Recurrence after orthodontics is a serious problem encountered by doctors, and its related factors are: (1) Orthodontic recurrence is directly related to orthodontic scheme, for example, in the process of orthodontic treatment, teeth should be moved slowly and lightly, and the corrective force is too strong or exceeds the limit. (2) Because the teeth, periodontal ligament, jaw and muscle fail to form a harmonious balance, it is easy to cause recurrence. (3) The bad habits that lead to deformity are not completely quit, and the correction effect will not be very stable. (4) Orthodontic treatment is generally carried out at the early stage of permanent teeth, which takes about 18-30 months, and generally ends at the age of 14- 15. However, vertical and vertical growth and development often last for several years, even to adulthood. If the patient's jaw still grows and develops in the original way after correction, malocclusion will reappear. (5) When the third permanent molar develops and erupts, especially when it is impacted forward horizontally, it has the power to push forward, which may cause recurrence.