Adhesive Materials
DHYG 113
Restorative Dentistry I
Objectives
Describe the difference between micromechanical and macromechanical bonding
Discuss the benefits of bonded restorations Compare the differences of enamel and dentin in
regards to etching and bonding Discuss the terms: ortho-phosphoric acid,
enamel tags, smear layer, primer and adhesive Summarize the differences between glass
ionomer cements and dentinal bonding
Why use adhesives?
Strong adhesion increases retention of appliance or restoration
Eliminates need to remove tooth structure (undercuts) for mechanical retention
Seals margins, reducing chance of recurrent decay
Adhesion or Bonding
Joining together of two objects using a glue or cement
Micromechanical bonding – Superglue Surface irregularities too small to be
seen Macromechanical bonding
Larger scale – wood glue
Acid Etch and Composites
Materials developed in the 50’s, ’60’s, ’70’s and 80’s Bonded ortho brackets Bonded bridges (Maryland bridge) Porcelain, plastic & composite veneers –
etched & bonded to facial surfaces Composite materials used to reshape teeth Periodontal splints, stabilize jaw fractures
Uses in Dentistry
Retention of restorations Undercuts not necessary Bond weak restoration to stronger tooth
Reduction of microleakage Reduce postoperative sensitivity
Reduction of recurrent decay Sealed margins more resistant to decay
Uses in Dentistry
Bond Porcelain Veneers
Before After
Attach Ortho Brackets
Surface Factors
Cleanliness Don’t want adhesive to bond to surface debris
– poor bonding Should be chemically compatible or adhesive
will not “wet” adequately Biofilms – contaminated by oral fluids
Enamel pellicle Reduces or prevents bonding Use rubber dam to keep surface dry
Testing Adhesion
Adhesive Failure – comes cleanly off tooth Orthodontic bracket may have been
contaminated
Cohesive Failure – bonding material fails Cement layer remains on both tooth &
bracket
Acid Etching
Etch is usually 37% ortho-phosphoric acid 15-30 seconds
Creates microscopically rough enamel surface Micropores Enamel tags
More effective to bond polymer resin to ends of enamel rods than to long axis of rods
Properly etched enamel appears ‘frosty’
Resin Systems Resins “wet” the etched surface and flow into the
microscopic irregularities
Enamel bonding resin – adhesive Set by polymerization Next step is to place the composite material –
chemically bonds to the resin
Dentinal Bonding
Micromechanical bonding and secondary atomic bonds
Bond to enamel and dentin to prevent leakage and recurrent decay
Etching removes dentin “smear layer” and decalcifies layer of dentin Dentin is rinsed, but not thoroughly dried
One Step Dentin Bonding
Etch/prime and adhesive in one bottle
2-Step Dentinal Bonding
Optibond solo
Prime and bond Primer and
Adhesive combined May take longer
than 3-step systems
3-Step Dentin Bonding
Etch Apply primer – wetting agent Apply adhesive – low viscosity resin Place the composite
Deep cavities – may use protective material to protect pulp from irritation
Polycarboxylate Cement
Chemically adhesive – ionic bonds between negative charge in cement and positive charge in tooth
Zinc oxide powder + polyacrylic acid dissolved in water = Polycarboxylate cement
Glass Ionomer Cements
Dentin surface “conditioned” with polyacrylic acid solution to remove smear layer and result in better bonding
No separate adhesive is used – chemically adhesive
Glass ionomers are the materials of choice for high caries risk & both dentin and enamel margins – fluoride-releasing
Glass Ionomer Material
Fuji Triage high-fluoride-release,
command-set glass ionomer
Suitable as a surface-protection
material for a root sensitivity.
Intermediate restorative material
for cases of rampant caries. It
light cures in 1 minute or can
self cure.
Desensitization
Gluma desensitizer