Şallı, Gülay AltanEgil, Edibe2021-12-232021-12-232021Imaging Science in Dentistry 2021; 51: 383-82227-7390https://doi.org/10.5624/isd.20210038Purpose: The aim of this study was to evaluate the root canal morphology of mesial roots of mandibular first molars. Materials and Methods: Forty extracted mandibular first molars were used in this study. The morphological examination of root canals was conducted in accordance with the Vertucci classification using micro-computed tomography (micro-CT). Any aberrant root canal configurations not included in the Vertucci classification were recorded, and their frequency was established using descriptive statistics. Intra-observer reliability was assessed using the Wilcoxon signed-rank test, while inter-observer reliability was assessed using the Cohen kappa test. Significance was evaluated at the P[removed]0.05) and the kappa value for inter-observer agreement was found to be 0.957. Conclusion: Frequent variations were detected in mesial roots of mandibular first molars. Clinicians should take into consideration the complex structure of the root canal morphology before commencing root canal treatment procedures to prevent iatrogenic complications. Micro-CT was a highly suitable method to provide accurate 3-dimensional visualizations of root canal morphology. (Imaging Sci Dent 20210038) © 2021 by Korean Academy of Oral and Maxillofacial Radiology This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.enAnatomyDental Pulp CavityDentitionPermanentX-Ray MicrotomographyAnimation10.5624/isd.202100382-s2.0-8511636104634987998Q2WOS:000744188500005N/A