1. Tooth decay: If the wisdom tooth is decayed, except for the simple decay on the occlusal surface that is not deep enough to be filled, we recommend extracting all the teeth that are decayed on the adjacent surface and require good technique, and those that are decayed so deeply that they even need root canal treatment to eliminate future problems. 2. Encroachment on adjacent teeth: Usually the patient is not aware of it, but the dentist can diagnose it by X-ray. Usually there is not enough space for the wisdom teeth to erupt and they fall on the second molars, thus making it difficult to clean the second molars and even causing partial resorption of the teeth, resulting in discomfort or toothache for the patient. Yu Zhe, Department of Stomatology, Xuanwu Hospital, Capital Medical University 3. Insufficient space: wisdom teeth belong to the fading state in the evolutionary history of mankind. Therefore, the dental arch is also getting smaller and smaller, and the lack of space is very common. The swelling and painful feeling can be felt most when taking eruption. Many people decide to remove their wisdom teeth because they cannot tolerate this painful feeling. 4. Difficult to clean: Due to the lack of space, wisdom teeth often grow crookedly, thus often causing difficulties in cleaning teeth and resulting in tooth decay. 5. There is no pair of teeth: As mentioned earlier, not everyone’s four wisdom teeth will grow together. Therefore, if there is no opposing wisdom tooth to bite, sometimes over-eruption of the wisdom tooth may occur, which may affect the bite. 6. Obstructed teeth: Usually this is the most annoying type, which the dentist finds difficult to handle, but the patient does not necessarily feel it and therefore ignores it. This type of tooth, usually buried in the alveolar bone inside, if it will be painful, or diagnosed when there will be lesions occur, it is necessary to remove. 7. If a young person has his or her wisdom teeth removed before the first one of the four wisdom teeth is removed, the wisdom teeth will automatically move forward and replace the extracted tooth.