The drugs that kill the nerve in teeth are: 1, arsenic trioxide is commonly used as a rapid deactivating agent, which can cause rapid capillary congestion in the pulp, resulting in impaired blood circulation, leading to tissue necrosis and cell death; 2, metallic arsenic mainly acts on the pulp deactivation of milk teeth, the sealing time is usually 2-4 days, with slow action, and oxidation to arsenous acid after contact with the pulp, causing pulp congestion, embolism and loss of vitality; 3, Paraformaldehyde is mostly used for pulp inactivation of milk teeth, with a sealing time of about 2 weeks, causing pulp cells and capillaries to become congested, swollen, nerve paralysis, and eventually gradual necrosis; 4. Toadstool preparation can quickly inactivate the pulp within 30-40 minutes.