Many patients and their parents often "stay at a respectful distance from others" and have great fear of it. In fact, this kind of worry is unnecessary. When the teeth are seriously crowded and dislocated, and the gap is obviously insufficient, the teeth must be extracted and corrected. Only tooth extraction can achieve the coordination of tooth quantity and bone quantity, the balance of dental arch and perioral muscle tension, so that the orthodontic effect is stable and the deformity is not easy to recur. The main purpose of orthodontic tooth extraction is to relieve crowding and arrange teeth. Patients with double dental arches or patients with sagittal and vertical dental arches also need to extract teeth to obtain gaps, retract the front teeth and move the rear teeth to obtain a stable, balanced and beautiful dental-maxillofacial relationship.