If a tooth is painful after filling when it does not hurt originally, it is usually considered to be related to a short period of stimulation of the tooth, gum and periodontal membrane during the filling process, which is mostly normal. After the filling, avoid eating too hot and hard food to avoid aggravating the local irritation, and it can generally recover on its own. If the pain persists or worsens, consider that it may be periodontal pain, pulpal pain, etc. 1. Periodontal pain: If the filling is too high, pain can occur when the patient bites after the filling, which can lead to the situation that the tooth originally does not hurt but is painful after the filling, which is periodontal pain. Patients are suggested to go to the hospital for follow-up consultation in time and adjust the height of the filling appropriately, which can usually make the pain and other discomfort relieved; 2. Pulpal pain: If the filling process is not operated properly, it will cause some stimulation to the pulp and lead to pulp congestion, which can also cause pain. When the tooth decay is deeper, if the tooth is directly treated with silver mercury and other materials without cushioning, it can also lead to irritating pain in the pulp after filling. In addition, if there are other pulp-penetrating parts in the tooth itself, but the filling is not detected in time, the spontaneous pain may also be manifested as the tooth originally does not hurt, but the filling is painful after the filling. Patients are advised to seek medical attention in a timely manner, and depending on the specific situation, they can choose to treat the tooth with soothing treatment, cushioning, root canal treatment, etc. to relieve the painful symptoms.