Dental sealants are a thin, plastic coating painted on the chewing surfaces of your molars to prevent tooth decay. Dr. Detar recommends placing on your 6 year and 12 years molars as soon as they erupt, once the gum tissue has receded fully, and before decay begins. It is important to note that once stain has become inherent in the grooves of these teeth that they are no longer a candidate for sealants because this will allow the bacteria to be sealed inside the tooth, causing a cavity that is often difficult to detect until it is quite large.