If the black color on the surface of the tooth is not painful, then it may be pigmentation, and it is possible to remove the pigmentation by sandblasting. However, if it is confirmed that there is damage to the tooth, and it is black and not painful, then it is considered to be the early stage of caries, and the caries has not yet penetrated into the adjacent pulp, so it is not too painful. At this time, the caries is shallow or medium caries, because it is still a certain distance from the pulp, it is only the decay and disintegration on the hard tissue, so there is no severe pain yet. However, this kind of cavity needs to be treated as soon as possible, and the carious part should be removed by the dental surgeon in the professional dentistry department with the high-speed turbine, and then the cavity should be repaired with the filling material.