Sealants are usually administered onto children's teeth as a preventative step towards a healthy smile, but they can also be used on adult teeth. Adults with deep grooves in their molars (called fissures) may also benefit from dental sealants. Dental sealants for adults and kids can be an essential part of keeping your teeth healthy as you age. Sealants are thin, plastic-like coatings applied to the chewing surfaces of your back teeth. They act as a barrier, protecting your teeth from the harmful bacteria and acid that can cause cavities.