What is the mechanism of Adhesion (resin-based)?
Replacement of minerals from hard tissue by resin monomers micromechanically interolocked
Why is enamel more predictable to bond to?
- More homogenous structure
- High inorganic content
- Higher surface energy
Why is dentin less predictable to bond to?
- high variability
- higher organic content
What is the composition of enamel?
- 86% Inorganic
- 12% Water
- 2% Organic
What does etching do?
- Creates microspores
- 5-50 microns deep
- Increases surface energy
- Increases wettability
What is the composition of Dentin?
- 50% Inorganic
- 25% Organic
- 25% Water
What is sclerotic dentin?
- Normal Aging
- Abrasion
- Erosion
- Hypermineralization
- Less receptive to bonding
What is reparative dentin?
- Results from caries/dental procedures
- Hypermineralization
- Less receptive to bonding
What percent does the dentin smear layer reduce dentin permeability?
86%
- Produced by instrumentation
- Composition: cut dentin debris, bacteria
How thick is the dentinal smear layer?
- 0.5 - 5.0 microns
- Will not wash off
- Weak bond to tooth
- Very soluable
What does a 4th generation bond system look like?
- Conditioner (etchant)
- Primer (hydrophilic)
- Adhesive (hydrophobic)
- Etch and Rinse
Example - Optibond FL, Scotchbond multi-purpose
What does a 5th generation bond system look like?
- Attempt to simplify…
- Reduce number of bottles
- Etch and Rinse…
- Conditioner (etch)
- Combined primer and adhesive
- More susceptible to hydrolysis over time…
Example: Optibond solo
What does a 6th generation bond system look like?
- No phosphoric acid!
- Combined conditioner and primer
- Clearfil SE!
- Separate adhesive
What does a 7th generation bonding agent look like?
- “All in one”
- Combined conditioner, primer and adhesive
- One step
- No mixing
What does conditioner (etch) do to the tooth?
- Chemical alteration of the surface
- ie: phosphoric, citric, maleic, nitric
- Removes dentinal smear layer
- Exposes collagen fibrils
- Simultaneous enamel etch
- Rinse
- Keep moist
What does a primer (wetting agent) do?
- Hydrophilic monomers
- Displaces water
- Promotes infiltration into collagen
- Lightly air dry
- Transforms hydrophilic to hydrophobic
- This is better for composite which is hydrophobic!
What does adhesive resin do?
- Chemically binds to primer
- Links primer to resin composite
What is the hybrid layer?
The hydrophilic resin infiltrated surface layer of collagen fibers in demineralized dentin
A separate enamel is etch is more predictable then self etches…T/F?
True
Study that supported optibond FL use (3 Step)…
- Van Meerbeek Study - 100% retention at 3 years for NCCLs
- Boghosian - 97% at 13 years
What do studies show about etch and rinse (two step)?
- Optibond Solo
- Swift - 93% retention at 3 years for NCCL
- More susceptible to hydrolysis at hybrid layer
If you are using a self etch bond system are you going to use phosphoric acid?
No!
Have controlled clinical studies found any difference in post op sensitivity between etch and rinse and self etch bonding systems?
No!
Does research support better bond strength with Clearfil SE it if is refrigerated?
Yes!
More Shear Bond Strength….
