When the gap between teeth and gums becomes black, there are two possibilities. 1, it is a tooth decay, when the tooth is decayed, it can be ground out and then filled with filling material, after repairing, it is recommended to maintain oral hygiene, and timely inspection and repair. 2, the gap between teeth and gums becomes black, it is possible that there is calculus, when there is calculus, it should be scaled and cleaned by ultrasonic shock, so as to remove the calculus between gums and teeth and avoid periodontal disease. This will restore the gap between the gums and the teeth, promote the fit between the gums and the teeth, avoid periodontal disease, and prevent the appearance of red and swollen gums, or loose teeth. In addition, if the gap between the teeth and gums becomes black, it is recommended that timely examination and treatment be carried out to avoid the phenomenon of tooth splitting.