There is a layer of dark red blood clot on the surface of the extraction wound after wisdom tooth extraction, and the surface is basically flat. If the extraction wound is sunken and empty, the blood clot is usually dislodged, and it is recommended that you can go to the hospital for specific examination. 1. After extracting wisdom teeth, the blood flowing from the extraction wound will form a blood clot in about 15 to 20 minutes after the pressure to stop bleeding, and the blood clot has the effect of promoting wound healing. 2. The clot will cover the surface of the extraction wound. When there is a clot, the extraction wound should look basically flat, sometimes slightly raised. When the clot falls off, the extraction wound is concave, empty, especially prone to local infection, pain and other phenomena, abnormalities recommend timely medical attention.