After the big tooth is black, it can be treated with ultrasonic cleaning, mobile resin filling, composite resin filling, pulp removal, etc., as follows: I. Ultrasonic cleaning: If long-term smoking and tea drinking cause smoke spots and tea stains to attach to the buccal surface or lingual surface of the molar, ultrasonic cleaning can be performed to remove the pigment, and if necessary, sandblasting can be used to remove the black pigment deposited in the sulcus point gap of the jaw surface. Flowing resin filling: When shallow caries is formed on the jaw surface of the molar, the discolored tooth tissue can be removed with a sharp and fine needle, and then the flowing resin can be used to fill the caries to reduce the adhesion of food residue. Compound resin and other filling: When the adjacent surface of the molar forms caries, the decayed tooth tissue can be removed from the jaw surface downward, and after preparing the cavity shape, compound resin and other filling can be applied, and if necessary, inlay restoration can be made. Removal of pulp: If the molar tooth has a large area of caries and the pulp is infected by bacteria, the pulp can be removed, and after completing root canal treatment, porcelain or all-ceramic crown can be made.