Composite resin: mixture of two or more a Major component
1.Organic resin matrix
2.Inorganic fillers
3.Coupling agents (silane), join filter and matrix
4.Pigments Components
*Resin matrix: chemically active component. Flu converts to a rigid polymer by free radical addition polymerization reaction
*Monomers used
a. Bis GMA (Bisphenol A-glycidyl methacrylate). Bowen's resin.
b. UDMA (Urethane dimethacrylate)
c. These resins are made of Oligomers (organic molecules) low molecular weight monomers (such as MMA, EDMA. TEGMA)
d. In addition an inhibitor is added (hydroquinone)
e. Resin matrix also contains initiators, activators. S. Fillers: silica, quartz, more recently silica based glasses some containing barium, strontium etc.
Properties affected by fillers ;
1. Improve the mechanical properties.
2. Radiopacity (barium, strontium).
3. Esthetics such as color, translucency due to glass.
4. Decrease the linear coefficient of thermal expansion.
5. Decrease the polymerization shrinkage.
6. Decrease heat evolved.