Why do dentists use resin for tooth fillings?

Dentists sometimes use resin for tooth fillings because it offers certain advantages over other materials used to make dental fillings. Dentists use fillings to repair teeth damaged by decay. Resin fillings (sometimes called composite resin fillings) are made from a mixture of plastic and very tiny, fine glass particles. Unlike a silver-colored amalgam filling, a resin filling blends in with the color of your teeth. Resin is also stronger than amalgam because it bonds directly to the teeth. One downside, however, is that resin fillings cost more than amalgam fillings.

Composite, resin, or white fillings have been in use for about 20 years. Composite fillings are made from an organic polymer called bisphenol-A-glycidyl methacrylate (BIS-GMA). They also contain inorganic particles including quartz, borosilicate glass and lithium aluminum silicate.

As advantages, resin fillings require a more conservative tooth preparation (less drilling) and can have a strengthening effect on the tooth. They also are very aesthetic, virtually blending in with the tooth. Resin fillings are the most popular material for repairing front teeth.

As far as disadvantages, they are more technique sensitive for the dentist and are highly susceptible to decay if placed improperly. Resin fillings usually cost more than an amalgam, and research has shown a by-product of some resin restorations called bisphenol-A might be estrogenic and increase the risk of breast cancer. Regardless of this research, composite fillings are considered safe and they are approved by the American Dental Association.