It may be normal for a child’s incisors to fall out and not grow back for six months, or it may be due to an ambulatory tooth, or it may be due to a congenital missing tooth. It is necessary to go to the hospital for examination to determine the situation and disposal. 1. Physiological factors: most of the children’s milk teeth to the eruption of permanent teeth need 1 to 2 months, some children may need 3 to 6 months to erupt permanent teeth, so the child’s incisors fell out of half a year did not grow out of the normal phenomenon, but if more than 6 months, you need to consult a doctor for examination in a timely manner. 2. Ambidextrous teeth: ambidextrous teeth is due to the jawbone of the teeth did not erupt normally caused by the phenomenon, if the surrounding teeth occupy the teeth eruption gap, then it may lead to ambidextrous teeth, and then appear the phenomenon of the child’s incisors lost half a year did not grow out. 3. congenital missing teeth: congenital missing teeth may be caused by heredity, there may also be due to the process of tooth development, the formation of dental plate is insufficient or inhibition of the proliferation of tooth germs, which will also lead to the child’s incisors fell out of the symptoms of half a year did not grow out. After eliminating the physiological factors, if the child’s symptoms of losing incisors for half a year continue to be unrelieved, it is recommended to consult a doctor in a timely manner.