Uncorrected Proof Shiraz E-Med J. In Press(In Press):e121613. Published online 2022 September 12. doi: 10.5812/semj-121613. Research Article Anatomical Variations of the Mandibular Canal and Mental Foramen in Full Edentulous Iranian Subpopulation: A Cone-Beam Computed Tomographic Study Yaser Safi 1 , Reza Amid 2 , Mahdi Kadkhodazadeh 2 , Sadaf Rezaei 3, * and Marjan Kazeminia 4 1 Department of Oral and Maxillofacial Radiology, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2 Department of Periodontics, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran 3 Department of Aesthetic and Restorative Dentistry, School of Dentistry, International Branch, Iran University of Medical Sciences, Tehran, Iran 4 Department of Oral and Maxillofacial Radiology, School of Dentistry, Golestan University of Medical Sciences, Gorgan, Iran * Corresponding author: Department of Aesthetic and Restorative Dentistry, School of Dentistry, International Branch, Iran University of Medical Sciences, Tehran, Iran. Email: sadaf.rezaei1370@gmail.com Received 2021 December 27; Revised 2022 July 11; Accepted 2022 August 21. Abstract Background: This study sought to determine the anatomical variations of the mental foramen (MF) and the mandibular canal (MC) in the full edentulous Iranian subpopulation using cone-beam computed tomography (CBCT). These variations can have significant clinical implications in dental implant surgery. Methods: This descriptive cross-sectional study evaluated the mandible CBCT scans of 384 completely edentulous patients that required dental implant treatment. The CBCT scans were retrieved from four radiology clinics in Tehran, Iran, using quota sampling. The reconstructed images were evaluated to determine the dimensions and position of the MC and its cortication at the site of the mandibular first molar, the branching of the MC, the existence of the anterior loop of the mental nerve, and anatomical variations of the MF. The correlations of variables with age and gender were analyzed using the independent t-test, chi-square test, and analysis of variance based on the type of the variable. Results: The cortication of the MC at the site of the mandibular first molar was present in 72.9% of the cases and was significantly more common in male patients (P = 0.0001). Bifid mandibular canal, accessory MF, and anterior loop of mental nerve were present in 9.9%, 65%, and 54.7% of the samples, respectively, and they had no significant correlation with age/gender. The mean MC diameter, the mean MF height, and the mean distance from the inferior border of the mandible to the center of MF were all significantly higher in male patients (P<0.05). The mean distance between the MC and the buccal and lingual cortical plates had no correlation with age/gender. The mean height between the superior part of the MC and the alveolar crest was significantly lower in female patients and those within the age range of 71-95 years (P<0.05). The MC opened in the MF superiorly in 40.1% of the patients with no significant correlation with age/gender. Conclusions: Anatomical variations in the course and location of the MC and MF necessitate the precise assessment of the edentu- lous ridge by CBCT prior to the placement of implants. Keywords: Cone-Beam Computed Tomography, Mandibular Canal, Mental Foramen, Dental Implants, Anterior Loop of Mental Nerve 1. Background The mandibular canal (MC) is an anatomical structure in the mandible that extends from the mandibular fora- men in the ramus to the mental foramen (MF). The MC con- tains the inferior alveolar nerve and vascular bundle, com- prising the inferior alveolar artery, vein, nerve, and lym- phatic vessels (1, 2). The MC is usually a single canal, bilat- erally present in the mandible in a symmetrical fashion. There might be some varieties regarding the position of the MC relative to the inferior border of the mandible and tooth apex. Therefore, the MC cannot serve as a reference point for prosthodontic or orthodontic diagnosis or treat- ment planning (3). As a result of the abnormal interaction of tissues dur- ing embryonic dental development, the morphological al- terations of the MC occur. It has been determined that at the time of embryonic maturation, there are three inferior dental nerves that fuse to make a single nerve; therefore, the bifid and trifid MCs manage to exist as a result of the inconclusive fusion of these three nerves (2). The develop- Copyright © 2022, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.