Composite Resins

Question 1

Mechanical properties of composite

Answer 1

Smooth surface, polishable
Technique sensitive 
Low setting shrinkage
When hybrid filled it has high compressive strength 
Corrosion resistant

Question 2

Thermal properties of composite

Answer 2

High thermal expansion coefficient compared to tooth tissue (bad)

Can shrink away from Cavosurface margins in cold

Question 3

Biological Properties

Answer 3

Biocompatible - ok- but unreacted monomer is an irritant

Anti-cariogenic- generally no but some release fluoride

Question 4

1) Filler Particles

Answer 4

Conventional- Glass/Quartz
Microfilled- microfine silica
Hybrid

High filler content = decreased thermal expansion coefficient

Question 5

2) Resin

Answer 5

Bis-GMA

Causes the setting part of the reaction when it undergoes free radical addition polymerisation

Question 6

3) Camphorquinone

Answer 6

Initiator for the reaction
When activated by blue light releases free radicals that breaks C=C double bonds in resin causing addition polymerisation

Question 7

4)Low weight dimethycrylate

Answer 7

TEGMA
Acts like a paint thinner
Higher proportion = decreased viscosity

Question 8

5) Silane Coupling agent

Answer 8

Selectively bonds resin to glass filler
Binds to OH groups in filler
Binds to absorbed water

Question 9

If it is a self cure composite what components will it have for free radical addition polymerisation

Answer 9

Benzoyl peroxide

Aromatic tertiary amine