The best age for orthodontic treatment is from about 12 to 18 years old, when the adolescent period is complete and when the permanent teeth are basically established. This also coincides with the child’s growth spurt. This is also the most appropriate age for children to go to college after the sixth grade exams, both in terms of time and growth and development. In addition, there is a special case of bony malocclusion, especially the three types of An’s three types, that is, the bony malocclusion of the ground, there is a class of patients may be 18 years old, the deformity can be completely determined. The severity of the deformity cannot be fully determined until the age of 12-18 years, and may sometimes be delayed until after the age of 18 years.