Dental sealants are effectively a chemical barrier, protecting your tooth enamel from plaque and acids. Dental sealants are most effective when applied at a young age, typically after the second molars break through. This happens for most people around age 12. Sealants can be thought of as raincoats for your teeth, and with normal dental care they will help prevent cavities. Children without sealants are about three times more likely to have cavities than children with sealants.