Tabriz University of Medical Sciences Journal of Dental Research, Dental Clinics, Dental Prospects 2008-210X 13 2 2019 08 14 Comparison of postoperative pain intensity following the use of three different instrumentation techniques: A randomized clinical trial 133 140 10.15171/joddd.2019.021 EN Mehmet Adiguzel Pelin Tufenkci ismail Ilker Pamukcu Journal Article 10.15171/joddd.2019.021 2018 11 29 2019 07 07 Background. The aim of this study was to compare the postoperative pain intensity following the root canal preparation carried out with XP-endo Shaper (XPS; FKG Dentaire SA, La Chauxde-Fonds, Switzerland), iRace (iRC; FKG Dentaire SA) and Reciproc Blue (REC Blue; VDW, Munich, Germany) files. Methods. Mandibular molar teeth with asymtomatic necrotic pulps in 69 patients were randomly divided into three groups (n=23). The root canals were prepared using XPS, iRC or REC Blue instruments and obturated using the lateral condensation technique. The patients were asked to record their pain intensity at 24-, 48- and 72-hour and 1-week postoperative intervals on VAS. For intolerable pain after the procedure, ibuprofen (400 mg) was prescribed. Data were analyzed using chi-squared, Friedman, Kruskal–Wallis, and Mann–Whitney U tests. Results. The postoperative pain gradually decreased during the study period in all the groups (P<0.05). No statistically significant difference was found between iRC system and the two other systems at 12-, 24- 48-hour and 1-week intervals (P>0.05). When compared to XPS system, a higher level of postoperative pain was observed with REC Blue system at 24- and 48-hour intervals (P<0.05). Conclusion. The XPS group exhibited less postoperative pain than the REC Blue group at 24- and 48-hour intervals. iRC, XPS and REC Blue systems were found to be similar in terms of postoperative pain severity.