Composite

Question 1

What are the components of composite?

Answer 1

Glass filler particles - quartz
Resin monomer (most common bis-GMA)
Camphorquinone - light-activator
Lowe weight di-methacrylates
Silane coupling agent

Question 2

What does silane coupling agent do within composite?

Answer 2

Acts as an intermediary to bond inorganic material to organic e.g. glass and resin
Increases strength

Question 3

What is the etch most commonly used?

Answer 3

37% phosphoric acid etch

Question 4

What does acid etching do to a tooth?

Answer 4

• Increases the surface roughness - creates spaces within enamel to allow for MICROMECHANICAL ADHESION
• Removes contaminants from surface - removes the SMEAR LAYER
• Unblocks dentinal tubules
• De-mineralises dentine surface, exposing collagen network.

Question 5

What does DBA do?

Answer 5

Increases surface wettability - facilitates bonding between wet, organic tooth material and dry composite.

Question 6

What is the HYBRID layer?

Answer 6

Formed when the composite resin penetrates into the dentinal tubules and forms a tight bond.

Question 7

What is the SMEAR layer?

Answer 7

Layer of organic debris remaining on the surface of dentine after tooth has been cavity prepped.

Question 8

What is a disadvantage to the setting reaction of composite?

Answer 8

Polymerisation setting reaction - some free monomer may be left after set.
Some people can be allergic to monomer - may not be biocompatible if toxic to pt.

Question 9

Advantages of composite?

Answer 9

Strong
Good bond strength to tooth
Good aesthetics
Low setting shrinkage
Low thermal conductivity
Radio-opaque
Rigid

Question 10

Disadvantages of composite?

Answer 10

High thermal expansion co-efficient - not similar to tooth.
Need moisture control to bond.

Question 11

What is composite bond strength?

Answer 11

40MPa