Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 17 0 2020 11 23 3342 3342 Sareh Aflaki Department of Endodontics, Faculty of Dentistry, Qazvin University of Medical Sciences, Qazvin, Iran Elham Boyerahmadi Student Research Committee, Qazvin University of Medical Sciences, Qazvin, Iran Amir Talaei Student Research Committee, Qazvin University of Medical Sciences, Qazvin, Iran Mohammad Raouf Safari Student Research Committee, Qazvin University of Medical Sciences, Qazvin, Iran Mahdis Mohammadpour Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Qazvin University of Medical Sciences, Qazvin, Iran Navid Mohammadi Department of Community and Preventive Medicine, Faculty of Medicine, Qazvin University of Medical Sciences, Qazvin, Iran Mamak Adel Department of Endodontics, Faculty of Dentistry, Qazvin University of Medical Sciences, Qazvin, Iran AND Dental Caries Prevention Research Center, Qazvin University of Medical Sciences, Qazvin, Iran 2019 11 05 2020 05 30 Objectives: This study aimed to assess root canal transportation of curved canals following glide path preparation by PathFile and Scout RaCe rotary systems compared with manual instrumentation with stainless steel (SS) hand files using cone-beam computed tomography (CBCT). Materials and Methods: This in-vitro experimental study was conducted on extracted human mandibular first and second molars (n=51) with 25-45° canal curvature in their mesiobuccal root. All teeth underwent CBCT and were randomly divided into three groups (n=17). In group 1, a glide path in the mesiobuccal canal was created using SS hand files to the working length. In groups 2 and 3, after canal negotiation with a #8 SS hand file, a glide path was created with PathFile and Scout RaCe systems, respectively. The teeth underwent CBCT. Pre- and postoperative CBCT scans were compared to calculate the magnitude of canal transportation at 3, 6, and 9 mm from the apex. The results were analyzed using the Kruskal-Wallis and Freedman tests (P<0.05). Results: Manual instrumentation caused significantly higher canal transportation at 3 and 9 mm from the apex compared with rotary systems (P<0.05). PathFile and Scout RaCe were not significantly different at 3 (P=0.39) or 9 mm (P=0.99). No significant difference was noted in canal transportation among the three groups at 6 mm (P=0.15). Conclusion: Scout RaCe and PathFile cause less canal transportation than manual instrumentation with SS files when used for glide path preparation in curved canals, especially in the apical third. https://fid.tums.ac.ir/index.php/fid/article/view/3342 https://fid.tums.ac.ir/index.php/fid/article/download/3342/1825