Cryotherapy, PGE2, NGF Levels and Pain After Endodontic Retreatment

This prospective, randomized, controlled, single-blind, parallel-group clinical trial evaluates whether intracanal cryotherapy reduces postoperative pain and inflammatory biomarker levels following single-visit endodontic retreatment of teeth with asymptomatic apical periodontitis. A total of 100 patients (18-65 years, systemically healthy, ASA I-II) requiring non-surgical retreatment of a single-rooted mandibular premolar tooth will be randomly assigned via computer-generated randomization to one of two equal groups (n=50 each): a cryotherapy group, receiving intracanal final irrigation with sterile saline cooled to 2.5°C for 5 minutes, and a control group, receiving the same irrigation protocol with saline at room temperature (20-22°C). Salivary nerve growth factor (NGF) and gingival crevicular fluid (GCF) prostaglandin E2 (PGE2) levels will be measured by ELISA at baseline (T0), 24 hours (T1), and 72 hours (T2). Postoperative pain will be assessed using a visual analog scale (VAS, 0-100 mm) at 6, 12, 24, 48, and 72 hours and on day 7, with the 24-hour VAS score as the primary comparison point. Rescue analgesic (paracetamol) consumption will also be recorded and compared between groups. The study aims to determine whether intracanal cryotherapy lowers postoperative pain and biomarker levels compared to standard-temperature irrigation, and to evaluate the correlation between PGE2/NGF levels and pain intensity.