There are two main reasons for the black spots in the mouth: first, suffering from dental caries; second, pigmentation on the tooth surface. Dental caries is a chronic bacterial infection of the hard tissue of the teeth, and the bacteria produce acid to cause the decay, decay and defect of the tooth tissue. When the cavity is formed, black pigmentation will appear inside the cavity, and the cavity on the tooth should be treated in time. If the cavity does not affect the nerve, it can be treated by removing the decayed material and filling the cavity with resin. Due to the poor oral hygiene, a lot of pigment and black-brown tartar will accumulate on the tooth surface, which makes it look very unattractive. The treatment is ultrasonic scaling, sandblasting and polishing, which uses ultrasonic shock to remove the soft tartar pigment and tartar from the surface of the teeth. Patients should pay special attention to the maintenance of oral hygiene on a daily basis by carefully brushing their teeth and using dental floss and interdental brushes to assist in cleaning the tooth surface, in addition to regular follow-up visits, with scaling required once every six months to a year.