Dental fillings that filling restoration, by filling restoration of the tooth inside the black is not a normal situation, if the filling body around the black may be the occurrence of secondary caries, if the crown as a whole black may be the occurrence of pulpal necrosis, specific as follows. 1. Secondary caries: secondary caries can occur because the cavity preparation is not clean of carious tissues, the edge of the cavity is not in the self-cleaning area, micro-leakage, etc., which can be seen as blackening of the tooth tissues at the edge of the cavity. 2. Pulp necrosis: Inflammation of the pulp may occur due to wrong judgment of the pulp condition, undetected small pulpal holes, etc., which gradually develops into pulp necrosis, and most or the whole of the crown may turn black. There may be other reasons why the inside of the tooth repaired by filling has turned black, so it is recommended that you go to the hospital in time to clarify the cause of the disease and then carry out targeted treatment.