Yes, sealants can be placed over fillings in certain situations. Sealants are typically applied to the chewing surfaces of teeth to protect against decay, especially in the grooves and pits where bacteria can accumulate. If the filling is intact and properly sealed within the tooth, placing a sealant over it can provide an extra layer of protection against future decay. However, a dentist needs to evaluate the specific condition of the filling and tooth to determine if applying a sealant is appropriate.