Toothache is mainly due to inflammation of the pulp or periapical tissues within the tooth, and the pressure in the pulp cavity or periapical area increases, causing pain. When the lesion involves the submucosal tissues in the apical region, pus collects in the mucosa, and the pressure in the pulp cavity is reduced, resulting in the phenomenon of no pain after swelling. When the tooth has deep caries, dental trauma, chemical stimulation, etc., can lead to lesions in the pulp and periapical tissues, resulting in pain, discomfort in biting, and loosening of the tooth when in acute periapical inflammation. When the lesion is in the acute inflammatory stage, it is necessary to open the pulp and drain, remove the irritant, adjust the grinding of the bite, anti-inflammatory and pain relief, and incision and drainage of pus are required when the fluctuation of the abscess is detected. After emergency treatment, complete root canal therapy is needed to eliminate infected tissue, repair defects, promote periapical healing or prevent periapical lesions from occurring. When the above situation occurs, it is necessary to be treated as soon as possible under the guidance of a doctor to prevent delays in the condition. Oral hygiene should be enhanced to prevent the occurrence of these diseases.