Orthodontics usually takes about two years, and longer for those with genetic factors. Orthodontics is a form of treatment for malocclusion, by applying an external force to the teeth to achieve the purpose of tooth movement, the orthodontic time for adults and children is different. Children’s alveolar bone reconstruction is faster, the movement of teeth is also faster, dental only simple dental problems, no combined bone or genetic factors, generally about a year and a half can be completed, post-operative maintenance time of about a year, chewing muscle balance is established, maintenance can end. In adults, the orthodontic treatment takes longer and the teeth move more slowly, about two and a half years. After the orthodontic treatment is finished, the post-operative retention time will also be longer, and some may need lifelong retention. In the case of simple malocclusion, orthodontic treatment usually ends in about two and a half years. If there is a family hereditary factor, such as hereditary diastemas, it will take a long time to correct, or orthodontic orthognathic surgery will be required after the age of 18 years. In cases where genetic factors are present, lifelong post-operative maintenance may be required to avoid recurrence. Therefore, orthodontic treatment is usually about two years for dental cases, and bone or hereditary cases require surgery and may require lifelong maintenance after surgery.