Primary and secondary school students are the main force of orthodontic treatment, more than half of the annual outpatient volume of holidays, but because many people do not understand, so most of the children who come to orthodontic treatment still miss the best orthodontic period. The reason for choosing orthodontic treatment around the age of 12 is that the entire dental arch of the child is basically fully developed, the milk teeth are basically finished replacing, the permanent teeth are basically fully grown, the permanent tooth roots are gradually developed and completed, the bite relationship between the upper and lower teeth is also adjusted and completed, the dentist can make a clear diagnosis of the type of malocclusion and take the appropriate orthodontic treatment. At the same time, children around 12 years old have good biological responsiveness to external stimuli, fast bone reconstruction, high plasticity, and vigorous tissue metabolism, so the treatment cycle is short and effective, and it is easy to maintain the effect after the orthodontic treatment is completed. However, there are some malocclusions such as “Geodon” and lip biting that need to be treated at the age of 3~5; some malocclusions should be treated at the age of 8~10 when permanent teeth have started to erupt. Bad oral habits should be broken as early as possible. Orthodontic treatment is mainly wearing orthodontic appliances, orthodontic appliances can be divided into two categories according to the way they are fixed in the mouth: movable appliances and fixed appliances. Each type of aligner has its own indications, and the orthodontist will choose according to the patient’s age, the nature and severity of the malocclusion. After wearing the braces, the teeth will be sore and soft due to the unadapted traction of the braces, so it is necessary to eat soft food for the first three days to avoid increasing the pain, such as soft rice and porridge. After a week of basic adaptation, you can eat normally, but in the 1 to 2 years of orthodontic treatment, you can not eat too hard and too sticky food, such as eating nuts such as walnuts, gnawing bones, etc., to prevent the loss of aligners. During the orthodontic treatment, there are different plans for tooth movement at different stages, so it is important to have regular follow-ups where the doctor will make adjustments to the aligners for a particular tooth movement. Fixed aligners are every 4 to 6 weeks and removable aligners are every 2 to 3 weeks.