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Good morning
1
Seminar on:-
Presented by:-NAYASHA
MANCHANDAPG-2011 BATCH
Dental cements
2
Contents:- Definition
History
Uses of dental cements
General requirements for dental cements
3
Classification of dental cements
Components and properties
Setting reaction
Mixing process
The uses of dental cements
4
Definition Cement – substance that produces a solid
union between 2 surfaces (Oxford dictionary)
The word Cement is derived from the Roman word (i.e.) ‘opus caementitium’ which refers to the concrete used in masonry
5
Dental cement - ADA no: 96Substance that hardens to act as a base, liner, filling material or adhesive to bind devices & prostheses to tooth structure or to each other.(Anusavice)
6
Powder + Liquid
Pastelike or flowable material
Hardens to a rigid solid
7
History Cement has been introduced in dentistry for more
than 10 decades.
The first cement to be introduced into dentistry by Fletcher in 1873- Silicate cement.
In the same year, Zinc oxide eugenol cement was introduced by Chisolm.
In the year 1879 Zinc phosphate was introduced by Pierce
8
In the year 1930 Calcium hydroxide was introduced by Herman and has been widely applied for clinical use.
In the year 1968, an adhesive cement, Polycarboxylate was introduced – Smith
In the year 1971, a revolutionary discovery of Glass ionomer cement was made by Wilson and Kent.
Many manufacturers introduced different cements to serve different purposes.
More recently Resin based cements have been introduced.
9
Uses of dental cements
Luting agent• Temporary cementation• Permanent cementation
Pulp protection or cavity sealer Cavity varnish Liner Base
10
Uses of dental cement
Restotation Temporary Restoration Permanent Restoration
Others Root canal sealers Calcium hydroxide cement Bite registration material
11
Luting agent
Luting : the use of moldable substance to seal a space between two component.
Most dental treatment necessitate attachment of prostheses to the teeth by means of luting agent.
12
General requirements for luting agents Biocompatibility Retention High tensile strength, fracture
toughness, fatique strength Good marginal seal Low film thickness Ease of use Radiopacity Aesthetics
13
Film thickness
The thickness of film between two flat surface
The maximum allowable thickness is 25 µm (ADA specification No. 96)
Low film thickness value is preferred
14
Cement base A thick layer of cement (>0.75mm) is
applied under restoration to protect pulp against injuries.
The base should be strong enough to resist the condensation force during the placement of restoration.
Well insulation ability
Good sealing
15
Classification of dental cements
BASED ON INGREDIENTS BASED ON TYPE OF
RESTORATION BASED ON USE ALONG WITH A
RESTORATION BASED ON TYPE OF BONDING BASED ON COMPOSITION
16
I. BASED ON INGREDIENTS: (Craig) Water-based
- Zinc phosphate- Zinc polycarboxylate- Glass ionomer cement
Resin-based- Composites and adhesive resin cements
Oil-based- Zinc oxide eugenol
17
II. Based on type of restoration: Permanent (few years) -Eg: GIC Intermediate (few weeks to months)-Eg: IRM Temporary (few days) -Eg: ZOE
III. Based on use along with a restoration: Liner Eg: Calcium Hydroxide, GIC Base Eg: ZnPO4
IV. Based on type of bonding: Mechanical - Micro (resin cements)
- Macro (Zn PO4) Chemical (GIC)
18
V. Based on composition:
ZnO powder
Ion leachable Glass particles
Phosphoric acid
Polyacrylic acid
Eugenol
Zinc Oxide Eugenol
Zinc Phosphate
Silicophosphate
Zinc
Polycarboxylate
GlassIonom
er
19
SILICATE CEMENTS Introduced as anterior esthetic filling
material They are attacked by fluids and degrade
over time. pH is <3. High conc. pH- leaching – pulp
irritation Powder: Silica, alumina, sodium fluoride,
cryolite & calcium phosphate Liquid: phosphoric acid, aluminum, zinc
phosphate/Mg phosphate & water.
Si, Na,F, Ca,
Al
H2O,H3PO4,Al, Zn
+Ca+2Al+3F-
Si+4
H+
Glass particleEtched periphery
Ca, Al, Na, ZnPhosphates andFluorides
REACTANTS PRODUCTS
Powder + liquid
Ions
Matrix is formed
20
Zinc Phosphate cement
21
One of the oldest luting cements.
Introduced by Pierce in 1879.
Also called ‘crown and bridge’ cement.
22
Zinc phosphate cement
Powder Liquid•Zinc oxide-90%
•Magnesium oxide-10%
•Other oxides (Bi2O3)
Silica
phosphoric acid
water
aluminum phosphate
zinc phosphate
23
Applications:
Luting of restorations High strength - base under metallic
restorations Luting of orthodontic bands and brackets Luting of posts and core
Classification: They are available as two typesType I- Fine grained for luting purpose(25μm)
Type II- Medium particle size used as thermal insulating bases (40μm)
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Setting reactionPowder mixes with liquid
Phosphoric acid attacks the surface of particles
Releases zinc ions
Aluminum complexes with phosphoric acid and reacts with zinc
Zinc aluminophosphate gel is formed
ZnO+2H3PO4 Zn(H2PO4)2 + H2O
ZnO + Zn(H2PO4)2 Zn3(PO4)4. H2O (Hopeite)25
Exothermic reaction Adding of water can accerlate the
reaction. Loss of water can lengthen the setting
reaction.
Set cement:Unreacted zinc oxide embedded in a cohesiveamorphous matrix of zinc aluminophosphate.
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ZnO
ZnO
ZnO
Zn+
Zn+Zinc aluminophosphate gel
27
UnreactedZnO
UnreactedZnO
UnreactedZnO
UnreactedZnO
Zinc aluminophosphate matrix
28
Working time and setting time Working time commonly is 3-6 minute
Setting time is 2.5-8 minute(ADA specification No.96)
Depending on the manufacturer instruction
29
How to extend the setting time ?
Reducing powder/ liquid ratio {not recommended}
Mixing on the cool glass slap {no moisture}
Mixing over a large area. Mixing cements in increments.
30
Mixing procedure
There are three steps: First : add the small amount of
powder into the liquid To achieve the slow neutralization of
the liquid. To control the reaction.
31
Mixing procedure
Second : Larger amount of powder is added to liquid
For further saturation of liquid to newly form zinc phosphate.
This steps may not effect by heat released from the reaction.
{because of the less amount of unreacted acid}
32
Mixing procedure
Finally: the small amount of powder is added again with brisk spatulation
To control the optimum consistency
Mixing time – 1.5-2 mins
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1
2
3
4 5
6
7
8
34
1
2
3
4 5
6
7
8
35
Characteristic properties
Setting time at 37O 5 – 9 minutes
Minimum compressive strength
75 MPa
Maximum film thickness
25 µm (for luting the prostheses)
Maximum Solubility 0.2% by weight
ADA specification NO.8 for Zinc phosphate cement
36
Effects of manipulation on some properties.
Manipulative variables
PropertiesCompressive strength
Film thickness
Solubility
Initial acidity
Setting time
Decreased powder/liquid ratio
Increase rate of powder incorporation
Increase mixing temperature
Water contamination
37
Biocompatibility
Acid can penetrate into the dentinal tubule irritate pulp
pH of cement Liquid = 2.0 3 minutes after mixing = 4.2 24 hours = 5.5 48 hours = 7
38
Modified zinc phosphate cement Fluoride cement
Add Stannous fluoride Higher solubility/ Lower strength
Zinc silicophosphate Zinc phosphate + Silicate Higher strength/ lower solubility Fluoride released Translucency Acidity is more
39
Clinical applications Zinc phosphate cement
Luting agent Base and temporary Restoration
Modified zinc phosphate Luting prostheses Luting the orthodontics band
40
Zinc oxide-eugenol cements Lower strength than Zinc phosphate cement. Sedative effect Mostly widely used temporary restorative
cement Developed from zinc oxy-chloride which was
slow setting Zinc oxide was then mixed with creosote and
oil of cloves Later it was replaced with eugenol
41
Most biocompatible material
Good insulator of the pulp-dentin organ
Antiseptic effect on remaining micro-organisms
Sedative and anti-inflammatory action on pulp dentin organ
Neutral pH-7
42
Zinc oxide-eugenol cement
Simple ZOE
Reinforced ZOE
EBA cement
43
Compositions of simple ZOE
Powder Zinc oxide Rosin : reduce the brittleness of the set cement Zinc stearate : plasticizer Zinc acetate : accelerator & improves strength
Liquid Eugenol olive oil : plasticizer Glacial acetic acid : accelerator
44
Setting reaction First (Hydrolysis of zinc oxide)
ZnO + H2O Zn(OH)2
Second (Acid base reaction to form a chelate)
Zn(OH)2+2HE ZnE2+H2O
45
Setting reaction
Water accelerates the reaction Zinc eugenolate is easily
hydrolized by moisture
46
Manipulation
Paste/paste Mix two equal pastes together until it
obtains the homogeneous color. Powder/liquid
Usually 4/1 for maximum strength Mix the large increment, firstly Not require cool glass slab
47
ClassificationAccording to specification no: 30 listed 4
types according to formulation 4 uses.
Type I – temporary cementation Type II – Permanent cementation Type III – Temporary restoration and thermal
insulating bases Type IV – Cavity liner
48
(According to anusavice 11th edition)
Type I – Temporary ZOE luting cement Type II – Long term ZOE luting cement Type III – Temporary ZOE restoration Type IV – Intermediate ZOE restoration
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50
Specification requirements
Type Setting time [min]
Compressive strength[MPa]
Solubility[%]
Film thickness[µm]
Type I 4-10 35 maximum 2.5 25
Type II 4-10 35 maximum 1.5 25
Type III 4-10 35 maximum 1.5 -
51
Compressive strengthWeak cement- 3-55 MPa
Tensile strength0.32 -5.3MPa
Thermal propertiesExcellent thermal insulating property
SolubilityHigh solubility due to hydrolysis of zinc
eugenolate to form zinc hydroxide and eugenol
Biological propertiespH- 6.6 to 8 Least irritatingBacteriostatic and obtundant properties
52
EBA cement Orthoethoxy benzoic acid added to improve
properties of zinc oxide eugenol
EBA chelates with zinc forming an ionic complex (zinc benzoate)
Powder Add 20-30% of aluminium oxide
Liquid Add 50-60% ethoxybenzoic acid in eugenol
Compressive strength 55-75 MPa 53
Reinforced ZOE Used as the intermediate restorative materials
(IRMTM)
Add 10-40% resin polymer in the powder for strengthening the set cement
Compressive strength 35-55 MPa
54
POLYMER REINFORCED ZINC OXIDE EUGENOL
commercially called IRM or Kalzinol
Uses:Luting agentbasetemporary filling materialcavity linerroot end filling material
Powder:Zinc oxideNatural or synthetic resin (Polymethyl methacrylate)
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LiquidEugenolAcetic acidThymol
Improved strength, shorter setting time, decreased brittleness, solubility
56
Clinical applications
Base Temporary cementation Permanent cementation Temporary restoration Permanent restoration
If cement contains eugenol, it is not to use with resin restorative material.
57
Advances To increase strength hexyvanillate and orthoethoxy
benzoic (HV-EBA) acid are used instead of eugenol.
LIQUID is mixed with ZnO powder.
58
Zinc polycarboxylate cement
Or called Zinc polyacrylate cement The first adhesive cement
Bond to tooth structure and metal
More biocompatibility than zinc phosphate cement Polyacrylic acid have more molecular weigth
Moderate strength/ moderate solubility
59
Composition Powder Zinc oxide Magnesium oxide- sintering Bismuth and aluminum oxide- Increases strength. Stannous fluoride- Increases strength modifies setting time anticariogenic
Liquid Aqueous solution of polyacrylic acid Coplymers of carboxylic acid like itaconic acid
and tartaric acid 60
61
Manipulation Mix first half of powder to liquid to obtain the
maximum length of working time.
The reaction is thixotropic
1:1 for luting and 3:1 for restorative purposeMixing is done on a glass slab or non absorbent
paper pad.
The viscosity decreases when the shear rate increases
62
Setting reaction Acid- base reaction
Mixing of powder and liquid- ionisation of polyacrylic acid
Surface dissolution of powder- release of zinc. Magnesium and tin ions.
Zinc and calcium form ionic bond with carboxyl groups
On a clean calcific surface, it sets through chelation
63
Polycrylic acid forms complexes with proteins which promotes its property of adhesion.
Water plays an important role in the cement structure.
ZnO H2O PAA
ZnO + COOH
HOOC
COOHHOOC -OOC
COO-
-OOC
COO-Zn++
Zn++COO-
-OOC
COO--OOC
ResidualZnO
Zinc polyacrylate gel
64
Bonding to tooth structure The polyacrylic acid is believed to react
with calcium ion via the carboxyl group.
The adhesion depends on the unreacted carboxyl group.
65
Specification requirements Maximum film thickness: 25µm Minimum compressive strength: 50 MPa Working time: 3-5mins Setting time : 7-9mins Strength : compressive 55-67 MPa- less than Zn
Phosphatetensile- greater than Zn Phosphate
Dimensional stability: 1-6% Bond strength : to enamel- 3.45-13.5 MPa
to dentin- 2.07 MPa Solubility: 0.10-0.25% Biological properties: pH-1.5 and rapidly neutralised
by powder.Larger size of polyacrylic molecule and its binding to
calcium and proteins limits it diffusion through the dentinal tubules
66
Applications
Cement inlays or crowns Used as base Temporary filling Lute the stainless steel crown
67
Glass ionomer cement Or called Polyalkynoate cements
Conventional glass ionomer cement
Resin-modified glass ionomer cement [RMGICs]
Developed by Wilson and Kent as derivatives of silicate cements.
68
Introduced first as ASPA (alumino silicate poly acrylate)
Has been referred to as ‘man made dentin’ or ‘dentin substitute’
69
DEVELOPMENTDEVELOPMENTTimeline for “direct restorative materials” usageTimeline for “direct restorative materials” usage
19701970 19801980 2000200019901990
Dental AmalgamDental Amalgam
Dental CompositeDental Composite
Glass IonomerGlass Ionomer
First GIC in 1972First GIC in 1972Dentsply A.S.P.A.Dentsply A.S.P.A.
A.S. = A.S. = AAluminoluminossilicate glassilicate glassP.A. = P.A. = PPolyacrylic olyacrylic aacid in watercid in water
70
CLASSIFICATIONCLASS I – ConventionalCLASS II –Metal ModifiedCLASS III – light curedCLASS IV –hybrid resin modified
Conventional GIC’sTYPE I- LUTING, liningTYPE II- restorationsTYPE III- liners and basis
71
TYPE IV – fissure sealants
TYPE V – orthodontic cements
TYPE VI- core build ups
72
Composition Powder• Silica-41.9%• Alumina-38.6%• Fluorides of calcium sodium and aluminum-25%• Calcium aluminum fluorosilicate glass
Liquid Polyacid
Copolymer of polyacrylic / itaconic acid/ maleic acid & Tricarboxylic Acid-40-55%
Tartaric acid : Improves Handling Characteristics-5-15%
Water-30%
73
Setting reaction
There are three stages: Dissolution Gelation Hardening.
Water hardening or water setting
74
Silica gel
Glass core
Ca2+
Al3+
F-
Polyacid liquid
Hydrogen ions
75
Polyacid liquid
Ca2+
Al3+
F-
-COOH
Cross-linkedpolyacid
76
Gelation
Calcium ions have more reactivity than aluminium ions.
This is critical phase of contamination.
77
Polyacid liquid
Al3+ -COOH
Cross-linkedpolyacid
78
Hardening
Last as long as 7 days.
The reaction of aluminium ions provides the final strength of set cement.
79
Cross-linked polyacid
Glass
core
Silica gel80
SiO2,Al2O3,Na, Ca, F
PAAin
H2O
SiO2,Al2O3,Na, Ca, F
Residual Glass Particle
POLYACRYLATE HYDROGEL(initially Ca polyacrylate geland later Al polyacrylate gel)
Si+4, Al+3, Ca+2, Na+, F- Ions
SiO2,Al2O3,Na, Ca, F
Si+4
Al+3
Na+
Ca+2 F-
PAA
H2O
GLASS IONOMERSGLASS IONOMERSHYBRID = HYBRID = SC [Powder]SC [Powder] and and PCC [Liquid]PCC [Liquid] = A.S.P.A. = A.S.P.A.
81
FLUORO-ALUMINO-SILICATEFLUORO-ALUMINO-SILICATEPARTICLEPARTICLE
CEMENTCEMENTMATRIXMATRIX
F-1, Ca+2, Al+3, Si+4
Initialdissolution
for startingreaction
rapid earlyF release
from matrixSlow long term
F releaseby diffusionfrom particle
FLUORIDE RELEASEFLUORIDE RELEASEFluoride comes from matrix and particles at different rates.Fluoride comes from matrix and particles at different rates.
82
Properties
Film thickness is similar or less than zinc phosphate cement.
Setting time 6 to 8 minutes from start of mixing.
Less pulpal irritation. Bacteriocidal or bacteriostatic. Prevent caries.
83
Strength
The 24-hour compressive strength is greater than zinc phosphate cement.
The compressive strength increase to 280MPa between 24 hours to 1 year after initial setting.
84
Bonding
It can be chemically bonded to the tooth structure.
The mechanism of bonding is the same as polyacrylate cement.
The dentine bond strength may be lower than polyacrylate because of technique sensitivity.
85
1. Cement2. Liner / Base3. Restoration4. Core / Foundation5. (Sandwich Restoration)7. Retrograde Filling Material8. P/F Sealant9. Root Caries Cervical Restoration10. Temporary, or ART Restoration
Technical modifications:> P/L Precapsulated> Addition of etching and then BA> Addition of different reinforcing fillers> Finer and finer particle sizes
General Properties:> Strength> Adhesion> Biocompatibility> Fluoride release
APPLICATIONSAPPLICATIONSGIC has been tried for about every conceivable application.
86
Manipulation of GIC:Use a plastic or agate spatula with a paper
pad. Powder is divided.First increment is mixed with the liquidSubsequent increments are folded in to
preserve the cross-linked structure.
87
Modified GI
Cermet Combination of glass and metal. No significant improvement in the
strength. More wear resistance and short
setting time.
Resin-modified GI88
MODIFICATIONS OF GIC Metal-modified GIC
- Cermet: Fusing silver to glass powder by sintering- Miracle mix: incorporating silver alloy powder with type II GIC powder. (silver alloy admix)
Less fluoride release from cermet
More fluoride release from admix cement
89
Resin-modified glass ionomer cement Add polymerizable function groups
Both chemical & light curing
Overcome moisture sensitivity & low early strength
- Names: Ligth cured GICs, Dual cured GICs - , Tri cured GICs, Hybrid ionomer, Compom
-ers, Resin ionomers
90
Setting reaction Polymerization
initial setting - Acid base reaction
maturing process & final strength Heat released from the
polymerization reaction.
91
Properties
Higher strength than conventional GI
Higher adhesion to resin material
Less water sensitivity Can be polished after curing
92
Relative properties of a glass ionomer and a resin-modified GI cements
Property GIC RMGIC
Working time 2 min 3 min 45 sec
Setting time 4 min 20 sec
Compressive strength
202 MPa 242 Mpa
Tensile strength
16 Mpa 37 Mpa
93
Applications
Type I : Luting agent Type II : Restorative material Type III : Base and liner
94
RelyX™ Luting Plus Cement Clicker™ Dispenser
95
Conventional GI for cementation
96
GI restorative material
97
Adhesive resin cement Occured later from the direct filling
resin
Become popular because of the improved properties, high bond strength.
Resin cement is flowable composite resin.
98
Trade name:-RelyX ARC Adhesive Resin Cement Paste A3 in Clicker Dispensing System
From 3M
RelyX™ Unicem Self-Adhesive Universal Resin Cement Aplicap™ Capsule Translucent Shade Refill
99
Calcium hydroxide cement Used as base and liner
High pH value
Good biocompatibility
100
Composition
2 Pastes system Base
Salicylate reaction Calcium tungstate and barium sulfate radiopacity
Catalyst Calcium hydroxide
101
Properties Lower compressive strength than others
Resist to the condensation force of amalgam filling
High pH 9.2-11.7 [Alkaline]
Bactericidal
High solubility102
Properties Stimulate the repairative dentin
formation in the area of thin dentine [<0.5mm]
Stimulate the dentine formation in the exposed-pulp lesion [Direct pulp capping]
103
Comparable properties of cements
104
Compressive strength [MPa]
0
20
40
60
80
100
120
140
160
Zinc phosphate Polycarboxylate GIC RMGIC Resin cement
Zhen Chun Li and Shane N. White, 1999 105
Bond strength
0
50
100
150
200
250
300
Zinc phosphate GIC RMGIC Resin
Separation forces [MPa]
Sule Ergin and Deniz Gemalmaz, 2002106
Film thickness [µm]
0
10
20
30
40
50
Zinc phosphate Polycarboxylate GIC RMGIC Resin
Shane N. White, Zhaokun Yu, 1992 107
Others
Solubility ZOE > Polycarboxylate > Zinc
phosphate~GIC > Resin cement
Irritation to pulp tissues Resin~Zinc phosphate > GIC >
Polycarboxylate > ZOE~Calcium hydroxide
108
References Textbooks
Kenneth J. Anusavice Phillips’ science of dental materials 11th edition W.B. Saunders company 2003
Textbook Robert G. Craig
Restorative dental materials9th editionMosby company 1993
109
References Textbook
Richard van NoortIntroduction to dental materials2nd editionMosby company 2002
Journals Li ZC, White SN. Mechanical properties of dental luting
cements. J Prosthet Dent 1999;81(5):597-609 White SN, Yu Z. Film thickness of new adhesive luting
agents. J Prosthet Dent 1992;67(6):782-90 Ergin S, Gemalmaz D. Retentive properties of five luting
cements on base and noble metal copings. J Prosthet Dent 2002;885:491-97
110
Thank you
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