If in the period of milk teeth, early fitting of movable orthodontic appliances, the use of double curved lingual arches to promote the upper front teeth lip to move, at the same time to open the frontal mesial gap, expanding the width and length of the dental arch, so that the upper and lower dental arches to form a normal cover, overlay relationship, 5-6 years of age when the beginning of the replacement of permanent teeth can be established when the normal occlusal relationship. If the patient develops severe antimandibularity and there is a significant difference between the upper and lower dental arches, or if the patient is not corrected in time and the patient still develops the habit of extending the lower jaw forward, the permanent teeth will develop antimandibularity after the replacement of the milk and permanent teeth, and fixed or invisible orthodontic appliances will be needed to further correct the problem.