Dental sealants are a dental treatment consisting of a plastic material to one or more teeth, for the purpose of preventing dental caries (cavities) or other forms of tooth decay.

Since the 1970s, in the United States, the incidence of tooth decay on the smooth surfaces of teeth has declined, in part because of fluoridation becoming widespread in public water supplies as well as improved dental hygiene among the public. However, because the back teeth (molars) have numerous pits and fissures, certain areas of these teeth cannot be propoerly cleaned of food particles and bacterial plaque even with vigorous tooth-brushing and flossing. As a result, decay among the molars remains nearly unavoidable even with a conscientious dental hygiene program. To remedy this, research into dental sealants began in the 1960s and by the early 1970s, the first generation of sealants became available and were approved by the FDA.

When correctly applied, dental sealants are nearly 100% effective in preventing dental caries on treated teeth. Despite this, and the fact that dental sealants have been widely available since the early 1970s, it is estimated currently that fewer than 20% of the population have dental sealants.

Dental sealants are usually applied in a dentist's office. The dentist or assistant first cleans and dries the tooth to be treated, then paints a thin layer of liquid plastic material on the pits and fissures of the tooth. After application of the plastic liquid, ultraviolet light is shined on the applied material for a few seconds to cure the plastic. Alternatively, some brands of sealants cure chemically.

After curing, the plastic becomes a hard, thin layer covering the treated portions of the tooth. Despite the incredible pressures effected on teeth during chewing each day, dental sealants often remain effective for five years or longer, although sealants do wear naturally and should be checked at regular intervals. If sealants wear or become damaged, they can be repaired or replaced simply by applying new sealant material to the worn or damaged portions.