Composite Proprties Flashcards
All describe VLC system except ?
1. 410-500nm wavelengths
2. 300mW/cm2 of irradiance
3. 2mm maximum cure depth
4. Camphorquinone initiators
2
How changing from UV light cure to VLC give a benefit to a dentist ?
By increasing working time , especially when large amount of composite need to be placed
What’s the mechanism of curing of VLC ?.
VLC composites are single-component pastes , and the polymerization process is activated by an external energy source
There is alpha diketone intiators ( camphorquinone generally ) absorb energy from a visible (474nm blue light ) light source .
Ketone absorbs energy and reacts with amine ( added to the system to enhance the effect of the light -sensitive catalyst ) to produce free radicals .
What’s the minimum acceptable level for visible curing light outputs ?
400 mW/cm2
How far the tip of light cure most be holded from the composite surface ? And what’s standard exposure time ?
1-2mm , to cure the light shade of material to a depth of 2-2.5mm
40 sec in above position
Which is true regarding composite resin ?
1. Low polymerization shrinkage
2. Increase occlusal wear
3.reduce micro leakage
4. All
4
Durability of composite resin based on ?
- Extent and nature of initial damage ( what’s nature ) ?
- The treatment procedure used
- Patient related factors ( awareness , cooperation , motivation in practicing preventing measures , Carie’s risk , diet , oral hygiene , adverse habits )
- Operators technique and resto material used ( isolation , resin placement , finishing ,polishing )
Which properties of filled resin is primarily to blame for the failure of class 2 composite restoration ?
1. Low flexular strength
2. Low compressive strength
3. Low tensile strength
4. Low wear resistance
4
May is ribbond most used in such class ?
Most desirable finished surface for composites is obtained by ?
Aluminum oxide disks
