Orthodontic treatment is a complex and lengthy process in which good cooperation between the doctor and the patient is required to achieve satisfactory orthodontic results. Generally speaking, orthodontics takes about 2 years for adolescents and 2.5-3 years or even longer for adults. So, what preparations are needed before orthodontic treatment begins? First, one should have an objective understanding of orthodontic treatment. Orthodontic forces act on the teeth to move them, and there are limits to this movement of teeth. Generally speaking, crowding, protrusion, gap, etc. are indications for orthodontic treatment; minor bony deformities can also be improved by orthodontic movement of teeth, which is called “masking treatment”. The more serious bony deformities need combined orthodontic-orthognathic treatment to solve. Before you go into the orthodontic office, try to be clear about what you want to solve with orthodontic treatment, whether it is crowding or protrusion? This will improve your communication with your doctor and help him/her to design a better treatment plan for your situation. Secondly, orthodontic treatment mainly addresses the “aesthetics” of the teeth, but before that, the “health” of the teeth should be addressed. Periodontal scaling (“scaling”) or systematic periodontal treatment and treatment of existing dental caries should be performed before orthodontic treatment begins, depending on the individual case. It is worth noting that periodontitis is not an absolute contraindication to orthodontic treatment. However, orthodontic treatment cannot be started in patients with progressive periodontitis and can only be further evaluated after systematic periodontal treatment and no further progression of the disease. You should develop good oral hygiene habits before orthodontic treatment. The presence of aligners and archwires inevitably makes oral cleaning more difficult. In addition to regular cleanings during orthodontic treatment, you should master the correct brushing method to minimize the appearance of problems such as tooth surface demineralization, gum recession and “black triangle”. In addition, although doctors and patients are reluctant to extract teeth, 60-70% of patients still need to have teeth extracted for orthodontic treatment. The orthodontist will allocate the extraction space according to each patient’s situation in order to solve problems such as crowded or protruding teeth. It is not excluded that some patients (such as those with congenital missing teeth) need to be treated with restorative treatment after orthodontic treatment.