In the orthodontic treatment process, many parents are most surprised by the orthodontist’s proposed treatment plan, which is the doctor’s proposal to extract teeth for orthodontic treatment. Whether orthodontics requires tooth extraction was controversial more than 100 years ago, when fixed orthodontics was just beginning, mainly due to the limited experience of doctors at the time, the understanding of orthodontics and today’s doctors are very different, the early inventor of fixed orthodontics Dr. Angle are not extracted, think that as long as the teeth are aligned to get a good facial shape, but as time goes by, many cases Crowding relapsed, along with overly prominent facial lips. Two of his students, Drs. Tweed and Begg, boldly proposed orthodontic extractions, by which the four first bicuspids were removed to relieve crowding, improve the facial shape, adjust the proximal, distal, and vertical relationships of the teeth, and achieve harmony with the jaws and muscles. Since the bone degenerates faster than the teeth throughout the evolutionary process, and modern people have a fine diet, the bone has less opportunity to be exercised and less developed, the teeth are less worn out, in short, the volume of teeth is greater than the volume of bone, the root of the teeth is too large and difficult to be accommodated by the smaller bone, so it is necessary to achieve the coordination of teeth with the bone and muscle by reducing the number of extractions. It facilitates stability at the end of orthodontic treatment. For many patients with a protruding facial shape, it is often necessary to reduce the number of extractions and to control reasonable support to achieve the purpose of internalizing the anterior teeth and changing the position of the upper and lower anterior teeth in order to improve the facial shape. In some cases where there is a disproportion between the proximal and distal mesial directions and vertical direction, tooth extraction is often used to coordinate the disproportion between the arch positions, establish a neutral molar relationship, and establish a normal anterior tooth relationship. There are also some cases that are more tangled in orthodontics, we call them critical cases, that is, there is a reason to extract teeth or not to extract teeth, for example, the facial shape is slightly protruding, if the teeth are extracted, the facial shape will be slightly concave, if the teeth are not extracted, the facial shape will be a little more protruding, often using the extraction of four second bicuspids or other methods to push the molar backward, can achieve good results. Due to the special facial shape and situation of Chinese people, according to the preliminary statistics of the Department of Orthodontics of Peking University Medical School (formerly Beijing Medical University), the number of tooth extraction cases reaches 60-70%, which is higher than that of European and American countries, mainly because of the smaller jaws, larger teeth, serious crowding, more protruding lips and less developed nasal and chin development in the East than in the West, in order to obtain a good facial shape and align the teeth in many cases In order to obtain a good facial appearance, tooth extraction is used in many cases. In the vast majority of cases, the four bicuspids are selected for extraction, but in a few complex cases or special circumstances, other tooth positions may be selected, or asymmetrical extractions may be performed. Extractions are more demanding on the orthodontist and tend to be longer compared to non-extraction orthodontics, and with the proper indications, the results are often better.