PMMA Acrylic Resin (revision questions)

Question 1

stages

Answer 1

activation - of intitator to provide free radicals
irritation - free radicals break C=C bond in monomer and trasnfer free radical
propogation - growing polymer chain
termination - of polymerisation

Question 2

Properties

Answer 2

non toxic
non iriitant
unaffected by oral fluids
easy to repair
high hardness/abrasion resistance
low thermal conductivity
mechanical properties are poor
high softening tem

Question 3

Self cured acrylic

Answer 3

more unreacted monomer - causes allergy
lower molecular weight
high monomer levels
poor colour stability

Question 4

Heat cured acrylic

Answer 4

less unreacted monomer
higher molecular weight
lower monomer levels
better colour stabilty
curing process may cause porosity

Question 5

Undercuring

Answer 5

free monomer - irritant

low molcecular weight

Question 6

Overcuring

Answer 6

gaseous porosity

polymerisation shrinkage

Question 7

Causes of contraction porosity

Answer 7

too much monomer
insuuficent excess material
insufficent clamp pressure