The gap on the top of the tooth is usually the gap on the biting surface of the tooth, and the black thing is considered as pigmentation or the performance of tooth caries, and its treatment is different. The pigmentation can usually be removed by scaling or sandblasting, and the occurrence of caries is related to microorganism and food, which can be treated by non-surgical treatment or surgical filling and restoration: a. Pigmentation: daily brushing may be difficult to clean the tooth gap completely, resulting in black pigmentation on the local tooth surface, scaling and sandblasting can effectively remove the pigmentation, plaque, and fine tartar, and it is more effective in cleaning tea scale, tobacco tartar, and soft food tartar. The cleaning effect of tea scale, cigarette scale and soft food scale is obvious. Second, caries: early caries can be shown as the reduction of tooth transparency, the surface of tooth enamel can be chalky, also can become yellowish brown or blackish brown, at first not accompanied by obvious tooth damage, but with the progress of caries, can gradually form cavities. 1, non-surgical treatment: such as remineralization treatment, mostly used in the early stage, that is, through the use of various fluoride preparations to restore the hardness of the teeth; also can carry out preventive resin filling, and can be used to restore the hardness of the teeth. The sulcus sealant can be used for the deep gap sulcus without caries, and the resin filling can be used for the suspected or already decayed teeth; 2.Surgical treatment: If it has caused the hard tissue defect of the tooth and formed the cavity, the carious tissue can be removed through surgery and the filling restoration material can be chosen to repair the defect, so as to terminate the development of caries and restore the form and function of the tooth. If the cavity exists inflammation and touches the nerve, root canal treatment is also needed.