Complete tooth dislocation means that the tooth is completely dislodged under external force, and the best time for reimplantation is within half an hour, and reimplantation within half an hour can mostly avoid root resorption. Therefore, once the tooth is dislodged, it should be reset immediately. If it cannot be reset immediately, the tooth should be put into the mouth or put under the tongue, or put into a cup with milk, saline or tap water, and then go to the hospital as soon as possible, and then reset. If more than 2 hours, at this time the activity of periodontal cells and pulp cells around the tooth may not be very optimistic, at this time, can only complete the root canal treatment of the tooth away from the tooth, and then reset, and then ligation and fixation. However, for young permanent teeth, i.e., teeth that have erupted within 3 years, because their roots are developing and their restorative ability is strong, it is also important to reset such teeth as much as possible, and after resetting them, observe them regularly. There are many cases, such as young permanent teeth, where the restorative ability is stronger and the cellular activity of the pulp and periodontium can be maintained better.