Frequency and Location of Anterior Loop of Mandibular Canal in an Iranian Population Using Cone-beam Computed Tomography

Abstract

Anterior loop of mandibular canal, an important anatomic structure, has been considered a vitally important structure in mandibular surgeries such as the placement of osseointegrated implants, reduction of mandibular fractures and orthognathic surgeries. The aim of this study was to evaluate the frequency and location of the anterior loop of mandibular canal in an Iranian population by using cone-beam computed tomography (CBCT).Materials and Methods: A total of 450 CBCT images were selected from the archives of Tabriz Faculty of Dentistry. The images were observed under standard conditions with a magnification of 1:1 by NNT viewer software (Ver 2.17). Digital radiographic images were evaluated in multiplanar sections (MPR), reformatted serial cross-sections and axial in order to determine the presence and extent of the anterior loop relative to the mental foramen by two oral and maxillofacial radiologists in a dimly-lit room. The inter-observer agreement kappa coefficient was 0.84, representing a high agreement rate. Statistical significance was set at P <0.05 in this study.Results: The prevalence of anterior lobe on the left side was 59.8% and 58.2% on the right side. The prevalence of left anterior loop in women was 59.6%, with 63% in men; the prevalence of the right anterior lobe in women was 56.5%, with 63% in men, indicating a similar prevalence on the left and right sides between men and women based on the results of chi-squared test. The distance between the anterior loop and the mental foramen on the left side was 1.77±2.57 mm, with 2.01±2.75 mm on the right side, with no significant differences between the left and right sides based on the results of Wilcoxon test. The mean distance between the anterior loop of the mental foramen on the left side in women was 2.57 mm, with 2.75 mm in men; this distance on the right side was 2.47 mm in women and 3.01 mm in men. Based on the results of Mann-Whitney test the distance was significantly higher on both sides in men compared to women.Conclusion: Based on the results of this study and previous studies, observing a safe distance from the mental foramen is recommended when the most distal implants are placed in the anterior region by evaluations carried out on CBCT images specifically for each patient in each specific area of interest.