Most patients and their parents know that the appropriate age for orthodontic treatment is around 12 years old. This is not always the case, as most children can begin fixed orthodontic treatment after the replacement of their baby teeth, which is around 11 or 12 years old for boys and possibly earlier for girls. There are some cases where we need to intervene early and interrupt the treatment: for example, the “enamel” of the baby teeth. Since the milk teeth are usually dental, they guide the growth of the permanent teeth, so if the milk teeth are left unattended, it is likely that the permanent teeth will be affected by the normal establishment of the occlusal relationship. Generally speaking, treatment of “bunions” in the milk teeth should be started around the age of 3 if the child can cooperate. If there are bony malocclusions, such as “encephalitis” caused by underdevelopment of the upper jaw, “small chin” caused by underdevelopment of the lower jaw, narrow dental arches, etc., functional orthodontics with growth and development can achieve good results, and the appropriate time is around nine or ten years old. The appropriate time is around nine or ten years old. Wait until the bony malocclusion factors are removed before starting fixed orthodontics. Therefore, parents are advised to take their children to the hospital for oral examination regularly. If the bony malocclusion has already formed and the growth spurt is missed, a combination of orthognathic surgery may be necessary to achieve good results. Then, preoperative orthodontics is performed first and the surgery is usually performed in adulthood, followed by postoperative orthodontics. Can adults be orthodontic? This is a question of concern to many of you. As long as your periodontal health is healthy, then age is not a hindrance to your orthodontic treatment and the most sought-after beauty.