Generally children’s malocclusion orthodontic treatment after the age of six years is appropriate, the younger children are less compliant, the effect is also poor, and there is no need to wear braces. However, at the age of six years into the period of mixed dentition, some malocclusion to intervene, such as the ground, oral malocclusion caused by bad habits, and the child can not automatically quit completely, to functional orthodontic intervention, and even to wear bad habits break the orthodontic appliance. Some are caused by poor breathing patterns such as mouth breathing, when the first step is to go to ENT to check for severe upper airway obstruction conditions, adenoid hypertrophy, the need for ENT treatment, and then with oral appliances, functional orthodontic appliances treatment. Some cases require fixed orthodontic treatment after the age of 12 in the permanent dentition, such as fixed aligners, stick-on brackets or invisible orthodontics. So it is generally done after the age of 6-12 years old, and there are different age stages for different situations.