The presence of a hard knot at the anesthetized site after tooth extraction is considered a possible cause of local hematoma and interstitial infection. Generally need to be treated according to the cause. 1. Local hematoma: hematoma usually occurs when the tooth extraction anesthesia, is due to the anesthesia next to the capillaries and injection site deeper caused by. This kind of hematoma generally cold compress for 2 days, and then hot compress, accelerate blood circulation and absorption. It can be eliminated in a few days. 2. Interstitial infection: after wisdom teeth extraction surgery, infection will appear slight pain, and the phenomenon of postoperative gums hard packs, may be postoperative swelling or infection, it is recommended to do intravenous fluids in a timely manner to anti-infection treatment. Commonly used drugs are cephalosporin, etimicin sulfate, erythromycin. Or oral metronidazole tablets, tinidazole tablets. If the anesthetized site of wisdom teeth extraction develops hard nodules, please consult a doctor as soon as possible to receive professional treatment to avoid delaying the condition. Use the medication under the guidance of your physician.