Composite Resin (White Fillings) is a dental restorative material made of acrylic resin mixed with finely ground glasslike particles. This white filling material must be bonded to the tooth. Composite resin match the color of your existing teeth, and can be used to restore a decayed tooth or repair a defect. It can also be used to improve esthetics by closing spaces between your teeth and by changing the color and shape of a tooth.
A bonded restoration integrates with the tooth and doesn’t act as a wedge to break the tooth like a silver amalgam filling does. Also, since composites bond to tooth structure, the tooth does not have to be cut or prepared as much to provide mechanical retention. Once the decay is removed, the composite resin can be placed into the defect, regardless of the shape of that defect. So, generally speaking, it is a more conservative and less destructive way to restore a tooth.
Composite restorations are technique dependent and take more time and finessing than silver fillings. The tooth must be well isolated from saliva, as this can compromise the bonding process. Just as with any restoration, you can develop decay around them, so it is important to clean around them and avoid frequent snacking. Eventually, these fillings will breakdown and need replacement much like amalgam fillings.
Dr. Jack M. Hosner, D.D.S. (2012)