Generally, the second root canal does not cause any significant pain, but if the first root canal was not done properly or if there is still inflammation in the root canal, then pain may occur during the second root canal. Usually, the first root canal is rinsed, sterilized, wetted and blown dry, in which case the inflammation, pulp, and other debris in the root canal are basically removed, and the tooth will not feel any special sensation. A second root canal in such a case will basically not touch too many pain-causing substances and usually will not produce significant pain. If the first root canal, did not remove the remaining pulp of the tooth cleanly or if the inflammation has returned, then pain may be produced during the second root canal. In this case, the doctor will usually determine whether local anesthesia is needed depending on the circumstances, and the patient needs to be prepared for this. If there is a problem of dental caries or pulpitis and you need to have a needle canal treatment, it is recommended to go to a regular hospital and have a regular operation.