Dental sealant is a plastic coating designed to protect the bicuspids and molars. Applied to the chewing surfaces of those teeth, it keeps plaque and acid from eating away at the enamel. Because the grooves on the bicuspids and molars help to grind food, certain food particles can collect in those grooves and pits, resulting in tooth decay. Brushing and flossing on a regular basis removes some particles and bacteria, but not all. Therefore, a sealant for teeth is sometimes necessary to protect those areas in the back of your mouth that brushing and flossing can't reach.