If you have lots of tooth decay that is the result of cavities, then your dentist might recommend that your teeth have a sealant put on them. A dental sealant refers to a type of coating made from a plastic material that is put on your teeth.
Typically, a sealant is put on the back teeth, since that is where chewing takes place. The coating prevents decay from taking place. Whenever a dentist decides to place a dental sealant on a tooth, it is to provide the tooth with more protection than a filling can offer, to help ensure the tooth remains healthy.