Adhesive Materials

1. Adhesive Materials DHYG 113 Restorative Dentistry I

2. 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

3. 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

4. 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

5. 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

6. 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

7. Uses in Dentistry

8. Bond Porcelain Veneers Before After

9. Attach Ortho Brackets

10. 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

11. 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

12. 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’

13. 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

14. 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

15. One Step Dentin Bonding • Etch/prime and adhesive in one bottle

16. 2-Step Dentinal Bonding Optibond solo Prime and bond • Primer and Adhesive combined • May take longer than 3-step systems

17. 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

18. 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

19. 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

20. 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.

21. Desensitization Gluma desensitizer