Some patients will encounter the situation that the cervical part of the tooth is sensitive to heat and cold, and if you look carefully, you may find that there is a groove on it, such as the one shown in the picture. This situation is diagnosed as wedge-shaped defect, which is different from caries. Huang Jinjie, Department of Stomatology, MCCCI Comprehensive Outpatient Center, has the following reasons: 1. Improper brushing method: brushing horizontally and bristles are hard and strong, just like pulling a saw, which causes abrasion to the neck of the tooth. It happens that the neck of the teeth is the weak point of the teeth and is not wear-resistant. 2. Stress fatigue: Eating hard foods, such as biting nut shells, fava beans, clenching teeth, improper knocking, etc. This factor is easily ignored. Some patients who do not have the habit of brushing their teeth horizontally also have wedge-shaped defects for this reason. The cervical part of the tooth is the area where the stress is concentrated when biting, and when it is overburdened it will disintegrate like twisting a wire, which will cause the wire to break if it is folded several times. The treatment is: first, let the patient know what is going on and what should be done to prevent it (of course, do not brush vigorously across the teeth and eat less hard objects). Then desensitize the shallow but sensitive defects and fill the obvious defects as shown below: filling can restore the integrity of the tooth, avoid deepening of the defect and avoid sensitivity