If you have never had a cavity, congratulations! If you have had one, you are not alone. About 78% of us have had at least one cavity by the time we reach age 17, according to a 2000 report by the U.S. Surgeon General. Fortunately there's a time-tested treatment for cavities: the dental filling.
Fillings do just what the name implies — seal a small hole in your tooth, i.e., a cavity, caused by decay. This prevents the decay (a bacteria-induced infection) from spreading further into your tooth and, if untreated, continue on to the sensitive inner pulp (nerve) tissue located in the root canal. Should that happen, you would need root canal treatment.
There are a variety of materials used to fill teeth these days, but the process of filling a tooth is similar regardless. The first step is a clinical exam of the tooth with x-rays, to determine the extent of the decay. Then the decayed area of the tooth is removed, usually with a handheld instrument such as a dental drill. Of course, your tooth will be anesthetized first, so you won't feel any discomfort. If you normally feel nervous about receiving numbing injections, it's possible that taking an anti-anxiety medication or using nitrous oxide can help you feel more relaxed. After removing the decay, the remaining tooth structure is roughened or “etched” with a mildly acidic solution; then translucent cement is applied to bond the tooth and the filling material together.