resin composite 1 Flashcards
what is the setting reaction for resin composite known as?
free radical addition polymerisation
what are the 4 stages of free radical addition polymerisation?
- activation
- initiation
- propagation
- termination
what is the resin matrix made of?
- methacrylate or dimethacrylate monomers such as BIS- GMA
- coconomers such as TEGMA to control viscosity as filler is to be mixed in and clinical handling
- inhibitors- prevent polymerisation reaction occurring too early
what are examples of fillers used in resin composites?
- quartz
- silica
- glasses
what is used in composite to help make it radiopaque and distinguishable from caries?
glasses contain some sort of heavy metal
what else is contained with a resin composite?
coupling agent- to react with resin matrix and the glass filler.
what is the name of the coupling agent used?
vinyl silane
how can resin composites be set/activated?
- chemical
- light
how is a photo initiator activated ?
blue light
what is the most common photo initiator used in light cured composite resin?
camphoroquinone
what may also set resin composite in clinics?
operating light to an extent
what does camphorquinone do?
yields the necessary free radicals needed to start polymerisation
at what wavelength does camphorquinone get excited?
460nm-480nm
what is the disadvantage of resin composites and what part is the problem ?
- resin makes resin composites susceptible to polymerisation shrinkage
how are resin composites classified?
- method of activation (chemical or light)
- filler particle size and distribution
- handling characteristics (packable- viscous or flowable- less filler more fluid)
