Effect of Anterior Disc Displacement With Reduction on Postoperative Pain After Root Canal Treatment

Inclusion Criteria: * Individuals aged between 18 and 65 years with no systemic disease * Patients diagnosed with symptomatic apical periodontitis * Presence of a vital permanent mandibular first or second molar tooth requiring root canal treatment * Teeth with no radiographic evidence of periapical changes or only slight widening of the periodontal ligament space * Patients reporting preoperative spontaneous pain with a Numeric Rating Scale (NRS) score between 4 and 10 (moderate pain: 4-6; severe pain: 7-10) * Patients reporting pain intensity of 4 or higher on the NRS during percussion testing * Patients diagnosed with isolated anterior disc displacement with reduction according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) (experimental group) or patients without any temporomandibular joint disorder or pathology (control group) Exclusion Criteria: * Teeth found to have necrotic pulp tissue during access cavity preparation * Patients in whom the study tooth was not located on the same side as the temporomandibular joint diagnosed with anterior disc displacement with reduction * Occurrence of any endodontic complications during treatment * Use of medications that could affect pain perception (e.g., analgesics or anti-inflammatory drugs) within at least 12 hours before treatment, or use of systemic antibiotics within one month prior to enrollment * History of major jaw trauma, dentofacial deformities, or previous temporomandibular joint surgery * Concurrent use of steroids, muscle relaxants, or narcotic medications * History of diagnosed neuropathic pain, myofascial pain, neuralgic pain, or chronic headache disorders * Presence of periodontal disease (probing depth \> 5 mm or tooth mobility greater than Grade I) or teeth lacking adequate coronal structure * Teeth without occlusal contact or with premature contacts, patients with bruxism or clenching habits, or patients with fewer than three teeth on one side of the mandible * Inability to read, understand, or complete the pain assessment scale or to provide the required follow-up data * Presence of significant cognitive impairment (e.g., communication deficits, intellectual disability) or diagnosed psychiatric disorders (e.g., depression, anxiety disorders) * Presence of immature teeth or teeth with open apices * Pregnant or breastfeeding women