Different malocclusions. With different optimal orthodontic periods, the child can consult with an orthodontist around the age of four, but does not necessarily need to be treated immediately. During the period of mastoid jaw (2-6 years old) only treatment of malocclusion that may affect jaw development with movable aligners can usually be released in 3-6 months and some patients will not relapse, but some patients will relapse in early replacement jaw or early permanent teeth and need to be closely observed. Bad oral habits such as lower lip sucking, nail biting, thumb eating, etc. need to be interrupted as soon as they are detected. During the period of tooth replacement (7-12 years old), the appearance of retrusion, jaw recession, and bad habits must be treated early, but there are some misaligned teeth that do not need to be orthodontically treated in time. Most malocclusions can be orthodontically treated in the early permanent dentition (11-13 years for girls and 12-15 years for boys). This is the “golden period” for orthodontic treatment, when the permanent dentition is fully established, the cranial, jaw and facial areas still have some potential, the metabolic function is good, and the movement of teeth is remarkable. For serious malocclusion, it is necessary to wait until the development is fully mature (about 18-20 years old) for orthognathic surgery to achieve satisfactory results.