If it is a cervical caries, if it does not invade the pulp, it can be solved by decaying and filling, if it invades the pulp, systematic root canal treatment is also needed. The blackness underneath the tooth may also be a periodontal problem. Severe periodontitis may cause gum recession, which may also seem to be the blackness underneath the tooth. The most basic is often called scaling, scaling is also known as supragingival scaling, is the most basic periodontal treatment, but if there is already periodontal disease, many times have to add subgingival scaling, if the effect is still not good, may also need to do periodontal surgery.