A good number of young people have heard of and have wisdom teeth, and some of them suffer from them. Wisdom teeth, medically known as the third molar, is the last tooth to erupt, mostly between the ages of 16 – 30 years old, this period is the stage of gradual maturation of human psychological and physical development, and therefore has the symbol of wisdom. Although the symbol of wisdom, often accompanied by pain, there are studies suggesting that in China, half of the population aged 16 to 25 years is not wisdom teeth, in the eruption of wisdom teeth obstructed and misaligned about 44%, of which the lower jaw obstructed teeth about 2.5 times more than the upper jaw. The reason for this may be related to the evolution of human beings and the fine diet, the jaw bone structure does not get sufficient chewing function exercise, gradually degraded, the number of teeth is not reduced, the need for eruption space is greater than the amount of jaw bone, so that when the third molar grows out often not enough position, so that eruption difficulties, which formed the “wisdom teeth obstruction”. Wisdom tooth obstruction often causes wisdom tooth pericoronitis, and it will lead to self-cariousness or adjacent tooth caries due to abnormal position, or even turn into tooth-containing cyst, above are the common clinical reasons for extraction, and there is also the need for orthodontics. For orthodontic eruption and normal occlusal relationship with the opposing teeth and complete bone buried wisdom teeth without any symptoms can be considered for retention. Since the extraction process is complicated, it is recommended to deal with it in a professional medical institution. The following contraindications need to be excluded before extraction: i. Patients with serious cardiovascular disease and hypertension, such as blood pressure above 180/100 mm Hg should be withheld. The following conditions should be considered as contraindications for tooth extraction: 1. myocardial infarction within 6 months; 2. unstable or recently started angina pectoris; 3. congestive heart failure; 4. uncontrolled arrhythmia; 5. uncontrolled hypertension. In terms of cardiac function classification, class III cardiac function should be considered as a contraindication to tooth extraction, while for patients with more severe cardiac function class II, tooth extraction should also be done with caution and appropriate countermeasures. Tooth extraction and oral surgery can be used to prevent the occurrence of temporary bacteremia: congenital heart disease, valve damage caused by rheumatic fever, and patients who have undergone cardiac repair surgery have the potential to cause bacterial endocarditis when bacteremia occurs; one of the most important factors causing the onset of bacteremia is green streptococcus (Streptococcus aureus) bacteremia. Green streptococci are highly sensitive to penicillin under normal circumstances, but resistant strains develop 24 hours after the use of penicillin. In general, patients with heart disease can have their teeth extracted as long as they do not show signs of cardiac insufficiency (e.g., shortness of breath with mild activity or lying down). However, when extracting teeth, it should be done as follows: do not add epinephrine to the anesthetic to avoid tachycardia and induce heart failure; complete anesthesia and gentle movements to minimize adverse stimulation, bleeding or injury. Second, bleeding diseases: Patients with hemophilia and primary thrombocytopenic purpura, for example, have disorders of coagulation process in their bodies, so they have bleeding tendency. The bleeding is difficult to stop after extraction, which can cause hemorrhage and life-threatening. As for patients with leukemia, since they are highly susceptible to infection, the incision after tooth extraction can also become a focus of infection, which can lead to serious systemic infection and is difficult to control. Therefore, when these patients suffer from dental disease, they should be treated conservatively and tooth extraction is contraindicated. III. Menstrual period: Women should, in principle, avoid tooth extraction during menstruation, because compensatory bleeding may occur in the alveoli during menstruation. IV. Severe liver and kidney insufficiency, and active period of liver disease, liver and kidney function should be checked. For example, in chronic hepatitis and cirrhosis, due to poor liver function, prothrombin, which is involved in coagulation, is reduced and has a tendency to bleed, and the incision after tooth extraction will bleed more than once. Therefore, appropriate amount of vitamin K should be supplemented before tooth extraction for such patients to promote prothrombinogen synthesis to supplement the deficiency of fibrinogen in order to avoid accidents. V. Diabetes mellitus, tooth extraction can be considered if the patient’s blood sugar is well controlled, and oral antimicrobial agents taken 2 hours before surgery can reduce infection and intraoperative trauma; if fasting blood sugar is greater than 8.88 mmol/L or postprandial greater than 11 mmol/L, tooth extraction should be postponed. Precautions after tooth extraction: 1. The cotton ball or gauze bitten in the mouth must be spit out after 40 minutes, local cold compress within 24 hours, and do not brush and rinse the mouth. 2. Do not lick the wound or suck the wound with your tongue after tooth extraction. 3. On the day of tooth extraction, you can eat soft food or liquid food, do not chew on the affected side, do not eat irritating food, and generally chew on the side of tooth extraction only after the wound heals after 7 days of tooth extraction. 4.Speak less on the day of tooth extraction and try not to spit, otherwise it will affect the wound healing and cause the wound to bleed. 5. If the pain gradually worsens 2~3 days after tooth extraction, you need to follow up or contact with the doctor in time.