When one incisor grows and the other one doesn’t, it may be that the tooth is still in the process of eruption, or the tooth eruption may be blocked or caused by congenital missing teeth. 1. Teeth are erupting: only one incisor has grown, the other has not grown, the teeth may be in the process of eruption, but not yet erupted, generally an incisor eruption, another incisor is about to erupt, you can first observe about two months. 2. Blocked eruption or congenital lack of teeth: If after observation, the incisors do not erupt for a long time may be caused by too thick gums. It may also be due to congenital lack of tooth germs, no incisor tooth germs on the X-ray, at this time need to consider prosthetic restoration. One incisor grows, the other does not grow, 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.