Why does pain still occur after root canal treatment for pulpitis?

Generally, pain after root canal treatment for pulpitis may be caused by normal postoperative tissue reaction, excessive occlusion or occlusal trauma, incomplete root canal treatment, uncontrolled periapical inflammation, or periodontal tissue infection. It is recommended to seek timely medical evaluation to identify the underlying cause and receive appropriate treatment under a doctor's guidance. The specific analysis is as follows:

1. Normal postoperative tissue reaction: During root canal treatment, instrument manipulation can irritate the periapical tissues, triggering mild local inflammatory response and causing short-term postoperative pain, which usually lasts 1–3 days. Avoid chewing hard foods with the treated tooth; pain can be relieved with cold compresses.

2. Excessive occlusion or occlusal trauma: If the restorative material is too high after root canal treatment or if occlusal forces are uneven, the treated tooth may bear excessive biting force, leading to pain. Prompt adjustment by a dentist is needed to reduce the height of the restoration, normalize occlusion, decrease tooth stress, and relieve pain.

3. Incomplete root canal treatment: Residual pulp tissue or bacteria remaining in the root canal that were not completely removed can sustain inflammation and cause pain. Patients may follow medical advice to use medications such as metronidazole tablets, amoxicillin capsules, or cefuroxime axetil tablets to control infection. Root canal retreatment may be necessary in some cases.

4. Uncontrolled periapical inflammation: If pre-existing periapical inflammation was severe, it may not fully resolve after treatment—or may even worsen—resulting in persistent or recurrent pain. Patients should follow medical instructions to take anti-inflammatory and analgesic medications such as ornidazole capsules, cefixime capsules, or ibuprofen sustained-release capsules.

5. Periodontal tissue infection: Poor oral hygiene after root canal treatment can lead to bacterial infection of the periodontal tissues, causing periodontitis. Inflammation may spread to the apex of the tooth, resulting in tooth pain. Patients should follow medical advice to use medications such as doxycycline hydrochloride tablets, tinidazole tablets, or compound chlorhexidine mouthwash for treatment.

In daily life, maintain good oral hygiene by thoroughly brushing teeth in the morning and evening, rinsing after meals, and using dental floss to clean interdental spaces. Avoid chewing hard or sticky foods with the treated tooth to minimize damage and irritation and promote healing.