Orthodontics according to the age and the stage of dental growth and development orthodontic methods are different, as follows: 1, the period of milk teeth: the main correction of oral habits, such as finger sucking, biting hard objects. The baby teeth appear anticlinal, it is best to correct and intervene at the age of about 4 years old, to facilitate the eruption of permanent teeth, as far as possible to achieve a normal bite; 2, the replacement period: 6-12 years old, the baby teeth are replaced in turn, it is recommended that every 3 months review, temporary malocclusion can be observed first, if necessary, intervention; 3, adolescence: functional orthodontics can be carried out, mainly to correct the misalignment of teeth and bite relationship; 4, the adult period: that is, after 18 years old In the adult period, the previous malocclusion will not correct itself, and orthodontics can be performed at any time.