The first plugging of the root canal is usually painful for 1-3 days, and the specific time is mainly related to the treatment method and individual patient’s condition, which should be analyzed for specific problems. If the pulp is opened under local anesthesia, and the deactivating agent is placed after removing the crown pulp, such as arsenic or formaldehyde cresol solution, the patient may have pain for 1-3 days, or there may be no obvious pain, mainly due to the stimulation of the pulp by the deactivating drug. If the pulp is opened under local anesthesia, the root pulp is removed directly with machine expansion or enlargement needle, and the root canal is temporarily sealed with camphorated phenol cotton twist, the patient may have pain in the apical region, which may also last 1-3 days, and the exact time varies from person to person. If the pain is obvious after the first plugging of the root canal, you can take anti-inflammatory drugs as prescribed by the doctor. In serious cases, it is recommended to consult the stomatology department in time to re-inflammation, and then seal the drug after the pain improves.