Dental wear can be caused during normal mastication, and this physiological wear becomes evident several years to decades after the eruption of permanent teeth, with chewing wear on the posterior surfaces and incisal margins of the anterior teeth. It begins with small smooth planes on the cusps or crests of the teeth and a slight flattening of the incisal margins; with age, masticatory wear also becomes more pronounced, with a decrease in tooth height and flattening of the bevels, as well as a decrease in the proximal and distal mesial diameters of the teeth. The enamel is completely worn down to a sharp edge and the dentin is exposed. The degree of wear depends on the hardness of the tooth, the hardness of the food, the chewing habits and the tension of the chewing muscles, and is directly proportional to age, the friction and chewing force of the food, and inversely proportional to the hardness of the tooth. Teeth wear that is not due to the normal chewing process is mainly due to bad habits and certain occupations are caused: for example, women use their teeth to support the development of clamps, carpenters, shoemakers and garment workers often use their teeth to hold nails and needles or bite thread with their teeth. Abrasion can also lead to severe wear and tear. Others are systemic diseases such as gastrointestinal disorders, neurosis, history of dry mouth; the presence of hard food chewing habits and bad oral habits such as unilateral chewing, etc. Clinical manifestations: partial wear of enamel to expose light yellow dentin, tooth sensitivity may occur. If all the enamel is worn away, pulp disease may occur or the pulp cavity may be atretic. Uneven wear can cause occlusal trauma, food impaction, and damage to periodontal tissue and mucosa. Severe wear of the entire mouth can also cause temporomandibular joint disease. Possible complications: 1, dentin hypersensitivity This painful symptom can sometimes be gradually reduced within a few months and disappear; sometimes it can last longer without improvement. The degree of sensitivity often varies from person to person, generally speaking, the faster the process of wear, the larger the exposed area, the more obvious the soreness. 2, food embedding chewing food, due to the edge of the ridge and the development of the groove established by the shape of the surface, usually conducive to food deviation from the gap. After the tooth is worn, the plane replaces the normal convex surface, thus increasing the role of the tooth cusp to wedge food into the gap; the shortening of the crown due to wear and the wear of the adjacent surface can cause food embedding and promote the occurrence of periodontal disease and adjacent surface caries. 3.Pulp and periapical lesions are caused by excessive wear to expose the pulp cavity. 4.Temporomandibular joint disorder syndrome severe facial wear can lead to the short vertical distance between jaws, thus causing temporomandibular joint lesions. 5.Traumatic uneven wear can leave high steep cusps, thus causing trauma. 6, traumatic ulcers uneven wear left behind over-sharp tooth tips and edges can stimulate the buccal and lingual mucosa, which can cause local ulcers. Treatment: 1, physiological wear, if no symptoms do not need to deal with. 2.Remove and correct the cause of pathological wear. 3.When there is dentin allergy, desensitization treatment should be done. 4, for uneven wear need to make appropriate adjustment, grinding sharp tooth tip and edge. 5.When there is pulpal and periapical disease, treatment of pulpal and periapical disease should be carried out as usual. 6.In case of food embedding, the normal contact relationship and reconstruction of the surface overflow groove should be restored. In case of excessive wear and temporomandibular joint syndrome, overdenture restoration should be made to restore the inter-vertical distance.