The causes of tooth pain are as follows: first, pulpitis, the pain caused by pulpitis is usually more intense, when eating cold, hot, sour, sweet and other irritating food, it will cause severe and continuous pain, and also find spontaneous pain and severe pain at night, affecting the quality of sleep. Second, tooth decay, when the damage area of decay is large, the cavity is very close to the pulp cavity, the external cool and hot stimulation will provoke the nerve reaction, resulting in tooth pain, the cavity is large and easy to store food, when the food is embedded into the cavity will also cause paroxysmal pain. Third, periodontitis, in the late stage of periodontitis due to the large amount of alveolar bone resorption, resulting in many teeth in the mouth have different degrees of root exposure, the root exposure in the oral cavity will cause tooth sensitivity, the symptoms of the light will lead to teeth after eating sore and soft, the heavy will appear teeth to external pain.