The 8-year-old boy Xiao Feng is a well-known “naughty king” in the class, summer vacation playing with the neighbor children, accidentally knocked out 4 just replaced the incisors. Mom and Dad were so distressed that they rushed Xiao Feng to the Department of Stomatology of Hangzhou First People’s Hospital. Dr. Duan Qingyun, deputy director of the Department of Stomatology, checked the affected area immediately and found that all four front incisors in the upper jaw had been lost, and they were permanent teeth. When Dr. Duan asked the parents where the lost teeth were, the parents looked bewildered and said they had thrown them away. Dr. Duan Qingyun, the deputy director of the clinic, said heartily that it was too bad! If you miss the chance of tooth replantation, you will have to rely on inlays or implants to make up for the missing teeth. During the summer holidays, the number of children with dental trauma has increased significantly, but many parents do not know how to handle their children’s knocked-out teeth. For example, Xiao Feng’s parents discarded the tooth. Children’s permanent teeth are “young permanent teeth”, the root has not yet completed development, the nerve regeneration ability is strong, the injury and the loss of proper treatment in a timely manner, if the affected teeth are in good condition, most of the reset and fixed effect is very good. Dr. Duan reminded parents to keep in mind: if you encounter this situation, you must take the lost tooth to the hospital. Many people throw away their lost teeth, this is not the right approach, if you can stuff the lost teeth again into the place where they fell out to the hospital is best, or the teeth in the mouth, or soaked in salt water to the hospital can be. Otherwise, there is nothing the doctor can do. The best time to reset a lost tooth is within 30 minutes. 90% of completely dislocated teeth can avoid root resorption, but if it takes more than 2 hours, the cells in the pulp and periodontium of the deciduous tooth are necrotic and it is impossible to expect the periodontium to be reconstructed, so the possibility of survival after resetting is greatly reduced. 2, retrieve the lost tooth. After the tooth is completely dislocated, the first priority is to find the fallen tooth, holding the crown, rinse with saline or sterile water, if conditions do not allow also use flowing water to wash away the surface stains, it is best to put the tooth back in place, if not also immediately to the hospital for the best treatment time. Pay special attention, firstly, do not scrape the surface of the deciduous tooth with your hand or sharp instrument; secondly, hold the crown in your hand and take care not to touch the root of the tooth. 3. Keep the deciduous tooth moist. In order to make the lost tooth “live”, we must keep the periodontal membrane on the root surface active, that is, keep the tooth moist, after retrieving the tooth, never wipe it with paper towels, etc., but put the lost tooth into milk, saline, or put the lost tooth back into the mouth. Immediately after arriving at the hospital, give the lost tooth to the doctor for treatment. 4, remember, do not use alcohol, disinfectant water, mouthwash, etc. to wipe or soak the deciduous tooth, which not only can not play a “disinfection” role, but will make the pulp and periodontal membrane cells rapidly necrosis. 5.If the tooth is embedded or elongated, do not force the dislocated tooth out or embed it in the socket by yourself, so as not to cause more trauma and induce resorption of the root and marginal alveolar bone. The right thing to do is to go to the hospital immediately and let the dentist deal with the dislocated tooth.