Periapical periodontitis is an inflammation of the periapical tissues of the tooth and is divided into two types: acute and chronic inflammation. Usually, periapical periodontitis results from advanced pulpitis or violent trauma to the periapical tissues. The clinical manifestations of periapical periodontitis are usually divided into acute periapical periodontitis and chronic periapical periodontitis. 1. Acute periapicalitis: In the early acute stage, some of the bodies feel mild pain, and the pain is temporarily relieved by clenching the teeth. Acute periapical pain is mostly persistent and spontaneous. If the inflammation is not controlled in time, it will continue to develop into an acute apical abscess with very strong pain and continuous throbbing pain. 2, chronic periapical infection: in general, there is no spontaneous pain patients will only feel the weakness of the bite, chewing discomfort, percussion with a strange feeling, etc.. However, the tooth is easily discolored, and the affected tooth will be seen to have an obvious abscess at the root tip when x-rayed. Patients with chronic periapical periodontitis who have low resistance are easily converted to acute attacks. When the body is suffering from periapical infection, attention should be paid to it, usually by incision and drainage, root canal treatment, open pulp drainage, and apical scraping. Patients with periapical inflammation are advised to take the appropriate treatment in a timely manner.