Resin Flashcards
What are the silicates?
These were products that were created before resin- they were an acid base reaction between aluminium silicate and phosphoric acid.
It released fluoride, which was good for the teeth however, it was really moisture sensitive and therefore had to kept hydrated, it was also prone to acid interaction.
It was protected with vaseline
What are silicates
They are the earliest restorative material that is an acid base reaction between alumni silicate with phosphoric acid. They release fluoride however are prone to acid attack- and need to be kept hydrated
What are acrlyics
Acrlyics are a powder that are mixed with liquid. It is a free radical addition polymerisation.
However- the material contracts upon polymerisation. The reaction is exothermic and poor colour stabilisation.
Although compared to silicates- less prone to corrosion and exhibit lower thermal difussivity.
What are resin composites
These are a combination of two chemically different materials with a distinct interface separating the two components and having properties that cannot be achieved by any of the components acting alone.
What is the composition of resin
These are generally based upon
1) Bis- GMA-
2) Co-monomers like TEGMA- controls viscosity by filler addition
3) inhibitor- prevents the polymerisation reaction from kicking off too readily e.g. when product is in storage.
What are the new products based on?
These are based on silorane ring opening- these produce an expansion however the overall contraction therefore shrinkage occurs.
What is the light cure that occurs
Camphorquinine (photosensitiser)- ring opening polymerisation, less shrinkage
What are the composites that are placed in Resin
Quartz
Silica
Glasses- Aluminiumsilicate, barium oxide- radiopaque and therefore can distinguish restoration from caries
What are the coupling agents
Fillers need to have coupling agents- they promote adhesion between the matrix and the filler. They need for good wetting- need a small quantity to coat all those filler particles.
Filler content and other properties
As filler content increases, the surface hardness increases.
As filler content increases, thermal expansion co-efficient decreases.
As filler content increases, % of volume setting contraction decreases.
What does camphorquonine do?
Yields the necessary free radicals to start polymerisation.
What are the types of resin
1) conventional- early resin, poor set, resin wears overtime increasing the roughness
2) microfilled- smaller filler size, good polish and good wear resistant because it is holding everything in place
3) hybrid- 80% filler, smaller filler particles
4) nano composites- extremely small filler size
Type 1 resin
restoration of cavities on the occlusal surface
Type 2 resin
All other polymer based filling and restorative material
What is resin strength depend on
1) porosity
2) decreased coupling
increased porosity and decreased coupling- reduce strength
