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Flashcards in Composite Deck (11)
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1
Q

What are the components of composite?

A

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

2
Q

What does silane coupling agent do within composite?

A

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

3
Q

What is the etch most commonly used?

A

37% phosphoric acid etch

4
Q

What does acid etching do to a tooth?

A
  • 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.
5
Q

What does DBA do?

A

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

6
Q

What is the HYBRID layer?

A

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

7
Q

What is the SMEAR layer?

A

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

8
Q

What is a disadvantage to the setting reaction of composite?

A

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.

9
Q

Advantages of composite?

A

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

10
Q

Disadvantages of composite?

A

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

11
Q

What is composite bond strength?

A

40MPa