The premolar and molar teeth are the largest teeth in the mouth. They have a larger surface area and have several grooves and pits on the chewing surface. These grooves can be deep and are a prime place for plaque and acid to build up and cause cavities. It is for this reason Dr. Emam may suggest applying sealants, especially on young children. A sealant is a coating that is applied to the chewing surface of the teeth creating a smooth surface to act as a barricade protecting it from decay.