A sealant is a clear or shaded plastic material that is applied to the chewing surfaces of the back teeth to help prevent cavities from forming in the developmental pits and fissures (grooves) of these teeth. These areas are where decay (cavity) occurs most often. The sealant is a liquid when placed on the tooth, so it flows into and fills up the pits and fissures of the tooth. A special light is shined onto the tooth which causes it to harden, thus creating a barrier protecting the area from plaque and food which can lead to the formation of a cavity. The pits and fissures of your teeth are impossible to keep clean, because the bristles of a toothbrush cannot reach them. Therefore, these areas are snug places for plaque and bits of food to hide.