Temporary Materials

Question 1

4 examples of temporary materials

Answer 1

1. PMMA - polymethylmethacrylate e.g. jet
2. PEMA - polyethylmethacrylate e.g. trim II
3. Bis-acryl composite e.g. protemp 4, quicktemp
4. UDMA - urethanedimethacrylate e.g. provipont DC

Question 2

how is PMMA formed

Answer 2

free addition polymerisation of methacrylate monomer via cross linking due to C=C

Question 3

advantages of PMMA

Answer 3

powder / liquid formulation
self curing
good marginal fit
good transverse strength
polishable

Question 4

disadvantages of PMMA

Answer 4

poor abrasion resistance
high shrinkage
high thermal release
free monomer may be toxic

Question 5

key properties to consider with temporary materials

Answer 5

1. temperature - exothermic reaction / material encapsulates tooth prep / safety / dentist’s concern
2. colour stability - aesthetics / anterior teeth / patient’s concern

Question 6

how is the pulp affect by materials

Answer 6

affected by temperature rise from exothermic reaction as well as duration of this