Decay is caused by dental plaque, a thin, sticky, colorless deposit of bacteria that constantly forms on everyone's teeth. When sugar comes in contact with teeth, the bacteria in plaque produce acids that attack the tooth enamel. After repeated acid attacks, the enamel breaks down, and a cavity is formed.
A sealant is a clear or shaded plastic material that is applied to the chewing surfaces of the back teeth (premolars and molars), where decay occurs most often. This sealant acts as a barrier, protecting the decay-prone areas of the back teeth from plaque and acid.
When the back teeth are developing, depressions and grooves form in the chewing surfaces of the enamel. These irregularities are called pits and fissures. They are impossible to keep clean, because the bristles of a tooth brush cannot reach into them. Therefore, pits and fissures are snug places for plaque and bits of food to hide. By forming a thin covering over the pits and fissures, sealants keep out plaque and food, and thus decrease the risk of decay.
Children receive the greatest benefit from having sealants applied to their teeth, especially to newly erupted permanent teeth. Sealants are recommended for all children, even those who receive topical applications of fluoride or who live in communities with fluoridated water. Fluoride helps fight decay on the smooth surfaces of the teeth, but it is less effective in pits and fissures.
Each tooth takes only a few minutes to seal. First, the teeth that will be sealed are cleaned. The chewing surfaces are then etched (roughened) with a weak acidic solution to help the sealant adhere to the teeth. Finally, the sealant is brushed on the tooth enamel and hardened with a special curing light.
Chewing surface of a molar before sealant is applied
The tooth is etched with a mild solution to help the sealant adhere
Chewing surface of a molar protected by a shaded sealant
Photos courtesy of the American Dental Association
When sealant is applied, finger-like strands penetrate the pits and fissures of the tooth enamel. Although the sealant cannot be seen with the naked eye, the protective effect of these strands continues. As a result, it may be several years before another application of sealant is needed. Reapplication of the sealant will continue its protection against decay and may save the time and expense of having a tooth restored. Sealants are continually checked during your child's regular dental visits to determine if reapplication is necessary.