Aesthetic Restorative Materials Flashcards
Direct Aesthetic Restorative Materials
Should be
radiopaque to enable detection of secondary caries, identification of overhang ledge and detection of incompletely filled cavities.
Lower initial pH in silicate cements , why ?
pulpal protection was required to minimize the irritation
Unfilled Acrylic Polymers, Early clinical failure of this material is ..
dimensional instability
(high polymerization shrinkage and thermal dimensional changes).
Unfilled Acrylic Polymers
Compositions:
Powder: polymethyl meth-acrylate, initiator benzyl
peroxide and pigment.
Liquid
Unfilled Acrylic Polymers
Disadvantage
cause pulpal irritation
Mechanical properties are poor.
Composite is
a combination of two or more chemically different materials
Composite Compositions
- Organic matrix .
- Inorganic filler.
- Coupling agent binds the inorganic filler to the organic matrix.
- Initiator activator system.
- Inhibitor.
- Ultraviolet.
- Pigments.
Organic matrix consist of
A. high molecular weight monomer (oligomer)
B. Diluents (lower molecular weight monomers)
high molecular weight monomer (oligomer)
1. bisphenol A-glycidyl methacrylate (BIS-GMA)
2. Urethane dimethacrylate (UDMA).
Oligomer product are superior to methyl methacrylate monomers by
- Lower polymerization shrinkage
- Lower volatility.
- More rapid hardening.
- Production of stiffer and stronger resin
The urethane dimethacrylates are superior to BIS-GMA by
I. lower viscosity.
II. Lower water sorption.
III. Greater toughness.
IV. Greater susceptibility to visible light curing
Diluents , These monomers are included in composite formulation to
reduce the viscosity , and to facilitate clinical manipulation.
Modification of resin composite have been made in order to
………of resin such as……
minimize polymerization shrinkage , Ormocers (organic modified ceramic)
Silorane (low shrinkage composite)
In this composite, polymerization occur by…..
ring opening polymerization
quartz.
Borosilicate glass.
Lithium aluminum silicate.
Barium aluminum silicate.
Strontium.
Colloidal silicate.
These elements contribute to
radiopacity
Role of inorganic filler
1- mechanical properties such as compressive strength,
modulus of elasticity and hardness .
2. Reduction in coefficient of thermal expansion.
3. Glass is able to reflect the color of surrounding tooth material
4. Reduction in polymerization shrinkage.
5. Less heat evolve
6. The composite is radiopaque if barium or strontium glasses are used.