Effect of Rotary File Number on MB2 Canal Negotiation and Postoperative Pain

Inclusion Criteria: * Systemically healthy individuals aged between 20 and 65 years * Requiring primary endodontic treatment of maxillary first molars * Diagnosis of asymptomatic apical periodontitis and pulp necrosis based on clinical and radiographic findings * Presence of a second mesiobuccal (MB2) canal in the maxillary first molar * Absence of or only minimal preoperative pain or symptoms * Periapical lesions smaller than 5 mm in diameter * Ability to comply with follow-up visits and effectively communicate during the treatment process Exclusion Criteria: * Presence of symptomatic apical periodontitis or acute apical abscess * Retreatment cases (teeth previously treated endodontically) * Use of medications such as narcotics, antibiotics, sedatives, or antidepressants within one week prior to treatment * Presence of a sinus tract, periapical abscess, or facial cellulitis * Pregnancy or breastfeeding * Inability to understand or follow the study instructions