If nerve necrosis is not treated in a timely manner, the decayed pulp tissue will gradually penetrate into the periapical region of the tooth and gradually lead to periapical inflammation and intracanal resorption of the tooth. The best treatment for nerve necrosis is root canal therapy, which thoroughly removes the pulp, removes the infected material in the root canal, and treats the root canal with anti-inflammation, disinfection and flushing, and finally seals the root canal with medicine to assist in anti-inflammation and pain relief, and after the inflammation is completely eliminated, the root canal of the tooth is tightly filled with special dental materials to close the root canal and prevent re-infection. After the root canal treatment is completed, the affected tooth can be retained and continue to perform its chewing function.