A sealant is a clear or white, acrylic-like material that bonds with the tooth to help a shield out decay-causing bacteria from the chewing surfacing of the back teeth. They form a protective barrier covering the pits and fissures (depressions and grooves) to prevent cavities in hard to clean back teeth.
Sealants are beneficial in teeth with very deep groove on the biting surface. They are recommend for many cases but there are instances where sealants are not recommended. This includes for children with rampant decay and where there is already decay in the tooth. In these cases the sealants will actually make it more difficult to diagnose an occlusal cavity which may get unnecessarily larger due to difficulty with visually diagnosing the lesion. Your dentist will determine if sealants are right for your child.