If the tooth is filled and the following situations occur, it needs to be filled again: 1) if the carious cavity is deep and close to the pulp, use zinc oxide with clove oil to close the cavity temporarily, and after the pain is relieved, the zinc oxide can be removed, and glass ionomer cementum or composite resin can be used to fill the cavity permanently. 2) if the filling and the edge of the cavity have secondary caries, or the filling body is cracked and loosened, it is necessary to remove the filling body and then grind off the decayed tooth tissue, prepare the cavity shape, and fill the cavity again. When composite resin is used to fill the anterior teeth, if the resin leaks slightly or the color becomes yellow or dark, which affects the aesthetics, the original filling can be removed and the cavity can be repaired again. 4. When the teeth have severe pain to cold or hot stimulation or pulpitis occurs, the original filling needs to be removed, the pulp cavity needs to be grinded open, and the cavity needs to be closed again after completing the root canal treatment.