Sealants are a material that is placed in the deep grooves of the teeth to prevent cavities from starting. Deep grooves, usually found on the biting surfaces of the back teeth, are places where bacteria and food can get in, but where the toothbrush bristles have a hard time reaching. Sealants fill up these grooves so that the surface is smoother and can be more easily brushed and kept clean. Sealants are often placed in the back teeth of children as they erupt and are checked carefully at each cleaning appointment to make sure they are still doing their job. Sealants can be placed in adults who have deep grooves also.