Dark teeth are mainly caused by pigmentation or dental caries, it is recommended to consult a doctor for pigmentation cleaning or caries filling and restoration. 1. Pigmentation: poor oral hygiene will lead to bacteria and food interaction to form plaque attached to the tooth surface, pigment easily attached to the tooth surface to make it become black and yellow. Therefore, it is necessary to go to the doctor for ultrasonic cleaning or sandblasting to remove the pigment completely. 2. Dental caries: teeth blackened by caries and cavities must be filled and repaired by a doctor for dental caries, i.e., the black carious part is grinded clean and then filled and repaired with oral restorative materials. It is recommended to consult a doctor to clarify the cause of the tooth black, symptomatic treatment, to avoid delaying the condition.