Sealants are a thin, protective coating over teeth that protect the chewing surfaces of the back teeth from developing cavities. They work as a great line of defense for cavities when done with regular flossing and brushing. Deep narrow openings run across the chewing surface of molars. Even if your child brushes the teeth properly, the bristles of a toothbrush cannot skim across these surfaces. Therefore, bacteria start developing beyond the reach of bristles. The cavities there start affecting the tooth nerve and may destroy the valuable teeth structure of your child. The sealant shuts the food particles out and protects the groove from cavities.