I. Those with severe cardiovascular disease and high blood pressure above 180/100 mmHg. Patients with heart disease in general can have their teeth extracted as long as they do not show signs of cardiac insufficiency (such as 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; anti-infection prophylaxis should be given before and after tooth extraction because the resistance of heart disease patients is reduced and they are more prone to co-infection than normal people. Second, bleeding diseases: Patients with hemophilia and primary thrombocytopenic purpura, for example, have a tendency to bleed because the coagulation process in their bodies is impaired. After extraction, bleeding is difficult to stop and 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. Menstruation, pregnancy and lactation: Women should, in principle, avoid tooth extraction during menstruation because compensatory bleeding may occur in the tooth socket during menstruation. However, the extraction of loose teeth during menstruation has little effect on the patient. Some “deep-rooted” teeth, such as obstructed teeth or buried teeth, should be extracted after menstruation. Some people believe that no tooth should be extracted during pregnancy because it may lead to miscarriage. However, a lot of clinical practice shows that tooth extraction during the third to seventh month of pregnancy is safe and has no adverse effects on pregnancy. During this period, the following points should also be noted: ① Intramuscular injection of progesterone 10 mg on the day before and on the day of tooth extraction. (ii) Epinephrine must not be added to the anesthetic for tooth extraction. ③Anesthesia must be complete and the pain relief effect should be good. For patients with a history of habitual miscarriage or habitual premature birth, tooth extraction is prohibited during pregnancy. Dental extraction is completely allowed during breastfeeding. Some people say that tooth extraction during this period will interrupt or reduce milk production. This statement is not scientific. Clinical practice shows that there is no effect on lactation. IV. Severe liver and kidney function impairment is extremely active in liver disease. Such as chronic hepatitis and cirrhosis, due to poor liver function, the content of prothrombin and fibrinogen involved in the coagulation process is reduced, there is a tendency to bleed, and the wound 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. Tooth extraction should be avoided in malignant tumors and during the onset of psychosis. VI. Before the symptoms of diabetes mellitus are controlled. Tooth extraction should be avoided after strenuous exercise, labor and alcohol consumption. VIII. Those with a history of allergy to procaine anesthetics (some can be changed to acupressure or needle anesthesia).