Sealants are a common preventive treatment in dentistry. Some teeth have fine grooves or pits that accumulate plaque, not because the person doesn't brush, but because the grooves are too narrow to allow even one bristle into them. When plaque accumulates, it can lead to cavities and other types of tooth decay. To apply sealants, a plastic material is brushed onto the tooth, filling these narrow grooves and preventing the cavity-causing buildup. Sealants make healthy teeth possible.