resin composties 2 Flashcards
what is optimal absorption of camphorquinone
460-480 nm
what types of lights curing avalible?
quartz tungsten halogen
fibre optic light guide
LEDs
What to LEDs provide?
narrow spectrum
low current
low heat
portable and less bulky
at what heat is irreversible pulpitis caused?
5.5-11.1 degrees
how long should you wait between cycles to prevent heat build up?
30 seconds
What components re plasma arc curing?
xenon bulb
considerable power- needs efficient cooling
apply for 2-3 seconds
what components re argon laser curing units?
blue light
collimated beam
minimal heat production
what is wear of composites influenced by?
abrasive
erosive
fatigue
What is resin matrix softening due to?
inhibition of polymreisation due to entrapped air pockets
chemical softening- food and plaque acids
what causes stress concentrations at resin/filler?
thermomechanical fatigue
water sorption
polymerisation shrinkage
mechanical stresses
If porosity increases what happen re. crack propogation?
increases
What causes crack propagation re. resin/ filler interface?
leakage of filler
stress corrosion of filler
what is the setting reaction re. silicates?
acid base reaction between illuminosilicate glass and phosphoric acid
what is the setting reaction re. acrylics?
free radical polymerisation
what are the stages of free radical addition polymerisaiton of methyl methacrylate?
activation
initiation
propogation
termination
