Anesthetic drugs such as lidocaine with epinephrine are used for local infiltration anesthesia or nerve block anesthesia for tooth extraction. The reasons for playing epinephrine include that it can reduce blood seepage, enhance the penetration ability of anesthetic drugs and ease the speed of anesthetic recession, etc., as follows I. Reduce blood seepage: epinephrine can effectively shrink capillaries and reduce the amount of blood seepage at the extraction incision, while the operation becomes clear and easy to operate, and the tooth can be extracted in a short time. II. Enhance the penetration ability of anesthetic drugs: epinephrine can enhance the penetration ability of anesthetic drugs, which can make the anesthetic effect appear in the surgical area in about 1-3 minutes and reduce the pain of patients. III. Relieve the declining speed of anesthetic drugs: Epinephrine can delay the declining speed of anesthetic drugs, which can make the surgical area continuously numb for 3-4 hours or more without causing pain to the patient.