In fact, not all wisdom teeth need to be extracted, but the following wisdom teeth need to be extracted. 1, there is no chewing function, and often bite through the buccal mucosa of the buccal biting wisdom teeth, may become the cause of buccal mucosa broken, infection, erosion, and even become a precancerous lesion of the focal tooth, should be extracted early. 2.Low vertical wisdom teeth with frequent acute and chronic pericoronitis have become focal teeth that affect health and should be extracted. Although there is no symptom at the moment, the presence of the wisdom tooth can cause cavity in the cervical part of the distal and middle adjacent teeth of the second molar. In order to protect the second molar which has important chewing function, it is recommended to extract this kind of obstruction at an early stage. 4.The position of the wisdom tooth is not normal, and it forms a gap with the neighboring teeth; although the position of the wisdom tooth is normal, the crown of the wisdom tooth is covered by bone tissue or gingival flap, and the pericoronal soft tissue is often inflamed, swollen and painful. 5.Wisdom tooth is decayed, or pulpitis occurs, and it is inconvenient to carry out endodontic treatment; orthodontic needs, such as preventing the back teeth from moving forward and preventing the aggravation of crowding of front teeth, can be considered for extraction. Traditionally, wisdom teeth can be used as one of the few abutment teeth for the elderly, which can solve the retention and stability of movable dentures. With the development of orthodontic treatment techniques and concepts, more and more wisdom teeth have been retained and are functioning, even if some support is still near-medium or horizontally blocked. At present, we have made a lot of attempts to receive good results in this regard. For patients with large area of decay of the first mandibular molar that cannot be preserved, we choose to extract the first molar and then replace the first and second molars by certain orthodontic means by moving the second and third molars forward, which avoids the extraction of wisdom teeth and the restorative treatment after the extraction of the first molar. 2.Some patients with bimaxillary protrusion have decayed first molars or have been treated before, sometimes the first molars are extracted and the third molars are incorporated into the orthodontic system to achieve better results. 3.Patients with mandibular protrusion (geodontia) can also take the initiative to extract the first molar to make the mandibular dentition inward and solve the facial deformity, while the mandibular anterior teeth are not tilted lingually in transition. 4, for adolescent patients who need to push the molars distally, the third molar will generally erupt automatically to an ideal position after the extraction of the second molar, which not only facilitates the orthodontic treatment but also preserves the wisdom teeth, the patient has less fate of future wisdom teeth extraction, and the maxillary and mandibular dentition also retains 28 teeth. In summary, the existence of wisdom teeth has its advantages and disadvantages, if you have this or that doubt about wisdom teeth, I hope you listen to the advice of the orthodontist, or you will have unexpected surprises or gains.