Tooth killing nerve selection method if it is direct pulp extraction, pulp extraction thoroughly pain can be relieved with it, pulp extraction is not complete pain will persist, if it is closed pulp inactivator, usually need 3~4 days, no longer pain, as follows. 1. Pulpotomy: also known as pulp extraction, is the insertion of the pulp extraction needle into the root canal, rotate the needle after extraction, the pulp is then extracted, after anti-inflammatory cleaning, if the pulp extraction is complete, the pain can be eliminated, if the pulp extraction is incomplete, there is still part of the pulp residue, will continue to cause pain. 2. Closed pulp inactivator: the pulp will gradually lose its vitality, the whole process takes 3~4 days, during which you may feel swelling or dull pain, and the pain will be eliminated after the pulp completely loses its vitality. If you still feel severe pain after killing the nerve, or the pain has not been relieved, it is recommended to go to the hospital in time.