composite resins Flashcards
what type of patient would composite, compomer and RMGIC be used in?
low caries risk = composite
compomer mid
RMGIC high
what are the main components of composite?
Glass filler
soft resin / DMA
camphorquinone
silane coupling agent
benefits of the glass/silica filler?
improved mechanical and handling properties
lower thermal expansion
lower shrinkage
better aesthetics in smaller fillers
why use camphorquinone? How does it work?
Use it to cure at time of choice, extends working time
light activator sensitive to blue light
blue light hits camphorquinone and induces free radical addition polymerisation to dimethylacrylate
why is the low weight dimethyl-acrylate used?
to decrease viscosity and reactivity
It is the flowable monomer component of the resin. It sets when the camphorquinone in the mix is hit by UV.
It polymerises fast and has little shrinkage.
what is the soft resin used for?
used to allow manipulation of composite before it is set, e.g. BIS-GMA
why use a silane coupling agent?
creates a bond between the resin and the filler particles
this helps to counter PCS
what properties make composite ideal for usage?
good aesthetics
good handling qualities
light or self cure
anti-cariogenic
radiopaque
biocompatible (not all monomer polymerised though)
polishable
what types of filler are there?
nano hybrid microfine fine conventional bulk
how is flowable composite different to conventional?
flowable composite has much smaller and less filler particles, hence increased viscosity however it is weaker.
viscosity allows it to adapt to base of cavity
what thermal properties does composite possess?
low thermal conductivity
low thermal diffusivity
high thermal coefficient (not good)
benefits of light cure? and cons?
cure on demand
extended working time
less waste
premature polymerisation from dental light
shrinkage
depth of cure
light and material mismatch
