A 32-year-old patient consulted a dentist with complaints of tooth sensitivity when eating cold food and abrasion of enamel in the gum area on the lateral teeth of the upper and lower jaws. Objectively: on the cervical surface of teeth 13, 14, 23, 24, 34, 44, triangular-shaped enamel defects were revealed up to the level of the enamel-dentin border, a smooth bottom, the reaction to temperature stimuli is sharply positive, percussion is negative. There is a shortening of the upper dental arch in the frontal section and a narrowing in the lateral sections, 13, 12, 11, 21, 22, 23, have a retrusion slope, the anterior buccal cusps of the first upper molars move anteriorly from the transverse fissures of the first beginning of the molars. In the observation group, tuberous closure was observed. The upper incisors overlap the lower incisors by half a crown. There are no changes observed on the orthopantomogram. From the anamnesis it was established that the patient had been using a toothbrush for the past three years. The doctor diagnosed: a wedge-shaped defect in the area of teeth 13, 14, 23, 24, 34, 44 and treatment. Questions 1. Make a diagnosis. 2. List the possible causes of the disease. 3. Any preventive measures can be aimed at preventing the occurrence of this disease. 4. Describe the relationship between bite processes and the occurrence of defects in the organic tissues of teeth. 5. List the methods of secondary prevention of this disease.