Killing the nerve is too painful, the following methods can be used: 1, using lidocaine and ativan for block anesthesia or local infiltration anesthesia, adding a small amount of adrenaline if necessary to increase the permeability of the drug, prolonging the anesthesia time and reducing the pain.2, placing a fast or slow deactivating agent in the pulp angle of the exposed area, so that the pulp gradually loses its vitality through the action of the drug, and the pain can not be felt.3, performing periodontal anesthesia If the crown pulp has been necrotic and only the root pulp exists vitality, endodontic anesthesia can be carried out in the open pulp cavity, so that the nerve fibers in the root of the tooth will lose pain quickly.