PRINCIPLES OF PRINCIPLES OF ADHESIONADHESIONDR ZURYATI AB GHANIDR ZURYATI AB GHANI
BDS (WALES), Grad Dip BDS (WALES), Grad Dip ClinClin Dent Dent (Adelaide), Doctor in Clinical Dentistry (Adelaide), Doctor in Clinical Dentistry ((ProsthodonticsProsthodontics), Adelaide, FRACDS ), Adelaide, FRACDS
(Australia).(Australia).22.10.0722.10.07
Lecture ContentLecture Content
PRINCIPLES OF ADHESIONPRINCIPLES OF ADHESIONTypes of adhesionTypes of adhesionDevelopment of adhesion in dentistryDevelopment of adhesion in dentistryAdvantages of adhesive in dentistryAdvantages of adhesive in dentistry
ADHESION TO ENAMEL AND DENTINEADHESION TO ENAMEL AND DENTINEAdhesion to enamelAdhesion to enamelAdhesion to dentineAdhesion to dentine
AdhesionAdhesion
Adhesion / bonding Adhesion / bonding -- The joining together of The joining together of two objects using glue or cement.two objects using glue or cement.All dental materials must function in a wet, All dental materials must function in a wet, hostile environmenthostile environmentThe oral environment limit the types of The oral environment limit the types of adhesives used in dentistryadhesives used in dentistry
ADHEREND
ADHESIVE
ADHERENT Resin CompositeCeramic, Acrylic
Enamel, dentine,Alloy, ceramic
Adhesive resinSilane primer, tin plating
Dr T. Berekallly
Types of adhesion/bondingTypes of adhesion/bonding
MacroMacro--mechanicalmechanical
MicroMicro--mechanicalmechanical
Interfacial/Chemical AdhesionInterfacial/Chemical AdhesionTrue adhesionTrue adhesion
The glue or cement flows into surface irregularities. The set cement is locked into the surface irregularities of the objects being joined
MacroMacro--mechanicalmechanical
Bonding using surface irregularities where Bonding using surface irregularities where surface roughness can be seen or felt.surface roughness can be seen or felt.Screws, nuts, bolts, glues join two pieces of Screws, nuts, bolts, glues join two pieces of woodswoodsIn dentistryIn dentistry-- cementation of crown or bridges to cementation of crown or bridges to teeth with teeth with ‘‘non adhesive cementnon adhesive cement’’DisadvantageDisadvantage-- stress is concentrated in the stress is concentrated in the vicinity of the fastenervicinity of the fastener
MacroMacro--Mechanical AdhesionMechanical Adhesion
Visible interlocking between dissimilar materialsAcrylic facings on alloy subframes for bridgesRemovable partial denturesOverlay denturesImplant-supported prostheses
Dr T. Berekally
Rochette Bridge
Dr T. Berekally
Dr T. Berekally
MicroMicro--mechanical adhesionmechanical adhesion
Bonding using surface irregularities smaller than Bonding using surface irregularities smaller than can be seen with naked eye or felt with the can be seen with naked eye or felt with the dental explorer.dental explorer.Increased number of surface irregularities are Increased number of surface irregularities are used thus forces are distributed evenly. used thus forces are distributed evenly. Stronger than macroStronger than macro--mechanical adhesion.mechanical adhesion.
Micromechanical AdhesionMicromechanical Adhesion
Microscopic mechanical interlocking Microscopic mechanical interlocking between dissimilar materialsbetween dissimilar materialsResin compositeResin compositeAmalgam bondingAmalgam bondingResinResin--bonded ceramicsbonded ceramics
Dr T. Berekally
Maryland BridgeEtching Units
SEM Etched Rexillium III
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Surface Coatings Enhancing AdhesionSurface Coatings Enhancing Adhesion
Sandblasting with alumina oxide (MicroSandblasting with alumina oxide (Micro--Etcher Danville Etcher Danville Engineering))Engineering))Silica oxide coating (Silicoater: Kulzer;RocatecSilica oxide coating (Silicoater: Kulzer;Rocatec®® ESPE)ESPE)Porous metal coatings (INZOMA P990)Porous metal coatings (INZOMA P990)Tin plating (Kura Ace, EX Tin plating (Kura Ace, EX OxisorOxisor, Micro Tin*), Micro Tin*)
Surface Preparation of Indirect Resins for Surface Preparation of Indirect Resins for Cementation: RocatecCementation: Rocatec®®
Al2O3
High temperature fusesSiO2 to resin surface
Dr T. Berekallly
Interfacial/ Chemical AdhesionInterfacial/ Chemical Adhesion
ENAMEL
CERAMICSilane layer
Resin Cement
Berekally
True/chemical adhesionTrue/chemical adhesion
Involves chemical bonds between the materials Involves chemical bonds between the materials being joinedbeing joinedBonding of GIC to tooth structureBonding of GIC to tooth structure
Advantages of adhesive in dentistryAdvantages of adhesive in dentistry
Retention of restorationRetention of restorationNo need to use undercut or mechanical lockNo need to use undercut or mechanical lockConservation of tooth structureConservation of tooth structureReduction in Reduction in microleakagemicroleakage-- ↓↓post operative post operative sensitivity, sensitivity, ↓↓ stainstainReduction in recurrent cariesReduction in recurrent cariesReinforcement of tooth structureReinforcement of tooth structureRepair of restorationsRepair of restorations
Development of adhesive materialsDevelopment of adhesive materials
19501950’’s Michael s Michael BuonocoreBuonocore introduced acid introduced acid etcingetcing to create to create micromechanical retention for pit and fissure sealantsmicromechanical retention for pit and fissure sealants19601960’’s composite restoration was developeds composite restoration was developed19701970’’ss--19801980’’ss-- many other composite materials developed many other composite materials developed with acid etching technique:with acid etching technique:orthoortho bracketsbracketsEtch the metal part of bridge and bond it to tooth.Etch the metal part of bridge and bond it to tooth.Plastic/composite/porcelain veneers bonded to labial tooth Plastic/composite/porcelain veneers bonded to labial tooth surface of tooth to hide surface of tooth to hide discolourationdiscolouration/ close space/ close spacePeriodontal splintPeriodontal splint
ACID ETCHING COMPOSITE IS ACID ETCHING COMPOSITE IS ‘‘GOLD STANDARDGOLD STANDARD’’OF ADHESIVE DENTISTRY. OF ADHESIVE DENTISTRY.
Chemical adhesionChemical adhesion19701970’’ss-- PolycarboxylatePolycarboxylate cement was introducedcement was introducedGIC introduced by Wilson, Cusp and McLeanGIC introduced by Wilson, Cusp and McLeanBUTBUT-- lack aesthetic and mechanical toughness lack aesthetic and mechanical toughness of compared to compositeof compared to composite
Factors affecting boding to tooth Factors affecting boding to tooth structurestructure
Surface factorsSurface factors-- Clean surfaceClean surface-- Compatible surface for Compatible surface for increased surface increased surface wettingwettingBiofilmsBiofilms-- Enamel pellicle decreased bondingEnamel pellicle decreased bonding-- The need to use rubber damThe need to use rubber dam
θ1 θ2
AB
B = Material has superior wetting, a desirable property
Adhesive FailureAdhesive Failure
ADHEREND
ADHERENT
Adhesive Resin
Berekally
Resin Fracture in Maryland Bridge PonticOR = Opaquer ResinRB = Metal Beads for resin retentionBerekally
Cohesive FailureCohesive Failure
A
AA
B
Failure within material
Failure in adhesive layer
Berekally
ADHESION TO ENAMEL ADHESION TO ENAMEL AND DENTINEAND DENTINE
Enamel CompositionEnamel Composition
95-98% by weight inorganic component (hydroxyapatite)Crystalline structure is fairly constant at different levelsMinor organic componentsWater (very low percentage)
Adhesion to EnamelAdhesion to Enamel
Etching of enamel with 37% Etching of enamel with 37% orthophosphoricorthophosphoric acid for 15acid for 15--30 30 secssecs produce produce microporesmicropores..30 – 40% phosphoric acid removes about 10mm of the enamel surfaceA low viscosity liquid polymer (bonding resin) applied A low viscosity liquid polymer (bonding resin) applied and flows into microscopic irregularities and set, and flows into microscopic irregularities and set, producing RESIN TAGSproducing RESIN TAGSThen layers of restorative materials bond to this bonding Then layers of restorative materials bond to this bonding resinresinBond strengthBond strength→→ 2020--25 25 mPamPaSimple and strong adhesionSimple and strong adhesionInitially used in fissure sealantInitially used in fissure sealant
Enamel: Etching PatternEnamel: Etching Pattern
Type 1 Type 3
Summit et al, 2001
Type 2
Factors Influencing Type ofFactors Influencing Type ofEtched SurfaceEtched Surface
Type of Type of etchantetchant (organic/ inorganic acid)(organic/ inorganic acid)EtchantEtchant concentrationconcentrationEtching timeEtching timeGel versus liquid Gel versus liquid etchantetchantEnamel instrumentation after etchingEnamel instrumentation after etchingTooth type (deciduous/ adult)Tooth type (deciduous/ adult)PrismlessPrismless enamelenamelPresence of contaminantsPresence of contaminantsStatus of the enamel (Status of the enamel (fluorosisfluorosis, , hypoplasiahypoplasia, , staining, staining, amelogenesisamelogenesis imperfectaimperfecta))
Adhesion to DentineAdhesion to Dentine
A typical cavity preparation has more dentine A typical cavity preparation has more dentine available for bonding than enamelavailable for bonding than enamel
InorganicInorganic 72%72%
OrganicOrganic 18%18%
WaterWater 10%10%
Dentine content
Problems in Dentine BondingProblems in Dentine Bonding
Dentine structure is more complex and variable Dentine structure is more complex and variable than enamelthan enamelOdontoblasticOdontoblastic processes are mostly waterprocesses are mostly water11°°, 2, 2°°, reparative, sclerotic dentine and dead , reparative, sclerotic dentine and dead tractstractsSmear layerSmear layer--extend to dentinal tubulesextend to dentinal tubules
Dentine Tubule DistributionDentine Tubule Distribution
Erosion
ReparativeDentine
Inner Occlusal Dentine
Outer Occlusal dentine
PULP
Multizoned Carious Lesion
Reactive Dentine (erosion, abrasion)Physiologic Dentine (aging, wear)Many Occluded Tubules
Dentine Bonding SystemDentine Bonding System
Bond to both enamel and dentineBond to both enamel and dentineHistoricallyHistorically-- enamel etched, washed, dried. enamel etched, washed, dried. Then dentine conditioned with chelating agent Then dentine conditioned with chelating agent or EDTA to remove smear layer. Primer or EDTA to remove smear layer. Primer applied, followed by adhesive, then composite.applied, followed by adhesive, then composite.NowNow-- 3 steps, 2 steps or 1 step3 steps, 2 steps or 1 step
3 Steps Dentine Bonding3 Steps Dentine Bonding
1. 1. Etch enamel and dentineEtch enamel and dentine with 37% with 37% orthophosphoricorthophosphoric acid.acid.(Etched dentine(Etched dentine-- smear layer removed, surface smear layer removed, surface disinfected, decrease fluid oozing from disinfected, decrease fluid oozing from odontoblastodontoblast, decalcify dentine a few micron , decalcify dentine a few micron thick)thick)Rinse with waterRinse with waterSlightly dry with gentle air stream or blot drySlightly dry with gentle air stream or blot dry
Smear LayerCollagen Fibres
Demineralised Zone
Summit et al, 2002
Peritubular dentine
2. Apply primer, 2. Apply primer, Primer is a wetting agent thatPrimer is a wetting agent that aids adhesive in aids adhesive in flowing into dentinal tubules around collagen.flowing into dentinal tubules around collagen.Contains volatile solvents such as acetone.Contains volatile solvents such as acetone.HydrophilicHydrophilic
3. Apply adhesive, light cure.3. Apply adhesive, light cure.Place compositePlace composite
Hybrid Layer Formation in Dentine
ETCHANTPRIMER
ADHESIVE RESIN
IntertubularDentine
PeritubularDentine
Dentinal Tubules
HybridZone
Berekally
Hybrid Layer in Dentine BondingHybrid Layer in Dentine Bonding
Summit et al, 2001Resin tag
AdhesiveHybrid layer
Lateral canal
Intertubular dentine
Peritubular dentine
Dentine BondingDentine Bonding
Resin tags in dentinal tubulesResin tags in dentinal tubules-- MicromechanicalMicromechanicalHybrid layer Hybrid layer
-- Adhesive resin interlocks with the dentinal Adhesive resin interlocks with the dentinal collagen (micromechanical)collagen (micromechanical)
- There are a small number of amino acids which are available for chemical reactions (eg; dicarboxylic acids, arginine, lysine)
- Attempts to measure the chemical bond strengths have been up to now been unsuccessful
2 steps2 stepsi) i) –– Etch (smear layer removed)Etch (smear layer removed)
--Primer + AdhesivePrimer + Adhesive
ii) ii) -- Etching primer (smear layer altered)Etching primer (smear layer altered)--AdhesiveAdhesive
1 step1 stepEtch, primer, adhesive in one bottleEtch, primer, adhesive in one bottleSmear layer alteredSmear layer altered
Smear layerSmear layer
•• A layer of dentine, enamel shavings, organic A layer of dentine, enamel shavings, organic matter, bacteria, blood products matter, bacteria, blood products crevicularcrevicular fluid fluid and saliva which is formed during cavity and saliva which is formed during cavity preparationpreparation
•• Bond strength to tooth structure ~ 2Bond strength to tooth structure ~ 2-- 3 3 MPaMPa•• Can be altered or removed because it is not a Can be altered or removed because it is not a very stable adhesion interfacevery stable adhesion interface
Dry Dry vsvs wet bondingwet bonding
Summit et al, 2001
Dry Wet
SummarySummary
There are There are macromechanicalmacromechanical, micromechanical, , micromechanical, and chemical adhesion/bonding.and chemical adhesion/bonding.Adhesion used in all aspects of dentistryAdhesion used in all aspects of dentistry--retention of restoration, fixed and removable retention of restoration, fixed and removable prosthetics, orthodontics and aesthetic dentistry.prosthetics, orthodontics and aesthetic dentistry.Bonding to enamel is simple, but not dentine.Bonding to enamel is simple, but not dentine.Therefore dentine bonding system was Therefore dentine bonding system was introduced. The system either by removing or introduced. The system either by removing or altering smear layer.altering smear layer.
REFERENCESREFERENCES
Clinical Aspects of Dental Materials. M Gladwin, M Clinical Aspects of Dental Materials. M Gladwin, M BagbyBagby. 2000. Lippincott, Williams & Wilkins. . 2000. Lippincott, Williams & Wilkins. Baltimore, USABaltimore, USADr Tom Dr Tom BerekallyBerekally’’ss Lectures: Adhesion Systems (Part Lectures: Adhesion Systems (Part 1, Part 2). Consultant 1, Part 2). Consultant prosthodontistprosthodontist, University of , University of Adelaide, South Adelaide, South AustralisaAustralisa..Introduction to Dental Materials. R van Introduction to Dental Materials. R van NoortNoort. 2002. . 2002. Mosby. Edinburgh.Mosby. Edinburgh.Fundamentals of Operative Dentistry. A Contemporary Fundamentals of Operative Dentistry. A Contemporary Approach. JB Summit, JW Robbins, RS Approach. JB Summit, JW Robbins, RS SchwartsSchwarts. 2001, . 2001, QiuntessenceQiuntessence Publishing Co, Inc. Chicago.Publishing Co, Inc. Chicago.
