Soreness after killing the nerve may be due to pulpitis, and may also be related to gingivitis of other teeth. 1. Pulpitis: Soreness after killing the nerve may be the result of incomplete removal of the nerve, or the tissue has not healed sufficiently, or the medication put into the root canal does not have a good therapeutic effect, thus producing the symptoms. 2. Gingivitis of other teeth: If gingivitis occurs in the neighboring teeth, it may cause inflammation to stimulate the root of the gums, which may lead to increased tooth sensitivity and tooth acidity. If the recurrence of tooth acid symptoms recommend timely medical care to understand the individual dental condition, the patient usually also need to pay attention to personal oral hygiene, to avoid food residues.