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

Since the 1980s, 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 and because of improved dental hygiene among the public. However, because the teeth in the back of the mouth (molars and premolars) have numerous pits and fissures on their biting surfaces, certain areas of these teeth are often difficult to clean even with vigorous tooth-brushing. 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.

Sealants painted over pits and fissures in the chewing surfaces of back teeth block food from being trapped and any carbohydrate like sugar being changed to acid by resident plaque bacteria and halts demineralisation and the caries process.