During the period of tooth replacement, the child’s teeth grow crooked, can be taken as follows: 1, due to the difference in the size of the crowns of the milk and permanent teeth, permanent teeth eruption will be temporarily located in the lip or tongue side of the tooth array, can not be dealt with.2, with the continuous development of the alveolar bone, the permanent teeth can be gradually moved to the normal position, you can let the child more chewing texture of the tough food, to stimulate the alveolar bone of the full development of the expansion of the arch length and width, to ensure that permanent teeth can be aligned. 3, if the retention of milk teeth occurs for a long time is located in the lip and cheek side of the teeth array. If the permanent teeth are located on the labial and buccal sides of the tooth row for a long time, the milk teeth can be extracted as early as possible.4 If the X-ray shows that there are supernumerary teeth in the root of the permanent teeth, it is also necessary to extract the supernumerary teeth as early as possible.5 If temporary crowding occurs during the replacement of the milk teeth and permanent teeth, the sequential extraction method can be applied, which will induce the movement of the permanent teeth.6 If the replacement of the milk teeth is completed and there is obvious crowding of the tooth row, the child can be Invisible or fixed orthodontic appliances can be used to align all the teeth.