1
Q
4 examples of temporary materials
A
- PMMA - polymethylmethacrylate e.g. jet
- PEMA - polyethylmethacrylate e.g. trim II
- Bis-acryl composite e.g. protemp 4, quicktemp
- UDMA - urethanedimethacrylate e.g. provipont DC
2
Q
how is PMMA formed
A
free addition polymerisation of methacrylate monomer via cross linking due to C=C
3
Q
advantages of PMMA
A
powder / liquid formulation
self curing
good marginal fit
good transverse strength
polishable
4
Q
disadvantages of PMMA
A
poor abrasion resistance
high shrinkage
high thermal release
free monomer may be toxic
5
Q
key properties to consider with temporary materials
A
- temperature - exothermic reaction / material encapsulates tooth prep / safety / dentist’s concern
- colour stability - aesthetics / anterior teeth / patient’s concern
6
Q
how is the pulp affect by materials
A
affected by temperature rise from exothermic reaction as well as duration of this
