A small black spot, either light or dark, on a tooth should always be repaired as soon as possible. A tooth from the discovery of small black spots, if allowed to develop, it will form obvious caries, to the whole tooth caries, about one year to two years. Once it reaches the deep dentin layer, there will be sweet, sour, cold and hot symptoms. When it reaches the pulp, it will be painful and affect daily life. This is where fillings alone cannot solve the problem and root canal treatment is needed sometimes the whole tooth needs to be extracted. Some also need to be staked to do crown protection after root canal treatment, costing a lot of treatment costs, which is not worth it. A tooth, a small black spot, must actively go to the hospital for examination and treatment, to retain the nerve of the tooth, to extend the life of the tooth.