In the process of orthodontics, there may be toothache in the first few days after each appliance replacement, which is caused by the force generated by the appliance after wearing it. This is a normal phenomenon and usually disappears in a few days. The appliance will give the teeth a constant force and pull them to move. The speed of tooth movement is usually slow, and it moves within the physiological range of periodontal ligament, so it will not cause tooth damage. After orthodontics, toothache will disappear naturally and will not affect normal life.