The earlier the loosening of a tooth trauma, the better the loosening fixation. The best fixation is especially when the tooth is completely dislocated, has fallen out of the mouth, completely fallen out and not broken, within 2 hours, the reset fixation effect is the best; within 2 hours reset fixation, after fixation 2 weeks after the conventional root canal treatment. After 2 hours, the cells of the periodontal membrane are basically necrotic, so before replantation, the tooth nerve should be disposed of in vitro before replantation. Therefore, it is necessary to consult the doctor in time. If the tooth is loose due to trauma, it is recommended to consult the doctor as soon as possible, and the 2 hours are called the golden 2 hours.