The cotton ball in the mouth after tooth extraction can usually be spit out in 30~40 minutes. After tooth extraction will be left in the mouth a large socket, some of the buried teeth also need to be cut and flap extraction, blood-rich mouth, there will be a certain amount of bleeding in the alveolar fossa, generally bite the cotton ball to stop bleeding. Generally after tooth extraction, bite a cotton ball for 30 minutes, will form a blood clot in the alveolar fossa, so as to achieve the purpose of hemostasis, if spit out the cotton ball and a certain amount of bleeding, you can bite the cotton ball for a while to an hour, and hemostasis, generally in the cotton ball spit out, there will be a small amount of blood seepage in the mouth within two to three days is a normal phenomenon, avoid brushing and rinsing within 24 hours, to avoid the shedding of blood clots caused by secondary hemorrhage. Spit out the cotton ball after 30-60 minutes after tooth extraction, if the wound bleeding is large, you need to consult a doctor in a timely manner, under the guidance of the doctor to check and deal with, to avoid adverse consequences.