Dental sealants are thin plastic coatings which are usually applied to the chewing surfaces of the first adult molars between ages 6 to 9 years old. The purpose of a sealant is to prevent decay. Most tooth decay in children and teens occur in the pits and fissures of chewing surfaces. By placing a sealant over these pits and fissures, the probability of a cavity forming on that tooth significantly decreases.