There is a lot of saliva after tooth extraction, so you must swallow it back and not spit it out frequently. Tooth extraction is a kind of traumatic surgery, which will leave wounds in the sockets after tooth extraction, but the human body has a self-healing function, and platelets in the blood will quickly adhere to the wounds when they are damaged and bleeding, and gather into a mass to form a looser hemostatic embolus, which is called a blood clot in dentistry. If frequent spitting, it will stimulate the blood clot, so that the blood clot can not play a normal role in clotting, and then cause more bleeding, wound infection, and is not conducive to healing. And the more spit always want to spit, only to swallow back in order not to stimulate bleeding from the sockets, but also conducive to normal wound recovery.