The time of blood seepage after tooth extraction firstly has certain individual differences, and secondly has a close relationship with the size of the extraction trauma. Take the clinical relatively traumatic wisdom tooth extraction as an example, generally in the extraction of teeth after 15-30 analysis, is the extraction of teeth trauma blood clot began to form time, that is, this period of time within the wound will have a slight oozing of blood. So accordingly in this time period, the extraction doctor will ask the patient in the extraction wound bite sterile cotton balls or cotton rolls, in order to play the role of pressure to stop bleeding. And 30 minutes after the spit out cotton balls and cotton rolls, theoretically, the extraction wound will not have obvious blood oozing under the naked eye. However, it is normal to have blood in the sputum in the mouth at this time, and the phenomenon of blood in the sputum usually disappears gradually after 24 hours.