Heat-cured acrylic

Question 1

Forms of acrylic?

Answer 1

heat-cured
cold-cured
light-cured
injection techniques
high-impact acrylics

Question 2

How does monomer and polymer interact?

Answer 2

monomer dissolves outer surface of the polymer bead

sad to dough

Question 3

How to know of heat-cured acrylic is ready to pack?

Answer 3

dough

comes away from container - doesn’t stick to container

dough snap

Question 4

factors affecting the time taken to reach the dough stage?

Answer 4

particle size of polymer

molecular weight of polymer

high temp = quicker reaction

presence of plasticiser - reduces dough time

polymer/monomer ratio - higher ratio then shorter the dough time

type of polymer - granular… increased permeation and decrease reaction time

Question 5

how to overcome contraction porosity?

Answer 5

excess acrylic dough used

placed into flask with thin polythene sheet

flask opened and excess removed

known as trail packing

can be repeated several times

Question 6

how long is heat-cured acrylic cured?

Answer 6

8 hours in water bath under pressure at 72 dc

usually overnight

Question 7

why slow cool PMMA?

Answer 7

Prevents stresses forming by plastic deformation within polymer

as there is a different contraction between gypsum and acrylic

Question 8

why heat slowly?

Answer 8

exothermic reaction and allow the gases to dissipate more readily

gypsum and slowly process the heat generated

Question 9

what is the usual investment material?

Answer 9

plaster of paris

Question 10

After deflasking, hat do you need to do?

Answer 10

acrylic flash remove

Question 11

polishing?

Answer 11

sift brown rubber points used

must keep moving as localised burn and distort prosthesis