Sealants are a common preventive treatment in dentistry, most often done on the back teeth of children and teens. Some teeth have fine, deep grooves or pits that accumulate plaque because the grooves are too narrow for the bristles of a toothbrush to clean. When plaque accumulates, it can lead to cavities and other types of tooth decay. To apply sealants, the tooth is cleaned with a special liquid, an adhesive bond is applied followed by thin liquid plastic, filling these narrow grooves and preventing the cavity-causing buildup of plaque. The plastic is hardened with a fiber-optic light applied to the surface of the sealed tooth. This technique is a non-invasive and comfortable procedure to help prevent cavities.