There are two main reasons for the black spots on the patient’s teeth, namely pigmentation and tooth caries, as follows: 1.Pigmentation: some people consume strong tea, coffee and other colored food for a long time, so it will form pigmentation on the tooth surface, which is not easy to clean, and cannot be solved by brushing, so it is necessary to consult in the hospital for full mouth cleaning to remove the pigmentation on the tooth surface, and the black spots will disappear. 2. Tooth caries: Caries is mainly due to bacterial infection, bacterial acid production, resulting in chronic progressive destruction of the hard tissue of the tooth, and finally demineralization, resulting in hard tissue loss of the tooth, forming a cavity, and the black spot is formed on it. If reduce the intake of sucrose in food, reduce the frequency of eating, protect the oral health, remove the local irritation factors and brush the teeth on time, the possibility of tooth decay will be greatly reduced.