Nerve killing methods for teeth include deactivation method and anesthesia method. Under local anesthesia, the pulp cavity can be directly ground open, the crown pulp can be scraped, and the pulp tissue can be wound and brought out as a whole using an enlargement needle or pulp extraction needle. Patients who are not effective in local anesthesia or allergic to anesthetic drugs can apply the deactivation method, in which chemical drugs are placed on the exposed pulp to necroticize and inactivate the pulp tissue and finally remove it. The commonly used deactivating agents are paraformaldehyde, metallic arsenic, arsenic trioxide, etc. For young permanent teeth whose apical foramen has not yet been formed, it is better not to use the drug inactivation method because the blood circulation is faster and the drug is easy to diffuse to reach the periapical tissue and cause chemical periapical inflammation.