In some cases, although the nerve is necrotic, the necrotic pulp and infected material, still sealed in the tooth, can form septic inflammation, prompting apical inflammation or apical granulation tissue growth and periapical abscess or periapical inflammation, both of which can lead to painful symptoms and even more intense pain for the patient. Self-perceived elongation of the tooth, fear of biting, and fear of eating are all caused by necrosis of the dental nerve. When tooth pain occurs, it is recommended that patients go to the dentistry department of a regular hospital as soon as possible for examination and treatment, and ask the doctor to perform dental pulp opening to release the infected material and relieve the patient’s pain.