The surface of teeth becomes black in various cases: 1, more common is the exogenous deposition, such as often drinking coffee, tea, cola, smoking, or some people need to eat Chinese medicine or Chinese medicine punch, the above behaviors for a long time lead to pigment deposition on the surface of teeth, forming black plaque or stains; 2, as a child ate drugs similar to tetracycline, forming heavy tetracycline teeth of patients whose teeth will also 3, because of trauma or tooth lesion caused by tooth necrosis, the teeth look black; 4, the surface of the teeth may become black because of tooth decay, there are some food residues or pigment deposited in the cavity, looks black. The above are the common external factors that lead to the black surface of teeth.