A six year old child’s teeth growing out from the back may be caused by retained milk teeth or supernumerary teeth. 1. Retained milk teeth: the patient is in the replacement period, the inherited permanent teeth have already erupted, but the milk teeth are not shed in time, the new permanent teeth will deviate from the correct position of the teeth, and there is a case of new teeth growing out from the back of the teeth, which is generally caused by the abnormal root resorption of milk teeth and the obstacle of the eruption of the inherited permanent teeth. 2. Multiple teeth: belonging to the number of teeth other than the normal number of teeth, mostly in the maxillary anterior region. One type of conical shape, the tooth body is small, often appear in the palate or maxillary implant between the incisors. The other type is normal in size and shape, often appearing symmetrically in the premolar region. Multiple teeth will lead to crowding, affecting the aesthetics. The six-year-old child teeth behind the back again, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.