The main causes of toothache are dentin hypersensitivity, tooth decay and receding gums, as follows. 1. Dentin allergy: If the patient likes to eat too hard food, it is easy to cause the enamel on the surface of the teeth partially defective, so that the dentin is exposed. Dentin exposure after eating cold, hot, sour, sweet and other foods will be more sensitive. In this case, you should avoid eating hot and cold stimulating food, and also need to adhere to the correct method of brushing, using fluoride mouthwash rinse and desensitizing toothpaste brushing, which can improve the wear resistance of the teeth to a certain extent. 2. Dental caries: When the caries lesions reach the dentin, it can cause toothache. It is recommended to change the habit of eating sweets and drinking carbonated beverages, and in serious cases, root canal treatment is needed to relieve the pain. 3. Receding gums: usually caused by disease, may make the root of the tooth covered by the gums partially exposed, which in turn leads to dentin exposure and toothache. In this case, the main target is to treat the original disease, such as periodontitis. Treatment measures include medication, scaling, and periodontal surgery.