Composite Flashcards
2 major components of composite
- organic polymer resin
- inorganic filler particles
First dental composite is a mixture of?
- silicate glass
- acrylic monomer
Makes composite radiopaque
Barium glass
For adhesive bonding of filler to the resin
Coupling agent/keying agent
Example of coupling agent (2)
- vinyl silane
- gamma methacryloxy propyl silane
Reduces viscosity of resin allowing easier filler incorporation
Diluent
Examples of diluent (2)
- methyl methacrylate
- alipathic dimethacrylate
Example of catalyst
Benzoyl peroxide
An aromatic tertiary amine that initiate polymerization
Accelerator
Increases shelf life by preventing spontaneous polymerization
Inhibitor
Example of inhibitor
Hydro quinones
Initially increases rate of polymerization
Methacrylic acid
4 types of composite
1 conventional
2 micro-filled
3 hybrid
4 nano-filled
Chemically cured composite
Conventional composite
“Polishable composite”
Microfilled
Inorganic filler content of conventional composite (%)
70-80%
Inorganic filler content of micro-filled composite (%)
35-60%
Inorganic filler content of hybrid composite (%)
75-85%
2 type of hybrid composite
1 flowable (ampules) 2 packable (syringe)
Diastema closure used for >2.5mm
Splints
Contraindications of composite (4)
- habitual bruxism
- deep gingival prep
- poor moisture control
- large restoration
The dimensional change of a material per unit change in temp
Linear coefficient of thermal expansion
Properties of composite (7)
- LCTE
- water absorption
- wear resistance
- surface texture
- radiopacity
- modulus of elasticity
- solubility
Stiffness of the material
Modulus of elasticity
Acid echant used for composite
37% phosphoric acid
4 types of light curing units
- quartz tungsten halogen
- blue LED
- argon laser
- plasma arc
Curing time using plasma arc curing light
9-10 secs
Required distance between composite and light curing unit
2mm
Used to measure the curing effectiveness of the unit
Radiometer
Duration for etching (in secs)
15 secs
Appearance after etching
Frosty appearance
In etching, if contaminated with saliva, what do you do?
Re-etch for 5 secs
White opaque appearance
Resin tags
Components of bonding agent (3)
- etchant
- primer
- adhesive
Component of bonding agent used as adhesive
EDTA (ethylene diamine tetracetic acid)
Consist of a gelatinous surface layer of coagulated protein
Smear layer
Primer that penetrates demineralized dentin & bond to the collagen network or layer
HEMA ( hydroxyethyl methacrylate)
HEMA + adhesive = ?
Wet bonding technique
Process by which 2 or more molecules of same substance combine to form a polymer
Polymerization
Energy required for optimum polymerization of composite
16 Joules
Most common available light curing intentisty
400-600mW/cm2
What component of ZOE will inhibit polymerization if used with composite?
-
Best used for finishing and polishing composite
Polishing disks
True or false: Moist tooth surface will bond more effectively than dry or very wet tooth surface
True