Acrylic Materials

Question 1

Name properties that acrylic should have

Answer 1

• Dimensionally stable/accurate
• High young modulus- rigid
• Should have similar thermal expansion coefficient to the artificial teeth
• Low density (especially for upper)

Question 2

describe the acrylic polymerisation reaction

Answer 2

1) Acrylic monomers
2) Polymerisation initiated by Benzoyl Peroxide when 72*C is reached
3) Polymer propagates and get larger
4) Polymerisation terminates

Question 3

Name powder components of Acrylic

Answer 3

• Benzoyl Peroxide initiator
• Pre polymerised PMMA beads
• Plasticiser (inc. solubility)
• Co-Polymers- (improve mechanical properties)
• Pigments for colouring

Question 4

Name liquid components of Acrylic

Answer 4

• Liquid monomer
• Hydroquinone inhibitor
• Co-polymers

Question 5

Problems with curing acrylic

Answer 5

under cured - low molecular weight, high monomer content is an irritant

overcured- gaseous porosity = voids, polymerisation shrinkage up to 20%