Methods of Caries Well-Timed Diagnostics X

Current adhesives and their development. Enamel and
dentine adhesion principles. Use possibility, working
procedure. Common mistakes and their consequences in
the clinical praxis.
Operative Dentistry 1
Stomatolog Julia Morozova, Ph.D.
Basic mechanism of adhesion
• The primary aim of dental adhesives is to provide
retention to composite fillings or composite cements
• Twofold adhesion
• Co-polymerization of residual double bonds (-C=C-) in
the oxygen inhibition layer
• Exchange process
– replacement of inorganic components
• from hard tissue
– by resin monomers
• micromechanically interlocked
Enamel structure
• The hardest tissue of the human body (96 % of mineral
• Prisms
Enamel bonding
• Developed by Buonocore (1955)
• Etching by 32–37% H3PO4:
– interprismatic and intraprismatic strucure will be disrupted
– creates micropores (5 – 50 microns deep)
– increases surface energy
– increases wettability
• 3 types of etching:
• Central intraprismatic
• Peripheral interprismatic
• Combined
Adhesion onto enamel
• Enamel adhesive (bond), strength >20 MPa
• It forms the interlayer allowing the resin adhesion
onto tne enamel
• Contain: unfilled or partially filled composite resin
with smaller molecules of monomers
Dentine structure
Live tissue with methabolism
Dentine composition
Hydrophilic tissue (10–30 % H2O)
Dentinal tubules with odontoblasts’ process and
tubular liquid
• Changes in dentine structure
• Smear layer
• Dentinal wetness
Adhesion onto dentine
• Presence of smear layer
• Hydrophilic tissue
• Etching → dissolving of smear layer and mineral components →
opening of dentinal tubules’ entrances, denaturation of surface
proteins → baring of collagenous fibers’ net
• Primer (has influence on hydrophilic properties of the dentine
and accents its hydrophobic properties)- hybridization of the
Requirements for adhesives
• High strength and permanence of adhesion onto dentine
and enamel
• Biocompatibility for tooth tissues, organismus in
generally and personnel
• Perfect marginal integrity without risk of microleakage,
secondary caries or marginal percolation
• Perfect and permanent contact with dentine and closure
of dentinal tubules
• Suitable for moist and dry environments
• Fluoride-releasing
• Easy procedure and application
• Sufficient long expiration time
Classification of adhesives
• According to chemical composition (type of solvent)
• According to influence on smear layer
• According to generation criterion
Chemical composition of adhesives
Monomers of composite resin
Initiators (photo- or self-curing)
Inhibitors or stabilizers
Anorganic filler (not allways)
Specific components (polyalkenoic copolymer,
glutaraldehyd, antibacterial components, fluorides,
dyes, acids)
Monomers of resin composite
Methacrylic acid (MA)
Methylmetacrylate (MMA)
Hydroxyethyl metacrylate (HEMA)
Di-HEMA-phosphate and HEMA-phosphate
Di-methacrylates (BisGMA (Bowen‘s monomer), UDMA,
• (Meth)acrylamides
• Water
• Ethanol
• Acetone
Initiator systems
• Camphorquinone/coinitiator system
• 1-phenyl-1,2
propanedione (PPD)
• Acylphosphine oxides
Chemical initiators
• Benzoylperoxide (BPO) in
conjunction with tertiary
• Tri-n-butyl borane (TBB)
• Antioxidants- scavenge free radicals originating from
prematurely reacted initiators
• Prevent spontaneous initiation and propagation of the
free-radical polymerization reaction
• Promote shelf life
• Butylated hydroxytoluene (butylhydroxytoluene BHT),
monomethyl ether hydroquinone (MEHQ)
1st generation
NPG-GMA (N-phenylglycin-glycidyl methacrylate)
Strength of adhesion: 1–3 MPa
S.S. White’s Cervident
2nd generation
• Late 1970s
• Combination of Bis GMA (bisphenol A and glycidyl methacrylate)
and HEMA (hydroxyethyl methacrylate)
• Strength of adhesion: 4.5–6 MPa
• 3 tendencies:
• Etching agent (25% citric acid - Dentin Bonding System, Den-Mat)
• Adhesive with phosphate aether (Bondite, Sybron/Kerr; Scotchbond
TM, 3M ESPE; Prisma Universal, Dentsply Caulk)
• Adhesive with polyurethan polymer (Dentin-Adhesit, Ivoclar Vivadent)
3rd generation
• Late 1980s
• 3 parts:
• Conditioner: weak organic acid (maleic acid) or anorganic acids in low
concentration (phosphoric or nitric acid)
• Primer: bifunctional monomer dissolved in solvent (acetone or ethanol)
Bifunctional monomer has one hydrophilic end (it is adapted onto the
dentine) and another one is hydrophobic (it is adapted onto composite
resin); HEMA, 4-META, NPG, NSMA
• Adhesive: non-filled or low-filled resin, that connects with primer and
forms hybrid layer (1–5 µm), that penetrates into dentinal tubules and
forms composite tags
• Strength of adhesion: 12–15 MPa
• Scotchbond TM Multi-Purpose (conditioner maleic acid);
Scotchbond TM Multi-Purpose Plus (conditioner phosphoric acid,
1994) (3 M ESPE)
• XR Bonding System (Sybron/Kerr), Gluma (Heraeus Kulzer), Tenure
(Den-Mat), Syntac Classic (Ivoclar Vivadent)
4th generation
Start of revolution in aesthetic dentistry (early 1990s)
Complet removing of smear layer
Total etching of enamel and dentine („total-etch“)
The dentine surface after gentle drying must be wet to
prevent the collapse of collagen fibres after the etching („wet
• Technique sensitive
• Gold standard
• OptiBond FL (Sybron/Kerr); All-Bond (Bisco, Inc.)
5th generation
• Mid 1990s
• „One bottle systems“ (primer and adhesive are in one bottle)
• Two steps technique: etching and adhesive application (Etch &
• OptiBond Solo (Sybron/Kerr), Gluma One Bond (Heraeus
Kulzer), Single Bond (3M ESPE)
6th generation
Early 2000s
„Self-etching“: acidic primer
Etching is not required→ decreasing of postoperative sensitivity
Strength of adhesion: 18–23 MPa
All-Bond SE (Bisco Inc.); ClearfilTM SE Bond (Kuraray); AdheSe
(Ivoclar Vivadent), Nano-Bond (Pentron)
7th generation
One-bottle self-etching systems
One step system
OptiBond All-In-One (Sybron/Kerr); Xeno IV (Dentsply
Caulk), ClearfilTM S3Bond (Kuraray), iBond (Heraeus
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
Pros/Cons of Etch & Rinse (Col Kraig S. Vandewalle Enamel and
Dentin Adhesives)
• Separate acid etch
– good enamel etch pattern
• Potential to over-etch dentine
– except sclerotic dentin
• Post-conditioning rinse is necessary
– sensitive to level of dentine wetness
• Multiple long-term clinical studies
Wet bonding (Col Kraig S. Vandewalle Enamel and Dentin Adhesives)
• Acetone and ethanol
based primers
– displace remaining water
– carry monomers into
– gently air-dried
– leaving monomers behind
• Examples
– One-Step
– Prime & Bond NT
• Overwet phenomen
– too moist (too much water)
– not completely displaced
• Phase separation
– blister and globule formation
• Disadvantages:
• Cannot check for enamel
“frosted” etch
• Technique sensitivity
– not too wet or too dry
• Solvents evaporate from
– may reduce monomer
Dry bonding (Col Kraig S. Vandewalle Enamel and Dentin Adhesives)
• Water-based primers
– effective on wet or dry dentine
– self-rewetting effect
– re-expand collapsed collagen
• Permits check of “frosted” enamel
• Examples
– Scotchbond Multi-Purpose
– Optibond
Pros/Cons of Self-Etch (Col Kraig S. Vandewalle Enamel and Dentin
• Good dentine conditioning
– simultaneous infiltration
– depth of demineralization
• Possible reduction in post-operative sensitivity
• No post-etching rinse
– not sensitive to level of dentine wetness
• Reduced application time
• Relatively lower bond strengths
Unit Dose (Col Kraig S. Vandewalle Enamel and Dentin Adhesives)
Improved infection control
Simple working procedure
Minimizes loss of volatile components over time
Higher cost
Optibond Solo Plus
Prime and Bond NT
Prompt L-Pop
Polymerization shrinkage and polymerization stress
3.5–4 %
They are affected by fast photopolymerization
C-factor (size and geometry of cavity)
Application technique
Light intensity and direction during the photopolymerization
Viscosity and elastic modulus of composite resin, value of
polymerization shrinkage
• Hydroscopic and thermal expansion of resin composite
• Consequences: bad marginal integrity, microleakage between
filling and cavity, filling percolation, secondary caries,
postoperative sensitivity, cusp break
Ratio of bonded to unbonded surfaces of cavity
Scientific Compendium SDR, 2011
C-factor of different classes
Karthic K., Sivakumar K., Geetha Priya P.R., Shankar S.: Polymerization Shrinkage of Composites-A Review.
JIADS, vol. 2, issue 2, April-June, 2001, pp. 32–36
Incremental technique minimizing C-factor
Common mistakes
Non-adequate etching
Insufficient drying or overdrying of dentine
Too thick or too thin layer of adhesive
Insufficient polymerization
Non-adequate material adaption onto the cavity walls
The influence of resins on the general health
• Contact allergy of personnel on adhesives and resins
• Cytotoxic and endocrine-disruptive effects of nonpolymerated monomers (esp. dimethacrylates)
Thank you for attention

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