Composite fillings, also referred to as bonding, is done using a tooth colored restorative material that is made of plastic or synthetic resins. The resin is most commonly made of Bis-GMA and other dimethacrylate monomers (TEGMA, UDMA, HDDMA). The is also a filler material that holds the resin and is made of either silica or a photoinitiator.
Composite restorative material is placed on the tooth using an adhesive or bonding material, hence the name bonding. These type of filling material is aesthetic, durable and provides enough strength to replace small to medium size cavities on the tooth surface. However, if there is more than 50% of the tooth structure lost, composite filling should be reconsidered in which case, crowns are a better option to replace the tooth structure.
Composite fillings are less durable than amalgam fillings and may need to be replaced more frequently. There is no mercury in composite fillings. Composite fillings are slowly replacing amalgam fillings because of cosmetic reasons. Composite material is more technique sensitive than amalgam filling and needs a totally dry environment for perfect adhesion to the tooth surface.