A 9 year old child who has lost an incisor can generally be treated with filling, pulp preservation, apical induction molding, etc., and if necessary, extraction is required. 9-year-old child incisor apical part is not yet mature, in the stage of young permanent teeth, fell out of a section of the tooth trauma led to dental defects, according to the different parts of the damage, can be used in different ways of treatment. 1. Filling: When the tooth defect does not involve the pulp, the defective shape can be repaired by resin filling to maintain the gap and prevent the loss of the three-dimensional gap of the tooth. 2. Pulp preservation: When the traumatized tooth has a small pulp hole and the injury time is short, direct pulp capping can be used to preserve the living pulp; when the pulp infection of the traumatized tooth is more limited or the pulp fails to survive the direct pulp capping, pulpotomy can be used. 3. Apical induction molding: When the pulp is diffusely infected and necrotic, apical induction molding can be used to remove the infected pulp and allow the root to continue to develop, and after the root development is completed, complete endodontic treatment is needed, and restorative treatment is needed after adulthood. When apical induction molding is unsuccessful, apical barrier surgery can be used to form an apical closure. 4. Extraction: When the tooth has no preservation value or the defect cannot be repaired, it needs to be extracted and the gap maintained to facilitate restoration in adulthood. In addition, if the tooth loss is small or the lesion is limited to the root tip or the middle of the root, it can be treated by adjusting and grinding the sharp edges, desensitizing treatment, and resetting and fixing. Post-traumatic dental injuries need to be reviewed regularly to detect pulp and root lesions in time for timely treatment.