Dentin hypersensitivity, which can occur alone or as a symptom of other dental or systemic diseases. For example, severe cervical wedge defects and traumatic fracture of enamel expose dentin and lead to dentin hypersensitivity. A few people, who have increased systemic stress due to long-term exposure to chemical work, insomnia, neurosis, pregnant women during menstruation or lactation, or after oral and maxillofacial firing line treatment, can also develop symptoms similar to dentin hypersensitivity. The most common is in older adults with large molars, where the teeth are gradually worn down and thinned, the enamel disappears and the dentin is exposed due to long-term food consumption. There are also some people, due to long-term use of non-standard poor quality toothbrushes, or unscientific cross-pull method of brushing teeth, wear the teeth enamel structure taught thin cervical part, in addition to the residual food decomposition in the mouth acid erosion, or have chronic stomach disease acid reflux, resulting in cervical defects, dentin exposed, mostly in single cusp teeth, bicuspid teeth above the gingival margin of the lip and cheek side. In a few people, night grinding, or the habit of biting food on the lateral side, accelerates the wear of enamel on the biting surface of the teeth and exposes the dentin. In the exposed dentin surface, especially the junction of enamel dentin, can appear one or several allergic points, when biting food, mechanical, chemical or temperature stimulation, there is a sour, soft, pain and other abnormal sensations, when the stimulation disappears, the above phenomenon also disappears immediately, this is commonly known as “inverted teeth”. In the above situation, first of all, we should pay attention to dietary hygiene, adjust the functions of the whole body, improve the working conditions, and eat less hard food and sweet and sour food. Correct the incorrect horizontal brushing method, and insist on using fluoride desensitizing toothpaste to brush your teeth. Correct the habit of biting food on the lateral side, and bite some food such as tea, almond, peach kernel or peanut kernel with the affected teeth daily, which can reduce the pain. When the symptoms are serious, you should ask a doctor to examine and find out the cause and treat the symptoms.