A dental filling, also called a "dental restoration," is intended to replace tooth structure lost to decay. Dental fillings may last many years but eventually all fillings need to be replaced.

Constant assault from eating and drinking, or stress from clenching or grinding, eventually may cause a dental filling to fail. Fillings that have worn away, chipped, cracked or fallen out may leave gaps between the tooth and the filling that can provide an entry point for food particles and decay-causing bacteria.

These bacteria cannot be removed easily with a toothbrush or other means, and decay may develop along the edge of the filling or underneath it. Decay that is undiagnosed and untreated can progress to infect the dental pulp (which contains the tooth’s nerve and blood supply), which often results in the need for root canal treatment or, possibly, loss of the tooth.

Regular dental examinations are important because problems with existing fillings generally can be detected in the early stage. Although you may not be able to tell that your filling is worn, your dentist can identify any weaknesses in it during a regular checkup.

During the examination, the dentist determines if the existing fillings are intact or if any have cracked or worn away. He or she uses an instrument called an explorer to gently detect any worn spots around the filling’s edge. This instrument will help your dentist determine if the dental filling is sealed to the tooth, or if it is sufficiently worn and needs replacement.

Dental X-rays, usually called "radiographs," may be taken to help detect decay under existing dental fillings or between teeth, neither of which can be seen simply by looking at the tooth. If the dentist finds evidence that a filling has failed or detects decay on the radiograph, the dental filling should be replaced promptly.

Don't wait until the tooth hurts or a crack appears in the filling of the tooth to talk to your dentist. Early detection and treatment can minimize the need for extensive and costly procedures.

Sources:

http://www.colgate.com