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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 edentulous ridge by CBCT prior to the placement of implants. [ABSTRACT FROM AUTHOR]

Introduction: Although using panoramic images of the third impacted molars and assessing their proximity to mandibular canal, this technique has limitations such as two-dimensional nature and magnifications occurred which calls to use a three-dimensional radiographic modalities such as CBCT. This study compared the location of the mandibular third molar’s roots regarding the inferior alveolar canal using panoramic radiography and CBCT techniques. Materials & Methods: In a descriptive-analytical trial, 103 radiographic images of the patients’ impacted mandibular third molars were selected from the archives of Radiology Department of Tehran Dental School and assessed by means of panoramic and CBCT techniques. Three oral & maxillofacial radiologists assessed the positions of the mandibular third molars’ roots regarding the inferior alveolar canal in the panoramic and CBCT images at 2 time intervals. The assessments were repeated for next 2 weeks again. And then they were done on CBCT images. Frequency and percent of panoramic signs indicating the proximity of the mandibular third molars regarding buccal, lingual and medial positions of the teeth were obtained among the observers and 2 time intervals and the results were statistically analyzed by chi-square test. Significance level was considered to be 0.05 (p value = 0.05). Results: Of total 103 impacted mandibular third molars, 56 (54.4%) had lingual location, 25 (24.3%) had medial location and 22 (21.3%) shoed buccal locations of the roots towards mandibular canal (p value < 0.002). The frequency of the root deflections (p value < 0.003), diversion of canals (p value < 0.03), narrowings of the roots (p value < 0.005), interruption of the borders (p value < 0.006) and narrowing of the canals (p value < 0.04) were higher in the buccal positions of the third molar roots towards the mandibular canal compared to other positions. The differences were statisticaly significant in some cases. However, the frequency of darkening of the roots (p value < 0.04) was higher in the lingual positions of the third molars than other positions. The agreements of the obervers was acceptable when assessing the images regarding indices of the proximity of third molars’ roots and mandibular canal. Conclusion: Then, CBCT technique is a valuable tool to assess the location of the mandibular impacted third molars regarding the inferior alveolar canal. Using CBCT images of impacted third molars, the risk of damage to the alveolar nerve can be reduced. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the prevalence and type of mandibular canal branching in a sample of the Iranian population through cone-beam computed tomography (CBCT) images. This cross-sectional study was performed on CBCT records of 300 patients (112 males and 188 females; mean age 30.14 ± 10.96 y). The presence of mandibular canal branch (MCB) was evaluated by reconstructing multiple panoramic views and buccolingual cross-sections, according to Naitoh's classification. The prevalence of MCB, the type of MCB, and the demographic information of all patients were recorded. The maximum number of branching and the maximum type of branching were also registered for each patient. Mandibular canal branching was observed in 131(43.7%) of 300 CBCT images without side or sex differences ( P > 0.05). The most frequent type was dental, followed by the retromolar, forward, and buccolingual types, respectively. There was a statistically higher frequency of retromolar canal in females than in males (odds ratio: 1.14 ± 4.25; P = 0.013). About 46% of patients with MCB had more than one accessory canal and 29% displayed more than one type of MCB. The coincidence of dental and retromolar canals in a patient was the most prevalent combination. Considering the relatively high prevalence of MCB (43.7%), it is recommended to keep in mind the possibility of anatomical variations of the inferior alveolar nerve during dental procedures to avoid postsurgical complications. The high possibility of observing multiple numbers and types of branching in the patients should also be considered during preoperative assessments., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 by Mutaz B. Habal, MD.)

Objectives: Bifid mandibular canal (MC) is an anatomical variation of the MC. This study aimed to assess the prevalence and shape of bifid MC in an Iranian population., Materials and Methods: A total of 681 patients who had undergone cone-beam computed tomography (CBCT) for different purposes between 2018 and 2020 were evaluated. After detection, bifid MCs were classified into four types forward, buccolingual, dental, and retromolar. CBCT images were assessed by two oral and maxillofacial radiologists. Data were analyzed by SPSS using an independent t-test and Chi-square test., Results: Bifid MC was found in 23 (3.4%) out of 681 patients, with a mean age of 32.21 years. Ten patients (1.5%) had a bifid MC on the right side, 6 (0.9%) on the left side, and 7 (1%) bilaterally. However, no significant correlation was found between laterality and the prevalence of bifid MC (P > 0.05). Bifid MC was found in 8 males (34.8%) and 15 females (65.2%). Gender had no significant correlation with the prevalence of bifid MC (P > 0.05). Forward type was the most common (n = 8, 1.2%) followed by buccolingual (n = 5, 0.73%), dental (n = 2, 0.3%), and retromolar (n = 1, 0.14%) types., Conclusion: According to the present results, bifid MC was not uncommon in the Iranian population of the present study, and forward type was the most common, followed by buccal and then dental bifid MCs. There was no significant correlation between sex and age with bifid MC but bifid MC was detected more frequently in females than males, and it was seen unilaterally in a higher percentage of the cases., (© 2023. The Author(s) under exclusive licence to Japanese Society for Oral and Maxillofacial Radiology.)