Composite

Question 1

good properties of composite

Answer 1

aesthetics
biocompatible
compressive strength
wear resistance
hardness
polishable
ease of use

Question 2

bad properties of composite

Answer 2

high thermal expansion
technique sensitive
polymerisation shrinkage
worse strength etc than amalgam

Question 3

components of composite

Answer 3

filler particles - glass/quartz/silica
reduce expansion, increase properties/strength

resin - BISGMA
c=c crosslinking, free radical polymerisation

camphorquinone - initiator
blue light activation release of free radicals + bonds BISGMA

low weight dimethacrylate
TEGDMA, thinner

silane coupling agent
glass to preferentially bond resin and not water

Question 4

at which wavelength does blue light activation curing of composite occur

Answer 4

440nm

Question 5

what is configuration factor

Answer 5

ratio of bonded to unbonded surfaces

Question 6

what is polymerisation shrinkage

Answer 6

volume reduction on setting

Question 7

consequences of polymerisation shrinkage

Answer 7

deformation, fracture, micro leakage, secondary caries

Question 8

how to reduce polymerisation shrinkage

Answer 8

incremental placement of composite
no more than 2mm, don’t join up all walls