Under normal anatomical and physiological conditions, there is a certain amount of sulcus point gap in the tooth itself, but no obvious hole is formed. If there is a hole inside the tooth, it is considered that it should be a pathological change. The more common clinical cases are dental caries of teeth and enamel defects formed by heavy wear. Dental caries is a very common bacterial infection disease, the bacteria gradually erode the tooth surface, causing the enamel dentin to demineralize and form a defect, forming a cavity. This must be repaired in hospital as soon as possible, otherwise it will easily hurt the nerve of the tooth and cause pulpitis and apical inflammation. The second case is tooth abrasion, there are bad chewing habits, such as night grinding teeth or love hard food patients, often appear the tooth surface enamel abrasion too much, forming local enamel defects, the form of cavity, this time can be repaired through the occlusal reconstruction.