Dental sealants are plastic resins that bond and harden in the deep grooves on the tooth's surface. When a tooth is sealed, the tiny grooves become smooth, and are less likely to harbor plaque. With sealants, brushing becomes easier and more effective against tooth decay.
Sealants are typically applied to children's teeth after their permanent teeth have erupted as a preventive measure against tooth decay. It is more common to seal “permanent” teeth rather than “baby” teeth, but every patient has unique needs, and the dentist will recommend sealants on a case-by-case basis.
Sealants last from three to five years, although it is fairly common to see adults with sealants still intact from childhood. A dental sealant only provides protection when it is fully intact so if your child's sealants come off, let the dentist know, and schedule an appointment for your child's teeth to be re-sealed.