Study aim: Assessment of pain intensity following endodontic retreatment of asymptomatic mandibular molars with Gutta-Percha, Mineral Trioxide Aggregate, and Cold Ceramic Design: An interventional, single-blind, randomized, parallel, phase 2/3 clinical trial on 60 patients Settings and conduct: All procedures will be performed by an endodontist at the Endodontic Clinic, Kurdistan University of Medical Sciences. After local anesthesia and isolation, canal access will be established and prepared with M3-Pro Gold rotary files, with working length determined using an apex locator (Root ZX) and radiographs. Apical patency will be ensured with a #10 K-file. Patients will be assigned to three groups: A: Obturation with Gutta-percha using the cold lateral compaction technique B: Obturation with Mineral Trioxide Aggregate (MTA) (Angelus, Brazil), Apical as an MTA plug and coronal by the backfill method C: Obturation with Cold Ceramic (Samin, Iran), Apical as a plug and coronal using the backfill method Pain intensity will be recorded at 8, 24, 48, and 72 hours using the Visual Analog Scale (VAS) Participants/Inclusion and exclusion criteria: Inclusion Criteria: Patients with at least one mandibular molar requiring retreatment, with asymptomatic teeth and periapical radiographic lesions, and systemically healthy, will be included in the study Exclusion Criteria: Patients with uncontrolled systemic diseases, pregnant women, and those with acute periapical infections causing swelling and abscess will be excluded from the study Intervention groups: Group A : Gutta-percha using cold lateral compaction Group B: Mineral Trioxide Aggregate, apical plug and coronal backfill Group C: Cold Ceramic, apical plug and coronal backfill Main outcome variables: Pain intensity after retreatment of mandibular molars obturated with three root canal filling materials: Gutta-percha, Mineral Trioxide Aggregate, and Cold Ceramic