molars, can be difficult for a person to clean because the grooves found on their chewing surface (the tooth's "pits and fissures") are deep and narrow. Even though the person brushes their teeth not all of the dental plaque that is present is cleansed off because the individual bristles of their toothbrush are simply too large to gain access into the depths of the tooth's grooves. Because some plaque has not been cleaned away, the tooth is at risk for the formation of decay.

By bonding plastic resin (the dental sealant) into the grooves of a tooth a dentist can create a tooth surface that is smoother. There are no longer any locations on the chewing surface of the tooth that the bristles of a toothbrush can't access and clean. Since dental plaque can be removed more easily and effectively, there is much less of a chance that tooth decay will form.