A cavity or tooth decay is a hole or holes in the enamel of the tooth. Cavities are found on all surfaces of the tooth. The size of the cavity is determined by the number of surfaces that the decay covers. Here is an example of what the tooth surfaces are called and where they are located.

Surfaces of the tooth:

Buccal:	Surface of the tooth closest to the lip and cheek.
Distal:	Surface of the tooth toward the throat.
Lingual:	Surface of the tooth closest to the tongue.
Occlusal:	These are the chewing surfaces of the tooth.
Mesial:	Surface of the tooth toward the middle of the mouth.

Cavities are recorded by naming the surfaces. For example: a two surface cavity may be written -- BO - meaning that the cavity is on the Buccal and Occlusal surfaces of the tooth. Cavities are recorded from one to four surfaces. If a cavity is very large and is on four or more surfaces it may need a crown.