Enamel and Dentine Bonding Flashcards
What are 3 approaches to achieving attachment to tooth surface?
– Micromechanical attachments • E.g. acid etch and application of resins
– Chemical adhesion to enamel/dentine
– Complex – involving wetting, penetration and formation of bound material of restorative substrate interface • E.g. modern dentine bonding agents
Who discovered acid etch for enamel margins?
Buonocore 1955
- Application of acid gel
- Selective decalcification of enamel prisms
- Micromechanical tags into which bonding resin may flow.
- 20-25 MPa
What does acid etch do?
- Increases surface roughness microscopically
- Increases enamel surface energy
- – removes surface contaminants*
- – increases wetting*
- – facilitates micromechanical retention*
What is the ideal dental adhesive?
- an immediate and durable bond
- a reliable bond
- prevent bacterial ingress
- be safe to use
- be simple to use
What are problems with dentine bonding?
• Dentine is
– hydrophilic (adhesives are hydrophobic)
– a vital tissue
– consists of inorganic & organic material
– is covered by a smear layer
What does a Primer of dentine do?
Primers = Dentine Conditioners
– acids – alter surface appearance & characteristics of dentine
- open dentinal tubules
What does a Coupling Agents for dentine do?
• Coupling Agents = Primers
– components that do the sticking
Bond hydrophobic composites to hydrophilic dentine
what does a sealer for dentine do?
• Sealer = Sealers
– flows into dentinal tubules
– seals dentine with surface layer rich in methacrylates
– ensures bonding to the resin in the composite
-resins
How does a bond finally fail?
Acid opening of tubules risks nano leakage
- Dentine etch greater than resin can penetrate
- Dentine microstructure disruption and failure
