Composite is the universally used tooth colored direct restorative material. Composites as a filling material has many advantages and is a now considered as most preferred tooth colored material for fillings. It has various components which are explained below:
Restoration of Lower Front Tooth with Composite Restoration
Components of Composites Are
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Resin Matrix (Organic Content)
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Fillers (Inorganic Part)
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Coupling Agents
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Coloring Agents
Composite Filling Material
Resin Matrix
1. Bisphenol-A glycidyl methacrylate(BISGMA)
2. Urethane dimethacrylate (UDMA)
3. Triethylene glycol dimethacrylate(TEGDMA)
The mixture of these three resins provides appropriate viscosity needed for binding of filler particles.
Fillers:
These are quartz, Silica, Tricalcium phosphate and Zirconium dioxide.
Addition of filler causes following effects:
1. Reduces the thermal expansion coefficient.
2. Reduces polymerization shrinkage.
3. Increases abrasion resistance.
4. Decreases water sorption.
5. Increases strength.
6. Increases fracture toughness
7. Provides radiopacity.
8. Improves handling properties.
9. Improves translucency
Coupling Agents:
These are Organic silanes such as gamma-methacryloxy propyl trimethoxy silane
Functions of coupling agents
1. Binds the filling particles to resin matrix
2. Allow more flexible polymer matrix to transfer stresses to stiffer filler particles
3. Provide hydrolytic stability by preventing the water from penetrating along the filler resin matrix.
Coloring Agents
1. Titanium dioxide in 0.001-0.007% by wt.
2. Aluminium oxide
They are added to improve the opacity of composite resins.