There are mainly the following reasons for black teeth: 1, endogenous factors: caused by the blackness of the tooth itself, such as fluorosis, tetracycline teeth, dental caries or dental nerve necrosis. Mild teeth blackening can be treated by decoloration, while heavy teeth blackening may need to be restored by resin veneers, porcelain veneers, etc.; 2, exogenous coloring: poor brushing or bad eating habits can cause the formation of pigmentation on the tooth surface. Once the tooth surface is found to be black, it is recommended to go to a regular dental hospital as soon as possible to avoid delaying the condition.