en پژوهشي Research <div style="text-align: justify;"><strong>Backgrounds: </strong>Cryotherapy might help in reducing pain after root canal treatment. This study aimed to investigate the effect of different methods of cryotherapy on post-endodontic pain of one-visit root canal treatment in mandibular molar teeth with symptomatic irreversible pulpitis.<br> <strong>Materials and Methods:</strong> This clinical trial study enrolled 60 patients with symptomatic irreversible pulpitis in a mandibular molar tooth. Before obturating the root canals, teeth were divided into four groups. Group 1: Control (without cryotherapy) Group 2: intracanal cryotherapy with final canal irrigation with 2.5 &deg;C normal saline for 5 minutes, group 3: intraoral cryotherapy with the application of an ice pack 30 minutes inside the mouth and Group 4: extraoral cryotherapy. Patients&rsquo; post-endodontic pain was recorded on the first and third days. Data were analyzed by two-way analysis of variance, Tukey, and LSD post hoc test at the error level of 5%.<br> <strong>Results:</strong> Pain reduction was highest, respectively, in the intracanal, control, and extraoral cryotherapy groups on the first and third days, although not significant (p>0.05). In each group, pain was reduced on the third day after treatment (P<0.05). Pain showed no relation to gender (p>0.05).<br> <strong>Conclusion:</strong> Despite the limitations, based on the results of this study, the application of cryotherapy has a limited effect in reducing pain after root canal treatment. Time is more effective than cryotherapy in reducing pain.</div> Cryotherapy, Postoperative pain, Symptomatic irreversible pulpitis 25 28 http://cofs.khuisf.ac.ir/browse.php?a_code=A-10-1-28&slc_lang=en&sid=1 Mahnaz Sadat Hoseini 1003194753284600204 1003194753284600204 No Faculty of dentistry, Isfahan (khorasgan) Branch, Islamic Azad University, Isfahan, Iran Parisa Ranjbarian 1003194753284600205 1003194753284600205 Yes Department of endodontics, Faculty of Dentistry, Isfahan (khorasgan) Branch, Islamic Azad University, Isfahan, Iran Amin Mortaheb 1003194753284600206 1003194753284600206 No Endodontist, Isfahan, Iran Ebrahim yousefi 1003194753284600207 1003194753284600207 No Faculty of dentistry, Isfahan (khorasgan) Branch, Islamic Azad University, Isfahan, Iran