Teeth are surrounded by a hard surface, called the enamel. Under the enamel is dense layer of tissue, called the dentin. The inside of the tooth is filled with soft, spongy tissue, called pulp. The pulp contains nerves and blood vessels that nourish the tooth.

A cavity is an area of decay in the enamel of the tooth. Two substances play an important role in the development of tooth decay - plaque and bacteria. Plaque is the sticky substance that forms a film on the teeth. When we eat foods containing carbohydrates, bacteria in the plaque metabolize the sugars and starches, producing an acid that slowly dissolves (demineralizes) the tooth enamel. Eventually a hole, or cavity, is formed in the tooth.

Detecting Cavities

Dental professionals have two main methods to look for cavities. The first is visual inspection of the teeth. Using a hand-held mirror and an instrument with a small, sharp hook, the dentist checks each tooth, looking for areas of suspected decay. The second tool for cavity detection is the dental X-ray. X-rays can be taken of a single tooth, the bitewing (to check for cavities between the teeth), or the whole mouth (panoramic X-rays).

Visual inspection and X-rays have long been the mainstay of dental examinations. But the techniques can miss cavities - especially those that are very tiny. By the time the decay is large enough to be seen on the X-ray or through visual examination, more of the tooth has been destroyed and the patient needs a bigger filling.

Now, some dentists are using a new high-tech detection device called the DIAGNOdent. The DIAGNOdent uses a process called fluorescence, in which light energy is reflected back from a surface. Cavities have a much higher degree of fluorescence than healthy tooth enamel. The DIAGNOdent handpiece is placed over the surface of a tooth. The device scans the tooth and measures the fluorescence of the surface. If it hits a cavity, the fluorescence increases and the DIAGNOdent registers the change. The larger the cavity, the higher the fluorescence. Thus, the dentist can determine not only the location of the cavity, but the size as well.

The manufacturer reports DIAGNOdent has a 90 percent accuracy rate in detecting cavities - many of which are too small to be seen with traditional detection methods. That enables the dentist to treat the cavity while it is very small and save more of the natural tooth surface.

Air Abrasion

Some dentists are taking advantage of another high-tech dental procedure called air abrasion (also known as kinetic cavity preparation). Air abrasion is used in place of the dental drill. A fine stream of particles is aimed at the cavity, sand-blasting away the decay. The technique is very useful for filling very small cavities, allowing the dentist to conserve more of the natural tooth. The cavity can then be filled with a bonded restoration.

Air abrasion produces no heat, sound, pressure or vibration. Thus there is no pain associated with the procedure and no need for dental anesthesia. Air abrasion can't be used for cavities between the teeth, because those surfaces require more preparation.

SOURCES

American Dental Association, http://www.ada.org