Pulp deactivation is what is commonly referred to as nerve killing, a method of deactivating the pulp tissue by sealing the pulp wound with a chemical drug preparation that causes pulp blood flow disorders. The deactivation method is used for patients with poor anesthesia or allergy to anesthetics for pulp removal treatment. The drugs used to deactivate the pulp are called deactivating agents and are commonly used such as paraformaldehyde or metallic arsenic. Paraformaldehyde deactivators are mainly composed of paraformaldehyde, appropriate amount of surface anesthetics such as cocaine, bupivacaine and nitrogen ketone, etc. Paraformaldehyde acts on the dental pulp to paralyze the smooth muscle of the blood vessel wall, and the blood vessel dilates to form thrombus causing blood supply disorder and deactivating the dental pulp. The effect of its coagulation protein can make the necrotic pulp tissue aseptic and dry, and the sealing time is about two weeks, and inactivation in the clinic because of its certain side effects. It is possible that the inactivating agent will cause some damage to the microstructure, so nowadays, anesthesia is mostly used in the clinic instead of inactivation.