When the middle of the tooth is black, oral examination can be carried out and the treatment plan can be formulated after taking X-ray film, as follows: a. If exogenous pigment is adhered to the adjacent surface of the tooth, it can be removed by applying smooth car needle transfer grinding or using diamond sand strip to repeatedly rub. If the tooth adjacent surface forms caries and the density of the black area is lower than the normal tooth tissue in the X-ray film, the discolored dentin can be removed by using the crack drill, and after preparing the cavity type, the composite resin and glass ion cementum can be used to fill the cavity and remove the excess material to restore the good adjacent relationship. Second, if the cavity on the adjacent side of the tooth is deeper and causes the pulp to be exposed, the pulp cavity can be ground open from the jaw surface, the pulp can be removed, and after completing the root canal treatment, the porcelain or all-ceramic crown can be made to restore the tooth.