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Flashcards in resin composties 2 Deck (17):
1

what is optimal absorption of camphorquinone

460-480 nm

2

what types of lights curing avalible?

quartz tungsten halogen
fibre optic light guide
LEDs

3

What to LEDs provide?

narrow spectrum
low current
low heat
portable and less bulky

4

at what heat is irreversible pulpitis caused?

5.5-11.1 degrees

5

how long should you wait between cycles to prevent heat build up?

30 seconds

6

What components re plasma arc curing?

xenon bulb
considerable power- needs efficient cooling
apply for 2-3 seconds

7

what components re argon laser curing units?

blue light
collimated beam
minimal heat production

8

what is wear of composites influenced by?

abrasive
erosive
fatigue

9

What is resin matrix softening due to?

inhibition of polymreisation due to entrapped air pockets
chemical softening- food and plaque acids

10

what causes stress concentrations at resin/filler?

thermomechanical fatigue
water sorption
polymerisation shrinkage
mechanical stresses

11

If porosity increases what happen re. crack propogation?

increases

12

What causes crack propagation re. resin/ filler interface?

leakage of filler
stress corrosion of filler

13

what is the setting reaction re. silicates?

acid base reaction between illuminosilicate glass and phosphoric acid

14

what is the setting reaction re. acrylics?

free radical polymerisation

15

what are the stages of free radical addition polymerisaiton of methyl methacrylate?

activation
initiation
propogation
termination

16

compared to silicates, how are acrylics superior?

less prone to erosion
less soluble
less acidic
less brittle

17

what effect does adding filler particles have?

reduces shrinkage
weakens material