Adhesives

Enamel and Dentin AdhesivesKraig S. Vandewalle, Col, USAF, DC

Official Disclaimer The opinions expressed in this presentation are those of the author and do not necessarily reflect the official position of the US Air Force or the Department of Defense (DOD). Devices or materials appearing in this presentation are used as examples of currently available products/technologies and do not imply an endorsement by the author and/or the USAF/DOD.

Overview Principles of adhesion Principles of bonding Historical development Classifications Features Conclusions

Advantages of Adhesion Help offset polymerization shrinkage reduce marginal leakage staining sensitivity caries

Adhesion conservation of tooth structure internal splinting

Esthetic restorations

Indications for Adhesion Direct resin composite restorations caries, fractures, reshaping, masking

Bond all-ceramic restorations veneers, inlays, onlays, crowns

Bond amalgam Resin-retained fixed-partial dentures

Indications for Adhesion Pit and fissure sealants Orthodontic brackets Treat dentinal hypersensitivity Core build-ups Repair fractured porcelain and composite

Basic Mechanism of Adhesion(resin-based) Exchange process replacement of minerals from hard tissue

by resin monomers micromechanically interlocked

Primarily mechanical retentive interlocking

Variations in Tooth Structure Enamel more predictable bonding more homogeneous structure higher inorganic content higher surface energy

Dentin less predictable bonding higher variability higher organic contentVan Meerbeek in: Summitt, Fund Oper Dent 2001

Enamel Composition Primarily inorganic hydroxyapatiteBy volume

Organic 2% Water 12%

Inorganic 86% Van Meerbeek in: Summitt, Fund Oper Dent 2001

Enamel Bonding Developed by Buonocore-1955 Etching various acids traditionally phosphoric acid

creates micropores 5 50 microns deep

increases surface energy increases wettabilityVan Meerbeek in: Summitt, Fund Oper Dent 2001

Surface Wetting Tooth surface contamination saliva, smear layer

Clean surface increase surface energy decrease contact angleVan Meerbeek in: Summitt, Fund Oper Dent 2001

Enamel Bonding Low-viscosity monomers examples Bis-GMA UDMA TEGDMA HEMA

Predictably high bond strengths > 20 MPaVan Meerbeek in: Summitt, Fund Oper Dent 2001

Dentin Structure Dentin composition Dentinal tubules Changes in dentin structure Smear layer Dentinal wetness

Dentin CompositionInorganic 50% Organic 25%

By volume

Water 25%

Van Meerbeek in: Summitt, Fund Oper Dent 2001

Dentinal Tubules Radiate from pulp Largest near pulp 2.5 microns at pulp 0.8 microns at DEJ

Concentrated near pulp 45,000/mm2 at pulp 20,000/mm2 at DEJVan Meerbeek in: Summitt, Fund Oper Dent 2001

Tubule Composition Peritubular dentin surrounds tubule hypermineralized

Intertubular dentin between tubules less mineralized

Odontoblastic process Dentinal fluidVan Meerbeek in: Summitt, Fund Oper Dent 2001

Changes in Dentin Structure Sclerotic normal aging abrasion erosion

Hypermineralization Less receptive to bonding

Reparative caries dental proceduresVan Meerbeek in: Summitt, Fund Oper Dent 2001

Smear Layer Produced by instrumentation Composition cut dentin debris bacteria

Reduces dentin permeability 86%Van Meerbeek in: Summitt, Fund Oper Dent 2001

Smear Layer Thickness 0.5 - 5.0 microns

Will not wash off Weak bond to tooth 2 3 MPa

Very soluble weak acidsVan Meerbeek in: Summitt, Fund Oper Dent 2001

Dentinal Wetness Increases dentinal depth removal of smear layer

Historically, more difficult to bond


Dentin Bonding Development seven generations chronologic

Classification


First Generation(1950-1970s) Hydrophobic monomers Very low bond strengths 2 to 3 MPa

First commercial dentinal adhesive

Cervident - SS White (1965)

claimed chemical bond to calcium

retention only 50% at 6 months

Class 5Harris, J Prosthet Dent 1974

Second Generation(late 70s to mid 80s) Phosphorous-ester monomers

enhanced surface wetting claimed chemical bond to calcium smear layer predominately intact

fear of etching dentin

Low bond strengths 5 to 6 MPa

Retention 70% at 1 year Class 5Van Meerbeek in: Summitt, Fund Oper Dent 2001

Third Generation(mid-80s) Mechanism of action mildly acidic hydrophilic monomer modified/altered smear layer

Moderate bond strengths Improved short / long term success


Fourth Generation(early 1990s) Multi-step condition dentin remove smear layer

primer adhesive

High bond strengths Retention 98 to 100 % at 3 yrs Class 5Van Meerbeek in: Summitt, Fund Oper Dent 2001

Fifth Generation(late 1990s) Attempt to simplify reduce number of bottles combined primer and adhesive

High bond strengths


Sixth Generation(late 1990s) Combined conditioner and primer moderate bond strengths

Combined conditioner, primer and adhesive lower bond strengths

Van Meerbeek, Oper Dent 2003 Click here for abstract

Seventh Generation(most recent) All-in-one adhesives combined conditioner, primer and adhesive one-step

No mixing Low bond strengthsVan Meerbeek, Oper Dent 2003 Click here for abstract

Currently Available Generations Fourth Generation Three-step Etch & rinse

Fifth Generation Two-step Etch & rinse

Sixth Generation Two-step Self-etch One-step Self-etch mix

Seventh Generation One-step Self-etch no mix

Classification of Newer Systems Interaction with tooth surface Number of clinical application steps 1) Etch & rinse (i.e., total-etch) 2) Self-etch 3) Resin-modified glass ionomerVan Meerbeek, Oper Dent 2003 Click here for abstract

Adhesive Categories Etch & Rinse Three-Step conditioner, primer, adhesive

Two-Step conditioner, (primer & adhesive)

Self-Etch Two-Step (conditioner & primer), adhesive

One-Step (conditioner & primer & adhesive)

Glass Ionomer Two-Step conditioner, resin-modified glass-ionomer mixture

Etch & Rinse (Three-Step) Conditioner Primer Adhesive resin Examples Scotchbond Multi-Purpose Optibond FL

Conditioner Chemical alteration of surface acids

phosphoric, citric, maleic, nitric

Removes dentinal smear layer exposes collagen fibrils

Simultaneous enamel etch Rinse keep moistVan Meerbeek in: Summitt, Fund Oper Dent 2001

Primer Hydrophilic monomers dissolved in acetone, alcohol, or water

Displaces water Promotes infiltration into collagen Lightly air dry drive off solvents, water

Transforms hydrophilic to hydrophobicVan Meerbeek in: Summitt, Fund Oper Dent 2001

Primer Bifunctional monomer Link hydrophilic collagen hydrophobic resin

Example HEMA

CH3 H2C=C-C-O-CH2-CH2-OH O

Adhesive Resin Unfilled or lightly-filled monomers equivalent to enamel bonding Bis-GMA, UDMA, TEGDMA

Stabilize the hybrid layer fills up remaining pores

Resin tags Links primer to composite resinVan Meerbeek in: Summitt, Fund Oper Dent 2001

Hybrid Layer Conditioner demineralizes dentin Interdiffused with low-viscosity monomer displaces water bifunctional

Resin mechanically interlocks collagenVan Meerbeek in: Summitt, Fund Oper Dent 2001

Etch & Rinse (Two-Step) Conditioner Combined primer and adhesive higher technique sensitivity higher solvent-to-monomer ratio risk of applying too thin

apply multiple layers

Examples Single Bond Optibond Solo Plus Prime & Bond NTHashimoto, Oper Dent 2004 Click here for abstract

Pros/Cons of Etch & Rinse Separate acid etch good enamel etch pattern

Potential to over-etch dentin except sclerotic dentin

Post-conditioning rinse necessary sensitive to level of dentin wetness

Multiple long-term clinical studies availableVan Meerbeek, Oper Dent 2003 Click here for abstract

Dentin WetnessEtch & Rinse

After conditioning dentin dentin must be wet prevent collagen collapse

Too little water collagen collapse

Ineffective resin penetration Leads to nanoleakageSano, Oper Dent 1995 Click here for abstract

Wet Bonding Acetone and ethanol based primers displace remaining water carry monomers into collagen gently air-dried leaving monomers behind

Examples One-Step Prime & Bond NTKanca, Quintessence Int 1992 Click here for abstract

Effect of Dentin WetnessOne-Step (Bisco)16 14 12 10 8 6 4 2 0 moist dry 1 sec dry 5 secs dry 5 secs + rewet Bond Strength (MPa)

Perdigao, Am J Dent 1998 Click here for abstract

Overwet Phenomena Too much water not completely displaced

Phase separation blister and globule formation

Tay, Dent Mater 1996 Click here for abstract

Disadvantages to Wet Bonding Cannot check for enamel frosted etch Technique sensitivity not too wet or too dry

Solvents evaporate from bottle may reduce monomer penetration


Dry Bonding Water-based primers effective on wet or dry dentin self-rewetting effect re-expand collapsed collagen

Permits check of frosted enamel Examples Scotchbond Multi-Purpose OptibondVan Meerbeek in: Summitt, Fund Oper Dent 2001

Class V Clinical StudiesEtch & Rinse Three-Step Scotchbond MP (3M ESPE) 100% retention at 3 yrs Van Meerbeek, Quint Int 1996

98-100% retention at 3 yrs Trevino, J Dent Res 1996

100% retention at 2 yrs Alhadny, Am J Dent 1996

Class V Clinical StudiesEtch & Rinse Two-Step Optibond Solo (Kerr) 93.3% retention at 3 yrs Swift, JADA 2001

Prime & Bond 2.1 (Caulk) 89.4% retention at 3 yrs Swift, JADA 2001

Laboratory StudyThree-Step vs Two-Step Etch & RinseShear Bond Strength30 25 20Two-Step Three-Step

MPa

15 10 5 0 Opti Opti FL Solo+ Single Bond MP + Excite SyntacPecora, J Prosthet Dent 2002 Click here for abstract

Laboratory StudyThree-step vs Two-step Etch & RinseMicrotensile Bond Strength

60 50 40 uTBS 30 20 10 0

24 hr 4 yr Single Bond Scotchbond Optibond MP Solo Optibond FL

De Munck, J Dent Res 2003 Click here for abstract






Self-Etch ComponentsAcidic monomersMDP Di-HEMA-Phosphate MA 154 Phenyl-P MAC-10 4-MET(A) BisGMA UDMA TEGDMA GDMA HEMA usually water based

Crosslinking monomersSolvent

Self-Etch (Two-Step) Combined conditioner and primer Adhesive resin Examples Clearfil SE AdheSE

Click here for table of self-etching adhesives

Self-Etch (One-Step) Combined conditioner primer adhesive

Examples Prompt L-Pop One-up Bond F Touch and Bond iBond Xeno IIIClick here for table of self-etching adhesives

Pros/Cons of Self-Etch Good dentin conditioning simultaneous infiltration depth of demineralization

Possible reduction in post-op sensitivity?? No post-conditioning rinse not sensitive to level of dentin wetness

Reduced application timeHara, Am J Dent 1999

Clinical Studies(Post-Operative Sensitivity) Class 1 or 2 composite restorations Clearfil SE self-etch

Prime & Bond NT etch & rinse

Tested for post-op sensitivity No difference Baseline, 2 weeks, 6 weeks, 6 months Perdigao, JADA 2003 Click here for abstract

Baseline, 2 weeks Perdigao, Quint Int 2004 Click here for abstract

80

Seconds

100

120

20Self-Etch

40

60

0

Application Time

Source: USAF DECS N=3

Pr om pt LPo Xe p n O ne o I II -u p B on C le d ar fil SE A dh eS E iB on d Ex c Si ng ite Pr im le e& Bo n B on d d N T Ty ria n O PQ pt ib 1 Sc on d ot ch So lo bo nd M PEtch&Rinse

Pros/Cons of Self-Etch Limited clinical indications Limited clinical data Relatively lower bond strengths Many require refrigeration

Van Meerbeek, Oper Dent 2003 Click here for abstract

Shear Bond Strength to DentinEtch&Rinse

50 40MPa

Self-Etch

30 20 10 0Clearfil PBNT PQ1 Excite 1-Up AdheSE Xeno III Tyrian iBond Prompt SE Bond L-Pop Source: USAF DECS Horizontal lines connect nonsig diff at 0.05 level N=10

Class V Clinical StudiesSelf-Etch Two-Step Clearfil SE Bond (Kuraray) 100% retention at 2 yrs Peumans, J Dent Res abstr #0911

93% retention at 2 yrs Turkun, J Dent 2003

Class V Clinical StudiesSelf-Etch One-Step Prompt L-Pop (3M ESPE) 65% retention at 1 yr Brackett, Oper Dent 2002

79% retention at 2 yrs van Dijken, Am J Dent 2004

Special Considerations Incompatibilities self-cure composites with simplified adhesives two-step etch & rinse one-step self-etch

Acidic monomers react with basic catalyst of overlying composite Adhesive permeability leads to superficial water blisters via water treesClick here for details

Adverse Acid-Base ReactionSimplified Adhesives

CompositeNeutral

O2 Inhibited Layer

CompositeBPO+Amine Acidic Monomers

Adhesive Primer Dentin

Dentin Two-step Etch & Rinse One-step Self-EtchSuh, 2002

Three-step Etch & Rinse Two-step Self-Etch

Water Trees Simplified adhesives Act as semi-permeable membrane Conduct fluid Osmotic blistering along the composite-adhesive interface slows self-curing of composite

Click here for details

Lindemuth 2004

Composite

Water Tree FormationHybrid Layer Trapped Moisture

Dentin

Lindemuth 2004

Hydrolytic Degradation of Resin Dentin Bond

Failure over time

Dual Cure Dual- and self-cure composites cores cements

Separate activator Examples Optibond Solo Plus Prime and Bond NT

Features Fluoride release Unit-dose

Fluoride Release Anti-caries effect? no proof of efficacy in resin-based adhesives

Examples FL-Bond One-up Bond F PQ1 Tenure Quick Optibond Solo Plus

Unit Dose Improved infection control Convenience Minimizes loss of volatile components over time Higher cost Examples Optibond Solo Plus Excite Prime and Bond NT Prompt L-Pop






Resin-modified Glass-Ionomer Weak conditioner pretreatment polyacrylic acid removes smear layer exposes collagen

Mechanical bonding hybrid layer

Chemical bonding carboxyl groups with calcium in tooth

Resin-modified Glass-Ionomer Two-step weak conditioner mix and apply glass ionomer adhesive

Fluoride release Example Fujibond LC

Pros/Cons of Resin-Modified Glass-Ionomer Chemical and mechanical bonding Fluoride release Limited clinical data Class V study Fuji Bond LC 96% retention at five years Class 5 Tyas, Oper Dent 2002

% 2015

Average Annual Failure RateClass V Restorations

Standard Deviation

10 5 01.9 %Glass Ionom er

4.8 %3-Step Etch&Rinse

4.7 %2-Step Self-Etch

6.2 %2-Step Etch&Rinse

8.1 %

1-Step Self-Etch

Peumans, Dent Mater 2005 Click here for details

Adhesive Preferences with Light-Cured Composites*Civilian Practitioners Total-etch Self-etch Other 70% 62% 3%

*Multiple responses

DPR 2005

Conclusions Etch & rinse favorable long-term data

Self-etch promising?? do not require rinsing demineralize and infiltrate to same depth

reduced technique sensitivity reduced application time potential decreased post-operative sensitivity??Van Meerbeek, Oper Dent 2003 Click here for abstract

Conclusions Trend toward simplified application reduced number of steps not necessarily better

Van Meerbeek, Oper Dent 2003

Purchasing Considerations(Federal Dental Services)

4th generation etch & rinse three-step several available

5th generation etch & rinse two-step multiple available

6th generation self-etch two-step Clearfil SE Bond

self-etch one-step ????Click here for synopsis of self-etching adhesives

Acknowledgements Dr. David Charlton Lt Col Steve Klyn

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