Children’s milk teeth did not fall out of the permanent teeth grow out, can return to the position, can not be unified, depending on the development of the teeth. 1. For most children, permanent teeth grow out before milk teeth fall out, with the passage of time, milk teeth will slowly fall out, permanent teeth can return to the normal position. However, it cannot be ruled out that in a small number of children who have permanent teeth, the milk teeth may not fall out for a long period of time, which will make it more difficult for the permanent teeth to return to their normal position, and the position of the permanent teeth may be crooked. 2. For the permanent teeth can not return to the normal position of the situation, the milk teeth need to be extracted in time to ensure that the permanent teeth position enough space to prevent crooked teeth. If children’s milk teeth are retained, but do not affect the normal growth and development of the teeth, you can not do special treatment, regular observation can be. During the period of time, we should regularly review the dental film to understand the growth of teeth.