Dental Materials - Composite Resin Flashcards
What are the components of composite resin?
Glass filler Resin Camphorquinone Low weight dimethcrylates Silane coupling agents
Increasing which component of composite resin would increase the hardness?
Filler particles
What is another name for composite resin?
Unfilled BIS - GMA resin
What activates the camphorquinone in composite?
Blue light
How does blue light activation cause hardening of the composite?
The blue light produces free radical molecules within the composite resin which initiate free radical polymerisation.
(crosslinking)
What component of composite prevents it from setting too quickly?
Low weight dimethacrylates
What are the classifications of composite?
Filler type
Curing method
Self
Light
Area of use
Handling characteristics;
Flowable
Syringable
Condensable
What are the advantages of adding filler particles? (4)
Increases mechanical properties
Increases appearance - glass reflects light to give translucent tooth like appearance.
Lowers thermal expansion
Lowers polymerisation contraction shrinkage
At what wavelength does the most effective light curing occur?
450 - 470nm
What are the advantages of light cured resins?
Longer working time as you set on command.
Less porosity - don’t need to mix 2 pastes.
Higher filler level
Less waste
What is the depth of cure?
2mm
What are the problems associated with light cure resins? (6)
Over exposure
Premature setting by dental lights
Have to ensure increments are < 2mm
Recommended setting times are too short
Problems with distance and angle of setting.
Polymerisation contraction shrinkage
What properties must be considered with composite resin? (7)
Hardness
Bonding to tooth
Biocompatibility
Thermal properties
Aesthetics
Anticariogenic
Setting shrinkage
Comment on the bond between the tooth and the composite resin.
Good
Use of acid etch before placement allows componiste to penetrate into the enamel and establish a strong bond.
What are the advantages of bonding to tooth substances? (5)
Reduces micorleakage
Counteracts polymerisation contraction shrinkage
No retentive features required
- minimal cavity design.
Minimises gap formation
Stress transferred over the contact are and bone.
