Composite Resin Update - on word doc

Question 1

Components of composite resin.

Answer 1

1. Matrix (continuous phase) Comonomer system, of 2-4 monomers
2. Filler: dispersed phase (filler particles of different shapes and sizes)
3. Coupline agent: internal interface coupling agent (binds filler to matrix)
4. Bonding system: external interface coupling agent

and:
- initiatory/accelerator system
- stabilisers (for storage stability)
- pigments (for colour and radiolucency)

Question 2

What are composite fillers?

Answer 2

glass or ceramic particles that give bulk to the composite material

particle distributions today are designed by computer models - about 80% volume of the material

come in many sizes

Question 3

What are the different sizes of filler particles? (5) How many are combined in a composite, what does this do? (3)

Answer 3

• macro
• micro
• nano
• nanomere
• nanocluster

higher amount of nanofillers:

• increases translucency (smaller than the wavelength of light)
• reduces polymerisation stress
• combination of many fillers for desired effect

Question 4

What is polymerisation/shrinkage stress? (not in lec)

Answer 4

as a result of the polymerisation process, the liquid or resin is converted into a solid, which results in a density change that reduces the overall volume - internal load

e.g. nanofillers will likely shrink as much as traditional fillers but create less polymerisations stress

Question 5

What is polymerisation stress the result of? (4)

Answer 5

• external constraint of the free shrinkage imposed by bonding to tooth structure
• size and nature of the monomers
• acquisition of stiffness during polymerisation
• rate of the reaction

Question 6

What is the external interface coupling agent?

Answer 6

a bonding system
- includes bonding to enamel, dentine adhesive and bonding agent (unfilled resin)

e.g. dentine adhesive -> self-etching primers -> one bottle bonds (enamel and dentine) -> self-adhesive composite