Dental trauma (dental traumatology) is a disease in which acute damage occurs to the hard tissues of the tooth, the pulp or the periodontal tissues in response to a sudden mechanical external force. Dental trauma can destroy one type of tissue alone or involve multiple tissues at the same time. A variety of factors can lead to dental trauma including collision with hard objects during a sudden fall, violent collisions in sports, traffic accidents and violence. Children often collide or fall during learning to walk, play sports, and games, which can also easily result in dental trauma. Oral and maxillofacial traumas are often accompanied by dental injuries. At present, many patients ask how to deal with tooth loss after trauma, whether the lost tooth can be reimplanted in the alveolar socket, and whether the reimplanted tooth can survive. Here is a brief introduction to the above-mentioned issues. Post-traumatic tooth loss refers to the separation of the crown and root from the alveolar socket after a maxillofacial trauma, accompanied by gum tearing and periodontal mucosal damage. The tooth can be reimplanted within half an hour after the tooth is lost, although the pulp tissue (often called the dental nerve) will be necrotic due to lack of blood supply, when the periodontal tissue can hopefully survive and form a re-fixation of the affected tooth. Factors that affect the effectiveness of dental reimplantation include the timing of dental reimplantation (the sooner the better, the lower the survival rate of reimplantation after half an hour of shedding); the way of preserving the shed tooth (when the shed tooth is not contaminated, the shed tooth can be restored to the socket, if the shed tooth has been contaminated, it can be stored in saline after rinsing in water. If saline cannot be found, milk can be used instead.