliminated in vivo (Eakle WS & Ito RK, 1990; Tjan AH ,1992). It

therefore becomes imperative to do whatever possible to limit the

occurrence of this phenomenon. At this objective have aimed the recent

63

advancements of research in the field of bonding. These have led to the

introduction of more hydrophilic adhesives, which have proved able to

improve the quality of marginal seal in Class II restorations (Duncalf WV,

Wilson NA, 2000). A parallel front of the research activity has been working

on the development of bonding systems with simplified handling, in the

attempt to control as much as possible the influence of the operating and

operator’s conditions on the properties expressed by the material (Kanca J,

1992; Sano H & Ciucchi B, 1995; Tay FR et al, 1996).

The aim of this study was to assess the ability of different combinations of

latest-generation adhesive systems and packable composites in creating a

valid seal on the margins of Class II restorations. The quality of marginal

adaptation was evaluated through microleakage tests. The null hypothesis

that the type of bonding system and packable composite used does not

significantly affect the quality of seal was tested.


Specimen Preparation One hundred human extracted molars were selected as being sound and

free from caries and/or restorations. The teeth were stored in a 1%

chloramine solution until used for the experiment, in any case no longer than

three month. A standardized adhesive Class II preparation was made in the

mesial and occlusal surface (Fig. 1). The cervical margin of the interproximal

box was placed 1mm below the cementum-enamel junction, in cementum-

dentin. Occlusally the tooth was reduced by 2 mm, and the cavity was 3 mm

wide. The proximal box was 4 mm wide bucco-lingually, whereas the pulpal

and axial walls measured 2 mm in depth. The dimensions of the prepared

cavities were checked with a Boley gauge. A ±0.3 mm tolerance in the

measurements was considered acceptable for including the specimen in the

trial. No bevels were added at any margin of the preparation.

64

The sample of teeth was randomly divided into ten groups of ten specimens

each. All of the specimens in each group were restored with the same

composite, used in combination with the proprietary adhesive system:

Group 1. Scotchbond1 and Filtek P60 (3M, St. Paul, MN, USA)

Group 2. Etch&Prime 3.0 and Definit (Dentsply Degussa, Bloomfield, CT,

USA)

Group 3. Prime & Bond 2.1 and SureFil (Dentsply/Caulk, Milford, DE, USA).

Group 4. Excite and Tetric Condensable (3 layers) (Ivoclar Vivadent, Schaan,

Liechtenstein).

Group 5. Gluma and Solitaire (Haereus Kulzer, Hanau, Germany).

Group 6. Kerr Bonding and Prodigy Condensable (Kerr, Orange, CA, USA).

Group 7. One-step and Pyramid (Bisco, Schaumburg, IL, USA).

Group 8. Tenure and Virtuoso Packable (DenMat, Santa Maria, CA, USA).

Group 9. Syntac Single Component (Ivoclar Vivadent, Schaan, Liechtenstein)

and Cavex Packable (Kuraray, Japan).

Group 10. Excite, Tetric flow, and Tetric Ceram (Ivoclar Vivadent, Schaan,

Liechtenstein).

In Groups 1-9 packable composites were tested. In Group 10, on the other

hand, a flowable composite was applied as a 1-2 mm thick base, which

remained exposed at the cervical margin, according to the “open-sandwich”

technique. On top of the flowable, a hybrid resin composite was stratified,

filling up the cavity. This group served as control, as the restoration

technique followed has provided quite satisfactory results in terms of quality

of the marginal seal.

All of the restorations were finished with a fine-grit diamond bur, polished

with abrasive disks, and stored in tap water for twenty-four hours.

Microleakage test After coating the roots and blocking the canal foramina with nail varnish, the

specimens were immersed in a dye solution (2% methylene blue) for twenty-

65

four hours, and subjected to 500 thermal cycling tests, each with a dwell time

of twenty seconds at 5 C° and 55 C°.

The specimens were then embedded in acrylic resin, and longitudinally

sectioned with a diamond saw (Isomet, Buehler, Lake Bluff, IL, USA) at three

different levels in the mesio-distal direction. The first cut was positioned in

the center of the restorations, whereas other two sections were made along

the lingual and buccal lateral walls, approximately at the interface between

the restoration and the cavity's wall (Fig. 2).

The extent of staining was measured at both the occlusal and cervical

margins. The depth of dye penetration at the occlusal level was scored as: 0

= no penetration; 1 = leakage no deeper than the enamel-dentin junction; 2 =

leakage deeper than the enamel-dentin junction; 3 = leakage along the

occlusal and/or axial lateral walls; 4 = leakage into dentinal tubules (Fig. 3).

The extent of cervical leakage was assessed according to the following score

method: 0 = no penetration; 1 = leakage not exceeding the middle of the

cervical wall; 2 = penetration past the middle of the cervical wall; 3 =

penetration to the axial wall; 4 = penetration to and along the axial wall or

into the dentinal tubules (Fig. 4).

The sections were observed under a stereomicroscope in double blind by

two different operators. In case of a disagreement between the two

investigators on the score assigned to a certain specimen, the worse score

was chosen for the statistical analysis.

Statistical analysis The differences in the microleakage data recorded for all of the groups at

either the occlusal or the cervical margin of the restorations were tested for

statistical significance using Kruskal-Wallis Non-Parametric ANOVA by

ranks, with Bonferroni alpha protection. In order to compare all of the scores

measured at the cervical margin with all the pooled data from the occlusal

margin, the Mann-Whitney-U test was performed. The level of statistical

significance was set at p=0.05.

66

Results In general, the scores recorded at the cervical margin were significantly

higher than those measured at the occlusal margin (p<0.05).

When all of the groups were compared for microleakage at the occlusal

margin, the only significant difference revealed by the statistical analysis was

that the specimens treated with Etch&Prime 3.0 and Definit (Group 2)

exhibited a marginal adaptation significantly worse than that seen in Groups

1, 3, 4, 6, 8, 10.

When the comparison was made among all groups for the scores at the

cervical margin, Group 5 restorations (Gluma/Solitaire) were revealed to

have leaked significantly more than Groups 1, 4, 8, 10 restorations. Also, the

difference between Group 9 (Syntac/Cavex Packable) and Group 1

(Scotchbond 1/Filtek P60) at the cervical margin was significant, with

Syntac/Cavex Packable giving a higher microleakage.

Discussion In order to be considered as a valid alternative to amalgam and indirect

restorations for Class II cavities, packable composites have to give proof not

only of adequate mechanical properties, but also of the ability to efficiently

seal the cavity margins.

In this investigation, the method of microleakage was chosen to assess the

quality of the marginal adaptation achieved by ten commercially available

packable composites. Measurements were taken at both the occlusal and

the cervical margins of the cavity, and not only in the middle of the

restoration, but also in the vicinity of the axial walls, along which gaps

between tooth substrate and material are more likely to develop (Rigsby DF

et al, 1990; Ferrari M et al, 1999).

67

The outcome of this trial, in agreement with the results of previous studies,

confirms that the cervical level remains the weakest point of the adhesive

restorations, as far as marginal integrity is concerned (Thonemann B et al,

1999; Tung FF et al, 2000). It has indeed been shown that when the margin

is placed below the cemento-enamel junction, an outer layer of cement 150-

200 microns thick is present, which provides a hypomineralized and

hyperorganic substrate to bonding (Cagidiaco MC et al, 1996). This tissue,

even after etching, does not provide the adequate conditions for the

micromechanical retention of an adhesive material. Although the

hybridization of the cementum has been demonstrated (Ferrari M et al,

1997), however the absence of resin tags in the first 150-200 microns from

the cervical margin testifies the relatively poor quality of the bonding that can

be achieved at this level.

Another factor that challenges the marginal integrity of an adhesive

restoration is the contraction stress of the composite resin. It is known that

the shrinkage of resin-based materials is inevitable, as related to the

chemistry of the polymerization reaction itself, that involves the conversion of

intermolecular distances in the order of 0.4 nm into covalent bonds 0.15 nm

long (Peutzfeld A, 1997). It has also been proved that some of the

contraction shrinkage can be absorbed through the material if its molecules

are free to flow at the exposed surfaces of the restoration (Feilzer AJ et al,

1990). When the material is in a more rigid state, most of the polymerization

shrinkage can not be absorbed, and is indeed transmitted to the adhesive

interface. Here the contraction stress can become responsible of the

opening of marginal gaps or of microfractures within the dental substrate

(Davidson CL & Feilzer AJ, 1997).

The polymerization stress transmitted by a resin-based material is directly

related to its modulus of elasticity (Feilzer AJ et al,1990; Davidson CL &

Feilzer AJ, 1997). It follows that packable composites, being relatively rigid

materials, can intensely stress the adhesive interface (Chen HY et al, 2001).

Under these conditions, if the bond is not strong enough, the marginal seal

68

can be violated, and microleakage can occur as a consequence. It has

earlier been proposed to incorporate an “elastic” layer at the restoration base

to act as a stress absorber not only of the functional loads, but also of the

internal tensions induced by composite polymerisation (Kemp-Scholte CM &

Davidson CL, 1990; Hilton TJ, 1998; Ferrari M, 1999; Hilton TJ & Ferracane

JL, 1999; Dietschi D et al, 2002). The insertion of an elastic liner is especially

advisable underneath packable composites restorations.

In a recent investigation (Dietschi D et al, 2002) it was found advantageous,

for the purposes of marginal adaptation, the application of a 1-1.5mm thick

layer of a compomer at the cervical margin of Class II cavities, then filled

with a hybrid composite. The compomer was applied following both the

“open-“ and the “closed-sandwich” technique, and a significant improvement

in the quality of marginal seal was obtained in particular when the layer of

low-modulus material was covered by the composite at the gingival margin

(closed-sandwich).

In this study, the “open-sandwich” technique was followed in the restoration

of the control group’s specimens (Group 10), where a layer of flowable

composite was applied at the cervical margin as a liner, on top of which a

hybrid composite was then stratified. In this Group relatively low

microleakage scores were recorded at the cervical margin, confirming that

the insertion of an elastic layer at this level definitely adds to the quality of

marginal adaptation.

As regards the results of the test at the occlusal level, it should be noted that

a significantly higher microleakage was reported in the only one group where

a self-etching primer was used to treat the substrate (Group 2). It can

therefore be inferred that the conditioning action of the self-etching primer

has failed to create the adequate conditions for the establishment of a

micromechanical bonding to enamel. To similar conclusions regarding the

efficacy of self-ecthing primers on the enamel substrate have led the results

of some previously published studies (Hara AT et al, 1999).

69

It should finally be pointed out that the same Group 2 specimens scored

relatively low for microleakage at the cervical margin, indicating that the

conditioning action of the self-ecthing primer was on dentin comparable to

that of the phosphoric acid used in the other experimental groups. Also this

finding is in line with the results of some previous trials, investigating the

performance of self-etching primers on dentin substrates (Pashley DH & Tay

FR, 2001).

In conclusion, in a Class II cavity restored with a packable composite:

1. Microleakage is significantly more noticeable at the cervical than at

the occlusal margin.

2. The application of a thin layer of a flowable composite at the cervical

margin, as a liner underneath the more rigid composite filling up the

cavity, enhances the marginal adaptation of the restoration.

3. The use of a self-etching primer to condition the dental substrate

results at the occlusal margin in a higher microleakage than if

phosphoric acid is applied as an etchant.

70

References



1996; 75 (Abstr 28) 1220.

Chen HY, Manhart J, Hickel R, Kunzelmann KH. Polymerization contraction

stress in light cured packable composite resins. Dent Mater 2001; 17: 253-

259.

Davidson CL, Feilzer AJ. Polymerization shrinkage and polymerization

shrinkage stress in polymer-based restorative. J Dent 1997; 25: 435-440.

Dietschi D, Bindi G, Krejci I, Davidson C. Marginal and internal adaptation of

stratified compomer-composite Class II restorations. Oper Dent 2002; 27:

500-509.

Duncalf WV, Wilson NA. A comparison of the marginal and internal


moderate-sized Class II preparations of conventional design. Quint Int 2000;

31: 347-352.



374.


Federation, Consensus statement on dental amalgam. FDI World 1995 : 9-

10.

Feilzer AJ, de Gee AJ, Davidson CL.Quantitative determination of stress

reduction by flow in composite restorations. Dent Mater 1990; 6: 167-171.


and V cavities to penetration by an adhesive system. Dental Mater 1997; 13:

152-162.


Influence of tissue characteristics at margins on leakage of Class II indirect


71

Ferrari M. “Advances in Glass-Ionomer Cements” in Davidson CL and Mjor

IA: Glass-Ionomer Cements. Quintessence Int, Berlin 1999: 137-148.

Hara AT, Amaral CM, Pimenta LA, Sinhoreti MA. Shear bond strength of

hydrophilic adhesive systems to enamel. Am J Dent 1999; 12: 181-184.


Class II composite restorations filled at intraoral temperatures. Am J Dent

1999; 12: 123-130.


cavities? In vitro investigation. Transaction of Academy of Dental Materials

Meeting, Banff, 1998; vol 12: 21-74.

Kanca J. Resin bonding to wet substrate. Quint Int 1992; 23: 39-41.

Kemp-Scholte CM, Davidson CL. Complete marginal seal of class V resin

composite restorations effected by increased flexibility. J Dent Res 1990; 69:

1240-1243.

Leinefelder KF, Bayne SC, Swift Jr EJ. Packable composites: overview and

technical considerations. J Esthet Dent 1999; 11: 234-249.

Leinefelder KF. New developments in resins restorative systems. J Am Dent

Assoc 1997; 58: 484-487.

Leinefelder KF. Posterior composite resins: the materials and their clinical

performance. J Am Dent Assoc 1995; 126: 663-676.

Manhart J, Kunzelmann KH, Chen HY, Hickel R. Mechanical properties and

wear behaviour of light-cured packable composite resins. Dent Mater 2000;

16: 33-40.

Pashley DH, Tay FR. Aggressiveness of contemporary self-etching

adhesives. Part I: Depth of penetration beyond dentin smear layers. Dent

Mater 2001; 17: 296-308.

Peutzfeld A. Resin composites in dentistry : the monomer systems. Eur J

Oral Sci 1997; 105: 97-116.

Rigsby DF, Retief DH, Russel CM, Denys FR. Marginal leakage and

marginal gap dimension of three dentinal bonding system. Am J Dent 1990;

3: 289-294.

72

Sano H, Ciucchi B. Nanoleakage: leakage within the hybrid layer. Oper Dent

1995; 20: 18-25.

Tay FR, Gwynnet AJ, Wei SH. Micromorphological spectrum from overdrying

to overwetting acid-conditioned dentin in water-free, acetone-based, single-


Thonemann B, Federlin M, Shmalz G, Grundler W. Total bonding vs

selective bonding: marginal adaptation of Class II composite restorations.

Oper Dent 1999; 24: 261-271.

Tjan AH, Bergh BH, Linder C. Effect of various incremental techniques on


66.


composite: an in vitro investigation. Quintessence Int 2000; 31: 430-434.

73

Table I Bonding procedures

Bonding system Clinical procedures

Conditioning

with

phosphoric

acid

Primer-

adhesive

application

Self-etching

primer

application

Bonding

application

Air

blowing

Light

curing

Scotchbond1 x x x x

Etch&Prime3.0 x x x

Prime&Bond2.1 x x x x

Excite x x x x

Gluma x x x x x

Kerr Bonding x x x x x

One Step x x x x

Tenure x x x x x

Syntac x x x x

Excite x x x x

74

Table 2. Microleakage scores recorded at the occlusal margin.

Frequency of scores Groups

0 1 2 3 4

Group 1 7 3 0 0 0

Group 2 0 0 1 1 8

Group 3 6 2 1 1 0

Group 4 9 1 0 0 0

Group 5 4 0 1 4 1

Group 6 7 1 1 1 0

Group 7 4 2 1 2 1

Group 8 5 2 1 1 1

Group 9 1 3 4 2 0

Group 10 9 0 0 1 0

75

Table 3. Microleakage scores recorded at the cervical margin.

Frequency of scores Groups

0 1 2 3 4

Group 1 7 2 1 0 0

Group 2 7 1 0 0 2

Group 3 1 2 2 5 0

Group 4 3 3 3 1 0

Group 5 0 0 0 2 8

Group 6 3 1 1 3 2

Group 7 3 2 1 2 2

Group 8 3 2 3 1 1

Group 9 1 0 0 8 1

Group 10 6 1 1 1 1

76


Fig. 1. The standardized Class II cavity prepared for the resin composite restoration.

Fig. 2. Each sample was longitudinally sectioned at three different levels in the mesio-

distal direction.

77

Fig. 3. Scores of dye penetration at the occlusal margin.

Fig. 4. Scores of dye penetration at the cervical margin

.

78

Chapter 5

Marginal integrity of ceramic inlays luted with a self-curing resin system. Abstract: Purpose: Aim of this study was to observe the efficacy of two

different composite cements on the prevention of marginal deterioration

around adhesive ceramic inlay restorations, under laboratory conditions, and

to test the null hypothesis that different luting procedures cannot affect

sealing ability of luted inlays. Methods. Twenty-six standardized mesio-

occlusal Class II cavities were prepared in extracted posterior teeth. Class II

inlays were fabricated with IPS Empress II system following the

manufacturer's instructions. The samples were divided into two groups of 13

teeth each at random. Group 1: The ceramic inlays of Group 1 were luted

using Excite DSC and an experimental self-curing resin cement (Multilink,

Vivadent); in this group, Excite DSC was self-activated and not light-cured.

Group 2: Excite DSC in combination with a dual-curing resin cement

(Variolink II, Vivadent) was used (as control). In this group Excite DSC was

light-cured for 20 s separately, before resin cement application. The ‘wet’

bonding technique was followed. Three samples of each group were

selected at random for SEM observations, while the other 10 samples were

processed for marginal leakage. The bonding mechanism to dentin and resin

cement thickness was evaluated. Results: Samples of both groups showed

resin tag and adhesive lateral branch formation. In Group 1 the hybrid layer

was mainly uniform along the interface between dental substrates and

adhesive material, and resin cement thickness was between 20 and 85 µm.

At the cervical margin no gap was detected. In Group 2 the cement

thickness was between 30 and 110 µm and hybrid layer formation was

observed along the interface but at the cervical margin it was not always

uniform and continuous. Resin tag formation was uniform in both groups. At

79

cervical margins, 80% of Group 1 samples showed a perfect seal at the

dentin–cementum margins, and 90% at enamel margins. Group 2 samples

showed only 50% of cervical margins free from leakage and 80% at the

occlusal enamel margins. Statistically significant differences were found at

cervical margins between the two groups, while no significant differences

were found at enamel site. Conclusions: It can be concluded that the self-

curing adhesive-resin cement combination can properly seal Class II

porcelain inlays.

80

Introduction

During recent years, increasing demand for aesthetics in dentistry resulted in

the development of restorative materials. Composite materials are

acceptable for restoring anterior teeth but it is possible to have problems

with their usage in stress bearing areas of the mouth (Vanherle G et al,

1985). The use of ceramic materials for aesthetic dental restorations has

increased substantially. This trend is attributed mainly to improvements in

the properties of ceramics and porcelain bonding systems.

A number of ceramic inlays techniques have been developed, e.g. castable

and pressed glass ceramic inlays which have excellent aesthetic properties.

They have satisfactory physic-mechanical properties and abrasion

resistance(Binns D, 1983). They are also resistant to wear (Krejci I et al,

1993), their plaque retention behaviour is lower than enamel (Savitt ED et al,

1987), they are biocompatible with the periodontal tissues and pulp (Cavel

WT et al, 1988), and transfer less heat (Adair PJ & Grossman DG , 1984;

Grossman DG , 1985) compared to metallic restorations.

However, a number of unsolved problems are associated with the fit of

ceramic inlays: the marginal adaptation and the resistance to fracture of

ceramic inlays seem to be probably the most important features that could

influence the durability of these restorations (Cavel WT et al, 1988;

Malament KA & Grossman DG, 1987; Bessing C & M. Molin, 1990; Van

Meerbeek BV et al, 1992; Krejci I et al, 1993; Thordrup M et al, 1994).

Different investigations have shown that inlays cemented with adhesive

materials exhibited superior fracture resistance compared to those cemented

with conventional cements (Dietschi D et al, 1990; Jensen ME et al, 1987).

Thus, the thickness of the layer of the luting cement may influence the risk of

disintegration of it, as well as microleakage along the inlay margins

(Leinfelder KF et al, 1989; Reich E et al, 1990).

The aim of this study was to observe the efficacy of two adhesive/resin

composite combinations on the prevention of marginal deterioration around

81

adhesive ceramic inlay restorations, under laboratory conditions, and to test

the null hypothesis that different luting procedures cannot affect the sealing

ability of luted inlays.

Method and materials

Preparation design Twenty-six recently extracted posterior molars, all free from previous

restoration and decay, were selected for this study. Mesio-occlusal Class II

cavities, designed according to manufacturer's instructions for making

porcelain inlays, were prepared under a copious water spray with medium-

grit diamond point burs, mounted in a high-speed handpiece. The proximal

boxes were extended 1 mm below the cementum–enamel junction (CEJ), to

place cervical margins in cementum–dentin (Fig. 1). An occlusal reduction of

2 mm was made, the bucco-lingual width of the proximal boxes was 4 mm,

the occlusal width 3 mm and the depth of the pulpal and axial walls 2 mm. A

tolerance of 0.3 mm was used to include preparations in the test. A butt-joint

margin preparation was made at the cervical margins of all samples. No

bevels were utilized in the preparation.

Restoration placement An impression for each tooth was made using polyether impression material

(Permadyne, Espe, Seefeld, Germany). Impressions were cast in type IV

stone (Fuji Rock, GC Dental, Tokyo, Japan). The inlays were fabricated with

IPS Empress II system (Ivoclar, Schaan, Liechtenstein) following

manufacturer's instructions. Before the luting procedure, Empress II inlays

were inspected under optical microscope at ×24 (Nikon 102, Tokyo, Japan):

when a marginal discrepancy higher than 25 µm was registered, the ceramic

inlays were remade; three inlays were remade.

The samples were randomly divided into two groups of 13 teeth each.

Adhesive-luting procedures are listed in Table 1.

82

Group 1. The ceramic inlays of Group 1 were luted to the corresponding

abutments using an experimental bonding system (Excite DSC, Vivadent,

Schaan Liechtenstein) and an experimental self-curing resin cement

(Multilink, Vivadent). In this group, Excite DSC was self-activated and not

light-cured.

Group 2. Excite DSC in combination with a dual-curing resin cement

(Variolink II, Vivadent) was used (as control). In this group Excite DSC was

light-cured for 20 s separately, before resin cement application.

Luting procedures The enamel margins of the teeth were acid-etched with 37% phosphoric acid

gel for 15 s. Then, the dentin and enamel were simultaneously etched for

another 15 s. The cavities were then thoroughly rinsed with water for 20 s

and gently air-dried for 1–2 s to remove the excess of water but leave the

cavity surfaces ‘wet’ (Kanca J, 1996). Then, the cementing procedures were

completed following manufacturers' instructions. The samples were

submitted to 500 thermal cycles (5 and 55°) and then stored for 24–48 h in

saline solution at room temperature before being processed for leakage.

Microscopic evaluation Three samples of each group were selected at random and split-fractured

along the long axis of the teeth, through the center of the restoration (Leitz

1600, Munchen, Germany). Then, one section of each tooth was gently

decalcified with 36% phosphoric acid for 10 s and deproteinized with 2%

sodium hypochlorite for 60 s at the interface site between the resin and

dentin layer. The other sections of each sample were kept in 30%

hydrochloric acid solution for 2 days in order to completely dissolve the

dental structures and to expose the resin replica of the interface (Cagidiaco

MC, 1995). Finally, all the sections and the resin replicas were mounted on

aluminum stubs, sputter-coated with gold using an Edwards Coater S150B

device, and observed under a Philips 515 scanning electron microscope.

83

Two different operators evaluated the samples in double blind. For each

sample of the two groups, observations and microphotographs of hybrid

layer, resin tags and adhesive lateral branches were detected to show the

most significant features. Also resin cement thickness was evaluated at

three different sites (at the cervical margin, along the axial wall and

occlusally); the media of each sample was recorded and evaluated

statistically.

Microleakage evaluation The other 10 samples of both groups, after being kept in 2% methylene blue

solution for 1 day, were embedded in resin (Technovit 2 100, Kuler,

Werheim, Germany). Each specimen was longitudinally sectioned into three

facio-lingual sections (Fig. 2) using a slow-speed diamond saw (Leitz 1600).

Dye penetration was evaluated according to the following parameters: 0, no

leakage; 1, microleakage at shoulder area; 2, microleakage at half of axial

wall(s); 3, microleakage at all of axial wall(s); 4, microleakage at occlusal

area. Two different operators scored the dye penetration in double blind,

using a binocular microscope (Nikon) at ×20. The worst score for the

sections of each tooth was used for scoring and further statistical analysis. In

case of discrepancy between the two evaluators, the worst score was

recorded. The leakage scores were evaluated statistically using the Kruskal–

Wallis multiple comparison test.

Results

Microscopic observations Samples of both groups in which dental substrates were completely

dissolved (Fig. 3) showed resin tag and adhesive lateral branch formation. At

the cervical margins short resin tags were noted (Fig. 4) while the occlusal

wall showed a high density of long resin tags (Fig. 5). Along the axial walls,

short resin tags were noted (Fig. 6). The morphology and density of resin

84

tags was directly related to tubule direction and density. In both groups, the

formation of resin tags, adhesive lateral branches and a hybrid layer were

evidenced. Also at the interface between enamel substrate and adhesive

resin, no gap was observed (Fig. 7). Resin cement thickness data are

reported in Table 2.

In Group 1 the hybrid layer was mainly uniform along the interface between

dental substrates and adhesive material (Fig. 8). The resin cement showed

very small voids/bubbles and its medium thickness was 62 µm, while

readings were between 20 and 85 µm. At the cervical margin, which was

placed below the CEJ, in cementum–dentin, the adhesion between adhesive

material and dental substrate was uniform and continuous (Fig. 8). No gap

was detected.

In Group 2 the medium cement thickness was 82 µm (readings between 30

and 110 µm). The hybrid layer formation was observed along the interface

(Fig. 9 and Fig. 10) but at the cervical margin, it was not always uniform and

continuous. No statistically significant difference was found between the

cement thickness of the two luting materials (Table 2).

Microleakage scores The results of this part of the study are summarized in Table 3.

Group 1: at cervical margins, 80% of specimens showed a perfect seal,

while 20% of them scored 1 as leakage. 90% of samples showed no dye

penetration at enamel–resin–porcelain interface and 10% of them had

scored 1.

Group 2: only 50% of samples were free from leakage at cervical margins.

Eight percent of specimens showed a perfect seal at the occlusal enamel

margins.

When the leakage scores of Groups 1 and 2 were evaluated, statistically

significant differences were found at cervical margins, while no significant

differences were found at the enamel (occlusal/axial) site.

85

Discussion

As it has been pointed out by several authors, marginal leakage is one of the

major drawbacks of a tooth-colored inlay (Torstensen B and Brännström M,

!988; Hofmann N et al, 1990).

Marginal fit of cemented restorations may be estimated by invasive or non-

invasive techniques. A non-invasive method leaving the tooth intact, may be

a quantitative SEM analysis, describing the whole margin of the area from

replicas and microphotographs (Remer R et al, 1989; Roulet JF et al, 1989)

or a microscopic assessment of the width of the luting cement at selected

points along the inlay margin (Hung SH et al, 1990; Thierfelder C et al,

1991; Dietschi D et al, 1992; Hass M et al, 1992; Inokoshi S et al, 1992).

The quantitative SEM analysis provides information of the surface area, but

not of the overall fit of the inlay.

The invasive methods are based on sections. The multiple sectioning

technique used in this study offers an advantage over the more simple

procedure of one-sectioned samples. According to Hung et al. (Hung SH et

al, 1990), the multiple-section technique can be more precise than the non-

invasive method, also from a statistical point of view. A possible explanation

might be that the absolute marginal discrepancy appears more well defined

on a section compared to an intact surface, and thus easier to determine.

The present investigation confirms these hypotheses.

It might also be possible to correlate the presence of a gap in several

samples of Group 2 and the absence of the gap at the interface between

conditioned dentin and adhesive material in Group 1 sample with the

leakage results: where a gap was present, dye penetration was deeper and

the score higher.

The clinical success of a tooth-colored inlay is correlated to the resin luting

cement properties. According to Leinfelder et al. (Leinfelder BP et al, 1989),

the maximum width of exposed luting cement should not exceed 100 ųm

86

occlusally due to the risk of abrasion. Disintegration caused by chemical

attack may present another problem for exposed resin luting cement (Larsen

IB & Munksgaard EC, 1991). Moreover, if the cement layer is too thick,

complete seating of inlay cannot be accomplished and the aesthetic

restoration will probably fail. In the present study, the average values of

occlusal thickness of the luting cements were below 100 ųm and the

experimental self-curing resin cement showed the lowest values.

In this study, microscopic evaluation of resin tag and adhesive lateral branch

formation was performed. In fact, the acid etching of dentin permits hybrid

layer, resin tags and adhesive lateral branch formation, thus creating a site

for micro mechanical retention of the resin into the demineralised substrate

(Nakabayashi N et al, 1991; Titley K et al, 1994; Perdigão J, 1995; Kanca J,

1996; Van Meerbek B et al, 1998) . Also, resin tags formed at the first part

of the tubule orifices can seal the tubules, avoiding any fluid movement and,

consequently, post-operative sensitivity(Nakabayashi N et al, 1991; Titley K

et al, 1994; Perdigão J, 1995; Kanca J, 1996; Van Meerbek B et al, 1998).

The efficacy of Excite DSC on forming resin tags, adhesive lateral branches

and a hybrid layer was already evaluated under laboratory and clinical

conditions (Dagostin A & Ferrari M, 2001; Ferrari M et al, 2001; Dagostin A &

Ferrari M, 2002). The uniformity of the bonding mechanism (hybrid layer,

resin tag and adhesive lateral branch formation) obtained using Excite DSC

might be correlated with the presence of the self-activating particles

(Dagostin A & Ferrari M, 2001; Ferrari M et al, 2001; Dagostin A & Ferrari M,

2002). In fact, the small particles of catalyst placed into the bristles of a very

thin microbrush included in the system, can carry the primer-adhesive

solution into the deepest area of the preparation and simultaneously also

self-activate it in the area that cannot be perfectly reached by the light

(Dagostin A & Ferrari M, 2001; Ferrari M et al, 2001; Dagostin A & Ferrari M,

2002).The difficulty of the light curing source to reach deep proximal areas

has also created the potential for marginal percolation and bacterial

penetration at the partially cured resin–dentin interface. This often leads to

87

marginal discoloration, secondary decay, and postoperative sensitivity (Eick

JD and Welch FH, 1986; Stangel I et al, 1987). The use of a self-curing

adhesive system in combination with self-curing resin cement like the

experimental one seems also to minimize these risks at cervical margins.

The results of this study rejected the null hypothesis that was tested.

Different luting material combinations and procedures can affect the sealing

ability of luted inlays.

88

References

Adair PJ, Grossman DG. The castable ceramic crown. Int J Period Rest

Dent 1984; 4: 32–38.

Bessing C, Molin M. An in vivo study of glass ceramic (Dicor) inlays. Acta

Odont Scand 1990; 48: 351–356.

Binns D. The chemical and physical properties of porcelain. In: J.W.

McLean, Editor, Dental Ceramics: Proceeding of the First International

Symposium on Ceramics, Quintessence, Chicago 1983:,41–83.

Cagidiaco MC. Bonding to dentin: mechanism, morphology and efficacy of

bonding resin composites to dentin in vitro and in vivo, De Batte ed., PhD

Thesis. Amsterdam, University of Amsterdam; 1995.

Cavel WT, Kelsey WP, Barkmeier WW , Blankenau RJ. A pilot study of the

clinical evaluation of castable ceramic inlays and a dual cure resin cement.

Quintessence Int 1988; 19: 247–252.

Dagostin A, Ferrari M. In vivo bonding mechanism of an experimental

bonding system. Am J Dent 2001; 14: 103–108.

Dagostin A, M Ferrari, Effect of dual bonding technique on the bond strength

of ceramic restorations. Dent Mater 2002; 18: 304–310.

Dietschi D, Maeder M, Meyer J-M. In vitro resistance to fracture of porcelain

bonded to tooth. Quintessence Int 1990; 21: 823–831.

Dietschi D, Maeder M, Holz J. In vitro evaluation of marginal fit and

morphology of fired ceramic inlays. Quintessence Int 1992; 23: 271–278.

Eick JD, Welch FH. Polymerization shrinkage of posterior composite resins

and its possible influence on postoperative sensitivity. Quintessence Int

1986 ; 17: 103–111.

Ferrari M, Vichi A, Grandini S, Goracci C. Efficacy of a self-curing

adhesive/resin cement system on luting Vectris fiber posts into root canals: a

SEM investigation. Int J Prosthodont 2001; 14: 543–549.

Grossman DG. Cast glass ceramics. Dent Clin North Am 1985; 29: 275.

89

Hass M, Arnetzl G, Wegscheider WA, König K, Bratschko RO. Klinische und

Werkstoffkundliche Erfahrungen mit Komposit, Keramik und Gold inlays.

Dtsch Zahnärzt Z 1992; 47: 18–22.

Hofmann N, Klaiber B, Heners M. Okklusale Randschlussqualität von Cerec-

Inlays nach mehrmonatiger Tragedauer. Dtsch Zahnärztl Z 1990; 45: 289–

292.

Hung SH, Hung KS, Eick JD, Chappel RP. Marginal fit of porcelain-fused-to-

metal and two types of ceramic crown. J Prosthet Dent 1990; 63: 26–31.

Inokoshi S., Van Meerbeck B, Willems G, Lambrechts P, Braem M,

VanherleG. Marginal accuracy of CAD/CAM inlays made with the original

and the updated software. J Dent 1992; 20: 171–177.

Jensen ME, Redford AD, Wilson BT. Posterior etched porcelain restorations.

an in vitro study. Compen Contin Edu Dent 1987; 8: 615–621.

Kanca J. Wet bonding: effect of drying time and distance. Am J Dent 1996;

9: 273-276

Krejci I, Lutz F, Reimer M. Marginal adaptation and fit of adhesive ceramic

inlays. J Dent 1993; 21: 39–45.

Krejci I, Lutz F, Reimer M, Heinzmann JL. Wear of ceramic inlays, their

enamel antagonists, and luting cements. J Prosthet Dent 1993; 69: 225–229.

Larsen IB,. Munksgaard EC. Effect of human saliva on surface degradation

of composite resins. Scand J Dent Res 1991; 99: 254–261.

Leinfelder KF, Isenberg BP, Essig ME. A new method for generating ceramic

restorations: a Cad–Cam system. J Am Dent Assoc 1989; 118: 703–708.

Malament KA, Grossman DG. The cast glass-ceramic restoration. J Prosthet

Dent 1987; 57: 674–681.

Nakabayashi N, Nakamura M, Yasuda N. Hybrid layer as dentin bonding

mechanism. J Esthet Dent 1991; 3: 133-138.

Perdigão J. An ultra-morphological study of human dentine exposed to

adhesive systems. Thesis. Leuven, Belgium: Catholic University of Leuven;

1995.

90

Reich E, Schmalz G, Federlin M. Randspaltverhalten von Keramik- und

Konpositinlays in vitri. Dstch Zahnärztl Z 1990; 45: 656–660.

Roulet J.F., Reich T, Blunck T, Noack M. Quantitative margin analysis in the

scanning electron microscope. Scan Elect Microsc 1989; 3: 147–159.

Savitt ED, Malement KA, Socransky SS, Melcer AJ, Backmann KJ. Effect of

colonization of oral microbiota by a cast Glass ceramic restoration. Int J

Period Rest Dent 1987; 7: 23–30.

Stangel I, Nathanson D, Hsu CS. Shear strength of the composite bond to

etched porcelain. J Dent Res 1987; 66: 1460–1465.

Thierfelder C, Fuhrmann I, Knappe M. Vergleichende Untersuchung zur

Passgenauigkeit des Kompositinlays Estilux posterior CVS. Die Quintessenz

1991; 9: 1399–1407.

Thordrup M, Isidor F, Hörsted-Bindslev P. Comparison of marginal fit and

microleakage of ceramic and composite inlays: an in vivo study. J Dent

1994; 22: 147–154.

Titley K, Chernecky R, Maric B. Penetration of a dentin bonding agent into

dentin. Am J Dent 1994; 7: 190–194.

Torstensen B, Brännström M. Composite resin contraction gaps measured

with a fluorescent resin technique. Dent Mater 1988; 4 : 238–245.

Van Meerbeek BV, Inokoshi S, Willems G. Marginal adaptation of four tooth-

coloured inlay systems in vivo. J Dent 1992; 20: 18–29.

Van Meerbek B., Y. Yoshida and P. Lambrechts, A TEM study of two water-

based adhesive systems bonded to dry and wet dentin. J Dent Res 1998;

77: 50–59.

Vanherle G, Lambrechts P, Braem M. Overview of the clinical requirements

for posterior composites. In: G. Vanherle and D.C. Smith, Editors, Posterior

composite resin dental restorative materials, 3M Co, St Paul, MN 1985: 21–

40.

91

Table 1. Clinical adhesive–luting and bonding–luting procedures (a, dentin conditioning with

phosphoric acid; b, primer-adhesive application with a small brush; c, primer-adhesive

application with a self-activating microbrush; d, light-curing; e, mixing resin cement; f, cement

application into the cavity; g, removing resin excess with a small brush; h, light-curing the resin

cement; EX/DSC, excite dual self-activating system (Vivadent, Schaan, Liechtenstein); EX,

Excite light-curing system (Vivadent, Schaan, Liechtenstein).

Group Bonding system Clinical steps Resin cements Clinical steps 1 EX/DSC a, b, d Multilink resin

cement e, f, g, h

2 EX a, c Variolink II e, f, g

Table 2. Resin cement thickness

Cement thickness (standard deviation) µm

Group 1 65 (35)

Group 2 82 (28)

Table 3: leakage scores

Score 0 1 2 3 4

Group 1 cervical 8 2 0 0 0

Group1 occlusal 9 1 0 0 0

Group 2 cervical 5 2 2 1 0

Group 2 occlusal 8 1 1 0 0

92


Fig. 1. Picture of standardized Class II cavity preparation

Fig. 2. Picture of sectioning procedure for evaluating dye penetration.

93

Fig. 3. Picture of a sample prepared for SEM observation after completely dissolving dental

substrates in an acid solution (SEM ×19) (1: cervical area; 2: occlusal area; 3: axial area).

Fig. 4. Picture at the cervical margin (area 1 of Fig. 3), placed 1 mm below the

cementum–enamel junction. Short resin tags and adhesive lateral branches are

visible (SEM ×710).

94

Fig. 5. Picture at the occlusal area (area 2 of Fig. 3). Long resin tags are noted (SEM

×710).

Fig. 6. Picture at the axial wall (area 3 of Fig. 3). Short resin tags are visible (SEM

×710).

95

Fig. 7. Picture at the enamel margin. Resin tags are formed (T: resin tags) (SEM

×1250).

Fig. 8. Picture at the interface between conditioned dentin and adhesive materials of

Group 1 sample. Hybrid layer formation is evident and no gaps are detected between

the different substrates (R: resin cement; D: dentin; H: hybrid layer) (SEM ×406).

96

Fig. 9. Picture of Group 2 sample. At the cervical margin this sample does not show

any gap interface between conditioned dentin and adhesive material (SEM ×1310) (H:

hybrid layer; D: dentin; R: resin cement).

Fig. 10. Picture of Group 2 sample. In this sample, at the cervical margin a gap (G)

was detectable at the interface between conditioned dentin and adhesive system

(SEM ×1250).

97

Chapter 6

Influence of tissue characteristics at margins on leakage of Class II indirect porcelain restorations.

Abstract: Purpose: to evaluate the sealing ability in class II porcelain inlays

with margins placed in cementum-dentin and enamel, luted by two new

different cementing materials. Materials and Methods: Thirty extracted

molars, free from caries and restorations were selected. The sample cavities

were prepared in a standardized manner and then were divided in three

groups (n=10) at random. Group 1: the cervical marginwas located 1 mm

below the CEJ and the inlays were luted EBS Multi (Espe) bonding system

in combination with Compolute 1.0 Aplicap (CLA 1.0 Espe) experimental

resin cement. Group 2: The cervical margin was placed 1 mm below the CEJ

and Syntac bonding system (Vivadent) and Variolink II resin cement

(Vivadent) were used. Group 3: The cervical margin was placed 0.5 mm

above the CEJ and the same matherials selected for Group 1 were used.

IPS-Empress (Ivoclar) inlays were made following manufacturer’s

instructions. After luting procedures and 2500 thermal cycles (5° and 55° C),

the samples were processed and evaluated for marginal leakage at cervical

and occlusal site. Samples of Group 3 were first selectioned in the center of

restorations as in Group 1 and 2 and scored (Group 3A) and then two other

cuts were made along the buccal and lingual areas (group 3B) and also

scored. After scoring dye penetration of Group 1 and 2 samples, half of the

sections were randomly selected to evaluate: (1) resin cement thickness, (2)

Hybrid layer formation at the interface between adhesive material and dental

substrate and (3) to observe the morphology of the class II cavity margins.

The leakage data were statistically evaluated with the Mann-Whitney U test

(P < 0.5). Results: statistically significant differences were found between

Groups 3A and 3B at the occlusal site, and not the cervical site. Samples of

98

Group 1 showed a cement thickness of 92 µm, 68 µm in Group 2. Hybrid

layer and resin tag formation was evident in Group 1. In Group 2 samples,

the hybrid layer formation was less evident and thinner than Group 1. At

cervical margins, an outer layer, not identifiable as sound dentin, of 200-300

µm thick, was noted. This layer was present in all three groups between

outer margin and sound dentin. The margins located both cervically and

axially in enamel mainly showed prisms cut along their long axis and low

level of structured etch pattern.

Conclusions : The results of this study suggest that an enamel thickness of

0.5 mm at the cervical margin of Class II indirect restorations in unable to

seal them completely. The two combinations of bonding-cement materials

performed similarly. The enamel axial margins of Class II inlays must be

considered one of the weakest margin of the cervical area.

99

Introduction

Knowledge on the aetiology of caries (Thylstrup A et al, 1986) and

observation of caries location lead to the conclusion that every plaque

retention site is a possible secondary caries zone (Anusavice KJ, 1989).

Defective wall-to-wall continuity between material and cavity walls facilitates

bacterial or toxin invasion, marginal staining, secondary caries and adverse

pulpal reactions (Branstrom M, 1982; Branstrom M, 1988). Therefore

marginal integrity of restorations in an important factor on preventing

leakage.

Unless the new developments on bonding to dentin (Nakabayashi N et al,

1991; Kanca J, 1992; Gwinnet AJ & Kanca J, 1992) improve marginal seal

and clinical performance of aesthetic restorations (Van Merbeeck B et al,

1994; Tyas MJ, 1996), poor adaptation and micro-leakage will still produce

problems at the gingival margins of Class II restoration (Donly KJ & Jensen

ME, 1990; Hilton TJ et al, 1997). Robinson et al (1987) and Dietschi et al

(1995) noted that marginal adaptation of indirect restorations was better than

that of direct restorations in Class II cavities. Dietschi et al (1995) also

pointed out that when residual enamel was less than 1mm in height or 0.5 in

thickness, indirect restorations had superior marginal quality. Less leakage

was found with indirect Class II restorations (inlays) compared to direct

aesthetic restorations. This is probably because aesthetic inlays reduce

polymerisation shrinkage, except for the small amount associated with a

layer of composite resin luting cement (Feilzer AJ et al, 1989), and

minimizes the variables of clinical procedures. The presence of leakage at

margins of Class II restorations was correlated with the type of dental

substrate at margins, etching procedures and type of bonding system used

(Cagidiaco MC, 1995; Ferrari M & Davidson CL, 1996). Hilton et al (1997)

pointed out an extensive leakage along the facial and lingual enamel walls of

Class II resin composite restorations. A variety of polymer-based resin

cement are now available. The ideal resin cement must be dual cured and

100

should demonstrate a film thickness of no more than 50 µm (Picard B et al,

1997). If the cement is too thick complete seating will not be accomplished

and the aesthetic crown will probably fail. The cement thickness is also

related to resin viscosity, its handling characteristics, clinical procedures and

experience of practitioners.

Recently two new combinations of bonding and resin cements were

proposed (Syntaca and Variolink II, a EBS Multib and CLA 1.0b) to increase

predictable clinical results. This study evaluated the marginal adaptation and

leakage of porcelain inlays luted with two different bonding resin cement

systems under laboratory conditions and correlated the dye penetration

depth with the morphology of dental substrates present at margins of the

preparations.


Thirty recently extracted posterior molars, all free from caries, cracks and

previous restorations on visual inspection, were selected for this study. The

average age of patients was 61 (range: 49-72). Tissue remnants on the

roots were removed by hand scaling. The teeth were stored in a saline

solution at room temperature (±22°C) for no longer than 4 weeks prior to

further preparation.

Preparations design

The selected molars were randomly ivied in three groups of 10 samples

each. Mesio-occlusal Class II cavities were prepared under a copious water

spray with medium-grit diamond-point burs, mounted in a high speed

handpiece. Twenty cavities for inlays were prepared with the proximal boxes

extending 1 mm below the cementum-enamel junction to place cervical

margins in cementum-dentin (groups 1 and 2). The last 10 samples were

prepared with the proximal boxes extending 0.5 mm above the CEJ to place

their margins in enamel (Group 3). Table 1 summarizes the three

101

experimental groups, variables, location of margins and materials of the

study.

The abutments were prepared according to manufacturer’s for making

single-unit all-porcelain inlay (Fig.1) with an occlusal reduction of 2 mm. The

bucco-lingual width of the proximal boxes was 4 mm, the occlusal width 3

mm and the depth of the pulpal and axial walls 2 mm. A tolerance of 0.3 mm

was used to include preparation in the test. A button-joint margin preparation

was made at the cervical margin of all samples. No bevels were utilized in

preparation. The dimensions of the cavity after preparation was confirmed

with a Boley gauge.

Although the mesio-distal and bucco-lingual dimensions of the preparations

were closely controlled, the length of the preparation was dependent on the

anatomy of the individual tooth. After all the preparations were completed

and dimensions recorded, the occlusal-gengival length of preparation varied

from 4.5 to 6.5 mm. The teeth were divided in two groups: short in which the

average length was 5.0 mm (range 5.6-6.5); and long in which the average

length was 6.1 mm (range 5.6-6.5). In addition, each experimental group had

an equal randomized number of teeth from the short and long occlusal-

gingival preparation categories.

Restoration placement Polyether impression (Permadyneb) of prepared teeth was madefor each

abutment, poured in type IV stone. The porcelain inlays (IPS-Empressc)

were fabricated strictly following manufacturer’s instructions. All porcelain

inlays were checked on the corresponding dies under optical microscope at

x20 (Nikon 102d). The inlays were made were made when a marginal

discrepancy greater than x20 µm was detected.

After making the inlays, sample teeth with cervical margins located below

the CEJ were randomly assigned to Groups1 and2 respectively (Table 1).

102

Group 1: EBS Multib enamel dentin bonding system and CLA 1.0

(Compolute 1.0 Aplicapb) experimental resin cement were used to lute the

porcelain inlays into the cavities.

Group 2: Syntaca enamel dentin bonding system in combination with

Variolink IIa resin cement was used.

Group 3: In the group of samples in which the cervical margins were located

above the CEJ (in the enamel), the same materials selected in Group 1 were

used.

The enamel margins of the teeth were acid-etched with 37% phosphoric acid

gel for 15 seconds. Then, the dentin and enamel were simultaneously

etched for another 15 seconds. The cavity was than thoroughly rinsed with

water for 20 seconds and gently air dried for 1-2 seconds to remove the

water but leave the cavity surface “wet”. Then, the cementing procedures

were completed following manufacturers’ instructions.

The inlay was seated and a small brush was used to remove the cement

excess from the margins. The complete removal of resin cement around the

margins was checked at x3 with loupes. To avoid oxygen inhibition of the

superficial layer of resin cement, a glycerine gel was applied along the

margins with a syringe. The composite resin luting material, protected by a

glycerine gel was finally light cured for 40 seconds from the lingual, gingival,

buccal and occlusal directions (total of 160 seconds). Table 2 summarizes

the two cementing procedures.

The samples werestored for 24-48 hours in saline solution at room

temperature (±22°C) before they were subjected to 2500 complete thermal

cycles in of 1-minute water baths alternatively at 5°C and 55°C.

Microleakage evaluation To visualize possible leakage, all samples were dried and apices of the roots

sealed with sticky wax. The surfaces of the tooth were coated with two

layers of fingernail polish, so that only the restorations and a surrounding

band of tooth structure approximately 1 mm wide were exposed. The

103

samples were immersed in 2 % methylene blue solution at room

temperature for 24 hours, washed, dried with compressed air and embedded

in slow-curing epoxyresin, prior to sectioning with a low speed diamond

blade saw through the center of the restorations in a mesial distal direction

(Groups 1-3). The samples of Group 3 were first sectioned in the center of

the restoration as those of Groups 1 and 2 (Group 3a). Then, two other cuts

were made in a medial distal direction along the buccal and lingual areas

between enamel and porcelain restoration to evaluate possible leakage

coming from these interfaces (Group 3b) (Fig. 2).

Dye penetration was observed with a binocular microscope (Nikond) at x 20.

Two different operators evaluated double-blind the sectioned samples for

leakage score. The amount of leakage viewed with the microscope was

scored. The worst score for the sections of each tooth area was used for

scoring and further statistical analysis. In case of discrepancy between the

two examiners, the worst score was used for evaluation.

The dept of cervical staining was measured according to the following

parameters (Fig. 3): 0= no penetration; 1= leakage not exceeding the middle

of the gingival wall; 2= penetration past the middle of gingival wall; 3=

penetration to the axial wall; 4= penetration to and along the axial cervical

wall or into dentin tubules.

The extent of the occlusal leakage was registered as the depth of dye

penetration according to the following scores (Fig. 4): 0= no penetration; 1=

leakage no deeper than the enamel-dentin junction; 2= leakage deeper than

the enamel-dentin junction; 3= leakage along the occlusal (Group 3a) and/or

axial walls (Group 3b).

The results of the staining measurements were statistically evaluated using

the Kruskal-Wallis non-parametric ANOVA by ranks with Bonferroni alpha

protection. The level of statistical significance was defined P= 0.05.

104

Microscopic evaluation Three different protocols were performed to evaluate: (1) resin cement

thickness, (2) hybrid layer formation at the interface between resin cement

and dental substrate, and (3) to observe the morphology of the cavity

margins.

After scoring for dye penetration of Group 1 and 2 samples, half of the

sections were randomly selected to observe hybrid layer formation and resin

cement thickness. To detect hybrid layer and resin tags formation, each

section was gently decalcified (with 37% phosphoric acid for 10 seconds)

and deproteinized (2% sodium hypochlorite solution for1 minute). Finally,

the sections were prepared for scanning electron microscope (SEM)

observations. The samples were critical-point dried (Blazer device). All

samples were gold coated, mounted on stubs and inspected by SEM (Joel

JXA-840f). The resin infiltration of cervical margins was studied at different

magnifications. Simultaneously, the same specimens were evaluated

regarding the resin cement thickness along the interface and the presence of

air bubbles along the cervical wall and at the angle between cervical and

axial wall of each abutment. The resin cement thickness was evaluated at

the cervical margin of Groups1, 2 and 3a, approximately 500 µm from the

margin toward the axial wall. With SEM, the resin cement thickness was

calculated for both the halves of each sample, and than the average score

was registered. To observe the morphology of the conditioned cavity

margins, 16 extracted posterior teeth were selected for the microscopic part

of the study. The selected teeth were randomly divided in two groups of

eight samples each. Group 4: Eight Class II cavities were prepared as

already described, for groups 1 and 2 (with cervical margins located below

the CEJ) and Group 5, another eight teeth were prepared as Groups 3a and

b (with cervical margins located above the CEJ).

Five samples each group (Groups 4a and 5a) were prepared to be directly

observed under SEM. The enamel margins of cavity preparations were

conditioned with 37% phosphoric acid for 15 seconds and then for another

105

15 seconds in the entire cavity surface, then washed for 20 seconds and

gently air-dried. This procedure was carried out to completely remove the

smear layer and open the dentin tubules as well as demineralise the inter-

tubular dentin at the interface and etch enamel. The samples were critical

point dried, gold coated and inspected by SEM.f Photographs were taken of

enamel sites along occlusal, lingual and buccal margins to document

significant aspects. Photographs were also taken at different sites

approximately every 200 µm on the abutments at different magnifications ,

starting at the cervical margin and moving towards the axial wall. The

appearance of the abutments was described close to the cervical margins

over a range of 100-500 µm along the interface between abutment and

bonding-cement system, and at the axial and occlusal areas.

The remaining three samples of each group (Groups 4b and 5b) were

restored as Groups 1-3 with an indirect porcelain restoration. After luting

procedures, the samples were stored for 24 hours in saline solution,

immersed in a 30% hydrochloric acid solution for 48 hours, and washed in a

2% sodium hypochlorite solution for 60 seconds to thoroughly demineralise

and deproteinize the tooth structure and to expose the resin replica of the

interface. In this way, it is possible to directly observe the resin tag formation

in the different areas of cavity walls. The resin specimens were gold coated,

mounted in metallic stubs and inspected by SEM.f Photographs were taken

of different sites along cavity margins to show significant aspects.

Results Microleakage data

Table 3 summarize the dye penetration depths by site for the three first

groups. In the samples of Group 1, 90% of samples showed no leakage at

the occlusal enamel margins, while only 40% of them showed no dye

penetration cervically. In the samples of Group 2, only 30% of specimens

106

presented a perfect seal at the cervical site and no leakage was observed at

the enamel site in 70% of the sections.

The samples of Group 3a showed 80% of samples without leakage at

enamel site after one section and 40% of the samples without leakage after

three seconds (Group 3b). In Group 3b, the dye mainly penetrated from axial

walls buccally or lingually. At the cervical site, the samples of Group 3a

showed 50% leakage after one section and 60% after three sections (Group

3b).

Statistical analysis of the data showed no significant differences between

occlusal sites of the same three groups.

When the leakage scores of Groups 3a and 3b, in which scoring after one

section and three sections were made, were compared, no statistically

significant differences were found at the cervical site, while they were found

at the enamel (occlusal/axial) site.

Microleakage observations

The thickness of resin cement, which represents the post cementation

marginal discrepancy, was higher in samples of Group 1 (92 µm) than in

those observed in Group 2 (68 µm) and a higher frequency of bubbles in the

resin cement was noted in the samples of Group 1 than in Group 2. In three

samples of Group 1, a cement thickness of 200 µm was noted. In another

five samples of the same group, the cement thickness was 50-70 µm.

However, no statistically significant difference was found between resin

cement thickness of the two groups.

The microscopic observation also showed hybrid layer formation at the

interface between resin and dentin of Group1 samples (Fig. 5). The hybrid

layer was 4-7 µm thick and many resin tags penetrating into the dentin

tubules were observed. The hybrid layer thickness clearly increased in each

sample moving from the cervical margin toward the axial wall (Fig. 6).

In the samples of Group 2 the hybrid layer was thinner than Group 1

between 0.5-4 µm (Fig. 7). In the cervical area, the hybrid layer thickness

107

was very thin (0.5 µm) or not detectable. Resin tag formation was also noted

(Fig. 8).

In both groups, close to the cervical margin, resin tag formation was rarely

seen. Only 200-300 µm from the cervical margin and moving towards the

inner dentin, resin tags were detectable.

Seldom, gap formation was noted between dentin substrate and bonding

system in the samples of Group 2 (Fig. 8) and between resin cement and

bonding system Group1.

At the enamel sites of the first groups, resin tags penetrating into the etched

enamel surface were observed (Fig. 9). The resin tags length was 5-8 µm.

At the cervical margin, all specimens of Group 4a, with margin located 1 mm

below the CEJ, presented an outer layer which was not identifiable as dentin

(Fig. 10). No open tubules were detectable in this area. The outer layer was

approximately 200-300 µm thick and consisted of a relatively thick inner

layer covered by a thin layer of cementum along the entire length of the

cervical margin. Moving inwards across the entire width of the gingival floor

of the proximal box, tubules cut in cross section were clearly visible. In the

samples of Group 5a, in which the cervical margin was located

approximately 0.5 mm above the CEJ, a thin enamel layer was visible. The

enamel prisms tented to be cut along their long axes (Fig. 11). The etched

patterns of the enamel layer was not uniform and frequently, areas without

characteristic enamel morphology were noted both at cervical (Fig. 11) and

axial margins (Fig. 12). Moving inwards across the entire width of the

gingival box, an outer dentin layer of 100-250 µm, similar to that observed in

Group 4 was also observed before finding dentin with cross-sectioned

tubules (Fig. 11). At the buccal and ligual margins, the enamel prisms were

mainly cut along their long axes and only close to the most occlusal area of

the buccal or lingual wall; prisms cut perpendicularly to their long axes were

noted and showed typical etch patterns.

The resin replica (Groups 4b and 5b) reproduced the morphology observed

in the micrographs taken on the empty cavities (Fig. 13). At the cervical

108

margin, it was very rare to observe resin tag formation. At the least after

200-300 µm from the cervical margin and towards the inner dentin, resin

tags were detected. At the edge of margins (cervically, buccally and

lingually) the resin reproduced the thin enamel layer (group 4a and 5a). The

enamel prisms at the margins presented a low level of structured

arrangement. The prisms, reproduced by the resin, were cut approximately

parallel to their long axis, both at cervical and lateral/occlusal margins.

Discussion Technical difficulties associated with the placement of the inlays has to be a

serious point of consideration in marginal integrity studies (Roulet JF, 1997).

In this study, the restorations of Group 1 free of leakage at the cervical

margins were of those inlays showing the thinnest resin cement thickness.

The presence of air bubbles within the material corresponded to the thickest

resin cement thickness and always to the highest leakage score. The

presence of bubbles may suggest that handling difficulties existed in mixing

the resin cement, placing and setting the inlays into the cavity during

cementing procedures. The thickness of resin cement and the presence of

bubbles can be also related to several properties of resin cement as its

viscosity and composition (Picard B et al, 1997).

The dye penetration was particularly observed at the cervical margins of

Groups 1 and 2: in this areas (Figs. 10, 13) the presence of an outer layer,

partially formed by cementum of 150-300 µm may affect the quality of

bonding when the margin is located below the CEJ (Cagidiaco MC, 1995;

Ferrari M & Davidson CL, 1996; Cagidiaco MC et al 1997). Although the

hybridisation of the cementum-dentin margins was demonstrated (Ferrari M

et al, 1997) and also showed in this study (Fig. 5), the absence of resin tags

in the first 200-300 µm from the cervical margin, determines no peritubular

dentin demineralisation and therefore, a limited increase of intertubular

surface area after conditioning (Pashley DH et al, 1995 ; Cagidiaco MC et al

109

1997) this can be responsible for a decrease of bond strength and,

consequently, of durability of the bonding to cavity margin. The outer layer is

partially formed by cementum, which is a hypo-mineralized hyperorganic

dentin matrix which has lost its tubular aspect. This outer layer is composed

of two different layers, the so called Tomes’ granular layer and hyaline layer

of Hopewell-Smith (Bradford EW, 1967) and by the outer part of dentin.

Blackwood (1957) pointed out that sound dentin can be separated from

cementum through a zone known as the “intermeditate cementum layer”,

which has not exhibit the characteristic features of either dentin or

cementum, and its formation is still unclear. The thickness of this layer

increases considerably in the apical direction (Vacel JS & Gher ME, 1993;

Bosshardt DD & Selving KA, 1997) . In the samples of Group 3b of this

study, the presence an “intermediate layer” or “outer layer” between sound

dentin and thin enamel cervical margin was also demonstrated.

A recent study performed with finite element analysis demonstrated that the

highest stresses are concentrated in the most external areas of cervical

walls of the Class II cavity (Apicella A et al, 1997). This stress concentration,

with values exceeding the strength of the materials, can contribute to

disruption of the seal at the cervical margin of Class II restorations.

From a clinical point of view, it seems that, if the bonding between adhesive

resin and the thin enamel layer at the cervical margin at the most external

area is broken and consequently infiltrated by bacteria, the “intermediate

layer” cannot stop the leakage of fluid and bacteria, causing post operative

sensitivity and secondary caries (Eick JD & Welch FH, 1986; Cox CF, 1994).

Resin replica technique also made it possible to study the cementum layer

(Cagidiaco MC, 1995). Replicas of Class II restoration done in this study

confirm the anatomical observations made directly on empty cavities. The

results of this investigation, which demonstrate the absence of resin tags in

the cervical area, reinforce the consideration that the cervical margins are

the weakest bonding area of Class II restorations (Ferrari M & Davidson CL,

1996). However, the superior sealing capacity of restoration which use the

110

latest dentin bonding systems, in comparison with the results obtained by

using the oldest systems, can be attributed to the hybridisation of the

conditioned substrate (Bayne SC et al, 1996). Many weak points on hybrid

layer formation were pointed out (Sano H et al 1995; Tay FR et al 1995; Tay

FR et al, 1997). Although it was demonstrated that from a quantitative view-

point the interfacial bond strength is not per se due to the infiltration of the

collagen rich zone (Wakabayashi Y et al, 1994; Gwinnett AJ, 1994; Kanca J,

1997), the qualitative role of hybrid layer on the marginal seal of Class V

restorations placed under clinical conditions was recently demonstrated

(Ferrari M et al, 1997; Vichi A et al, 1997).

Further research is needed to determine which bonding procedures, related

to different substrates, can be ideal for obtaining a perfect and durable seal

of Class II indirect aesthetic restorations.

In this study two bonding-cementing systems were evaluated. The

experimental bonding system used in Group 1 (EBS Multi and CLA 1.0b)

showed hybrid layer and resin tag formation along the interface between

adhesive material and conditioned dentin (Fig. 5). Because of vacuum

pressure during the procedures for preparing samples for microscopic

examination, and the negative pressure in the chamber of SEM, a gap

between hybrid layer and resin cement was sometimes noted. However, in

this area where gap formation was observed, the dentin tubules remained

sealed by resin tags. Recent investigations concluded that the most

important feature of resin tag formation in demineralised dentin is the resin’s

ability to plug the dentin tubules to the depth of funnelling produced by the

etching agent (Nakabayashi N et al, 1992; Pashley DH et al, 1993; Titley K

et al, 1995).

Probably because of these same reasons, a gap formation was also noted in

Group 2 samples (Figs. 8, 9) in which porcelain restorations were luted with

Syntaca bonding system and Variolink IIa resin cement. In the latest group,

the gap was mainly located between demineralised dentin and adhesive

system. This fact can be correlated with the thin hybrid layer probably due to

111

the high wettability of this enamel-dentin bonding system (Moello FS-TC et

al, 1996). For that reason, the bonding system of Group 1 may be

considered superior to that used in Group 2.

At the occlusal margins of Group 1, 2 and 3a samples, which were located in

the enamel, 70%-90% of restorations showed a perfect seal. Apparently, the

total etch technique using phosphoric acid etched tooth enamel sufficiently.

At the occlusal site of Groups 1, 2 and 3a, the thickness of the enamel was

between 1.0 and 1.8 mm and the prisms orientation probably permitted a

high bond level. When the enamel site of buccal and lingual cavity walls

were evaluated (Group 3b) the dye penetration considerably increased. This

is in agreement with the study by Hilton et al (1997). The high leakage score

was probably due to the fact that the enamel thickness ranged between 0.3

mm, more cervically, to 0.8-1.0 mm occlusally. Also, the enamel prisms were

mainly cut along their long axes, creating an etch enamel pattern less

retentive than when cut perpendicular to their long axes (Attal JP &

Degrange M, 1996 ; Dietschi D & Sperafico R, 1997). The interdependency

between enamel thickness and prisms orientation was noted, in such a way

that in thinner cervical enamel the prisms predominantly run straight, while in

thicker cuspal enamel they show a wavy path and their orientation towards

the enamel surface is predominantly oblique (Radlanski RJ et al, 1990;

Radlanski RJ, 1995). A higher bond strength to transverse cut enamel

prisms than to longitudinal sectioned prisms was found (Munecika T et al,

1984) and, for that, the wavy path of the prisms in human enamel is

assumed to lead to higher strength than a parallel structural pattern

(Fernandes CP, Chevitarese O, 1991; Martin T, 1997; Pfrentzschner HU,

1997). These facts may explain the higher dye penetration found at the

cervical (Group 3a), lingual and buccal (Group 3b) sitesthan that at occlusal

site (Groups 1,2).

The technique used in the present study of sectioning the leakage samples

of Group 1-3a allowed standardized visualization of the dye penetration

along the cervical and occlusal margins. While this is the most common

112

sectioning procedure for leakage test, which allows visualization of leakage

that penetrates down dentin tubules in a pulp ward direction, it does not

permit a three dimensional assessment of the leakage pattern. To evaluate

the leakage at axial walls of cavities, Group 3 samples were sectioned

approximately along the interface between buccal, lingual walls and indirect

restorations. Because the dye penetration was staining the axial cavity walls

mainly in an occlusal-pulpal direction, the leakage scores registered in this

areas were compared with the occlusal data of the first score of the same

samples. The dye penetration resulted more evident at the axial walls than

occlusally, and statistically significant differences were found between the

two groups. To ameliorate the dye infiltration reading, the demineralisation

was and clearing procedure advocated by Gwinnet et al (1995) can be

useful. However, the sample process performed in this study also permitted

the SEM evaluation of the same specimens after leakage scoring, the

possibility to correlate the leakage data with the morphological appearance

of the dental substrates and with bonding material behaviour. The statistical

evaluation of scores obtained in Group 3b at axial/occlusal site and cervical

margins of Groups1, 2, 3a and 3b showed no significant differences. For

that, the enamel axial walls of Class II cavities must be considered, from

clinical viewpoint, as one of the weakest margins in the cervical area of

Class II restorations.

This would seem to be in favour of placement of conservative bevels on the

enamel of the facial, lingual and cervical walls of Class II restorations

(Dietschi D et al, 1995;Hilton TJ et al, 1997). Unfortunately, with indirect

porcelain inlays, if a bevel is placed at the margins, it can produce unstable

margins, can fail at the margins and a bevelled ceramic inlays would be

difficult to fabricate. Clinical conditions cannot permit the bevel placement at

this margins without mechanically damaging the adjacent tooth and or the

root of the tooth interproximally. Beside the difficulties in making porcelains

restorations with bevelled margins, clinical experience has demonstrated the

low risk of marginal fracture when a butt-joint is made at the margin.

113

However, further long term assessment of Class II restorations is required to

determine their success addition to their excellent aesthetic qualities.

a. Vivadent, Schaan, Liechtenstein.

b. Espe, Seefeld, Germany.

c. Ivoclar, Schaan, Liechtenstein.

d. Nikon Ltd, Tokyo, Japan.

e. Balzer Ltd, London England.

f. Jeol Ltd, Tokyo, Japan.

This study was partially supported by ESPE GmbH and Research Center for

Dentistry/Tufts University, Boston, USA.

114

References

Anusavice KJ. Quality evaluation of dental restorations. Chicago:

Quintessance, 1989.

Apicella A, Raddi S, Ausiello P, et al. FEM study of shrinkage stress build-up

on adhesive restorations. J Dent Res 1997; 76: 49 (Abstr 435).

Attal JP, Degrange M. Influence de l’orientation des prismes et du traitment

de surface sur l’adhesion et l’adherence a l’email. J Biomater Dent 1996 ;

11 : 41-57.

Bayne SC, Heymann HO, Wilder AD, et al. Clinical performance of bonding

systems with and without hybrid layers. J Dent Res 1996; 75: 23 (Abstr 47).

Blackwood HJJ. Intermediate cementum. Br Dent J 1957; 102: 345-350.

Bosshardt DD, Selving KA. Dental cementum: The dynamic tissue covering

the root. Periodontal 2000 1997; 13: 41-75.

Bradford EW. Microanatomy and histochemistry of dentin. In: Miles AEW.

Structural and chemical organization of teeth. New York: Academic Press,

1967; Vol II, 49.

Branstrom M. Dentin and pulp in restorative dentistry. London: Wolfe

Medical Publ., 1982.

Branstrom M. Etiology of dentin Hypersensivity. Proc Finn Dent So 1992; 88

(Suppl. 1): 7-13.

Cagidiaco MC, Ferrari M, Vichi A, et al. Mapping of tubule and intertubule

surface areas available for bonding in Class V and Class II preparations. J

Dent 1997; 25: 379-389.

Cagidiaco MC. Bonding to dentin: Mechanism morphology and efficacy of

bonding resin composites to dentin in vitro and in vivo. Amsterdam,

University of Amsterdam, Ph D Thesis, De Batte Ed. 1995.

Cox CF. Evaluation and treatment of bacterial microleakage. AM J Dent

1994; 7: 293-295.

115

Dietschi D, Scampa G, Campanile U, et al. Marginal adaptation and seal of

direct and indirect Class II composite restorations: An in vitro evaluation.

Quint int 1995; 26: 127- 138.

Dietschi D, Sperafico R, Adesive metal-free restorations. Current concepts

for the esthetic treatment of posterior teeth. Berlin: Quintessence 1997.

Donly KJ, Jensen ME. Posterior composite Class II restorations: In vitro

comparison of preparation designs and restorations techniques. Dent Mater

1990; 6: 88-93.

Eick JD, Welch FH. Polimerization shrinkage of posterior composite resins

and its possible influence on postoperative sensitivity. Quit Int 1986; 17: 103-

111.

Feilzer AJ De Gee AJ, Davidson CL. Increased wall-to-wall curing

contraction in thin bonded resin inlays. J Dent Res 1989; 68: 48-50.

Fernandes CP, Chevitarese o. The orientation and directions of the rods in

dental enamel. J Prosthet Dent 1991; 65 : 793-800.

Ferrari M, Cagidiaco MC, Davidson CL. Resistence of cementum in Class II

and V cavities to penetration an adhesive system Dental Mater 1997; 13:

152-162.


Z100 in Class II restorations. Am J Dent 1996; 9: 145-149.

Gwinnet AJ, Kanca J. Micromorphological relationship between resin and

dentin in vivo and in vitro. Am J Dent 1992; 5: 19-23

Gwinnett AJ, Tay FR, Pang KM, et al. Comparison of three methods of

critical evaluation of microleakage along restorative interfaces. J Prosthet

Dent 1995; 74: 575-585.

Gwinnett AJ. Chemically conditioned dentin: A comparison of conventional

and environment scanning electron microscopy findings. Dent Mater 1994;

10: 150-155.


composite insertion techniques at intraoral temperature. Quit int 1997; 28:

135-144.

116

Kanca J Resin Bonding to wet substrate. I. Bonding to dentin. Quit int 1992;

23: 39-41

Kanca J. Investigation into dentin adhesion mechanism. J Dent Res 1997;

76: 277 (Abstr 2111).


9: 273-276.

Martin T. Schmeltzmikrostrukturen bei Saugetieren. In: Alt KW, Tucrp J. Die

evolution der zahne. Philogenie –ontogenie variation. Berlin: Quintessenz,

1997.

Moello FS-TC, Feiltzer AJ, De Gee AJ, et al. The influence of the presence

of a bonding layer on marginal sealing of resin composite Class II

restorations. J Dent Res 1996; 75: 26 (Abstr 224).

Munecika T, Suzuki K, Nishiyama M, et al. A comparison of the tensile bond

strengths of composite resins to longitudinal and transverse sections of

enamel prisms in human teeth. J Dent Res 1984; 63: 1079-1082.

Nakabayashi N, Ashizawa M, Nakamura M. Identification of a resin dentin

hybrid layer in vital human dentin created in vivo: Durable bonding to vital

dentin. Quit int 1992; 23: 135-141.



Pashley DH, Ciucchi B, Sano H, et al. Bond strenght versus dentine

structure: A modelling approach. Archs Oral Biol 1995; 40: 1109-1118.

Pashley DH, Ciucchi B, Sano H, et al. Permeability o dentin to adesive

agents. Quint int 1993; 24: 618-631

Pfrentzschner HU. Biomechanik des zanhschmelzes. In: Alt KW, Tucrp J.

Die evolution der zahne. Phylogenie-Ontogenie variation. Berlin Quintessenz

1997.

Picard B, Jardel V, Tirlat G. Ceramic bonding: Reliability. In Degrange M,

Roulet JF. Minimally invasive restoration with bonding. Chicago

Qiuntessence 1997; 103-127.

117

Radlanski RJ, Jager A, Seidi W, et al. Uber die ausrichtung der prismen im

zahnschmelz menschlicher permanenter zahne. Anat Anz 1990; 170: 329-

337.

Radlanski RJ. Prism arrangement in early layers in human fetal enamel. In :

Radlanski RJ, Renz H. Proceeding of the 10th international symposium on

dental morphology. Berlin: C & M Brunne, 1995.

Robinson PB, Moore BK, Swartz ML. Comparison of microleakage in direct

and indirect composite resin restorations in vitro. Oper Dent 1987;12: 113-

116.

Roulet JF. Longevity of glass ceramic inlays and amalgam-results up to 6

years. Clin Oral Invest 1997; 1: 40 -46.

Sano H, Takatsu T, Ciucchi B, et al. Nanoleakage within the hybrid layer.

Oper Dent 1995; 20 : 18-25.

Tay FR, Gwinnett AJ Pang KM, et al. Variability in microleakage observed in

a total-etch wet-bonding technique under different handling conditions. J

Dent Res 1995; 74: 1168-1178.

Tay FR, Gwinnett AJ, Wei Shy. Ultrastructure of the resin-dentin interface

following reversible and irreversible rewetting. Am J Dent 1997; 10: 77-82.

Thylstrup A, Bille J, Qvist V. Radiographic and observed tissue in approximal

carious lesions at the time of operative treatment. Caries Res 1986; 20: 75-

84.

Titley K, Chernecky R, Chan A, et al. The composition and ultrastructure of

resin tags in etched dentine. Am J Dent 1995; 8: 224-230.

Tyas MJ. Clinical performance of two dentin adhesives: 2-year results. Aust

Dent 1996; 41: 324-7.

Vacel JS, Gher ME. Cementum anomalies of the dentogigngival junction. Int

J Perio Dent 1993; 5: 443-449.

Van Merbeeck B, Peumans M, Verschueren M, et al. Clinical status of ten

dentin adhesive systems. J Dent Res 1994; 73: 1690-1702

118

Vichi A, Ferrari M, Davidson CL. In vivo leakage of an adhesive system with

and without NaOCl as preatreatment. J Dent Res 1997; 76: 398 (Abstr

3077).

Wakabayashi Y, Kondou Y, Suzuki K, et al. Effect of dissolution of collagen

on adhesion to dentin. Int J Prosthodont 1994; 7: 302-306.

119

Table 1. Experimental groups.

Group # Materials Margin

Location

No of

sections

Type of

investigation

1 ESPE 1 mm below

CEJ

1 ML/RCT/HLF

2 Vivadent 1 mm below

CEJ

1 ML/RCT/HLF

3a ESPE 0.5 mm

above CEJ

1 ML/RCT/HLF

3b ESPE 0.5 mm

above CEJ

3 ML/RCT/HLF

4a / 1 mm below

CEJ

/ MDO

4b ESPE 1 mm below

CEJ

1 Resin replica

5a / 0.5 mm

above CEJ

/ MDO

5b ESPE 0.5 mm

above CEJ

1 Resin replica

ML: Microleakage; RCT: resin cement thickness; HLF: hybrid layer formation; MDO:

Microscopic direct observation by SEM; Resin replica observation by SEM;

120

Table 2. Cementing procedures.

Product Bonding

System

Clinical

steps

Resin

cement

Clinical

steps

ESPEb

VivadentaEBS Multi

Syntac

a b c d

a b c d e

CLA 1.0

Variolink II

f g h i k l m n

f g h j k l m n a Enamel etching with phosphoric acid

b Dentin conditioning with phosphoric acid

c Primer application

d Adhesive application

e Heliobonda application

f Inlay etching with fluoridric acid

g Silanization of etched porcelain surface

h Heliobonda application

i Aplicap capsule application

j Mixing of resin cement

l Removing cement access

m Margins isolation with glycerine

n Light-curing

Table 3. Leakage scores, resin cement thickness at the cervical margins and the presence of

bubbles in cement of the three experimental groups (n=10).

Group1

0 1 2 3 4

Group 2

0 1 2 3 4

Group 3a

0 1 2 3 4

Group 3b

0 1 2 3 4

Occlusal 9 1 - - - 7 3 - - - 8 2 - - - 4 2 3 1 -

Cervical 4 2 1 2 1 3 3 2 1 1 5 1 2 2 - 4 1 2 3 1

Cement

thickness

92 µm

(SD:40)

68 µm

(SD:25)

Not

evaluated

Not

evaluated

Bubbles 2 at occlusal

area

3 at cervical

area

1 at occlusal

area

1 at cervical

area

Not

evaluated

Not

evaluated

121


Fig. 1. Preparation characteristics of standard Class II cavity

Fig. 2. One section was made on Groups 1, 2 and 3a, and three sections were made on Group 3b

122

Fig. 3. Scale of cervical interfacial dye penetration.

Fig. 4. Scale of occlusal interfacial dye penetration.

123

Fig. 5. Hybrid layer formation at interface between resin cement and dentin (Group 1: EBS Multi, Espe). The hybrid layer thickness was 4-7µm. ( SEM x 2000; bar = 10 µm) (hybrid layer between arrows).

Fig. 6. Hybrid layer thickness increases from the cervical margin towards the pulpal wall (Group 1 EBS Multi, Espe) (SEM x 1000; bar = 10 µm) ( HL= Hybrid Layer; M= cervical Margin; T= resin Tags).

124

Fig. 7. Hybrid layer formed in a sample of Group 2 (Syntac, Vivadent). The thickness of the layer is of 3-4 µm ( SEM x 3500; bar= 10 µm) (Hybrid layer between arrows).

Fig. 8. Resin tag formation in a Group 2 sample ( Syntac, Vivadent) (SEM x 2000; bar= 10 µm).

Fig. 9. Resin tag penetration into the etched enamel of Group 1 sample (EBS Multi, Espe) (SEM x 2000; bar= 10 µm).

125

Fig. 10. At cervical margin located 1 mm below the CEJ, an outer layer not identifiable as sound dentin was detectable (SEM x 500; bar = 100 µm) (C= Cementum; D= Dentin; OL= Outer Layer).

Fig. 11. Cervical margin located 0,5 mm above the CEJ. The etched pattern was not uniform and the prisms tended to be cut along their long axes. Moving towards the pulpal wall, an outer layer of 250-300 µm was observed (SEM x 500; bar= 100 µm) (E= Etched Enamel; OL= Outer Layer; D= Dentin).

126

Fig. 12. Axial margin of a Class II cavity. The enamel prisms are cut along their long axes and the etched pattern is not uniform (SEM x 1000; bar = 20 µm) (UE= unprepared Enamel; E= Etched Enamel; CW= dentin Cavity Wall).

Fig. 13. Resin replica showing an empty cavity. The section goes from outer enamel to outer layer to dentin in a mesial-distal direction. Resin tags were not observed close to the cervical margin. (SEM x 500; bar= 100 µm) (E= Enamel; OL= Outer Layer; T= resin Tags formed on dentin).

127

Chapter 7

A clinical trial of Empress II porcelain inlays luted to vital abutments with the self-light-curing adhesive system Excite DSC and MultiLink. Abstract: Purpose: The aim of the study was to evaluate the quality

expressed in marginal integrity and sealing of Empress II inlays cemented

under clinical conditions with the self/light-curing Excite DSC and MultiLink

adhesive luting system. Materials and methods: Forty patients were

selected and each received one Empress II inlay. Empress II is a heat

pressed glass ceramic and contains lithium di-silicate and lithium ortho-

phosphate crystals, from which higher stress resistance and improved

strength is claimed. The restorations were placed within the time span March

2000 until May 2000. Recalls were performed after 6, 12, 24 and 36 months.

At the 3-year recall, seven patients were lost for this study. Inlays were

evaluated for postoperative sensitivity, marginal integrity, marginal leakage,

color stability, surface staining, retention, surface crazing (micro-cracks).

Results: At the 3-year recall, all restorations were still in place, no fracture of

any inlay was observed and only one restoration showed post-op sensitivity

(at the first recall, 1 week after placement). Only few inlays showed slight

marginal staining and gaps, with little surface staining and crazing, but no

inlay needed replacement. Conclusions: No inlay came loose or fractured

during the whole period of observation and all the inlays were still clinically in

service.

Patient‘s satisfaction was high and no hypersensitivity was present at three-

year recall.

128

Introduction Concern about the potential toxicity of amalgam fillings and their limited

anaesthetic aspect motivates a call for substitute restorative materials also

for the posterior area (Roulet JF, 1997). Resin-based composite, glass-

ionomer, and compomer direct restorations, as well as composite, porcelain

and gold inlays form the wide spectrum of options for more aesthetic and

biocompatible alternatives to amalgam. Disadvantages of above listed direct

restorative materials are setting shrinkage, limited color stability and limited

strength, eventually leading to leakage, decreasing esthetics and premature

fracture under stress. These undesirable deficiencies are less likely to arise

with indirect composite or porcelain restorations, which therefore are to be

preferred above the others, when aesthetics is a prerequisite. Other

advantages of the utilization of inlays in large cavities are enhanced

mechanical properties, better occlusal and inter-proximal morphology.

However, also these restorations have their limitations. Possible causes of

failure for indirect esthetic restorations are debonding (Sjögren G et al, 1998)

and bulk fracture of the chosen material (Banks RG, 1990).

There are many reason used to explain premature fractures of all ceramic

restorations (Kelly JR et al, 1996), such as uncorrect indications, limited

strength of the specific ceramic or, more often, insufficient thickness of the

inlay (Pallesen U, 1996) . The intrinsic weakness of ceramics is brittleness

due to the per se existence of numerous internal micro-cracks that, with time,

can propagate into connecting networks of cracks and consequently

fracture(Chen HY et al, 1999). Such premature failures represent a major

problem as they require replacement of restorations and constitutes

undesired additional workload in the dental office: in fact it represents around

60% of our daily work (Mjör IA, 1989).

Empress II, a lithium di-silicate and lithium orthophosphate reinforced glass

ceramic is proposed in order to extend the use of resin bonded ceramic

restoration even for bridges. Empress II derives its additional strength from

129

the microstructure that consists of many little interlocking needle-like crystals

randomly oriented, meant to arrest the propagation of micro-cracks through

the material.

Prerequisite for application of full porcelain inlays is perfect bonding, which

has to integrate all parts into one coherent structure (Davidson CL, 2001).

Therefore the luting material and technique, as well as the substrate

characteristics form success determining factors.

The aim of the study was to evaluate the sealing ability of Empress II inlays

cemented under clinical conditions with the self/light-curing adhesive system

Excite DSC and MultiLink resin cement.

Materials and methods

Forty patients were selected and each received one Empress 2 (Vivadent,

Schaan, Liechtenstein) inlay each. The selection of the patients followed the

next parameters:

1. Need for a Class II inlay, 2. Informed written consent of the patients.

Inclusion criteria Selection of male and female subjects was restricted to those aged 18-60

years and in good general and periodontal health.

Exclusion criteria Patients with the following factors were excluded from the clinical trial: 1)

Patients receiving drugs that modify pain perception, 2) pregnancy or breast

feeding, 3) eating disorders, 4) periodontal surgery, 5) orthodontic therapy in

the preceding three months, 6) teeth with carious lesions (after clinical and

radiographic examination) or restored in the preceding three months, 7)

extensively restored teeth (excessively wide Class II and/or Class V), 8)

allergy to drugs or chemicals used in the study materials, 9) active

periodontal disease, 10) patients spontaneously sensitive.

130

Test stimuli and assessment Before applying the adhesive material, pain measurement was performed

utilizing a simple pain scale based on the response method. Response was

determined to a one second application of air from a dental unit syringe (at

40-65 p.s.i. at approximately 20 oC) directed perpendicular to the root

surface at a distance of 2 cm and by tactile stimuli with a sharp #5 explorer.

The subject was asked to rate the perception of the sensitivity experienced

during this thermal/evaporative stimulation by providing mark on a visual

analog scale or line beginning at 0 and ending at 10 (where 0=no pain and

10=excruciating pain). In order to translate these scores to easily understood

pain levels a score of 0 was defined as no pain, 1-4 as mild sensitivity (which

was provoked by the dentists’ air blast) and 5-10 as strong sensitivity (which

was spontaneously reported by the patient during drinking, eating, etc.).

At baseline all patients were tested for dentin sensitivity. The same

measurement was performed again at each recall. The status of the gingival

tissues adjacent to the test sites was observed at baseline and at each

recall.

Clinical Procedure After suitable teeth have been chosen, clinical photographs were taken and

set aside for later use. After anesthesia, the preparation was made. All

carious structures were excavated, any restorative material was removed.

Inlay preparation was achieved using conventional diamond burs in a high-

speed hand-piece; preparation was dictated by extent of decay, extent of

pre-existing restoration. At the end of preparation all cervical margins of the

cavities were located below the cementum-enamel junction (approximately

1.0 mm below the CEJ). The Residual Dentin Thickness (RDT) was

evaluated by x-ray and abutments with RDT thinner than 0.5 mm were

excluded.

131

After preparation, impression was taken with a poly-vinyl-siloxane material

(Virtual, Vivadent, Schaan, Liechtenstein) and sent to the technician .

Lab works were performed strictly following manufacturer’s instructions. At

the moment of cementation no liner was applied; dentine and enamel

surfaces were conditioned with 37% phosphoric acid gel for 20 seconds ,

washed with water and then gently dried; Excite DSC (Vivadent, Schaan,

Liechtenstein) self-curing was applied in one layer; MultiLink (Vivadent,

Schaan, Liechtenstein) resin cement was used following manufacturer’s

instructions; Empress 2 (Vivadent, Schaan, Liechtenstein) inlays was made

of glazed core material (Staining technique). The internal surface of

Empress 2 (Vivadent, Schaan, Liechtenstein) was etched with fluoridric acid,

rinsed,dried and silanated (Monobond, Vivadent, Schaan, Liechtenstein)

.The restorations were placed within the time span March 2000 until May

2000. The inlays were next examined by the same operator at different

periods. The patients were recalled before the end of November 2000 in

order to complete the data on post-operative sensitivity. The post-operative

sensitivity was evaluated after 1, 7 and 30 days.

Then, they were recalled after 6 and 12, 24 and 36 months. During the

recalls, it was attempted to collect data on post-operative sensitivity, stability

and longevity by assessing the restorations regarding the following aspects:

postoperative sensitivity, marginal leakage, marginal integrity, color stability,

surface staining, retention, surface crazing (micro-cracks).

The following methodology was utilized in the evaluation process:

1. Postoperative Sensitivity (assessed both with sharp #5 explorer and

with cold and warm stimuli): a) Absent; b) Present.

2. Color stability: a) No mismatch; b) Slight discoloration not requiring

replacement; c) Discoloration requiring replacement.

3. Marginal integrity (assessed both digitally with sharp #5 explorers and

visually): margins a) Excellent continuity at the restorative/tooth

interface; b) Slight ledge or ditch at the interface: c) Visible marginal

ditch or ledge or actual separation of interface.

132

4. Marginal leakage: a) Excellent continuity at the restorative/tooth

interface, no discoloration; b) Slight discoloration at the interface; c)

Moderate discoloration at the interface measuring 1 mm or greater or

recurrent decay at margins.

5. Surface staining: a) Absent; b) Present.

6. Retention: a) Present; b) Partial loss; c) Absent

7. Surface crazing (Micro-cracks): a) Absent; b) Slight crazing not

requiring replacement; c) Crazing requiring replacement

Results

The results at 3-year recall are summarized in table 1. The ceramic

restorations were made and placed following manufacturer’s instructions.

Experimental temporary resin cement was used (Fermit with chlorhexidine.,

Vivadent, Schaan, Liechtenstein). No particular discomfort was noted by the

patients. The temporary restorations remained approximately 1 week in the

mouth of the patients. The materials were a little too sticky (when used with

metallic hand instruments). In order to keep in place the temporary

restorations for, at least few days, in wide cavities the temporary material

was light cured, removed, refined and finally cemented with temporary no-

eugenol cement. It was possible to recall the patients in order to collect 1-

month data. The use of self-activating microbrush and MultiLink dual-curing

resin cement (Vivadent, Schaan, Liechstenstein) was very useful. The

setting time of the resin cement was directly correlated to room temperature,

glass plate temperature and, of course, mouth temperature. The setting time

is probably a little too fast for common practitioner (the material sets within

1.30 - 2 min.).

After 3 years all the restorations were still in place so the survival rate was of

100%.

133

At 3-year recall, seven patients did not come back to the office (the same of

the 2-year recall plus 3 other). For that, the results are based on 33

restorations instead 40.

Only one restoration showed post-op sensitivity at the first recall (1 week).

The patient referred immediately after cementing procedure post-op

sensitivity, which disappeared after 3 weeks. No post-op sensitivity was

present in the patients rechecked.

All the restorations were still in place at the 3-year recall.

Only four restoration scored C about marginal leakage, which means they

had moderate discoloration at the restorative-tooth interface measuring 1

mm or greater or recurrent decay at margins.

Also marginal integrity was good and only 3 inlays showed visible marginal

ditch or ledge and interface between the restoration and tooth. The color

stability was excellent, while only 3 restorations had little surface staining.

About surface crazing at 3 year recall 2 inlays presented slight crazing not

requiring replacement.

All the data are reported and summarized on Table 2.

Discussion It is hard to compare longevity of different types of restorations, mainly

because of differences in clinical procedures, different study designs and non

comparable materials. However even with these limitations it is possible to

get certain indications from the comparison of all the clinical studies

available. A first extrapolation learns that ceramic inlays are considered as a

safe kind of restoration and that they are reported to last longer than any

other esthetic indirect restoration (Manhart J et al, 2000). Yet,

notwithstanding the inlay material, debonding and thus microleakage at the

gingival margins, particularly where the outline is located under the

cementum- enamel junction cannot completely be prevented (Alavi AA &

134

Kianimanesh N, 2002). All these factors are related to three subjects: patient,

dentist and material(Hickel R & Manhart J, 2001).

In the present study, a new glass ceramic containing a high volume of

lithium di-silicate and lithium-ortho-phosphate crystals, which claims higher

stress resistance and in improved strength, marketed as Empress II

(Vivadent, Schaan, Liechstenstein) was used.

During this study no restoration fractured, confirming the enhanced strength

of this material and its good performance in comparison with data of other

ceramics as reported in other studies (Molin MK & Karlsson SL, 2000) .

Another aspect of this new ceramic system was the observed accurate fitting

of the inlay, even if this property was not explicitly measured. Ideal values of

all porcelain fit still has to be defined (Davidson CL, 2001) but this aspect

requires attention. In several studies it had been reported (Kawai K et al,

1994, Guzman AF et al, 1997) that the marginal wear of composite luting

cement can undermine the mechanical support. To prevent excessive

marginal wear, it is therefore mandatory to have the narrowest gap between

cavity preparation and ceramic restoration. Optimal fit (ranging from 50 to

100 µm) is to be preferred (Audenino G et al, 1999), particularly if the inlay

extends under the cementum-enamel junction (Hahn P et al, 2001). The

post-op sensitivity with this system was satisfactory: only a patient reported

sensitivity at baseline that disappeared after few days. No patient referred

pain or sensitivity in the next recalls.

This observation is in contrast with a study that reports hypersensitivity to be

the most common post-op complication (Millediing P et al,1995).

The utilization of a correct bonding technique is mandatory to achieve good

clinical results on luting ceramic inlay (Frankenberger R et al, 2000). The

dual cure dental adhesive application allows a good polymerisation even

under a thick layer of ceramic. In fact incomplete transmission of the curing

light through the ceramic restoration can compromise polymerisation of the

only light-curing adhesive system (Lee IB & Um CM, 2001). In direct resin

restorations, light curing the bonding agent prior to insertion of the

135

composite is routine. In ceramic luting procedures this pre-curing of the

resin-based adhesive is also considered as an important step, but can lead

to interfere with complete seating of the ceramic inlay (Hahn P et al, 2000)

and therefore clinicians might wrongly choose to cure bonding agent and

cement in one step. So it can be helpful to use a dentin bonding agent that

does not need any pre-polymerisation. To prevent these problems, in the

present study a dual-curing cement was chosen for luting the inlays. Dual-

cure cements offer a safe and a good degree of conversion also at sites

where light-curing might be hindered as is the case with thick inlays. In

recent studies it was reported that inlays luted with chemical-cure cements

performed better than inlays luted with dual-cure ones (Studer S et al,

1996; Van Dijken JWV et al, 1998). However it has to be emphasized that

when inlay margins are in cementum, perfect margins and perfect seal is

still very difficult to achieve (Haller B et al, 2003). In addition, the absence

of any coming loose of the observed inlays confirmed acceptable adhesion

of the system.

At three years recall, 4 restorations scored C for marginal leakage and 3

scored C for marginal integrity. This observation that reveals decreasing

marginal quality with aging due to either marginal wear of the luting cement

or other forms of degradation was for us not a reason for replacement in

accordance with literature (Molin MK & Karlsson SL, 1996). Another

compromising factor for perfect seal was that cavity extension was in all

cases in areas with high probability of micro- infiltration so a marginal

leakage was possible to occur (Ferrari M et al, 1999). These restorations are

still in place and capable of further clinical service and do not require

replacement.

A further aspect to evaluate was color stability and surface staining. In

general, the high chemical stability of ceramics guarantees good color

stability and eventually only mild surface staining. In this respect ceramics

are far superior to composite direct or indirect restorations (Wassell RW et

al, 2000) .

136

At three years recall all Empress II inlays perform clinically satisfactory,

which agrees with literature (Felden A et al, 1998; Kramer N et al, 1999;

Manhart J et al, 2001).

Conclusions After 3-year period of service, the following conclusions can be drawn:

Seven out of 40 patients were lost.

No inlay came loose during the whole period of observation and all the

inlays were still clinically in service.

No fracture was observed.

After 3 years moderate discoloration and visible marginal ditching were

present in some of the restorations that were still rated satisfactory. Slight

crazing and little surface staining were also reported after 3 years. Patient‘s

satisfaction was very high whilst no hypersensitivity was present. The results

of this three-year study are in accordance with the other lately published

prospective studies and exhibit good clinical performance of the Excite

DSC/Multilink/Empress II system over a 3 years survey period.

137

References Alavi AA, Kianimanesh N. Microleakage of direct and indirect composite

restorations with three dentin bonding agents. Op Dent 2002; 27: 19-24.


adhesively luted ceramic inlays. Int J Prosthodont 1999; 12: 342-347.

Banks RG. Conservative posterior ceramic restorations: a literature review. J

Prosthet dent 1990; 63(6): 619-626).

Chen HY, Hickel R, Setcos JC, Kunzelmann KH. Effects of surface finish and

fatigue testing on the fracture strength of CAD/CAM and pressed ceramic

crowns J Prosthet Dent 1999; 82: 468-475.)

Davidson CL. Luting Cement, the Stronghold or the Weak Link in Ceramic

Restorations. Advanced Engineering Materials 2001, 3, 10: 763-767.

Felden A, Schmalz G, Federlin M, Hiller KA. Retrospective clinical

investigation and survival analysis on ceramic inlays and partial ceramic

crowns: results up to 7 years. Clin Oral Invest 1998; 2: 161-167.


Influence of tissue characteristics at margins on leakage of class II indirect


Frankenberger R, Kramer N, Petschelt A: Technique sensitivity of dentin

bonding: effect of application mistakes on bond strength and marginal

adaptation. Oper Dent 2000; 25: 324-330.

Guzman AF, Moore BK, Andres CJ. Wear resistance of four luting agents as

a function of marginal gap distance, cement type and restorative material. Int

J Prosthodont 1997; 10:25-30.

Hahn P, Attin T, Gröfke E, Hellwig E. Influence of resin cement viscosity on


Hahn P, Schaller HG, Hafner P, Hellwig E. Effect of different luting

procedures on the seating of ceramic inlays. J Oral Rehabil 2000; 27: 1-8.

138

Haller B, Häßner K, Moll K. Marginal adaptation of dentin bonded ceramic

inlays: effect of bonding systems and luting resin composites. Op Dent 2003;

28-5: 574-584.

Hickel R, Manhart J. Longevity of dental restorations in posterior teeth and


Kawai K, Isemberg PD, Leinfelder KF. Effect of gap dimension on composite

cement wear. Quintessence Int 1994; 25: 53-58.

Kelly JR, Nishimura I, Campbell SD. Ceramics in dentistry: historical roots

and current prospectives. J Prosthet Dent 1996; 75: 18-32.

Kramer N, Frankenberger R, Pelka M, Petschelt A. IPS Empress inlays and

onlays after four years- a clinical study. J Dent 1999; 28: 325-331.

Lee IB, Um CM. Thermal analysis on the cure speed of dual cured resin

cements under porcelain inlays. J Oral Rehabil 2001; 28: 186-197.

Manhart J, Chen HY, Neuerer P, Scheibenbogen-Fuchsbrunner A, Hickel R.

Three-year clinical evaluation of composite and ceramic inlays. Am J Dent.

2001;14(2): 95-99.

Manhart J, Scheibenbogen-Fuchsbrunner A, Chen HY, Hickel R. A 2-year

clinical study of composite and ceramic inlays. Clin Oral invest 2000; 4: 192-

198.

Millediing P, Örtengren U, Karlsson S. Ceramic inlay systems: some clinical

aspect. J Oral Rehabil 1995; 22: 571-580.

Mjör IA. Amalgam and composite resin restorations: longevity and reasons

for replacement. In: Anusavice K, Quality evaluation of dental restorations,

Chicago Quintessence 1989: 61-80.

Molin MK, Karlsson SL. A 3- year clinical follow-up study of a ceramic

(Optec) inlay system Acta Odontol Scand 1996; 54: 145-149.

Molin MK, Karlsson SL. A randomized 5-year clinical evaluation of 3 ceramic

inlay systems. Int J Prosthodont 2000; 13: 194-200.

Pallesen U. Clinical evaluation of CAD/CAM ceramic restorations: 6-years

report in CAD/CAM esthetic dentistry. Cerec 10 year anniversary

symposium. (Ed Mormann) Quintessenz Berlin 1996: 241-253.

139

Roulet JF Benefits and disadvantages of tooth-coloured alternatives to

amalgam J Dent 1997; 25:459-473.




Studer S, Lehner C, Brodbeck U, Shärer P. Short-term results of IPS

Empress inlays and onlays. J Prosthodont 1996; 5: 277-287.

Van Dijken JWV, Höglund-Åberg C, Olofsson AL. Fired ceramic inlays: a 6-

year follow up. J Dent 1998; 26: 219-225.

Wassell RW, Walls AWG, McCabe JF. Direct composite inlays vs

conventional composite restorations: 5-year follow-up. J Dent 2000; 28: 375-

382.

140

Table 1. Clinical evaluation of all restoration after 3 years.

parameter A

n %

B

n %

C

n %

Total

Post op

sensitivity

33 100%

0

0

33

Retention 33 100% 0 0 33

Marginal

leakage

29 87,9%

0

4 13,1%

33

Marginal

integrity

30 90,9%

0

3 9,1%

33

Color stability 33 100% 0 0 33

Surface

staining

30 90,9%

3 9,1%

0

33

Surface

crazing

31 93,2%

2 6,1%

0

33

141

Table 2. Clinical evaluation of all restorations at each recall

Post-operative sensitivity (n=40)

Absent A Present B Not recalled

Baseline 39 (96 %) 1 (4%)

1 week 40 (100 %)

1 month recall 40 (100 %)

5-6 month recall 40 (100 %)

12 month recall 38 (100%) 2



Retention (n=40)

Present A Partial loss B Completely loss C

Baseline 40 (100%)

1 month 40 (100%)

5-6 month recall 40 (100%)

12 month recall 38 (100%)

24 month recall 36(100%)

36 month recall 33(100%)

142

Marginal leakage (n=40)

A B C

Baseline 40 (100%)

1 month 40 (100%)


12 month recall 36 (92.4%) 2 (7.6%)

24 month recall 34 (94,4%) 2 (5,6%)

36 month recall 29 ( 87,9%) 4(12,1%)

Legends: A= excellent continuity at the restorative-tooth interface, no

discoloration; B= Slight discoloration at the interface; C= Moderate

discoloration at the restorative-tooth interface measuring 1 mm or greater or

recurrent decay at margins.

Marginal Integrity (n=40)

A B C

Baseline 40 (100 %)

1 month 40 (100 %)


12 month recall 37 (96.2%) 1 (3.8%)

24 month recall 34 (94,4%) 2 (5,6%)

36 month recall 30 (90,9%) 3( 9,1%)

Legends: A= excellent continuity at the restorative-tooth interface, no ledge,

no discoloration; B= Slight ledge or ditch at the interface detectable with

explorer; C= Visible marginal ditch or ledge or actual separation of interface

between the restoration and tooth.

143

Color stability (n=40)

A B C

Baseline 40 (100 %)

1 month 40 (100 %)





Legends: a) No mismatch; b) Slight discoloration not requiring replacement;

c) Discoloration requiring replacement

Surface staining (n=40)

A B

Baseline 40 (100 %)

1 month 40 (100 %)


12 month recall 37 (96%) 1 (3.8%)

24 month recall 35 (97,2%) 1 (2,8%)

36 month recall 30 (90,9%) 3( 9,1%) Legends: a) Absent; b) Present.

144

Surface crazing (Micro-cracks)(n=40)

A B C

Baseline 40 (100 %)

1 month 40 (100 %)


12 month recall 37 (96.2%) 1 (3.8%)

24 month recall 35 (97,2%) 1 (2,8%)

36 month recall 31 (93,9%) 2 (6,1%)

Legends: a) Absent; b) Slight crazing not requiring replacement; c) Crazing

requiring replacement

145

Legends to illustrations Fig 1: Pre-op : a mod inlay will be prepared on tooth 15 for a mesial and distal decay

Fig 2: inlay preparation

146

Fig 3: the inlay after luting procedures

Fig 4: inlay in service

147

Chapter 8

Leakage and SEM evaluation of in vitro Class V cavities restored with diverse materials.

Abstract: Purpose: This in vitro study evaluated the marginal integrity of

standardized Class V cavities, restored with 3 different sorts of filling

materials. Materials and Methods: In each experimental Group (n=12) a

different restorative material was employed. Group 1: gold foil; Group 2:

amalgam; Group 3: resin-based composite in addition with a three steps

dentin bonding system. After storage and thermo-cycling, a leakage test was

carried out and dye penetration scoring was performed at the cervical

margins of each specimen. The differences in microleakage score were

tested for statistical significance comparing all Groups, (Kruskal-Wallis Non-

Parametric ANOVA and Tukey test, p<0.05). SEM observations of the tooth-

restoration interfaces were also performed in each Group. Results:

Amalgam had the worst marginal integrity. The sealing ability exhibited by

gold foil and composite resin was satisfactory and statistically superior to

amalgam. Conclusion: Gold foil and composite resin perform equally regard

to microleakage and achieve better sealing ability than amalgam.

148

Introduction

Improved dental care, preventive programs and longer life have changed the

disease pattern of decay processes (Krejci I & Lutz F, 1991).

Also gingival recessions, occlusal inhabits, inappropriate tooth brushing and

several scaling and root planning may lead to promote cervical loosening of

substance where root caries may develop (Rees JS, 1998 ; Schüpbach P et

al, 1989).

The gingival area may be affect by carious and non-carious lesions.

Cervical non-carious lesions may develop as loss of dental substance at

cementum-enamel level for erosive and abrasive reasons (Ibbetson R &

Eder A, 2000).

Also cuspal flexure due to occlusal loads may generate stresses at

cementum-enamel margins, with disruption of hydroxyapatite crystals and

loss of enamel (Lee WC & Eakle WS, 1984).

While little non-carious cervical lesions, without any symptom, can be

treated only with occlusal adjustment, oral hygiene instructions and dietary

suggestions, deep sensitive defects and caries affected lesions have to be

treated, in order to stop progression, solve symptomatology and avoid pulp-

disease (Hickel R, 1994).

To restore this kind of lesion many restorative materials were proposed

through dental history: amalgam (Wood R et al, 1993), gold (Stibbs GD,

1980; Medina J, 1969), resins based composite (Ianzano JA & Gwinnett AJ,

1993), glass ionomer cements (Powell LV et al, 1992), compomer (Sjodin L

et al, 1996).

Demand for tooth-coloured restorations rather than anaesthetic metallic

fillings is increasing day by day (Federatin Dentaire Internationale, 1995).

149

Resin-based composite materials are the most common alternatives to

amalgam or gold and the use of resin based composite in Class V cavities is

an actively developing technology.

In this study we wanted to compare the quality of resin-based composites in

the Class V cavity with the established materials amalgam and gold.

Gold foil restorations are known as high quality and most lasting dental

provisions. It is remarkable that literature is scarce on successful treatments

and abundant on failures. Although we know by experience about the

success of compacted gold restorations in Class V situations and composite

in Class IV we cannot find too much reference on this, whilst there are

countless articles on the problems with composites in the Class V situation.

The cervical gold foil restoration it is time consuming, expensive, requires an

extensive non conservative preparation, needs a very skilled operator and,

above all, in our society, it’s absolutely not aesthetic. On the other hand gold

foil needs one chair session only, is biocompatible, has a thermal expansion

coefficient similar to enamel and has an excellent stability with time.

Amalgam used to be the standard material for Class V fillings for its

effectiveness, low cost, easy to use. Drawbacks are poor aesthetics, non

conservative preparation, need of macro mechanical retentions, and a still

questionable biocompatibility (Dodes JE, 2001).

Resin-based composites are nowadays the most common materials to

restore Class V lesions.

Their utilization in association with minimal invasive treatment, conservative,

adhesion with dentin bonding systems, permits to have highly aesthetic and

quite reliable restorations (McCoy RB et al, 1998; Manhart J et al, 2001),

however the complex morphology of this type of cavity and dentin leads

unpredictable preservation of the cervical sealing (Dietrich T et al, 1999;

Ferrari M & Davidson C, 1996; Schuckar M & Geurtsen W, 1997; Cagidiaco

MC & Ferrari M, 1995; Van Meerbeck B et al, 1994).

150

In box like Class V cavities the relation between bonded and free surfaces is

unfavourable (high C factor) whereby flow is restrained, which raises

shrinkage stresses (Davidson CL, 1986; Feilzer AJ et al, 1987).

Another problem related to Class V restorations is the location of its apical

margin. If it is positioned near the gingiva, serious control of saliva and

bleeding is essential and application of rubber dam becomes obligatory

(Penschke A et al, 2000).

The interface between restoration and dental substrate is an area of clinical

concern that can result in gap formation, marginal discoloration, leakage,

post-operative sensitivity, pulpits, recurrent decay and loss of retention

(Bränström M &Vojinovic, 1976; Sparrius O & Grossman ES 1989).

The aim of this study was to convey a quality of Class V restorations by

qualitative SEM observations along the margins and quantitatively

evaluating the sealing capacity of the various materials expressed in degree

of dye penetration at the restoration-tooth interface.

Materials and methods

Thirty six extracted sound molars and premolars were collected for this

study. The selected teeth were hand-scaled, cleaned with slurry of pumice,

and stored in distilled water at room temperature until use in the experiment.

Teeth were randomly divided into three Groups of twelve specimens each.

Standardized Class V cavities were prepared under copious water spray,

with diamond burs in a high-speed hand-piece, with upper margins in

enamel and lower margins in cementum. The occlusal margins of the cavity

had 4 mm length, the gingival margins had 3 mm length, with a traditional

trapezoid aspect of the cavity. The dept of the cavities was 2 mm.

The dimensions of the prepared cavities were checked with a Boley gauge.

A ±0.3 mm tolerance in the measurements was considered acceptable for

including the specimen in the trial. Butt margins were created in cavities

meant to receive gold foil restorations and amalgam restorations (Groups 1

151

and 2), whereas on the teeth to be restored with composite resins (Group3),

a bevel was added at the preparation margins on enamel; all the specimens

were stored in distilled water.

In Group 1 cavities were filled with gold foil only( Williams Gold Foil, Ivoclar,

Amherst, NY, USA, lot 98397B090696): no base was added to protect the

cavity, and all the specimens were prepared by the same operator. After the

complete filling of the cavity the outer face of the restorations were

burnished with a Spratley burnisher , finished with Moore discs (E C Moore

Company, Inc. Dearborn, 48126 MI) of decreasing abrasiveness and

polished with pumice and tin oxide.

The instruments used are listed in table I.

In Group 2 cavities were filled with a non-gamma 2 (Phasalloy, Wykle

Research ,Larson City NV, USA; lot 1194): no base was added and a very

accurate polishing was performed. Even in this group there was only one

operator performing the fillings. In Groups 3 cavities were filled with

composite resins. After 20 seconds of total etch, rinsing and gentile drying,

a three steps dental adhesive (Scotchbond MPS,3MESPE St Paul, MN

55144, USA, 7540 S) was employed (table II) and a flowable composite

resin (Filtek Flow, 3MESPE St Paul, MN 55144, USA, 3700 A3 3FB) was

used as elastic base.

The outer composite material was a hybrid composite resin (Filtek 250,

3MESPE St Paul, MN 55144, USA, 6020 A3 3CF).

All photo-curing materials were light-cured with a light-curing unit (3MESPE

St Paul, MN 55144, USA) for the required time.

The bonding systems and restorative materials were used following strictly

manufacturers' instructions. Once the restorations were completed and

submitted to 500 thermo-cycling each with a dwell time of 20 s. at 5 and 55

Co , the specimens were coated with two layers of nail varnish up to 2 mm

from the margin of the restorations. After a 24-hour immersion in a 2%

methylene blue solution each tooth was embedded in acrylic resin and

sectioned longitudinally with a low-speed diamond saw (Leitz 1600, Munich,

152

Germany) at three different levels perpendicular to the restoration in a

bucco-lingual direction (Fig. 1). The first cut was positioned in the middle of

the restoration, and the other ones mesial and distal.

Dye penetration at the cervical margin of the cavity was quantified according

to the following score method: 0 = no penetration; 1 = leakage not exceeding

the middle of the cervical wall; 2 = penetration past the middle of the cervical

wall; 3 = penetration to the axial wall; 4 = penetration to and along the axial

wall and into the dentinal tubules (Fig 2). Two operators observed the

sections separately by means of an optical microscope at 20 magnifications

(Bausch&Lomb, Rochester, NY, USA). In case of a disagreement between

the two investigators on the score assigned to a certain specimen, the worst

(higher) score was chosen for the statistical analysis.

Statistical analysis The results of the staining measurements were statistically evaluated using

Kruskal-Wallis Non-Parametric ANOVA by ranks with Bonferroni alpha

protection. The Tukey test was applied for multiple comparisons. All of the

statistical tests were run by the Winks 4.62 software (Texasoft, Cedar Hill,

Texas, USA), setting the level of significance at p<0.05.

SEM evaluation After scoring the specimens for dye penetration, in each Group one section

per tooth was chosen at random to be observed with the scanning electron

microscope (Philips 515, Philips, Eindhoven, Netherlands). The purpose of

the SEM analysis was to assess the integrity and continuity of the tooth-

restoration interfaces. Specimen preparation for SEM involved a gentle

decalcification with a 37% phosphoric acid solution for 10 s., followed by de-

proteinization with a 2% sodium hypo chlorite solution for 1 minute. Finally,

the specimens were mounted on an aluminum stub with a colloid silver paint,

and sputter coated with gold-palladium (Edward’s Coater S105B, London,

England).

153

Results

Leakage observations Frequency of recording of the microleakage scores for the different

combinations of restorative materials are given in Table III.

When comparing all of the combinations on trial (Graph 1), it appeared that

the amalgam Group had the worst microleakage score. In general, gold foil

Group and composite restoration Group gave a better seal than amalgam

Group.

The difference in microleakage between gold foil and composite restoration

Groups and amalgam Group were statistically significant (p<0.001).

As regards using gold foil or resin restoration, the results were not

significantly different (p>0.05) at the cervical margin and also at the occlusal

one.

Microscopic observations As expected, the typical features of adhesion, such as the formation of a

hybrid layer at the interface between restoration material and dental

substrate, were absent from the SEM views of specimens with amalgam and

gold foil. On the other hand, an excellent adaptation between gold foil and

dental substrate was visible in the specimens. (Fig. 3 a,b).

The typical features of adhesion, with the formation of a hybrid layer and

resin plugs at the interface between restorative material and dental

substrate, were present in all the specimens filled with resin composite in

association to dentin bonding agent. ( Fig 4).

Discussion

Data based on aetiology of decay lead to the conclusion that every site of

plaque retention has the possibility to be the location of secondary

decay.(Olgart L et al, 1974;Cagidiaco MC et al, 1996). For this reason

154

marginal integrity is very important to prevent secondary caries and pulp

inflammation (Roulet JF, 1994).

With the rapid turn-over of new composite materials it is very difficult to have

long term clinical test . The functioning of the composite in the present study

was not chosen to be compared with previous composites, but with

completely other materials that have an established value for clinical

dentistry.

In vitro tests are a very useful for screening dental material (Ferrari M &

Garcia-Godoy F, 2002). One of these, to valuate the presence of micro-

leakage or not, encompasses the theoretical ability to transport these dates

reliably to in vivo conditions (Söderholm KLM, 1991; Roulet JF, 1994).

Microleakage may be defined as “the clinically undetectable passage of

bacteria, fluids, molecules or ions between a cavity wall and the restorative

material applied to it” (Kidd EAM, 1976).

Based on above reasoning, in vitro micro-leakage tests were chosen for this

study as a reliable indicator for clinical performance. In fact micro-leakage

tests are very common in literature (Raskin A et al, 2001).

The shape of the cavities (high C factor) in this study was most challenging

as spherical and rounded cavities have less microleakage than box shaped

ones, specially if adhesively filled with resin-based composite (Douvitsas G,

1991; Hakimeh S et al, 2000).

In addition to the critical cavity shape, the restored teeth submitted to

thermo-cycling in order to get the most serious performance conditions.

The use of thermo-cycling as simulation of clinical aging is quite common

artificial aging technique. There are different opinions about the influence of

thermo-cycling on microleakage: some authors report the absolute absence

of influence of thermo-cycling on microleakage (Doerr CL et al, 1996), while

others show increase of microleakage at cementum-dentin-restoration

interface after thermal stress (Yap AUJ, 1997).

In this study methylene blue was the tracer employed to evaluate the degree

of infiltration. The small particle size and the permeability of dentinal tubules

155

may lead to the overestimation of the penetration (Gale MS & Darvell BW,

1999): bacteria have diameter of 0,3-1,5 µm or larger and this technique

cannot discern smaller gaps not enough wide for bacteria’s penetration.

The dwelling time of specimens in methylene blue seems to have no

influence on microleakage scores (Hilton TJ, 1998).

In this study the number of specimens, twelve cavities for each group, is in

accord with other studies (Hormati AA & Chan KC, 1980; Bauer JG &

Henson JL, 1985), even if this small number of specimens limits the choice

of statistical tests, permitting the use of less powerful ones (Norman GR &

Streiner DL, 1999).

The evaluation of penetration was scored after three cuts and optical

microscope observation.

This evaluation method may be less sensitive than three-dimensional

evaluation (Gale MS et al, 1994), however it is reported that the use of three

section may avoid under-estimation of in vitro microleakage (Raskin A et al,

2003).

This qualitative part of the method of evaluation can show the pattern of dye

penetration and can indicate where the penetration occurs (Alani AH & Toh

CG, 1997).

Regarding microleakage gold foil demonstrated a good sealing ability, in

accord with other studies (Thye RP, 1967; Martin DW, 1981).

The statistically equal ability to seal of gold foil and composite is very

interesting.

In fact the good scores achieved by gold foil, a very old non adhesive

technique, is very surprising in comparison to the modern adhesive resin-

based restorations. It has to be emphasized that gold foil techniques is

operator sensitive, and good results may only be achieved by very skilled

operators and with a lot of chair time. The absence of adhesion may very

well be compensated by gold’s dimensional and chemical stability and

thermal expansion coefficient similar to dental tissues.

156

Although composite restorations also are operator sensitive, they still are

easier to make in less time.

Unfortunately the coefficient of linear thermal expansion of resin composite

is 3-4 times that of tooth structure (Yazici AR et al, 2003).

This physical property in association with polymerization shrinkage may be

responsible of microleakage in resin restorations (Feilzer AJ et al, 1988;

Davidson CL & Feilzer AJ, 1997).

Partly to reduce the polymerization shrinkage stress, a layer of a low module

flowable composite was applied under the hybrid restorative material to

restore the cavities of Group 3 of this study (Davidson CL & Davidson-Kaban

SS, 1998; Unterbrink GL & Liebenberg WH, 1999; Chuang SF et al, 2001).

In agreement with these findings, a layer of flowable composite was applied

under the hybrid restorative material to restore the cavities of Group 3 of this

study . This operative protocol is able to reduce microleakage, as reported in

literature (Leevailoj C et al, 2001).

The results of the amalgam group are the poorest of this study.

The amalgam specimens showed total leakage involvement of the cavity’s

wall, notwithstanding it is reported in earlier studies that the initial poor seal

of fresh amalgam fillings improves with aging due to deposition of corrosion

products at the cavity-restoration interface (McCurdy CR,. 1974).

Amalgam restorations have been used for more than 150 years (Peyton FA

& Craig RG. 1971) and in clinical longevity surveys perform very satisfactory

(Hickel R & Manhart J, 2001; Ben-Amar A et al, 1995).

The SEM analysis revealed the quality of the restoration-cavity interface, with

the well-known morphological aspects of resin-bonding-dentin area. A very

intimate contact between gold and dental substrate was also confirmed with

SEM.

In this in vitro study only marginal integrity and seal was studied. It has to be

stressed that one leakage is not the other one. As important is to know

whether the materials alongside the eventual gap exhibit any bacteriostatic

157

effect. In this respect leakage in metal restorations is hard to compare with

leakage in resin restorations. This problem requires further study.

Conclusions

Gold and composite show a better seal than amalgam in Class V

restorations.

Surprisingly, an old, non adhesive restorative technique as compacted gold

foil still shows satisfactory results.

The quality of seal is related to dimensional and chemical stability and to

thermal expansion coefficient that is similar to dental tissues.

Close adaptation of restorative materials to the cavity wall is operator

dependant.

158

References


review. Op Dent 1997; 22(4): 173-185.


restorations using thermal cycling. Quintessence Int 1985;16(11): 765-769.


interface by corrosion products. J Oral Rehab 1995; 22(2): 101-104.

Bränström M, Vojinovic O. Response of dental pulp to invasion of bacteria

round threefilling materials. J Dent r Child 1976; 43: 15-21.

Cagidiaco MC, Ferrari M. Bonding to dentin: Mechanism morphology and

efficacy of bonding resin composites to dentin in vitro and in vivo.

Amsterdam, University of Amsterdam, Ph D Thesis, De Batte Ed. 1995.

Cagidiaco MC, Ferrari M, Garberoglio R. Dentin contamination protection

after mechanical preparation for veneering. Am J Dent 1996;9(2): 57-60.




183.


Prosthet Dent 1986; 55(4): 446-447.


shrinkage stress in polymer-based restoratives. J Dent 1997; 25: 435-440.

Davidson CL, Davidson-Kaban SS. Handling of mechanical stresses in

composite restorations. Dent Update 1998; 25: 274-279.

Dietrich T, Lösche AC, Lösche GM. Marginal adaptation of direct composite

and sandwich restorations in Class II cavities with cervical margins in

dentine. J Dent 1999; 27(6): 119-128.

Dodes JE. The amalgam controversy: an evidence-based analysis. J Am

Dent Association 2001; 132(3): 348-355.

159



1996; 9(1): 19-21.


composite resin restorations. J Prosthet Dent 1991; 65(4): 475-479.



10.

Feilzer AJ, De Gee AJ, Davidson CL. Setting stress in composite resin in

relation to configuration of the restoratives. J Dent Res 1987; 66(11): 1636-

1639.





Ferrari M, Garcia-Godoy F. Sealing ability of new generation adhesive-

restorative materials placed on vital teeth. Am J Dent 2002: 15(2): 117-28.



22(6): 370-375.


dental restorations. J Dent 1999; 27(2): 105-108.




203.

Hickel R. Die zervikale füllung. Dtsch Zahnärzt Z 1994; 49(11): 13-19.



160







418-422.

Ianzano JA, Gwinnett AJ. Clinical evaluation of Class V restorations using a

total etch technique: 1 year results. Am J Dent 1993; 6(4): 207-210.

Ibbetson R, Eder A. Tooth surface loss. BDJbooks 2000: 3-8.

Kidd EAM. Microleakage: a review. J Dent 1976; 4: 199-205.



Lee WC, Eakle WS. Possible role of tensile stresses in the aetiology of

cervical erosive lesions of teeth. J Prosthet Dent 1984, 52(3): 374-380.



Dent 2001; 26(3): 302-307.

Manhart J, Chen HY, Mehl A, Weber K, Hickel R. Marginal quality and

microleakage of adhesive Class V restorations. J Dent 2001; 29(2): 123-130.

Martin DW. Interface leakage in microfilled composites, amalgam,

conventional composites and gold foil: a comparative in vitro study. J Calif

Dent Association 1981; 1(1) : 33-39.

McCoy RB, Anderson MH, Lepe X, Johnson GH. Clinical success of class V

composite resin restorations without mechanical retention. J Am Dent

Association 1998; 129 (5): 593-599.


restorations. J Am Dent Association 1974;88(3): 592-602.

Medina J. Matt gold-gold foil restoration. Journal of the American

Association of Gold Foil Operators 1969; 12-1: 13-26.

161

Norman GR, Streiner DL . PDQ statistics. BC Decker inc 1999. Hamilton.


tubules: Experiments in vivo and in vitro. Act Odontol Scand 1974 ; 32(1):

61-70.

Penschke A, Blunck U, Roulet JF. Influence of incorrect application of

Optibond FL on the marginal adaptation of Class V restorations. Am J Dent

2000; 13(5): 239-244.

Peyton FA, Craig RG (1971) Restorative Dental Materials ,Mosby 4th

edition, St Luis: 358-397.

Powell LV, Gordon GE, Johnson GH. Clinical comparison of Class V resin

composite and glass ionomer restorations. Am J Dent 1992; 5(5): 249-252.





evaluations. Am J Dent 2003; 16(3): 207-210 .

Rees JS. The role of cuspal flexure in the development of abfraction lesions:

a finite element study. Euro J Oral Sci 1998; 106(6): 1028-1032.


Schuckar M, Geurtsen W. Proximo-cervical adaptation of Class II composite

restorations after thermo cycling: a quantitative and qualitative study. J Oral

Rehab 1997 ; 24(10) : 766-775.

Schüpbach P, Guggenheim B, Lutz F. Human root caries. Oral Path Med

1989; 18(3): 146-156.

Sjodin L, Uunsitalo M, van Dijken J. Resin modified glass ionomer cements.

In vitro microleakage. Swed Dent J 1996; 20(3): 77-86.



Sparrius O, Grossman ES. Marginal leakage of composite resin restorations

in combination with dentinal and enamel bonding agents. J Prosthet Dent

1989; 61(6): 678-684.

162

Stibbs GD. Direct golds in dental restorative therapy. Op Dent 1980; 5(3):

107-114.

Thye RP. A comparison of the marginal penetration of direct filling golds

using Ca45. J Am Acad Gold Foil Op 1967; 34 (4): 12-16.



1999; 30(4): 249-257.

Van Meerbeck B, Braem M, Lambrechts P, Vanherle G. Morphological

characterization of the interface between resin and sclerotic dentine. J Dent

1994; 22(3): 141-146.

Wood RE, Maxymiw WG, McComb D. A clinical comparison of glass

ionomer and silver amalgam restorations in the treatment of Class V caries

in xerostomic head and neck cancer patients. Op Dent 1993; 18(3): 94-102.


glass ionomer cement. J Oral Rehab 1997; 25(1): 40-44.



163

Table I

BBuurrss ((ffoorr hhiigghh--ssppeeeedd aanndd llooww--ssppeeeedd hhaannddppiieeccee))

CChhiieesseellss

GGoolldd

PPlluuggggeerrss

BBuunnsseenn bbuurrnneerr

CCaarrvveerrss//kknniivveess

RRuubbbbeerr ccuuppss aanndd ddiisskkss

Table II: Composition of Scotchbond MPS

Primer: 40%HEMA, 15% polyalkenoic acid copolymer, water

Adhesive: 40%HEMA, 70% bis-GMA, photoinitiator

164

Table III: Leakage scores recorded at cervical margin and median

0 1 2 3 4 median

Group 1 8 1 3 0 0 0

Group 2 2 0 0 10 0 3

Group 3 8 4 0 0 0 0

Graph 1

0123456789

10

0 1 2 3 4

goldamalgamcomposite

165


Fig. 1. After immersion in a dye solution, each tooth was embedded in acrylic resin and

longitudinally sectioned at three different levels in the bucco-lingual direction.

.

Fig. 2. Dye penetration scores at the cervical margin

166

Fig. 3a. SEM image of the tooth- restoration interfaces in gold foil restorations that shows a

good adaptation on the dental substrate

Fig. 3b. SEM image of the enamel-restoration interface in gold foil a higher magnification

167

Fig. 4. Typical aspect of resin-bonding-dentin interface achieved in composite resins restoration

168

Chapter 9

Discussion

Since the introduction of resin-based materials in dentistry around the early

fifties of last century, increased concern and research was generated. There

are various reasons for this. One is that research and particularly dental

research underwent considerable upgrading, not at least because of improved

technical possibilities. Another one is that in that post-war period polymers

were introduced on a wide scale and application was accordingly.

Unfortunately, the early “plastics” were usually of questionable quality and so

were the resin-based dental materials. In contrast to their ease of handling,

these materials were mechanically inferior to the established ones such as

amalgam or casting alloys. One particular mediocre property of polymer

materials was their dimensional instability. Thermal expansion and water

swelling were huge and the polymerisation is still accompanied by substantial

volume reduction.

Since, exciting development brought about more stable, bondable, good

looking and easy applicable restorative materials that by now almost replaced

the established metal materials.

Parallel to the technical developments, enlarged interest in cosmetics

conquered the world and thus, also dentistry. With the need of new aesthetic

treatments in restorative dentistry a great interest has developed on the

prediction of the reliability and longevity of restorations. Paramount interest

was given to colour and colour stability and, because, for a great deal, resin-

based material had to do the job, attention had and has to be paid to

dimensional stability. The absence of the latter particularly affects marginal

169

integrity. Even the option of bonding cannot prevent gap formation and

consequently leakage.

To study marginal integrity, several in vitro and in vivo tests are available. In

this thesis the use of a dye, 2% methylene blue was the chosen as the

laboratory method for the study of leakage, whilst marginal staining was used

as an indication for clinical malfunction, both in agreement with the literature.

The in vitro project encompassed dye penetration measurements on several

types of restorations, restored in various ways, ranging from traditional non-

adhesive restorative materials such as gold foils, gold inlays, amalgams, to the

newest adhesive restorative techniques, direct fillings, combined use of

different composite resins, use of aesthetic inlays and self-adhesive luting

cements. Also the influence of different substrates was investigated; in

particular attention was given to the more risky sites where the margins are

placed in cementum-dentin.

A most striking finding was that almost all restorations demonstrated more or

less staining along the restoration-cavity interface, even if the restoration was

placed in theoretically ideal conditions. Taken that staining is indicative for

leakage, leaking restorations were consistently found in practically all our

specimens, though of course there were statistically significant differences

among the various experimental Groups. Moreover, adhesion showed not to be

the guarantee for perfect sealing. This was dramatically shown by the

frequently observed marginal dying of adhesive restorations, whilst the non-

adhesive gold foil fillings showed hardly any leakage. The latter comparative

experiment on straight-forward Class V restorations was carried out because

during the course of the project, doubt arose about the real meaning of the

colour dye penetration experiment as indicative for true leakage. It has to be

emphasized that if one desires to screen new materials, it is impossible to

perform the clinical screening at the same speed as the laboratory tests. Apart

from more complicated sample selection and making, clinical trials take at least

1 – 2 years, whilst the laboratory test can be done within one week. It was

therefore inevitable that there grows a significant time lag between laboratory

170

and clinical experience about a new material or procedure. As our results were

in conformity with literature where laboratory studies show many defects, whilst

the materials perform clinically relatively satisfactory, in vitro leakage should be

regarded as a theoretical maximum amount of leakage that may or may not

occur in vivo. Pashley (1990) stated that results of in vitro studies are often

presumed to be more negative than in vivo ones. (Pashley DH, 1990), but

possibly such a general statement should be differentiated with regard to the

specific in vitro test. Moreover, to date there are no accepted scientific methods

to correlate leakage results and clinical findings (Camps J et al, 2000; Mior IA

& Toffenetti F, 2000).

Based on the present study, it has to be questioned whether the widely

accepted methylene blue dying technique has a reliable clinical implication.

Apart from some sources (Gale MS & Darvell BW, 1999), there are no data

available on an eventual correlation between dye penetration and bacterial

invasion along the interface between restoration and cavity wall.

Another matter that has to be considered is that an eventual perfect initial seal

might be lost with time. It is reported in the literature (Lundin SA & Noren JG,

1991; Hakimeh S et al, 2000 ). that a breakdown of seal happens with aging of

the adhesive interface between resin composite and dental substrate. On the

other hand, corrosion and hygroscopic expansion may improve the sealing

ability of certain restorative materials.

In vitro leakage studies on adhesive constructions can also function as

indication whether the wall-to-wall integrity is persisting. Preliminary studies

(Fabianelli et al. 2004) indicated that the methylene blue staining does not per

se mean loss of adhesion as determined in a micro-tensile bond strength

measurement. Probably the dye penetration, especially the one labelled with a

low score, is a rather a diffusion of small molecules rather than a true stream of

liquid.

171

References Camps J, Dejou J, Remusat M, About I. Factors influencing pulpal response



dental restorations. J Dent 1999;27:105-108.




203.




Quint Int 2000; 31: 165-179.

Pashley DH. Clinical considerations of microleakage. J Endodont 1990; 16: 70-

77.

172

Chapter 10

Summary and Conclusions One of the most important needs of a restoration is to protect exposed

dentin against the infiltration of bacteria and their toxins along the interface

between restoration and dental substrate. For that reason, perfect sealing

should be the plan of each clinical performance and the ideal restorative

material should have a perfect and complete seal of the restoration’s margin.

In this thesis the aim was to measure the quantity and the quality of leakage

in relation to different dental materials, different luting agents, different

restorative techniques and , if possible, to explain the eventual discrepancy

between the in vitro methylene blue leakage findings and the in vivo

appreciations of our restorations.

After a review on leakage and its aspects in chapter 1, in chapter 2 sealing

ability of different types of restorative-adhesive combinations was measured

and etch patterns were correlated with leakage scores. Four combinations

of bonding system/restorative material were tested. Specimens of each

group were processed for leakage test, scored on dye penetration and resin

replicas were observed by SEM. The results of the staining measurements

were statistically evaluated. Our conclusions were that when gingival

margins are placed below the CEJ, the tested material-combinations

performed equally well; Adhesive systems that include etching with

phosphoric acid, sealed enamel margins significantly better than self-etching

primers and self-etching priming bonding agents.

In chapter 3 the in vitro wall-to-wall adaptation of a new self-adhesive resin-

based cement, Relyx Unicem 3M Espe, was evaluated, in comparison with

that of other cements when luting inlays in standardized Class II cavities in

extracted teeth. As a result of new chemistry, it is claimed by the

173

manufacturer that this cement does not require any substrate pretreatment

or adhesive application. Powder is a radiopaque fluoro-aluminosilicate glass,

potassium per-sulfate and ascorbic acid catalyst system mixed with an

aqueous solution of a poly-carboxylic acid modified with pendant

methacrylate Group HEMA and Tartaric acid.

Different combinations of inlay and luting material were tested: porcelain and

gold inlays, resin-based, zinc-oxy-phosphate, glass-ionomer cements. Zinc-

oxy-phosphate cement showed the highest microleakage and the sealing

ability exhibited by the new self-adhesive resin-based cement was

satisfactory with both gold and porcelain inlays, and comparable respectively

to that of resin-based and glass-ionomer cements. Conclusions were that

this new self-adhesive resin-based cement achieved an adequate seal,

similar to a standard adhesive procedure on both enamel and dentin when

used to lute in vitro gold and porcelain inlays.

In chapter 4 the purpose was to evaluate in Class II restorations the

marginal adaptation of 10 different packable composite resins in combination

with the proprietary adhesive system in one hundred human extracted

molars. The quality of marginal adaptation was evaluated through

microleakage tests. Microleakage was significantly higher at the cervical than

at the occlusal margin of the restorations, and the application of a thin layer

of a flowable composite at the cervical margin, as a liner underneath the

packable composite enhanced the marginal adaptation of the restoration.

The use of a self-etching primer to condition the dental substrate resulted at

the occlusal margin in a higher microleakage than when phosphoric acid was

applied.

Chapter 5 describes the observations on the in vitro efficacy of two different

composite luting cements on the prevention of marginal deterioration around

adhesive ceramic inlay restorations, testing whether different luting

procedures can affect sealing ability of luted inlays. Specimens were

selected at random for SEM observations, while others were processed for

marginal leakage. The bonding mechanism to dentin and resin cement

174

thickness was evaluated. The conclusion was that with the use of a self-

curing adhesive system in combination with self-curing resin cement like the

experimental one it seems possible to minimize risks of micro infiltration at

cervical margins.

In chapter 6 attention was given to the evaluation of the in vitro sealing

ability of Class II porcelain inlays with margins placed in cementum-dentin

and enamel, luted with two different cementing materials, correlating the dye

penetration depth with the morphology of dental substrates present at

margins of the preparations. Also in this study a SEM evaluation was

performed to assess with three different protocols: (1) variation of resin

cement thickness, (2) hybrid layer formation at the interface between resin

cement and dental substrate, and (3) to observe the morphology of the

cavity margins. The results of this study suggest that an enamel thickness of

0.5 mm at the cervical margin of Class II indirect restorations in unable to

seal them completely. The two combinations of bonding-cement materials

involved on the protocol performed similarly. The axial enamel margins of

Class II inlays have to be considered as one of the weakest margin of the

cervical area.

Chapter 7 presents a clinical trial, based on the quality expressed in

marginal integrity and sealing of Empress II inlays cemented under clinical

conditions with the self/light-curing Excite DSC and MultiLink adhesive luting

system. All patients received one Empress II inlay with the same clinical

protocol and were recalled after 6 and 12, 24 and 36 months. After 3-year

period of service no inlay came loose during the whole period of observation

and all the inlays were still clinically in service. No fracture was observed and

only moderate discoloration and visible marginal ditching were present in

some of the restorations that were still rated satisfactory. Slight crazing and

little surface staining were also reported. The results suggest that all the

restorations leak, notwithstanding satisfactory clinical performance are

achieved.

175

Chapter 8 was meant to obtain more insight in the discrepancy between

clinical positive appreciation and apparent in vitro leakage. It was evaluated

marginal integrity of standardized Class V cavities, restored with 3 different

sorts of filling materials, each of them generally accepted in the dental

profession. The restorative materials were: gold foil, amalgam and resin-

based composite in addition with a three steps dentin bonding system.

Dye penetration scoring was performed at the cervical margins, whilst also

each specimen was evaluated by SEM observations. Gold and composite

showed a better seal than amalgam in Class V restorations, bearing in mind

that even an non adhesive restorative technique as compacted gold foil still

shows satisfactory results.

General conclusions:

At the end of this thesis several conclusions can be drawn on occurrence of

leakage as demonstrated by methylene blue staining:

Microleakage was significantly higher at the cervical than at the occlusal

margin of restorations.

The application of a thin layer of a flowable composite at the cervical

margin, as a liner underneath the packable composite enhanced the

marginal adaptation of the restoration.

The use of a self-etching primer to condition the dental substrate resulted

at the occlusal margin in a higher microleakage than when phosphoric acid

was applied.

When we evaluated sealing ability of different types of restorative-adhesive

combinations, the tested material combinations performed equally well,

although adhesive systems including etching with phosphoric acid sealed

enamel margins significantly better than self-etching primers and self-etching

priming bonding agents.

176

Luting material combinations and handling procedures can affect the sealing

ability of luted inlays and enamel with a thickness of 0.5 mm at the cervical

margin of Class II indirect restorations was unable to guarantee the seal .

The sealing ability exhibited by RelyX Unicem, Fuji Cem and Variolink II

was satisfactory with both gold and porcelain inlays and an adequate seal

was achieved both on enamel and dentin.

Gold foil and composite resin perform equally with regard to microleakage

and achieve better sealing ability than amalgam.

In the clinical study where Empress II and Variolink were employed no

inlay came loose during the whole period of observation and all the inlays

were still clinically in service.

Discrepancy between observed in vitro staining of at the interface of

restorations and clinical acceptability requires further investigation.

Appendix In vitro leakage studies on adhesive reconstructions are widely accepted as an

indication whether the wall-to-wall integrity is persisting. In a preliminary study

it was indicated that methylene blue staining does not per se mean loss of

adhesion as determined in a micro-tensile bond strength measurement. After

preparing specimens (composite resin bonded to dentin with a Prime and

Bond dental adhesive) for microtensile test, half of the specimens were left for

two hours in methylene blue, where after the microtensile test were performed

( Fig 1 and Fig 2). The scores were the same for the two group, and the group

dipped in methylene blue presented stained surface where the failure occurred

( adhesive interface).

Probably the dye penetration, especially the one labelled with a low score in

leakage tests, is a diffusion of the small methylene blue molecules rather than

a true stream of liquid and doesn’t interfere with adhesion. Another clue might

be that staining indicated only partial conversion of the resin and not true

leakage. In another preliminary study a mass of dentin bonding agent

177

polimerized in a cut needle cap was dipped in methylene blue. After four days,

the specimens were washed. It was observed that the specimen was mainly

stained on the surface, but also staining was found inside the bulk material.

Apart from staining incompletely cured resin, the hydrophilicity of the

monomers in dentin bonding agents is responsible for uptake of the methylene

blue ( Fig.3, Fig.4 and Fig 5).

Staining vs. leakage will be subject for further investigation of the relevance of

color dying as a means to study marginal integrity of restorations.

A second approach will be the study of the narrowest space in which

Streptococcus Mutans can colonize with the use of calibrated micro-pipes and

living bacteria.

References

De Gee AJ, Ten Harkel-Hagenaar E, Davidson CL. Color dye for identification

of incompletely cured composite resins. J Prosthet Dent. 1984 Nov;52(5):626-

31.

178

Riassunto e conclusioni

Uno degli scopi più importanti di un restauro è quello di proteggere la

dentina esposta dall’aggressione dei batteri e delle loro tossine a livello

dell’interfaccia substrato dentale-materiale da restauro. Per questa ragione

un sigillo perfetto dovrebbe essere il fine di ogni attività clinica ed il materiale

ideale da restauro dovrebbe essere in grado di ottenere un sigillo marginale

perfetto. Lo scopo di questa tesi e’ di misurare la quantità e la qualità della

infiltrazione in relazione all’utilizzo di diversi materiali da restauro, diversi

cementi, diverse tecniche di restauro e , se possibile, capire il perché esista

una discrepanza tra le infiltrazioni misurate con il blu di metilene in vitro e il

reale buon funzionamento dei nostri restauri in vivo.

Dopo una review sulla infiltrazione ed i suoi aspetti nel capitolo 1, nel

capitolo 2 si è misurato la capacità di sigillo di diverse combinazioni

materiale da restauro-adesivo, e si sono paragonate diverse strategie di

mordenzatura in rapporto al grado di infiltrazione. Quattro combinazioni di

adesivi dentinali e materiali da restauro sono state sperimentate. I campioni

di ciascun gruppo venivano trattati per essere sottoposti a test di

microinfiltrazione, ne venivano misurate le infiltrazioni, e venivano fatte

repliche da osservare al SEM. I risultati delle misurazioni delle penetrazioni

di colorante venivano poi valutati statisticamente. Le nostre conclusioni

erano che, quando i gradini cervicali erano piazzati sotto la giunzione amelo-

cementizia, le combinazioni di materiali testate funzionavano ugualmente

bene, mentre i sistemi che includevano un passaggio con acido ortofosforico

sigillavano lo smalto significativamente meglio dei self-etching primers e

degli adesivi all-in-one.

Nel capitolo 3 si è valutato in vitro l’ adattamento parete-parete di un nuovo

cemento resinoso auto adesivo, Relyx Unicem 3M Espe, comparandolo con

altri cementi per la cementazione di intarsi in cavità standardizzate di II

Classe su denti estratti. Dotato di una innovativa chimica, secondo le

intenzioni del produttore, questo cemento resinoso non richiederebbe alcun

179

trattamento acido o passaggio di primer per effettuare cementazione

adesiva. La polvere è costituita da vetro fluoro-amino-silicato, potassio pre-

solfato ed un sistema catalitico in base acido ascorbico, mentre il liquido è

una soluzione acquosa di acido policarbossilico modificato con gruppi

metacrilici, HEMA e acido tartarico.

Varie combinazioni di inlays e cementi sono state testate: ceramica ed oro

come materiali per inlays e cementi a base resinosa, all’ossifosfato e vetro-

ionomerici come agenti cementanti. Il cemento all’ossifosfato è stato quello

che ha mostrato i peggiori risultati all’infiltrazione, mentre la capacità di

sigillo del nuovo cemento auto-adesivo si è dimostrata soddisfacente a

prescindere dal materiale utilizzato per gli intarsi, e comparabile ai risultati

ottenuti con le cementazioni adesive classiche. Le conclusioni tratte sono

state che questo nuovo cemento è riuscito ad ottenere un sigillo adeguato e

simile a quello ottenibile con procedure adesive standard, sia a livello di

smalto che di dentina radicolare quando utilizzato per cementare inlays in

oro o ceramica in vitro.

Nel capitolo 4 si è studiata la capacità di adattamento marginale in restauri

di Classe II di 10 diversi compositi compattabili associati ai loro rispettivi

sistemi adesivi. Tale adattamento marginale veniva studiato attraverso tests

di infiltrazione. Tale infiltrazione era maggiormente riscontrabile a livello del

gradino cervicale rispetto al margine occlusale. L’applicazione di un sottile

strato di composito fluido riusciva a diminuire, ma non ad azzerare, il grado

di infiltrazione a livello del gradino cervicale. L’utilizzo di sistemi auto-

mordenzanti dava risultati di infiltrazione peggiori a livello della superficie

occlusale rispetto all’applicazione di mordenzatura acida.

Il capitolo 5 descrive la efficacia in vitro di due diversi agenti cementanti nel

prevenire l’infiltrazione attorno a restauri adesivi in ceramica, valutando se

diverse procedure di cementazione possono dare risultati differenti al test di

infiltrazione. Alcuni campioni venivano scelti a caso per l’osservazione al

SEM, mentre altri venivano avviati al test di micro-infiltrazione. Venivano

analizzati anche I meccanismi di adesione e gli spessori dei cementi

180

resinosi. La conclusione era che l’utilizzo di un sistema adesivo auto-

polimerizzante associato ad un cemento resinoso anch’esso auto-

polimerizzante si riusciva a minimizzare il rischio di infiltrazione a livello del

margine cervicale.

Nel capitolo 6 si è posta l’attenzione alla capacità di sigillo in vitro di intarsi

in ceramica con gradino cervicale posto in cemento-dentina e smalto,

cementati con due diversi sistemi di cementazione, correlando grado di

infiltrazione alla morfologia tissutale presente a livello del margine di

preparazione. Anche in questo studio sono state fatte osservazioni al SEM

con tre diverse analisi: (1) variazione di spessore del cemento, (2)

formazione di strato ibrido a livello dell’interfaccia cemento-dentina, (3)

morfologia dei margini di cavità. I risultati di questo studio sembrano

suggerire che a livello del gradino cervicale in presenza di smalto sottile 0,5

mm non si riesca ad ottenere un adeguato sigillo. I due sistemi di

cementazione hanno dato risultati simili. I margini assiali degli inlays di

Classe II devono essere considerati come margini a rischio, similarmente

all’area del gradino cervicale.

Il capitolo 7 presenta un trial clinico basato sulla qualità della integrità

marginale e del sigillo di inlays in Empress II cementati in vivo utilizzando

come sistema adesivo Excite DSC e come cemento resinoso il Multilink. Tutti

I pazienti di questo studio avevano ricevuto un restauro di questo tipo con lo

stesso protocollo e sono stati richiamati dopo 6, 12, 24 e 36 mesi. Dopo un

periodo di osservazione di 3 anni nessun intarsio è andato perso e tutti i

restauri erano ancora in servizio. Nessuna frattura è stata registrata e solo

una moderata discolorazione marginale e una modesta determinabilità dei

bordi era presente su alcuni inlays. Piccole incrinature e pigmentazioni superficiali erano anche riscontrabili. Tali risultati suggeriscono che anche se

in vitro non riusciamo ad ottenere un sigillo assoluto, clinicamente possiamo

riscontrare buone performances. Il capitolo 8 si propone di meglio

approfondire la dicotomia tra I risultati clinici positivi dei nostri restauri e

l’apparente infiltrazione in vitro. si è valutato la integrità marginale di cavità di

181

Classe V trattate con 3 diverse tipologie di restauro diretto, ciascuna

generalmente accettata dai clinici. I materiali da restauro utilizzati sono stai

oro coesivo, amalgama e composito associato a sistema adesivo. Si è

misurato il grado di infiltrazione a livello del gradino cervicale, oltre ad una

osservazione al SEM.

Oro coesivo e composito hanno dato risultati simili, mentre l’amalgama

sigillava significativamente peggio. Una tecnica non adesiva come quella

dell’ oro coesivo sembra dare risultati soddisfacenti a questo tipo di test.

Conclusioni generali Alla fine di questa tesi diverse conclusioni possono essere tratte sulla

determinazione dell’infiltrazione dimostrata con l’impiego del blu di metilene.

La infiltrazione si presenta maggiormente a livello cervicale rispetto al livello

occlusale

L’utilizzo di uno strato sottile di composito fluido a livello del gradino

cervicale migliora l’adattamento marginale e diminuisce la penetrazione del

blu di metilene.

L’applicazione di un self-etching primer a livello occlusale da come risultato

maggiore infiltrazione rispetto ad adesivi che prevedono l’impiego di

mordenzatura con acido ortofosforico.

Diverse combinazioni di sistemi adesivi e rispettivi compositi danno risultati

positivi ai tests di infiltrazione, sebbene i sistemi che prevedano una

mordenzatura acida diano risultati migliori comparati a quelli che

impiegano dei self-etching primers.

Diversi materiali da cementazione e diverse procedure possono influenzare

la capacità di sigillo degli inlays.

Uno spessore di 0,5 mm di smalto a livello del gradino cervicale non

garantisce un adeguato sigillo.

182

La capacità di sigillo dimostrata da RelyX Unicem, Fuji Cem e Variolink II è

soddisfacente sia se si impiegano inlays in oro o in ceramica.

Gold foil e composito danno risultati simili riguardo l’infiltrazione e superiori a

quelli forniti dai restauri di Classe V in amalgama.

Nel clinical trial dove abbiamo Empress II e Variolink, non si è perso nessun

restauro nel periodo di osservazione e tutti I restauri sono ancora

clinicamente in servizio, con ottima soddisfazione dei pazienti.

La discrepanza tra la penetrazione a livello delle interfacce della sostanza

tracciante e la accettabilità clinica dei nostri restauri deve essere

ulteriormente approfondita.

Appendice

Gli studi sulla micro-infiltrazione dei restauri adesivi sono generalmente

accettati come indicatori della esistenza di integrità tra le pareti del restauro

e del substrato dentale. In uno studio preliminare si è evidenziato che la

colorazione della sostanza tracciante non vuol dire perdita di adesione,

come si è evidenziato con il test micro-tensile per la forza di adesione. Dopo

aver preparato i campioni da sottoporre al micro-tensile test ( composito e

dentina con utilizzo di un adesivo prime and bond dopo mordenzatura

acida), metà campioni sono stati immediatamente processati, mentre gli altri

sono stati lasciati in soluzione di blu di metilene per due ore e poi anch’essi

testati ( Fig 1 and Fig 2). I risultati sono stati gli stessi per i due gruppi, ed il

gruppo blu di metilene presentava pigmentazione a livello della zona di

frattura (interfaccia adesiva).

Probabilmente la penetrazione della sostanza tracciante, specialmente

quella che dava punteggi bassi a livello dei test di infiltrazione, è una

diffusione delle piccole molecole di blu di metilene piuttosto che un vero

flusso di liquido e non interferisce con l’adesione. Un’ altra indicazione

potrebbe essere che la colorazione indica solamente la parziale conversione

del monomero resinoso e non la vera infiltrazione (De Gee AJ et al, 1984) .

183

In un altro studio in fieri si è polimerizzata stratificando una massa di adesivo

dentinale in una punta di un copriago e poi si è immerso il campione in

bagno di blu di metilene al 2% per 4 giorni.

Successivamente I campioni venivano lavati ed osservati con l’utilizzo di

sistemi ottici ingrandenti. Si è osservato che i campioni erano

particolarmente pigmentati in superficie, ma si è reperito anche colorante

all’interno del materiale.

Oltre quindi a pigmentare il monomero resinoso non polimerizzato, il blu di

metilene potrebbe essere assorbito dalla idrofilicità dei monomeri presenti

negli adesivi dentinali. ( Fig.3, Fig.4 and Fig 5).

Il paragonare pigmentazione e infiltrazione sarà il soggetto di ulteriori studi

sulla importanza della penetrazione del colorante come mezzo per valutare la

qualità del sigillo marginale nei restauri.

Un altro approccio sarà lo studio sulla capacità di colonizzazione dello

Streptococcus Mutans di spazi sempre più piccoli con l’utilizzo di

micropipette disponibili nei laboratori di microbiologia.

Referenze

De Gee AJ, Ten Harkel-Hagenaar E, Davidson CL. Color dye for

identification of incompletely cured composite resins. J Prosthet Dent. 1984

Nov;52(5):626-31.

Fig. 1. Campioni pronti al test microtensile

Fig. 2. Campioni dopo test microtensile: notere la presenza di colorante a

livello della interfaccia.

Fig. 3. Campioni di adesivi dentali polimerizzati in un copriago.

Fig. 4. Campioni di adesivi dentali dopo bagno in soluzione di blu di

metilene.

Fig. 5. Sezione del campione dopo bagno in blu di metilene.

184

Résumé et Conclusions Un des principaux objectifs de la restauration est de protéger la dentine

exposée contre l’infiltration des bactéries et de leurs toxines sur l’interface

entre la restauration et le substrat dentaire. Pour cette raison toute

intervention clinique devrait avoir comme but un scellage parfait et le

matériau de restauration idéal devrait permettre de sceller parfaitement et

complètement les bords de la restauration. Notre thèse a comme but de

mesurer la quantité et la qualité des fuites concernant les différents

matériaux dentaires, ciments et techniques employées et dans la mesure du

possible d’expliquer les différences éventuelles qui auraient pu être

remarquées entre les fuites de bleu de méthylène observées in vitro et les

appréciations in vivo de nos restaurations.

Après avoir passé en revue les fuites et leurs différents aspects dans le

1.ier chapitre, nous avons mesuré dans le 2.ième chapitre les propriétés

de scellage des différentes combinaisons restauratrices – adhésives et nous

avons corrélé les schémas de mordançage avec les performances de

fuites. Nous avons soumis à épreuve quatre combinaisons de systèmes

adhésifs et de matériaux de restauration. Des éprouvettes de chaque

groupe ont été soumises à des essais de fuite, on a mesuré la pénétration

de colorant et les répliques en résine ont été observées sous le SEM. Les

résultats des colorations ont été évalués statistiquement. Nos conclusions

montrent que quand les bords gingivaux sont placés en dessous de la

limite CEJ, les combinaisons de matériaux testés ont des performances

égales. Les systèmes adhésifs comprenant le mordançage à l’acide

phosphorique ont scellé les bords significativement mieux que les primers

auto-corrosifs et les adhésifs avec primer auto-corrosif.

L’adaptation in vitro aux parois (wall-to-wall) d’un nouveau ciment

autoadhésif sur base de résine, RelyX Unicem 3M Espe, fait l’objet de

l’examen du chapitre 3 , suivie par une comparaison avec d’autres types de

ciment avec inlay à cimentation dans les cavités de classe II de dents

185

extraites. Nous avons analysé différentes combinaisons d’inlays et de

produits à cimentation : inlays en porcelaine et or, produits à base de résine,

zinc-oxy-phosphate, ciments en verre ionomère. Le ciment zinc-oxy-

phosphate présentait le taux les plus élevé de micro-fuites et les propriétés

de scellage du nouveau ciment autoadhésif sur base de résine étaient

satisfaisantes avec les inlays en porcelaine tout comme avec ceux en or, et

comparables respectivement avec les ciments à base de résine et de verre

ionomère. Nous avons conclu que ce nouveau ciment autoadhésif à base de

résine permettait d’obtenir un scellage approprié et sur l’émail et sur la

dentine lors de l’utilisation in vitro pour cimenter les inlays en or et en

porcelaine.

Le chapitre 4 s’occupe de l’évaluation de l’adaptation marginale de

restaurations de Classe II de 10 types différents de résines composites

condensables en combinaison avec le système adhésif propriétaire sur cent

molaires humaines extraites. La qualité de l’adaptation marginale a été

évaluée par des essais de micro-fuites. Les micro-fuites étaient

significativement plus élevées sur le bord cervical que sur le bord occlusal

des restaurations. Notamment l’application d’une fine couche d’un composite

fluide sur le bord cervical, posée en dessous du composite condensable, a

permis d’améliorer l’adaptation marginale de la restauration. L’emploi d’un

primer auto-corrosif pour la préparation du substrat dentaire a donné lieu a

un nombre plus élevé de micro-fuites sur le bord occlusal, par rapport aux

cas où l’acide phosphorique a été utilisé.

Le Chapitre 5 décrit nos observations de l’efficacité in vitro de deux produits

composites de cimentation pour la prévention de la détérioration marginale

sur le contour des restaurations avec inlays adhésifs en céramique : Nous

avons testé si différentes procédures de cimentation peuvent influencer les

propriétés du scellage des inlays cimentés. Les éprouvettes ont été choisies

de manière randomisée pour l’observation par SEM, tandis que d’autres ont

été examinées pour relever les micro-fuites. On a évalué le mécanisme de

collage à la dentine et l’épaisseur du ciment en résine . Les conclusions

186

montrent que l’emploi d’un système adhésif autorenforçant combiné avec un

ciment en résine auto-renforçante , comme les produits expérimentaux,

semble effectivement minimiser les risques de micro-infiltration sur les bords

cervicaux.

Dans le chapitre 6 nous avons examiné les propriétés de scellage in vitro

des inlays en porcelaine de Classe II avec les bords placés dans le cément

– dentine et dans l’émail, cimentés avec deux produits de cimentation

différents, en établissant une corrélation entre la profondeur de pénétration

du colorant et la morphologie des substrats dentaires qui se trouvaient sur

le contour des préparations. Dans cette étude nous avons également fait

recours à l’observation par SEM avec trois protocoles différents d’évaluation:

(1) la variation de l’épaisseur du ciment résine, (2) la formation d’une couche

hybride sur l’interface entre le ciment résine et le substrat dentaire et (3)

l’observation de la morphologie des bords de la cavité.

Les résultats de cette étude font penser qu’une épaisseur de l’émail de 0,5

mm sur le bord cervical des restaurations indirectes de Classe II empèche le

scellage complet.

Les deux combinaisons de matériaux adhésifs et de ciment prévues par le

protocole ont eu des performances semblables. Les bords axiaux de l’émail

des inlays de Classe II sont à considérer comme les plus faibles de la zone

cervicale.

Dans le Chapitre 7 nous présentons un essai clinique basé sur la qualité en

termes d’intégrité marginale et du scellage des inlays Empress II cimentés

sous conditions cliniques avec un système adhésif de cimentation

autorenforçant à la lumière Excite DSC et MultiLink. Les résultats montrent

que toutes les restaurations présentent des fuites, malgré les performances

cliniques satisfaisantes. Tous les patients ont eu un inlay Empress II en

suivant le même protocole clinique et ont été réexaminés après 6, 12, 24 et

36 mois. Après une mise en place d’une durée de 3 ans aucun inlay ne s’est

détaché pendant toute la période d’observation et tous les inlays étaient

encore cliniquement en service. Nous n’avons observé aucun cas de

187

fracture et il n’y avait qu’une décoloration modérée et des sillons marginaux

visibles dans certaines restaurations qui étaient toutefois considérées

satisfaisantes. On a également signalé de légères craquelures et quelques

taches superficielles.

Avec le Chapitre 8 nous nous sommes proposé de mieux connaître les

différences entre l’appréciation clinique positive et des pertes apparentes in

vitro : l’intégrité marginale des cavités de Classe V standardisées, restaurées

avec trois matériaux d’obturation différents qui sont généralement acceptés

par les dentistes. Les matériaux de restauration étaient : la feuille d’or,

l’amalgame et les composites à base de résine ensemble avec un système

à trois phases d’adhésion à la dentine.

Nous avons évalué la pénétration du colorant sur les bords cervicaux, mais

chaque éprouvette a également été évaluée par SEM. L’or et le matériau

composite ont donné lieu à un meilleur scellage que l’amalgame dans les

restaurations de Classe V, tout en sachant que même une technique de

restauration non adhésive comme la feuille d’or compacté donne encore des

résultats satisfaisants.

Conclusions générales: A la fin de notre thèse plusieurs conclusions peuvent être tirées concernant

la fréquence des fuites comme nous avons pu prouver à l’aide de la

coloration au bleu de méthylène:

Les micro-fuites étaient significativement plus élevées sur les bords

cervicaux que sur les bords occlusaux des restaurations.

L’application d’une fine couche de composite fluide sur le bord cervical,

comme revêtement en dessous du composite condensable, a amélioré

l’adaptation marginale de la restauration.

L’emploi des primers autocorrosifs pour préparer le substrat dentaire a

donné lieu a plus de micro-fuites sur le bord occlusal que l’emploi de l’acide

phosphorique.

188

Quand nous avons évalué les propriétés de scellage de différents types de

combinaisons restauratrices – adhésives, les combinaisons testées se sont

comportées de manière semblable, même si les systèmes adhésifs

comprenant le mordançage à l’acide phosphorique scellaient les bords de

l’émail significativement mieux que les primers auto-corrosifs et les agents

adhésifs auto-corrosifs utilisés comme primer.

Les combinaisons des produits de cimentation et les techniques de mise en

oeuvre peuvent influencer les propriétés de scellage des inlays cimentés et

une épaisseur de l’émail de 0,5 mm sur le bord cervical des restaurations

indirectes de Classe II n’était pas en mesure d’assurer le scellage. Les

propriétés de scellage montrées par RelyX Unicem, Fuji Cem et Variolink II

étaient satisfaisantes, avec les inlays en or tout comme avec ceux en

porcelaine et le scellage obtenu était adéquat sur l’émail et sur la dentine.

La feuille d’or et la résine composite se comportent de la même manière en

matière de micro-fuites et ont des propriétés de scellage supérieures à

celles de l’amalgame.

Dans l’étude clinique qui a utilisé Empress II et Variolink aucun inlay ne s’est

détaché pendant toute la période d’observation et tous les inlays étaient

encore cliniquement en service.

Les différences entre les colorations observées in vitro sur l’interface entre

les restauration et l’acceptabilité clinique nécessitent des

approfondissements ultérieurs.

Appendice

Les études in vitro sur les micro-fuites dans les reconstructions adhésives

sont généralement considérées comme une indication de la persistance de

l’intégrité wall-to– wall. Une étude préliminaire avait indiqué que la coloration

au bleu de méthylène ne signifiait pas en tant que telle une perte de

l’adhésion, comme cela a été mesuré lors des essais sur la micro- traction de

l’adhésion. Après avoir préparé les éprouvettes (résine composite liée à la

189

dentine par un Prime et un Bond dentaire adhésif) pour l’essai de micro-

traction, la moitié des éprouvettes ont été laissées pendant deux heures

dans le bleu de méthylène, ensuite les essais de micro-traction ont été

réalisés. (fig. 1 et fig. 2). Les résultats étaient les mêmes dans les deux

groupes. Mais le groupe trempé dans le bleu de méthylène avait des

surfaces tachées au point de rupture (interface adhésive).

Probablement dans le cas de la pénétration du colorant, notamment lorsque

les résultats concernant les fuites étaient faibles, il s’agissait d’une diffusion

de petites molécules de bleu de méthylène et non pas d’une véritable

infiltration de liquide et il n’y avait pas de conséquences sur l’adhésion. Une

autre explication pourrait être que la coloration n’indiquait qu’une conversion

partielle de la résine et non pas une véritable fuite. (De Gee AJ, Ten Harkel-

Hagenaar E, Davidson CL. Color dye for identification of incompletely cured

composite resins. J Prosthet Dent. 1984 Nov;52(5):626-31).

Dans une autre étude préliminaire une masse d’adhésif de dentine

polymérisée dans une tête d’épingle était trempée dans le bleu de

méthylène. Après quatre jours les éprouvettes ont été lavées. On a observé

que l’éprouvette était surtout colorée sur la surface, mais on a trouvé

également des traces de coloration à l’intérieur du matériau. A part le fait

qu’on observe une coloration des résines qui ne sont pas complètement

renforcées, le caractère hydrophile des monomères des adhésifs de la

dentine est responsable de l’absorption du bleu de méthylène. (fig.3, fig.4 et

fig 5).

La coloration en fonction du degré de fuites sera le thème de la recherche

ultérieure sur l’importance de la coloration comme moyen pour étudier

l’intégrité marginale des restaurations.

Dans une deuxième approche nous examinerons les espaces les plus étroits

susceptibles d’être colonisés par le Streptococcus Mutans à l’aide de micro-

tuyaux et de bactéries vivantes.

190

Fig. 1. l’éprouvette prête pour l’essai de micro-traction.

Fig. 2. l’éprouvette après l’essai de micro-traction: à noter la

présence d’agent colorant sur la zone d’interface.

Fig 3. Éprouvettes avec adhésif de la dentine polymérisé dans une tête

d’épingle.

Fig. 4. Une éprouvette restée quatre jours dans une solution de bleu de

méthylène.

Fig. 5. Coupe d’une éprouvette trempée dans du bleu de méthylène.

191

Resumen y conclusiones

Uno de los requisitos más importantes de la restauración consiste en

proteger la dentina expuesta frente a la infiltración de bacterias y de sus

toxinas a lo largo de la interfase de la restauración y de la superficie dental.

Por ese motivo, la finalidad de toda intervención clínica debería ser

conseguir un sellado perfecto, por lo que el material restaurativo ideal ha de

garantizar un sellado perfecto y completo del margen de la restauración. El

objetivo de este estudio es medir la cantidad y la calidad de las filtraciones

de los distintos materiales dentales, de los agentes de sellado y de las

técnicas de restauración, y en la medida de lo posible, explicar la eventual

discrepancia entre las filtraciones de azul de metileno in vitro y las

apreciaciones in vivo de nuestras restauraciones.

En el capítulo 1 se hace un repaso de las filtraciones y de sus aspectos. En

el capítulo 2 se mide la capacidad de sellado de distintos tipos de

combinados adhesivo-restaurativos y se establece una relación entre los

patrones de grabado y los niveles de filtración. En concreto, se han tomado

en consideración cuatro combinaciones de adhesivos/materiales

restaurativos. En primer lugar, se realizó una prueba de hermeticidad con

muestras de cada combinación, con el fin de medir la penetración de tintura

y se observaron las réplicas de resina por Microscopia de Escaneo de

Electrones (SEM). Los resultados de la prueba de hermeticidad se

analizaron estadísticamente. El estudio llega a la conclusión de que cuando

los márgenes gingivales se sitúan por debajo de la unión cemento-esmalte

(CEJ), los combinados de materiales estudiados actúan igual de bien; los

sistemas adhesivos que incluyen grabado con ácido fosfórico sellan los

márgenes de esmalte considerablemente mejor que los sistemas de

autograbado y que el adhesivo total autograbante.

En el capítulo 3 se evalúa la adaptación parietal in vitro de un nuevo

cemento autoadhesivo a base de resina, RelyX Unicem 3M Espe,

192

comparándola con la de otros cementos a la hora de sellar inlays en

cavidades estandarizadas de clase II de piezas extraídas. Se tomaron en

consideración distintas combinaciones de inlays y de material sellante: inlays

de porcelana y oro, inlays a base de resinas, fosfato de zinc y óxido de zinc,

cementos de ionómero de vidrio. El cemento de fosfato /óxido de zinc mostró

los mayores niveles de microfiltración y la capacidad de sellado del nuevo

cemento autoadhesivo a base de resina fue buena, tanto con inlays de oro

como de porcelana, y comparable a la de los cementos a base de resinas y

ionómeros de vidrio. El estudio concluye que este nuevo cemento

autoadhesivo a base de resina ofrece un sellado adecuado tanto del esmalte

como de la dentina, cuando se utiliza para sellar inlays de oro y porcelana in

vitro.

El objetivo del capítulo 4 es evaluar la adaptación marginal de 10 resinas de

composite condensable en restauraciones de clase II combinadas con un

sistema de adhesión comercial en cien molares humanos extraídos. La

calidad de la adaptación marginal se midió a través de pruebas de

microfiltración. Se comprobó que las microfiltraciones eran

considerablemente mayores en el margen cervical que en margen oclusal de

la restauración, y que la aplicación de una fina capa de composite fluido en

el margen cervical, a modo de "liner" del composite consensable, mejoraba

la adaptación marginal de la restauración. La utilización de un adhesivo

autograbante para preparar la superficie dental produjo más microfiltraciones

en el margen oclusal que la utilización de ácido fosfórico.

El capítulo 5 recoge observaciones sobre la eficacia in vitro de dos

cementos de sellado composite a la hora de prevenir el deterioro marginal

en torno a las restauraciones con inlays de cerámica, y comprueba si la

capacidad de sellado de los inlays se ve afectada por el procedimiento de

sellado adoptado. En este estudio se tomaron varias muestras aleatorias

para realizar las observaciones SEM y se prepararon otras muestras para

detectar filtraciones marginales. Se evaluó el mecanismo de adhesión a la

dentina y el grosor del cemento de resina. El estudio llega a la conclusión de

193

que utilizando sistemas adhesivos autocurantes junto a cementos de resina

autocurantes, como el experimental, es posible minimizar el riesgo de que se

produzcan microfiltraciones en los márgenes cervicales.

En el capítulo 6 se evalúa la capacidad de sellado in vitro de inlays de

porcelana clase II con márgenes situados en cemento-dentina y esmalte y

sellados con dos tipos de cemento distintos. Este estudio relaciona la

profundidad de penetración de la tintura con la morfología que presenta la

superficie dental en los márgenes de las preparaciones. Este estudio

también incluye una evaluación SEM basada en tres protocolos distintos

para comprobar: (1) la variación del grosor de los cementos de resina, (2) la

formación de capa híbrida en la interfase entre el cemento de resina y la

superficie dental, y (3) la morfología de los márgenes de la cavidad. Los

resultados de este estudio indican que un grosor de esmalte de 0,5 mm en el

margen cervical impide sellar completamente las restauraciones indirectas

de clase II. Los dos combinados de materiales adhesivos a base de cemento

que se utilizaron en el estudio dieron los mismos resultados. El margen axial

de esmalte de los inlays clase II ha de ser considerado como uno de los

márgenes más débiles de la zona cervical.

El capítulo 7 presenta un ensayo clínico de la calidad (expresada en

integridad marginal y sellado) de los inlays de Empress II cementados en

condiciones clínicas con los sistemas adhesivos autocurante/ligero Excite

DSC y Multilink. Los resultados indican que todas las restauraciones filtran,

independientemente de su buen resultado clínico. Todos los pacientes

recibieron un inlay de Empress II con el mismo protocolo clínico y pasaron

revisiones a los 6, 12, 24 y 36 meses. A los tres años de la restauración no

se había desprendido ni un solo inlay durante todo el período de observación

y todos los inlays funcionaban correctamente desde el punto de vista clínico.

No se apreciaban fracturas y tan sólo se pudo detectar una moderada

descolocación y un surco marginal visible en algunas restauraciones, que

aun así, se calificaron de satisfactorias. También se detectó un ligero

craquelado y pequeñas manchas en la superficie.

194

El capítulo 8 tiene como objetivo ahondar en las diferencias entre el juicio

clínico positivo y a aparente filtración in vitro. La integridad marginal de las

cavidades estandarizadas de clase V, restauradas con tres tipos distintos de

materiales de relleno, todos ellos de uso corriente en la profesión: lámina de

oro, amalgama y composite de resina, además de un sistema de adhesión a

dentina de tres fases.

Se midió la penetración de la tintura en los márgenes cervicales y se

realizaron observaciones SEM de cada muestra. El oro y el composite

mostraron un sellado mejor que la amalgama en las restauraciones de clase

V, teniendo en cuenta que incluso una técnica restauradora no adhesiva

como la lámina compacta de oro sigue dando buenos resultados.

Conclusiones generales Este estudio arroja varias conclusiones en relación a la presencia de

filtraciones detectadas con tintura azul de metileno:

Las microfiltraciones fueron bastante más frecuentes en el margen cervical

que en el margen oclusal de la restauración.

Aplicando una fina capa de composite fluido en el margen cervical, a modo

de "liner" del composite condensable, se consiguió mejorar la adaptación

marginal de la restauración.

La utilización de un adhesivo autograbante para preparar la superficie dental

produjo más microfiltraciones en el margen oclusal que la aplicación de

ácido fosfórico.

Al evaluar la capacidad de sellado de los distintos tipos de combinados

adhesivos-restaurativos, todos los combinados estudiados dieron los

mismos resultados, aunque los sistemas adhesivos con grabado de ácido

fosfórico sellaron los márgenes de esmalte bastante mejor que los primers

autograbantes y los adhesivos totales autograbantes.

Los combinados de material sellante y los procedimientos de manipulación

pueden alterar la capacidad de sellado de los inlays. De igual manera, un

195

grosor de esmalte de 0,5 mm en el margen cervical no garantiza el sellado

de la restauración indirecta de clase II.

La capacidad de sellado de RelyX Unicem, Fuji Cem y Variolink II, tanto con

inlays de oro como de porcelana, fue buena. Estos productos sellaron bien

tanto en esmalte como en dentina.

La lámina de oro y la resina de composite son igual de buenos frente a las

microfiltraciones y poseen más capacidad de sellado que la amalgama.

En el estudio clínico con Empress II y Variolink no se desprendió ningún

inlay durante todo el período de observación y todos los inlays seguían

funcionando bien desde el punto de vista clínico.

Se ha de seguir investigando la discrepancia entre las manchas observadas

in vitro en el interfase de las restauraciones y la aceptabilidad clínica dichas

restauraciones.

Apéndice Los estudios in vitro sobre las filtraciones de las reconstrucciones adhesivas

se consideran como un buen indicador del estado de integridad parietal. En

un estudio anterior se indica que la filtración de azul de metileno no significa

de por sí que se haya producido una pérdida de adhesión, tal como se

determina en una medición de la fuerza de unión microtensil. Para realizar la

prueba microtensil se prepararon una serie de muestras (resina composite

adherida a dentina con un adhesivo dental prime and bond). Seguidamente

se sumergió la mitad de estas muestras en azul de metileno durante dos

horas, al cabo de las cuales se realizó la prueba microtensil ( fig 1 y fig 2).

Ambos grupos obtuvieron la misma puntuación y el grupo sumergido en azul

de metileno presentó manchas en aquellas partes de la superficie en las que

se produjo un fallo (interfase adhesiva).

Probablemente la penetración de la tintura en las muestras, especialmente

en aquellas con baja puntuación en las pruebas de filtración, se debe a la

difusión de pequeñas moléculas de azul de metileno y no a un flujo real de

196

líquido, por lo que no interfieren con la adhesión. Otra señal es que las

manchas indicaban tan sólo una curación parcial de la resina y no una

filtración auténtica (De Gee AJ, Ten Harkel-Hagenaar E, Davidson CL. Color

dye for identification of incompletely cured composite resins. J Prosthet Dent.

1984 Nov;52(5):626-31).

En otro estudio anterior se sumergió en azul de metileno una determinada

cantidad de agente adhesivo a la dentina polimerizado en un capuchón de

aguja cortado. Al cabo de cuatro días se lavó la muestra. Se observó que la

mayoría de las manchas de la muestra eran superficiales, pero también se

encontraron machas en el material interior. Aparte de manchar la resina no

curada totalmente, la hidrofilicidad de los monómeros de los adhesivos a

dentina es la responsable de la absorción de azul de metileno ( Fig.3, Fig.4 y

Fig 5).

Para estudiar la integridad marginal de las restauraciones se deberá

investigar la relevancia de la coloración en las manchas y cotejarla con la de

las filtraciones.

El segundo enfoque de investigación consistirá en estudiar con microtubos y

bacterias vivas el espacio mínimo que el Streptococcus Mutans necesita

para colonizar

Fig. 1. Muestra preparada para la prueba microtensil.

Fig. 2. Muestra tras la realización de la prueba microtensil: notar la presencia

de tintura en la zona interfase.

Fig 3. Muestras de agente adhesivo a la dentina polimerizadas en capuchón

de aguja cortado.

Fig. 4. Aspecto de las muestras tras permanecer cuatro días en una solución

de azul de metileno.

Fig. 5. Sección de muestra sumergida en azul de metileno.

197

Zusammenfassung und Schlussfolgerungen

Eines der wichtigsten Erfordernisse bei der Restauration ist, freiliegendes

Dentin am Übergang zwischen Restauration und natürlicher

Zahnhartsubstanz vor Infiltration von Bakterien und Toxinen zu schützen.

Beim klinischen Eingriff ist daher auf einen einwandfreien Abschluss zu

achten und ein Restaurationsmaterial zu wählen, das den Restaurationsrand

perfekt und vollständig schließt.

Ziel dieser Arbeit ist es Quantität und Qualität der Undichtigkeit bezogen auf

verschiedene Zahnsubstanz, Zemente, verschiedener Füllstoffe,

verschiedene Restaurationstechniken zu messen und wenn möglich die

eventuelle Diskrepanz zu klären zwischen den in vitro Ergebnissen mit

Methylenblau und den in vivo Erkenntnissen bei Restaurationsarbeiten.

Kapitel 1 gibt einen Überblick über Undichtigkeit und ihre Aspekte Kapitel 2 untersucht die Haftfähigkeiten verschiedener Kombinationen von

Füllmitteln und setzt Ätzmodelle in Korrelation zu Messergebnissen der

Undichtigkeit.

Vier Tests mit jeweils verschiedenen Kombinationen von Bonding /

Restaurationsmaterial- Kombinationen wurden durchgeführt.

Die Proben jeder Gruppe wurden auf Undichtigkeit geprüft und nach

Farbstoffeindringung gestuft, die Schaumodelle wurden mit Hilfe von SEM

untersucht. Die Ergebnisse der Verfärbungsmessungen wurden statistisch

ausgewertet. Wir kamen zu folgenden Schluss: bei Gingivallücken unter

dem Schmelzzement (CEJ) erzielen die getesteten Materialkombinationen

gleichgute Ergebnisse; Adhäsivtechniken, die mit Phosphorsäure verätzen,

dichten Zahnschmelzränder besser ab als selbstverätzende Primer und

selbstverätzende Bondingmittel.

Kapitel 3 untersucht den in vitro Wand-zu-Wand Abschluss eines neuen

selbsthaftenden Harzzements im Vergleich zu anderen Zementen und prüft

seine Eignung zur Zementierung von Füllung von Standard II- Kavitäten

nach Zahnextraktion . Getestet wurden verschiedene Verbindungen von

198

Füllungen und Zementen wie: Porzellan- und Goldinlays, Harz,

Zinkoxidphosphat und Glasionomerzement.

Bei Zinkoxidzement trat die höchste mikroskopische Undichtigkeit auf,

während der neue, selbsthaftende Harzzement, RelyX Unicem 3M Espe, mit

Gold- oder Porzelanfüllung ebenso gute Ergebnisse zeigte, wie Harzzement

und Glasionomerzement .

Daraus wurde gefolgert: bei in vitro Zementierung von Gold- und

Porzellanfüllungen gewährt der neue selbsthaftende Harzzement eine

adäquate Versiegelung von Schmelz und Dentin .

Kapitel 4 untersuchte den Randschluss bei Klasse II-Restaurationen; dazu

wurden 10 verschiedene, formbare Komposite in Kombination mit dem

System der Eigenhaftung bei hundert extrahierten Molaren getestet. . Die

Qualität des Randschlusses wurde mittels mikroskopischer Undichtigkeit-

Tests bestimmt. Die mikroskopische Undichtigkeit lag am Zahnhalsrand

wesentlich höher als am Okklusalrand der Restauration. Daher wurde eine

dünnen Schicht von Flüssig- Komposit am Zahnhalsrand als Haftgrund

unter dem formbaren Komposit aufgetragen und somit der Randschluss

verbessert. Die Verwendung von selbstverätzendem Primer zur

Vorbehandlung des Zahnsubstrats führte am Okkusalrand zu höherer

mikroskopischer Undichtigkeit als bei Verwendung von Phosphorsäure.

Kapitel 5 beschreibt die in vitro Effizienz von zwei Kompositzementen, um

einer Rand -Verschlechterung rund um die Keramikfüllung der Restauration

vorzubeugen und testet, ob verschiedene Zementierungsverfahren die

Verschlussfähigkeit von Zementfüllungen beeinträchtigt. Einige Stichproben

wurden für die SEM Beobachtung ausgewählt, die übrigen wurden wegen

Randundichtigkeit besonders behandelt. Die bonding- Eigenschaften zu

Dentin und zur Dicke des Harzzement wurde bestimmt. Daraus wurde

gefolgert, dass eine selbsthärtende Adhäsivtechnik in Kombination mit

selbsthärtendem Harzzement wie dem im Experiment verwendeten, das

Risiko einer Mikroinfiltration am Zahnhalsrand vermutlich reduziert.

199

Kapitel 6 betrachtet die in vitro Verschlusskapazität von Porzellanfüllungen

der Klasse II mit Cementum- Dentin und Schmelzrand und mit zwei

verschiedenen Zementmaterialien zementiert, und stellt eine Korrelation

zwischen Tiefe der Farbpenetration und Morphologie des Zahnsubstrats an

den Präparationsrändern her. Des Weiteren enthält die Studie eine SEM

Bewertung mit drei verschiedenen Protokollen: (1) Variationen der

Harzzementdicke (2) Bildung einer Hybridschicht an der Schnittstelle

zwischen Harzzement und dem Zahnsubsubstrat, (3) Beobachtung der

Morphologie der Kavitätsränder. Die Studie zeigt, dass 0,5 mm dicker

Schmelz bei Indirekt Restaurationen der Klasse II am Zahnhalsrand keinen

vollständigen Verschluss gewährt. Die Zemente des Protokolls verhielten

sich in beiden Kombinationen ähnlich. Die Axial-Schmelzränder von Klasse

II- Einlagen sind deshalb als eine der schwächsten Ränder im

Zahnhalsbereich anzusehen.

Kapitel 7 beschreibt einen klinischen Versuch und geht aus von der

Qualität, d.h. der Integrität des Randbereichs und der Verschlusskapazität

von Empress II- Einlagen, die unter klinischen Bedingungen und mit

lichthärtendem Excite DSC und nach der MultiLink-Technik zementiert

wurden. Die Prüfung ergabt: Undichtigkeit bei allen Restaurationen trotz

befriedigender klinischer Ergebnisse. Alle Patienten erhielten eine Empress

II- Füllung mit gleichem klinischem Protokoll und wurden nach 6 und 12, 24

und 36 Monaten wieder einbestellt. Nach 3 Jahren saßen alle Füllungen

noch fest und waren noch im klinischen Einsatz. Bruch wurde nicht

festgestellt, bei einigen Restaurationen wurde lediglich eine leichte

Verfärbung und sichtbares ditching an den Rändern beobachtet, das aber

noch als befriedigend eingestuft wurde. Leichte Rissbildung und Verfärbung

an der Oberfläche. Kapitel 8 versucht Einblick zu gewinnen in die Diskrepanz zwischen

positiver klinischer Bewertung und der festgestellten in vitro Undichtigkeit.

Randintegrität bei standardisierten Klasse V- Kavitäten, die mit 3

verschiedenen, von Zahnärzten allgemein akzeptierten, Füllstoffen

200

restauriert wurden, nämlich: Gold, Amalgam, und Komposite sowie einem 3-

Stufen Dentin Bonding-System.

Kerben am Zahnhalsrand wurden Die Farbpenetration am Zahnhalsrand wurde untersucht und jede Probe

wurde nach SEM bewertet. Bei Klasse V- Restaurationen gewährten Gold

und Komposite einen besseren Randschluss als Amalgam, wobei zu

berücksichtigen ist, dass selbst bei nicht adhäsiver Restaurationstechnik

z.B. mit Kompakt- Gold befriedigende Ergebnisse erzielt wurden.

Aus den Beobachtungen von Undichtigkeit bei Methylenblau- Verfärbung

lassen sich folgende Schlussfolgerungen ziehen:

Wesentlich größere mikroskopische Undichtigkeit am Zahnhalsrand als am

Okklusalrand der Restauration. Besserer Randschluss durch Aufstreichen

einer dünnen Schicht Flüssigkomposits am Zahnhalsrand, zur Haftung unter

dem verformbaren Komposit. Die Verwendung eines selbstverätzenden

Primers zur Behandlung des Zahnsubstrats verursachte am Okklusalrand

größere Undichtigkeit als Phosphorsäure.

Bei der Prüfung der Verschlussfähigkeit der einzelnen Haftkombinationen

schlossen die einzelnen Materialkombinationen gleich gut ab, obwohl bei

Verätzen mit Phosphorsäure, die Schmelzränder weit besser verschlossen

wurden als mit Selbst-verätzendem Primer und selbstverätzendem Bonder.

Zementkombinationen und Arbeitsverfahren können Verschlussfähigkeit von

zementierten Füllungen beeinflussen. Zahnschmelz in 0,5 mm Dicke am

Zahnhalsrand von Indirekt-Restaurationen der Klasse II konnte keinen

Verschluss gewährleisten.

Gold- und Porzellanfüllungen wurden mit RelyX Unicem, Fuji und Variolink II

zufrieden stellend verschlossen und gewährleisteten einen adäquaten

Verschluss auf Zahnschmelz und Dentin.

Gold und Kunststoffharz zeigen ein gleiches Verhalten gegenüber

mikroskopischer Undichtigkeit und verschlossen besser als Amalgam.

201

Die klinische Studie verwendete Empress II und Variolink; während der

gesamten Beobachtungszeit löste sich keine Füllung und alle Füllungen

waren noch im klinischen Einsatz.

Die Diskrepanz zwischen in vitro Verfärbung an der Schnittstelle der

Restauration und der klinischen Akzeptanz muss noch weiter untersucht

werden.

Anhang

Untersuchungen der in vitro Undichtigkeit bei Adhäsivrekonstruktionen

werden weitgehend als Hinweis auf eine anhaltende Wand zu Wand-

Integrität verstanden. Eine Preliminar- Studie besagt, dass die

Methylenblaufärbung per se noch nicht auf den Verlust von Haftung

hinweist wie Mikro-Zugfestigkeit-Messungen ergaben. Die Proben wurden

für den Mikro-Zugfestigkeit Test vorbereitet (Kompositharz an Dentin

gebondet mit Hilfe eines Prime and Bond Dentaladhäsivs ), danach wurde

eine Hälfte zwei Stunden in einer Methyklenblau-Bad getaucht und auf

Mikro-Zugfestigkeit getestet.(Abb. 1 und 2). Beide Gruppen erzielten die

gleichen Meßwerte, wobei bei der Gruppe des Methylenblau-Bads an den

Schadstellen Verfärbungen auftraten ( Adäsivschnittstelle).

Die Farbpenetration, insbesondere die mit niedrigerem Undichtigkeits-

Meßwert, entsteht wahrscheinlich durch Diffusion kleiner Methylenblau –

Moleküle, nicht durch austretende Flüssigkeit und beeinträchtigt die Haftung

damit nicht. Die auftretenden Verfärbungen könnten ein weiterr Hinweis auf

eine Teil- Umwandlung des Harzes sein,nicht aber auf tatsächliche

Undichtigkeit. (DeGee AJ, Ten Harkel-Hagenaar E, Davidson CL.Color dye

for identification of completely cured composite resins.J Prosthet Dent. 1984

Nov; 52 (5) 626-31).

In einer anderen Preliminar- Studie wurde eine Klumpen Dentin-Bonding in

einer halbierten Kapsel polymerisiert und in ein Methylenblau- Bad getaucht.

Vier Tage später wurden die Proben gewaschen und nicht nur an der

202

Oberfläche, sondern auch im Inneren waren Verfärbungen aufgetreten.

Gehärtetes Harz verfärbt sich nur unvollständig und die Aufnahme von

Methylenblau ist in erster Linie auf die hydrophilen Monomere des Dentin –

Bondingmittels zurückzuführen. ( Abb. 3,4,5 ).

Die Gegenüberstellung von Verfärbung und Undichtigkeit wird Gegenstand

weiter Untersuchungen sein, um festzustellen, inwiefern Färbung Aufschluss

über die Zahnrandintegrität in Restaurationen gibt.

In einem zweiten Ansatz wird untersucht werden auf welch engem Raum

Streptococcus Mutans mit Hilfe von kalibrierten Mikroröhren und

Lebendbakterien Kolonien bilden können.

Abb. 1 Probestück für die Prüfung der Mikro-Zugfestigkeit

Abb. 2 Probestück nach der Prüfung . Man beachte den Farbstoff an der

Schnittstelle

Abb. 3 polymerisierte Dentin-Bonding Proben in einer offenen Kapsel

Abb. 4 Probe nach 4-tägigem Methylenblau- Bad

Abb. 5 Teil der Probe im Methylenblau-Bad

203

Figures Fig. 1. Specimen ready for micro-tensile test.

Fig. 2. Specimen after micro-tensile test: note the presence of the staining agent at the interface

area.

204

Fig 3. Dentin bonding agent specimens polymerised in needle cap.

Fig. 4. Specimen after four days dwelling in a methylene blue solution.

205

Fig. 5. Section of the specimen dipped in methylene blue

206

Chapter 11

References

ADA Council on Scientific Affairs/ADA Council on Dental Benefit Programs.

Statement on posterior resin-based composites. J Am Dent Assoc 1998;

129: 1627-1628.

Adair PJ, Grossman DG. The castable ceramic crown. Int J Period Rest

Dent 1984; 4: 32–38.

Affleck MS, Denehy GE, Vargas MA. Microleakage with incremental vs bulk

placement utilizing condensable composites. J Dent Res 1999; 78: 155.


review. Op Dent 1997; 22(4): 173-185.

Alavi AA, Kianimanesh N. Microleakage of direct and indirect composite

restorations with three dentin bonding agents. Op Dent 2002; 27: 19-24.

Almeida JB, Platt JA, Oshida Y, Moore BK, Cochran MA, Eckert GJ. Three

different methods to evaluate microleakage of packable composites in class

II restorations. Op Dent 2003; 28: 453-460.

Andrews JT, Hembree JH Jr. Marginal leakage of amalgam alloys with high

content of copper: a laboratory study. Op Dent 1980; 5: 7-10.

Anusavice KJ. Quality evaluation of dental restorations. Chicago:

Quintessance, 1989.

Apicella A, Raddi S, Ausiello P, et al. FEM study of shrinkage stress build-up

on adhesive restorations. J Dent Res 1997; 76: 49 (Abstr 435).

Attal JP, Degrange M. Influence de l’orientation des prismes et du traitment

de surface sur l’adhesion et l’adherence a l’email. J Biomater Dent 1996; 11:

41-57.


adhesively luted ceramic inlays. Int J Prosthodont 1999; 12: 342-347.

207

Ausiello P, Apicella A, Davidson CL. Effect of adhesive layer properties on

stress distribution in composite restorations--a 3D finite element analysis.

Dent Mater 2002; 18: 295-3003.

Banks RG. Conservative posterior ceramic restorations: a literature review. J

Prosthet dent 1990; 63(6): 619-626.


restorations using thermal cycling. Quintessence Int 1985;16(11): 765-769.

Bayne SC, Heymann HO, Wilder AD, et al. Clinical performance of bonding

systems with and without hybrid layers. J Dent Res 1996; 75: 23 (Abstr 47).

Belli S, Inokoshi S, Ozer F, Pereira PNR, Ogata M, Tagami J. The effect of

additional enamel etching and a flowable composite to the interfacial

integrity of class II adhesive composite restorations. Op Dent 2001; 26: 70-

75.


interface by corrosion products. J Oral Rehab 1995; 22(2): 101-104.

Bessing C, Molin M. An in vivo study of glass ceramic (Dicor) inlays. Acta

Odont Scand 1990; 48: 351–356.

Beznos C. Microleakage at the cervical margin of composite Class II cavities

with different restorative techniques. Oper Dent 2001; 26: 60-69.

Binns D. The chemical and physical properties of porcelain. In: J.W.

McLean, Editor, Dental Ceramics: Proceeding of the First International

Symposium on Ceramics, Quintessence, Chicago 1983:,41–83.

Blackwood HJJ. Intermediate cementum. Br Dent J 1957; 102: 345-350.

Bosshardt DD, Selving KA. Dental cementum: The dynamic tissue covering

the root. Periodontal 2000 1997; 13: 41-75.

Bradford EW. Microanatomy and histochemistry of dentin. In: Miles AEW.

Structural and chemical organization of teeth. New York: Academic Press,

1967; Vol II, 49.

Bränström M, Vojinovic O. Response of dental pulp to invasion of bacteria

round threefilling materials. J Dent r Child 1976; 43: 15-21.

208

Brännström M, Nordenvall KJ. Bacterial penetration, pulpal reaction and the

inner surface of enamel bond, composite fillings in etched and un etched

cavities. J Dent Res 1978; 57: 3-10.

Branstrom M. Dentin and pulp in restorative dentistry. London: Wolfe

Medical Publ., 1982.

Branstrom M. Etiology of dentin Hypersensivity. Proc Finn Dent So 1992; 88

(Suppl. 1): 7-13.

Cagidiaco MC, Ferrari M. Bonding to dentin: Mechanism morphology and

efficacy of bonding resin composites to dentin in vitro and in vivo.

Amsterdam, University of Amsterdam, Ph D Thesis, De Batte Ed. 1995.


cementum layer at cervical margins of Class II restorations. CED-IADR

Congress, Lubliana, September 1995.

Cagidiaco MC, Ferrari M, Garberoglio R. Dentin contamination protection

after mechanical preparation for veneering. Am J Dent 1996;9(2): 57-60.

Cagidiaco MC, Ferrari M, Vichi A, et al. Mapping of tubule and intertubule

surface areas available for bonding in Class V and Class II preparations. J

Dent 1997; 25: 379-389.



1996; 75 (Abstr 28) 1220.

Camps J, Dejou J, Remusat M, About I. Factors influencing pulpal response


Carvalho RM, Pereira JC, Yoshiyama M, Pashley DH. A review of

polymerisation contraction: the influence of stress development versus

stress relief. Op Dent 1996; 21(1): 17-24.

Cavel WT, Kelsey WP, Barkmeier WW , Blankenau RJ. A pilot study of the

clinical evaluation of castable ceramic inlays and a dual cure resin cement.

Quintessence Int 1988; 19: 247–252.

209

Chen HY, Hickel R, Setcos JC, Kunzelmann KH. Effects of surface finish

and fatigue testing on the fracture strength of CAD/CAM and pressed

ceramic crowns. J Prosthet Dent 1999; 82: 468-475.

Chen HY, Manhart J, Hickel R, Kunzelmann KH. Polymerization contraction

stress in light cured packable composite resins. Dent Mater 2001; 17: 253-

259.

Chuang SF, Liu JK, Jin YT. Microleakage and internal voids in Class II

composite restorations with flowable composite linings. Op Dent 2001; 26:

193-200.




183.

Coli P, Brannstrom M. The marginal adaptation of four different bonding

agents in Class II composite resin restorations applied in bulk or in two

increments. Quintessence Int 1993; 24: 583-591.

Cooley R, Barkmeirer W. Dental shear bond strength, microleakage and

contraction gap of visible light- polymerised liner/bases. Quintessence Int

1991; 22: 467-474.

Cox CF. Evaluation and treatment of bacterial microleakage. AM J Dent

1994; 7: 293-295.

Crim GA, Chapman KW. Effect of placement techniques on microleakage of

a dentin bonded composite resin. Quintessence Int 1986; 17: 21-24.

Dagostin A, Ferrari M. In vivo bonding mechanism of an experimental

bonding system. Am J Dent 2001; 14: 103–108.

Dagostin A, M Ferrari, Effect of dual bonding technique on the bond strength

of ceramic restorations. Dent Mater 2002; 18: 304–310.

Davidson CL, De Gee AJ, Feilzer A. The competition between the composite

dentin bond strength and the polymerisation contraction stress. J Dent Res

1984; 63(12) :1396-1399.

210

Davidson CL, De Gee AJ,. Relaxation of polymerisation contraction stresses

by flown in dental composites. J Dent Res 1984; 63: 146-148.


Prosthet Dent 1986; 55(4): 446-447.

Davidson CL. Glass Ionomer Bases Under Posterior Composites. In: Glass

Ionomers: The Next Generation. Proc. of the 2nd Int. Symp. on Glass

Ionomers. Ed.: P.R. Hunt, Philadelphia PA, USA. June 1994; p. 175-179


shrinkage stress in polymer-based restoratives. J Dent 1997; 25: 435-440.

Davidson CL, Davidson-Kaban SS. Handling of mechanical stresses in

composite restorations. Dent Update 1998; 25: 274-279.

Davidson CL. Luting Cement, the Stronghold or the Weak Link in Ceramic

Restorations. Advanced Engineering Materials 2001; 3, 10: 763-767.

Davidson-Kaban SS, Davidson CL, Feilzer AJ, de Gee AJ, Erdilek N. The

effect of curing light variations on bulk curing and wall-to-wall quality of two

types and various shades of resin composites. Dent Mater 1997; 13: 344-

352.

De Gee AJ, Ten Harkel-Hagenaar E, Davidson CL. Color dye for identification

of incompletely cured composite resins. J Prosthet Dent. 1984 Nov;52(5):626-

631.

De Gee, A.J. Personal communications, 2004.

Dietrich T, Lösche AC, Lösche GM. Marginal adaptation of direct composite

and sandwich restorations in Class II cavities with cervical margins in

dentine. J Dent 1999; 27(6): 119-128.

Dietschi D, Maeder M, Meyer J-M. In vitro resistance to fracture of porcelain

bonded to tooth. Quintessence Int 1990; 21: 823–831.

Dietschi D, Maeder M, Holz J. In vitro evaluation of marginal fit and

morphology of fired ceramic inlays. Quintessence Int 1992; 23: 271–278.

Dietschi D, Scampa G, Campanile U, et al. Marginal adaptation and seal of

direct and indirect Class II composite restorations: An in vitro evaluation.

Quintessence Int 1995; 26: 127- 138.

211

Dietschi D, Sperafico R. Adesive metal-free restorations. Current concepts

for the esthetic treatment of posterior teeth. Berlin: Quintessence 1997.

Dietschi D, Bindi G, Krejci I, Davidson C. Marginal and internal adaptation of

stratified compomer-composite Class II restorations. Oper Dent 2002; 27:

500-509.

Dixit V, Bini E, Drozda M, Blum P. Mercury inactivates transcription and the

generalized transcription factor TFB in the archaeon Sulfolobus solfataricus.

Antimic Ag Chem 2004; 48 (6): 1993-1999.

Dodes JE. The amalgam controversy: an evidence-based analysis. J Am

Dent Association 2001; 132(3): 348-355.



1996; 9(1): 19-21.

Donly KJ, Jensen ME. Posterior composite Class II restorations: In vitro

comparison of preparation designs and restorations techniques. Dent Mater

1990; 6: 88-93.


composite resin restorations. J Prosthet Dent 1991; 65(4): 475-479.

Duguid R. Copper-inhibition of the growth of oral streptococci and

actinomyces. Biomat 1983; 4(3):225-227.

Duncalf WV, Wilson NH. A comparison of the marginal and internal


moderate-sized Class II preparations of conventional design. Quintessence

Int 2000; 31: 347-352.



374.

Eick JD, Welch FH. Polymerization shrinkage of posterior composite resins

and its possible influence on postoperative sensitivity. Quintessence Int

1986 ; 17: 103–111.

212

Eick JD, Gwinnett AJ, Pashley DH, Robinson SJ. Current concepts on

adhesion to dentin. Critical Reviews of Oral Biology and Medicine 1997;

8(3): 306-335.

El Mowafi OM, Benmergui C, Levinton C. Meta- analysis on long-term

clinical performance of posterior composite restorations. J Dent 1994; 22:

33-43.

El Zohairy AA, De Gee AJ, Hassan FM, Feilzer AJ. The effect of adhesives

with various degrees of hydrophilicity on resin ceramic bond durability. Dent

Mater, 2004 in press.



10.

Feilzer AJ, De Gee AJ, Davidson CL. Setting stress in composite resin in

relation to configuration of the restoratives. J Dent Res 1987; 66(11): 1636-

1639.



Feilzer AJ, De Gee AJ, Davidson CL. Increased wall-to wall curing

contraction in thin bonded resin layers. J Dent Res 1989 ; 68 : 48-50.

Feilzer AJ, de Gee AJ, Davidson CL. Quantitative determination of stress

reduction by flow in composite restorations. Dent Mater 1990; 6: 167-171.

Felden A, Schmalz G, Federlin M, Hiller KA. Retrospective clinical

investigation and survival analysis on ceramic inlays and partial ceramic

crowns: results up to 7 years. Clin Oral Invest 1998; 2: 161-167.

Fernandes CP, Chevitarese O. The orientation and directions of the rods in

dental enamel. J Prosthet Dent 1991; 65 : 793-800.




and V cavities to penetration by an adhesive system. Dental Mater 1997; 13:

152-162.

213


Influence of tissue characteristics at margins on leakage of class II in direct


Ferrari M. “Advances in Glass-Ionomer Cements” in Davidson CL and Mjor

IA: Glass-Ionomer Cements. Quintessence Int, Berlin 1999: 137-148.

Ferrari M, Vichi A, Grandini S, Goracci C. Efficacy of a self-curing

adhesive/resin cement system on luting Vectris fiber posts into root canals: a

SEM investigation. Int J Prosthodont 2001; 14: 543–549.

Ferrari M, Garcia-Godoy F. Sealing ability of new generation adhesive-

restorative materials placed on vital teeth. Am J Dent 2002: 15(2): 117-28.

Finger WJ, Inoue M, Asmussen E. Effect of wettability of adhesive resins on

bonding to dentin. Am J Dent 1994; 7: 35-38.

Frankenberger R, Kramer N, Petschelt A. Technique sensitivity of dentin

bonding: Effect of application mistakes on bond strength and marginal

adaptation. Oper Dent 2001;4: 324-330.

Frankenberger R, Kramer N, Petschelt A: Technique sensitivity of dentin

bonding: effect of application mistakes on bond strength and marginal

adaptation. Oper Dent 2000; 25: 324-330.

FusayamaT. Indicationfor self-cured and light-cured adhesive composite

resins. J Prosth Dent 1992; 67: 46-51.



22(6): 370-375.


dental restorations. J Dent 1999; 27(2): 105-108.

Goracci C, Ferrari M, Grandini S, Monticelli F, Tay FR. Bonding of a self-

adhesive resin cement to dental hard tissues. J Adhes Dent 2003 (in press).

Griffiths BM, Watson TF, Sherriff M. The influence of dentine bonding

systems and their handling characteristics on the morphology and micro

permeability of the dentine-adhesive interface. J Dent 1999; 27: 63-71.

Grossman DG. Cast glass ceramics. Dent Clin North Am 1985; 29: 275.

214

Guzman AF, Moore BK, Andres CJ. Wear resistance of four luting agents as

a function of marginal gap distance, cement type and restorative material. Int

J Prosthodont 1997; 10:25-30.

Gwinnet AJ, Kanca J. Micromorphological relationship between resin and

dentin in vivo and in vitro. Am J Dent 1992; 5: 19-23

Gwinnett AJ, Tay FR, Pang KM, et al. Comparison of three methods of

critical evaluation of microleakage along restorative interfaces. J Prosthet

Dent 1995; 74: 575-585.

Gwinnett AJ. Chemically conditioned dentin: A comparison of conventional

and environment scanning electron microscopy findings. Dent Mater 1994;

10: 150-155.

Hahn P, Attin T, Gröfke E, Hellwig E. Influence of resin cement viscosity on


Hahn P, Schaller HG, Hafner P, Hellwig E. Effect of different luting

procedures on the seating of ceramic inlays. J Oral Rehabil 2000; 27: 1-8.




203.

Haller B, Häßner K, Moll K. Marginal adaptation of dentin bonded ceramic

inlays: effect of bonding systems and luting resin composites. Op Dent 2003;

28-5: 574-584.

Han L, Okamoto A, Iwaku M. The effect of various clinical factors on

marginal enamel micro-cracks produced around composite restorations.

Dent Mat 1990; 11: 26-37.

Hara AT, Amaral CM, Pimenta LA, Sinhoreti MA. Shear bond strength of

hydrophilic adhesive systems to enamel. Am J Dent 1999; 12: 181-184.

Hass M, Arnetzl G, Wegscheider WA, König K, Bratschko RO. Klinische und

Werkstoffkundliche Erfahrungen mit Komposit, Keramik und Gold inlays.

Dtsch Zahnärzt Z 1992; 47: 18–22.

215

Hecht R, Ludstek M, Raia G. Tensile bond strength of first self adhesive

resin based dental material. J Dent Res 2002; 81: A-75.

Herrera M, Castillo A, Bravo M, Lièbana J, Carrion P. Antibacterial activity of

resin adhesive, glass ionomer and resin-modified glass ionomer cements

and a compomer in contact with dentin caries samples. Op Dent 2000; 25:

265-269.

Hickel R. Die zervikale füllung. Dtsch Zahnärzt Z 1994; 49(11): 13-19.

Hickel R, Manhart J, García-Godoy F. Clinical results and new developments

of direct posterior restorations. Am J Dent 2000; 13: 41D-54D.




Class II composite restorations filled at intraoral temperatures. Am J Dent

1999; 12: 123-130.


composite insertion techniques at intraoral temperature. Quintessence Int

1997; 28: 135-144.


cavities? In vitro investigation. Transaction of Academy of Dental Materials

Meeting, Banff, 1998; vol 12: 21-74.





Hofmann N, Klaiber B, Heners M. Okklusale Randschlussqualität von Cerec-

Inlays nach mehrmonatiger Tragedauer. Dtsch Zahnärztl Z 1990; 45: 289–

292.



418-422.

216

Horn HR. Porcelain laminate veneers bonded to etched enamel.

Dent Clin North Am. 1983 Oct;27(4):671-84.

Hung SH, Hung KS, Eick JD, Chappel RP. Marginal fit of porcelain-fused-to-

metal and two types of ceramic crown. J Prosthet Dent 1990; 63: 26–31.

Ianzano JA, Gwinnett AJ. Clinical evaluation of Class V restorations using a

total etch technique: 1 year results. Am J Dent 1993; 6(4): 207-210.

Ibbetson R, Eder A. Tooth surface loss. BDJbooks 2000: 3-8.

Inokoshi S., Van Meerbeck B, Willems G, Lambrechts P, Braem M,

VanherleG. Marginal accuracy of CAD/CAM inlays made with the original

and the updated software. J Dent 1992; 20: 171–177.

Inoue S, Van Meerbeek B, Vargas M, Yoshig’da Y, Lambrechts P, Vanherle

G. Advanced adhesive dentistry, 3rd Int Kuraray Symposium, Como, Italy

2000.

Jensen ME, Redford AD, Wilson BT. Posterior etched porcelain restorations.

an in vitro study. Compen Contin Edu Dent 1987; 8: 615–621.

Kanca J. Resin Bonding to wet substrate. I. Bonding to dentin. Quitessence

int 1992; 23: 39-41.


9: 273-276

Kanca J. Investigation into dentin adhesion mechanism. J Dent Res 1997;

76: 277 (Abstr 2111).

Kawai K. Effect of eluate from composite resin on Gtase and growth of

Streptococcus Mutans. Jpn J Conserv Dent 1988; 31: 322-351.

Kawai K, Isemberg PD, Leinfelder KF. Effect of gap dimension on composite

cement wear. Quintessence Int 1994; 25: 53-58.

Kawai K, Tsuchitani Y. Effects of resin composite components on

glucosyltransferase of cariogenic bacterium. J Biomed Mat Res 2000;51:

123-127.

217

Kelly JR, Nishimura I, Campbell SD. Ceramics in dentistry: historical roots

and current prospectives. J Prosthet Dent 1996; 75: 18-32.

Kemp-Scholte CM, Davidson CL. Complete marginal seal of class V resin

composite restorations effected by increased flexibility. J Dent Res 1990; 69:

1240-1243.

Kidd EAM. Microleakage: a review. J Dent 1976; 4: 199-205.

Kramer N, Frankenberger R, Pelka M, Petschelt A. IPS Empress inlays and

onlays after four years- a clinical study. J Dent 1999; 28: 325-331.



Krejci I, Lutz F, Reimer M. Marginal adaptation and fit of adhesive ceramic

inlays. J Dent 1993; 21: 39–45.

Krejci I, Lutz F, Reimer M, Heinzmann JL. Wear of ceramic inlays, their

enamel antagonists, and luting cements. J Prosthet Dent 1993; 69: 225–229.

Iida K, Inokoshi S, Kurosaki N. Interfacial gaps following ceramic inlay

cementation vs direct composites. Op Dent 2003; 28: 445-452.

Imazato S. Antibacterial properties of resin composites and bonding

systems. Dent Mat 2003; 19: 449-457.

Labella R, Lambrechts P, Van Meerbeek B, et al. Polymerization shrinkage

and elasticity of flowable composites and filled adhesives. Dent Mat 1999;

15: 128-137.

Larsen IB,. Munksgaard EC. Effect of human saliva on surface degradation

of composite resins. Scand J Dent Res 1991; 99: 254–261.

Lee IB, Um CM. Thermal analysis on the cure speed of dual cured resin

cements under porcelain inlays. J Oral Rehabil 2001; 28: 186-197.

Lee WC, Eakle WS. Possible role of tensile stresses in the aetiology of

cervical erosive lesions of teeth. J Prosthet Dent 1984, 52(3): 374-380.



Dent 2001; 26(3): 302-307.

218

Leinefelder KF, Bayne SC, Swift Jr EJ. Packable composites: overview and

technical considerations. J Esthet Dent 1999; 11: 234-249.

Leinefelder KF. New developments in resins restorative systems. J Am Dent

Assoc 1997; 58: 484-487.

Leinefelder KF. Posterior composite resins: the materials and their clinical

performance. J Am Dent Assoc 1995; 126: 663-676.

Leinfelder KF, Isenberg BP, Essig ME. A new method for generating ceramic

restorations: a Cad–Cam system. J Am Dent Assoc 1989; 118: 703–708.

Löfstrom LH, Barakat MM. Scanning electron microscopic evaluation of

clinically cemented cast gold restorations. J Prosth Dent 1989;61:664-669.

Lösche GM. Marginal adaptation of Class II composite fillings:guided

polymerisation vs reduced light intensity. J Adhes Dent 1999; 1(1): 31-39.



Lutz F, Krejici I, Barbakow F. Quality and durability of marginal adaptation in


Malament KA, Grossman DG. The cast glass-ceramic restoration. J Prosthet

Dent 1987; 57: 674–681.

Manhart J, Kunzelmann KH, Chen HY, Hickel R. Mechanical properties and

wear behaviour of light-cured packable composite resins. Dent Mater 2000;

16: 33-40.

Manhart J, Scheibenbogen-Fuchsbrunner A, Chen HY, Hickel R. A 2-year

clinical study of composite and ceramic inlays. Clin Oral invest 2000; 4: 192-

198.

Manhart J, Chen HY, Mehl A, Weber K, Hickel R. Marginal quality and

microleakage of adhesive Class V restorations. J Dent 2001; 29(2): 123-130.

Manhart J, Chen HY, Neuerer P, Scheibenbogen-Fuchsbrunner A, Hickel R.

Three-year clinical evaluation of composite and ceramic inlays. Am J Dent.

2001;14(2): 95-99.

Marquis RE. Antimicrobial actions of fluoride for oral bacteria. Can J

Microbiol 1995; 41(11): 955-964.

219

Martin DW. Interface leakage in microfilled composites, amalgam,

conventional composites and gold foil: a comparative in vitro study. J Calif

Dent Association 1981; 1(1) : 33-39.

Martin T. Schmeltzmikrostrukturen bei Saugetieren. In: Alt KW, Tucrp J. Die

evolution der zahne. Philogenie –ontogenie variation. Berlin: Quintessenz,

1997.

McCabe JF, Walls AW. Properties used to characterize materials. Applied

Dental Materials. 8th ed Oxford: Blackwell Science; 1998: 4-28.

McCoy RB, Anderson MH, Lepe X, Johnson GH. Clinical success of class V

composite resin restorations without mechanical retention. J Am Dent

Association 1998; 129(5): 593-599.


restorations. J Am Dent Association 1974;88(3): 592-602.

Medina J. Matt gold-gold foil restoration. Journal of the American

Association of Gold Foil Operators 1969; 12-1: 13-26.

Miguez PA, Pereira PNR, Suh IB et al. Gap formation and bond strength of

composites lined with flowable resin. J Dent Res 2001; 80 (Sp. Issue abstr.

n. 1270)194.

Millediing P, Örtengren U, Karlsson S. Ceramic inlay systems: some clinical

aspect. J Oral Rehabil 1995; 22: 571-580.

Mjör IA. Amalgam and composite resin restorations: longevity and reasons

for replacement. In: Anusavice K, Quality evaluation of dental restorations,

Chicago Quintessence 1989: 61-80.

Mjör IA. Long term cost of restorative therapy using different materials.

Scand J Dent Res 1992; 100: 60-65.


Quintessence Int 2000; 31: 165-179.

Moello FS-TC, Feiltzer AJ, De Gee AJ, et al. The influence of the presence

of a bonding layer on marginal sealing of resin composite Class II

restorations. J Dent Res 1996; 75: 26 (Abstr 224).

220

Molin MK, Karlsson SL. A 3- year clinical follow-up study of a ceramic

(Optec) inlay system Acta Odontol Scand 1996; 54: 145-149.

Molin MK, Karlsson SL. A randomized 5-year clinical evaluation of 3 ceramic

inlay systems. Int J Prosthodont 2000; 13: 194-200.

Moore DS, Johnson WW, Kaplan I. A comparison of amalgam microleakage

with a 4-META liner and copal varnish. Int J Prosthodont 1995; 8: 461-466.

Moreira Jr G, Sobrinho APR, Nicoli JR, Bambirra EA, Farinas LM, Carvalho

MAR, Vieira EC. Evaluation of microbial infiltration in restored cavities- an

alternative method. J End 1999; 25:605-608.

Mota CS, Demarco FF, Camacho GB, Powers JM. Microleakage in ceramic

inlays luted with different resin cements. J Adhes Dent 2003; 5: 63-70.

Munecika T, Suzuki K, Nishiyama M, et al. A comparison of the tensile bond

strengths of composite resins to longitudinal and transverse sections of

enamel prisms in human teeth. J Dent Res 1984; 63: 1079-1082.



Nakabayashi N, Ashizawa M, Nakamura M. Identification of a resin dentin

hybrid layer in vital human dentin created in vivo: Durable bonding to vital

dentin. Quit int 1992; 23: 135-141.

Nakabayashi N, Pashley DH. Hybridization of hard dental tissues. Berlin:

Quintessence, 1998; 20-30.

Norman GR, Streiner DL . PDQ statistics. BC Decker inc 1999. Hamilton.


tubules: Experiments in vivo and in vitro. Act Odontol Scand 1974 ; 32(1):

61-70.

Opdam NJM, Roeters JJM, Burgersdijk RCW. Microleakage of Class II box-

type composite restorations. Am J Dent 1998; 11: 160-164.

Özturk N, Aykent F. Dentin bond strengths of two ceramic inlay systems

after cementation with three different techniques and one bonding system. J

Prosthet Dent 2003; 89: 275-281.

221

Pallesen U. Clinical evaluation of CAD/CAM ceramic restorations: 6-years

report in CAD/CAM esthetic dentistry. Cerec 10 year anniversary

symposium. (Ed Mormann) Quintessenz Berlin 1996: 241-253.

Pashley DH. Clinical considerations of microleakage. J Endodont 1990; 16: 70-

77.

Pashley DH, Ciucchi B, Sano H, et al. Permeability o dentin to adesive

agents. Quint int 1993; 24: 618-631

Pashley DH, Ciucchi B, Sano H, et al. Bond strenght versus dentine structure:

A modelling approach. Archs Oral Biol 1995; 40: 1109-1118.

Pashley DH, Sano H, Ciucchi B, Yoshiyama M, Carvalho RM. Adhesion

testing of dentin bonding agents: a review. Dent Mater 1995; 11: 117-125.

Pashley DH, Tay FR. Aggressiveness of contemporary self-etching

adhesives. Part I: Depth of penetration beyond dentin smear layers. Dent

Mater 2001; 17: 296-308.

Penschke A, Blunck U, Roulet JF. Influence of incorrect application of

Optibond FL on the marginal adaptation of Class V restorations. Am J Dent

2000; 13(5): 239-244.

Perdigão J. An ultra-morphological study of human dentine exposed to

adhesive systems. Thesis. Leuven, Belgium: Catholic University of Leuven;

1995.

Peutzfeld A. Resin composites in dentistry : the monomer systems. Eur J

Oral Sci 1997; 105: 97-116.

Peyton FA, Craig RG (1971) Restorative Dental Materials ,Mosby 4th

edition, St Luis: 358-397.

Pfrentzschner HU. Biomechanik des zanhschmelzes. In: Alt KW, Tucrp J.

Die evolution der zahne. Phylogenie-Ontogenie variation. Berlin Quintessenz

1997.

Picard B, Jardel V, Tirlat G. Ceramic bonding: Reliability. In Degrange M,

Roulet JF. Minimally invasive restoration with bonding. Chicago

Qiuntessence 1997; 103-127.

222

Piwowarczyk A, Berge HX, Lauer H-Ch, Soresen JA. Shear bond strength of

cements at zirconium and lithium di-silicate ceramics. J Dent Res 2002; 81:

A-401.

Powell LV, Gordon GE, Johnson GH. Clinical comparison of Class V resin

composite and glass ionomer restorations. Am J Dent 1992; 5(5): 249-252.

Radlanski RJ, Jager A, Seidi W, et al. Uber die ausrichtung der prismen im

zahnschmelz menschlicher permanenter zahne. Anat Anz 1990; 170: 329-

337.

Radlanski RJ. Prism arrangement in early layers in human fetal enamel. In :

Radlanski RJ, Renz H. Proceeding of the 10th international symposium on

dental morphology. Berlin: C & M Brunne, 1995.





evaluations. Am J Dent 2003; 16(3): 207-210 .

Rees JS. The role of cuspal flexure in the development of abfraction lesions:

a finite element study. Euro J Oral Sci 1998; 106(6): 1028-1032.





Rigsby DF, Retief DH, Russel CM, Denys FR. Marginal leakage and

marginal gap dimension of three dentinal bonding system. Am J Dent 1990;

3: 289-294.

Robinson PB, Moore BK, Swartz ML. Comparison of microleakage in direct

and indirect composite resin restorations in vitro. Open Dent 1987;12: 113-

116.

Roulet J.F., Reich T, Blunck T, Noack M. Quantitative margin analysis in the

scanning electron microscope. Scan Elect Microsc 1989; 3: 147–159.


223

Roulet JF Benefits and disadvantages of tooth-colored alternatives to

amalgam. J Dent 1997; 25:459-473.

Roulet JF. Longevity of glass ceramic inlays and amalgam-results up to 6

years. Clin Oral Invest 1997; 1: 40 -46.

Sano H, Ciucchi B. Nanoleakage: leakage within the hybrid layer. Oper Dent

1995; 20: 18-25.

Sano H, Takatsu T, Ciucchi B, et al. Nanoleakage within the hybrid layer.

Oper Dent 1995; 20 : 18-25.

Sano H, Kanemura N, Burrow MF, et al. Effect of operator variability on

dentin adhesion: Students vs. dentists. Dent Mater 1998; 17: 51-58.

Savitt ED, Malement KA, Socransky SS, Melcer AJ, Backmann KJ. Effect of

colonization of oral microbiota by a cast Glass ceramic restoration. Int J

Period Rest Dent 1987; 7: 23–30.

Schubach P, Krejci I, Lutz F. Dentin bonding: effect of tubule orientation on

hybrid layer formation. Eur J Oral Sci 1997:105: 344-352.

Schuckar M, Geurtsen W. Proximo-cervical adaptation of Class II composite

restorations after thermo cycling: a quantitative and qualitative study. J Oral

Rehab 1997 ; 24(10) : 766-775.

Schüpbach P, Guggenheim B, Lutz F. Human root caries. Oral Path Med

1989; 18(3): 146-156.

Sindel J, Frankenberger R, Kramer N, Petschelt A. Crack formation of all

ceramic crowns dependent on different core build-up and luting materials. J

Dent 1999; 27: 175)

Sjodin L, Uunsitalo M, van Dijken J. Resin modified glass ionomer cements.

In vitro microleakage. Swed Dent J 1996; 20(3): 77-86.




Skjörland KKR. Plaque accumulation on different dental filling materials.

Scand J Dent Res 1973; 81: 538-542.

224

Skogendal O, Erikensen HM. Effect of composite resin restorations in

monkey’s teeth with experimentally induced pulpitis. Scand J Dent Res

1976; 84(5): 297-303.

Smales RJ, Hawthorne WS. Long-term survival and cost-effectiveness of

five dental restorative materials used in various classes of cavity

preparations. Int Dent J 1996; 46: 126-130.



Sparrius O, Grossman ES. Marginal leakage of composite resin restorations

in combination with dentinal and enamel bonding agents. J Prosthet Dent

1989; 61(6): 678-684.

Stangel I, Nathanson D, Hsu CS. Shear strength of the composite bond to

etched porcelain. J Dent Res 1987; 66: 1460–1465.

Staninec M, Mochizuki A, Tanizaki K, Jukuda K, Tsuchitani Y. Interfacial

space, marginal leakage and enamel cracks around composite resins. Op

Dent 1986; 11: 14-24.

Stibbs GD. Direct golds in dental restorative therapy. Op Dent 1980; 5(3):

107-114.

Studer S, Lehner C, Brodbeck U, Shärer P. Short-term results of IPS

Empress inlays and onlays. J Prosthodont 1996; 5: 277-287.

Tay FR, Gwinnett AJ Pang KM, et al. Variability in microleakage observed in

a total-etch wet-bonding technique under different handling conditions. J

Dent Res 1995; 74: 1168-1178.

Tay FR, Gwinnett AJ, Wei SH. Micromorphological spectrum from overdrying

to overwetting acid-conditioned dentin in water-free, acetone based, single


Tay FR, Gwinnett AJ, Wei Shy. Ultrastructure of the resin-dentin interface

following reversible and irreversible rewetting. Am J Dent 1997; 10: 77-82.

Thierfelder C, Fuhrmann I, Knappe M. Vergleichende Untersuchung zur

Passgenauigkeit des Kompositinlays Estilux posterior CVS. Die Quintessenz

1991; 9: 1399–1407.

225

Thonemann BM, Federlin M, Schmalz G. SEM analysis of marginal

expansionand gap formation in Class II composite restorations. Dent Mater

1997; 13: 192-197.

Thonemann B, Federlin M, Shmalz G, Grundler W. Total bonding vs

selective bonding: marginal adaptation of Class II composite restorations.

Oper Dent 1999; 24: 261-271.

Thordrup M, Isidor F, Hörsted-Bindslev P. Comparison of marginal fit and

microleakage of ceramic and composite inlays: an in vivo study. J Dent

1994; 22: 147–154.

Thye RP. A comparison of the marginal penetration of direct filling golds

using Ca45. J Am Acad Gold Foil Op 1967; 34 (4): 12-16.

Thylstrup A, Bille J, Qvist V. Radiographic and observed tissue in approximal

carious lesions at the time of operative treatment. Caries Res 1986; 20: 75-

84.

Titley K, Chernecky R, Chan A, et al. The composition and ultrastructure of

resin tags in etched dentine. Am J Dent 1995; 8: 224-230.

Titley K, Chernecky R, Maric B. Penetration of a dentin bonding agent into

dentin. Am J Dent 1994; 7: 190–194.

Tjan AH, Bergh BH, Linder C. Effect of various incremental techniques on


66.

Torstensen B, Brännström M. Composite resin contraction gaps measured

with a fluorescent resin technique. Dent Mater 1988; 4 : 238–245.


composite: an in vitro investigation. Quintessence Int 2000; 31: 430-434.

Tyas MJ. Clinical performance of two dentin adhesives: 2-year results. Aust

Dent 1996; 41: 324-7.



1999; 30(4): 249-257.

226

Vacel JS, Gher ME. Cementum anomalies of the dentogigngival junction. Int

J Perio Dent 1993; 5: 443-449.

Van Dijken JWV, Höglund-Åberg C, Olofsson AL. Fired ceramic inlays: a 6-

year follow up. J Dent 1998; 26: 219-225.

Van Dijken J, Horsted P. Directed polymerisation shrinkage in Class II

cavities in vivo. J Dent Res 1998; 77: 1326.

Van Meerbeek BV, Inokoshi S, Willems G. Marginal adaptation of four tooth-

coloured inlay systems in vivo. J Dent 1992; 20: 18–29.

Van Meerbeck B, Braem M, Lambrechts P, Vanherle G. Morphological

characterization of the interface between resin and sclerotic dentine. J Dent

1994; 22(3): 141-146.

Van Merbeeck B, Peumans M, Verschueren M, et al. Clinical status of ten

dentin adhesive systems. J Dent Res 1994; 73: 1690-1702

Van Meerbeek B. Perdigao J, Lambrechts P, Vanherle G. The clinical

performance of adhesives. J Dent 1998; 26: 1-20.

Van Meerbek B., Y. Yoshida and P. Lambrechts, A TEM study of two water-

based adhesive systems bonded to dry and wet dentin. J Dent Res 1998;

77: 50–59.

Van Noort R. Introduction to dental materials. Mosby pub 2002: 267.

Vanherle G, Lambrechts P, Braem M. Overview of the clinical requirements

for posterior composites. In: G. Vanherle and D.C. Smith, Editors, Posterior

composite resin dental restorative materials, 3M Co, St Paul, MN 1985: 21–

40.

Vichi A, Ferrari M, Davidson CL. In vivo leakage of an adhesive system with

and without NaOCl as preatreatment. J Dent Res 1997; 76: 398 (Abstr

3077).

Wakabayashi Y, Kondou Y, Suzuki K, et al. Effect of dissolution of collagen

on adhesion to dentin. Int J Prosthodont 1994; 7: 302-306.

Wassell RW, Walls AWG, McCabe JF. Direct composite inlays vs

conventional composite restorations: 5-year follow-up. J Dent 2000; 28: 375-

382.

227

Watanabe I, Nakabayashi N, Pashley DH. Bonding to ground dentin by a

phenyl-P self-etching primer. J Dent Res 1994; 73: 1212-1220.

Wood RE, Maxymiw WG, McComb D. A clinical comparison of glass

ionomer and silver amalgam restorations in the treatment of Class V caries

in xerostomic head and neck cancer patients. Op Dent 1993; 18(3): 94-102.

Yamashita J, Takakuda K, Shiozawa I, Nagasawa M, Miyairi H. Fatigue

behavior of the zinc-phosphate cement layer. Int J Prosthodont 2000; 13:

321-326.


glass ionomer cement. J Oral Rehab 1997; 25(1): 40-44.



228

Acknowledgements

The present thesis is respectfully submitted to Prof Piero Tosi of the

University of Siena, to Prof Alberto Auteri, Dean of the Faculty of Medicine,

University of Siena, to Prof Egidio Bertelli, Vice-Dean of the Faculty of

Medicine and Director of the Department of Dental Science and to Prof

Marco Ferrari, Pro-Rector for International Affairs and President of Dental

School, University of Siena. This research has been carried out in the

Dental Materials’ Department at the School of Dentistry at Siena University.

I wish to thank everyone who has been involved in this Project, among

these are:

Prof Marco Ferrari, my Promotor, for the chance he gave me to enter for this

magnificent Program and the precious suggestions and encouragements.

Prof Carel Davidson, my Co-promotor, who provided guidance, scientific

advice and continued encouragement throughout this project and without

whose help, this work would not have come to fulfilment. It was a great

pleasure for me to have his support, be it both on a professional and

friendship level. I’ll never forget his help.

Prof Richard Van Noort, who helped me to focus on my vision of this thesis.

A grateful thank you to many colleagues at the Dental Materials’ Department

at the School of Dentistry at Siena University, especially Cecilia Goracci,

Ornella Raffaelli, Alessandro Vichi and Simone Grandini, whom I worked

together with, forming a team spirit.

In this particular occasion I wish to mention the late Prof Riccardo

Garberoglio, who was the person that initially made me curious about dental

research, through his dedication and stimulation.

229

Finally, a big thank you to my wife, Roberta, who has encouraged and

supported me during this time, to my parents, who were always at my side

and to Tommaso…who is arriving!.

230

CURRICULUM VITAE Date of birth: July, 20th, 1962

Place of birth: Firenze, Italy

Civil status: Married to Roberta Plahuta

Citizenship: Italy

Research activity

2002: Master of Science in Dental Materials.

Professional positions: Institutional

1997-1999- Contract Professor of Dental Materials, School of Dental

Hygenist

1999-2000- Contract Professor of Dental Materials, School of Dentistry,

University of Siena, Italy

2000-2001- Contract Professor of Operative Dentistry, School of Dentistry,

University of Siena, Italy

2002-2003- Clinical Professor of Basic Principles of Dentistry, School of

Dentistry, University of Siena, Italy

Private Office: 42/b via Gramsci, Cortona (AR) 52042, Italy

Telephone and fax: +39(0575)630487

E-mail: [email protected]

Professional Organizations membership 1997 to 2004 International Association for Dental Research

2000 Academy of Operative Dentistry

1993- Academy of R.V. Tucker Gold Inlay Study Club.)

231

List of publications included in the thesis Fabianelli A, Kugel G, Ferrari M. Efficacy of self-etching primer on sealing

margins of Class II restorations. Am J Dent 2003; 16 (1): 37-41.

Fabianelli A, Goracci C, Ferrari M. Sealing ability of packable resin

composites in class II restorations. J Adhes Dent 2003; 5: 217-223.

Fabianelli A, Goracci C, Bertelli E, Monticelli F, Grandini S, Ferrari M. In vitro

evaluation of wall-to-wall adaptation of self-adhesive resin cement used for

luting gold and ceramic inlays. J Adhes Dent; Accepted for publication.

Fabianelli A, Goracci C, Thorbourn D, Davidson CL, Ferrari M. In vitro

microleakage and SEM observations of class V restorations. Submitted.

Fabianelli A, Goracci C, Bertelli E, Ferrari M. A clinical trial of Empress II

porcelain inlays luted to vital abutments with the self-light-curing adhesive

system Excite DSC and MultiLink. Int J Prosthodont; Submitted.


Influence of tissue characteristics at margins on leakage of Class II indirect

porcelain restorations. Am J Dent 1999; 12(3): 134-142.

Ferrari M, Dagostin A, Fabianelli M, Marginal integrity of ceramic inlays luted

with a self-curing resin system. Dent Mat 2003; 19: 270-276.

232

Other publications Goracci C, Tavares AU, Fabianelli A, Monticelli F, Raffaelli O, Cardoso PEC,

Tay F, Ferrari M. The adhesion between fiber posts and root canal walls:

comparison between microtensile and push-out bond strength

measurements.European Journal of Oral Sciences 2004, in press.

Goracci C, Sadek FT, Fabianelli A, Tay FR, Ferrari M. Evaluation of the

adhesion of fiber posts to intraradicular dentin. Submitted for publication on

Operative Dentistry, 2004.

Abstracts Fabianelli A, Ferrari M, Grandini S, Vichi A. Clinical evaluation of Class II

restorations using two enamel-dentin adhesives: 12 months results. J Dent

Res, 1997; 76: Abstract 1375.

Fabianelli A, Mason PN, Kugel G, Ferrari M, Davidson CL. Influence of

different margin substrates on leakage of Class II indirect restorations. J

Dent Res, 1998; 77: Abstract 2248.

Fabianelli A, Grandini S, Vichi A, Ferrari M, Davidson CL. Influence of self-

etching-priming bonding systems on sealing ability of ClassII restorations:

leakage and SEM evaluation. J Dent Res, 2000; 79: Abstract 305.

Ferrari M, Grandini S, Fabianelli A ,Vichi A. Sem study on the efficacy of a

self-activating adhesive system used for bonding fiber posts in root canal. J

37th IADR/CED, Rome, 2001: Abstract 420.

233

Fabianelli A, , Ferrari M, Dagostin A, Grandini S. Operator variability

influence on marginal seal of Class II resin restorations. Dent Mat 2001; vol

15: Abstract P 57.

Borracchini A, Fabianelli A, Grandini S, Ferrari M. Clinical trial of Empress 2,

self curing Excite and Multilink luting materials. J Dent Res, 2002; 81:

Abstract 2634.

Fabianelli A, Grandini S, Bertelli E, Ferrari M. Clinical trial of Gradia in direct

restorations. J Dent Res, 2002; 81: Abstract 2654.

Fabianelli A, Grandini S, Goracci C, Ferrari M. One-year clinical trial of

Gradia Direct Class II restorations. J Dent Res, 2003; 82: Abstract 1472.

Documents

PHD PROGRAM: “DENTAL MATERIALS AND CLINICAL APPLICATIONS” · · 2010-03-02PHD PROGRAM: “DENTAL MATERIALS AND CLINICAL APPLICATIONS ... pulpal pathology or pulpal death, partial