If there is black tartar on the inner side of the teeth, you should visit a hospital for basic periodontal treatment. The black tartar on the inner side of the teeth is most likely due to the formation of plaque on the surface of the teeth after eating and inadequate oral care, and after mineralization, it forms calculus or pigmentation. If you find black tartar on the inner side of your teeth, you should visit a hospital and have a full mouth cleaning, that is, ultrasonic supragingival cleaning and subgingival scraping, to remove the pigmentation, plaque, calculus, food debris and other local stimuli on the surface of your teeth, so that your teeth become clean, and you should have a periodontal cleaning every six months to a year to maintain the health of periodontal tissue.