While brushing and flossing can easily remove plaque (a sticky mixture of bacteria, food and debris) from the smooth surfaces of the teeth, they are ineffective at getting into the minute pits and fissures. Tooth decay is caused by the bacterial breakdown of food into acid, which dissolves away the enamel cover of the tooth. Sealants act as a barrier against plaque and acids in these vulnerable areas on the chewing surface of the tooth.

Sealants are most effective if applied to the tooth soon after eruption into the mouth. A child's first permanent molars erupt at about age six and at about 12 years of age for the second, permanent molars. The pre-molars (bicuspids) are also prime candidates for sealants.

The application of sealant requires no anesthesia. It can be painted on in just a few minutes per tooth. As part of the procedure, the teeth are first cleaned and the chewing surface is "conditioned" with a solution that helps the sealant bond to the enamel. Sometimes a "curing" light is utilized to hasten the bonding.

Sealants last up to five years and are easily replaced if lost. They should be examined at each check-up visit. Dental sealants are a cost-effective way of preventing tooth decay. According to a 1995 survey by the American Dental Association, the average cost per tooth for sealants was half the cost of an average filling.