Purpose: The aim of our study is to evaluate the location of the foraman mandible using three-dimensional computed tomography.
Materials and Methods: 102 patients who underwent cranial computed tomography for any reason were included in our study. Data were compared by gender and location, and age-related correlation of parameters were evaluated.
Results: In our study, the mean distance between foramen mandible and incisura mandible was 15.0 mm in male and 13.7 mm in female. The mean distance between foramen mandible and anterior border of mandibular ramus was 14.8 mm in male and 13.5 mm in female. There was no significant difference between genders and location comparisons.
Conclusion: Knowing the exact location of the foramen mandible is of great importance in terms of reducing anesthetic complications in mandibular anesthesia. 
Keywords: Mandibular Foramen; Inferior Alveolar Nerve Block; Computerized Tomography

In the foramen mandible, arteria alveolaris inferior, vena alveolaris inferior and nervus alveolaris inferior course together [1]. Mandibular anesthesia is a preferred anesthetic technique in mandibular fractures and in all surgical procedures to be performed within the bone involving the mandible. Localization differences of foramen mandibulae should be considered when applying mandibular anesthesia technique many complications, from trismus to transient facial paralysis, are encountered as a result of anesthesia performed in the wrong place [2].
The aim of our study is to determine the localization of the foramen mandible to describe its changes with age. We think that the results we found can guide oral, dental and maxillofacial surgeons and anesthetists especially in mandibular anesthesia applications.

Our study was performed retrospectively. We evaluated the location of the foramen mandible by cranial computed tomography of 102 patients aged 18-36 years, 36 girls and 66 boys, who applied to our department for any reason. Computed tomography images of individuals with mandibular pathology and/or malformation that may affect the measurement and those with poor shooting quality were excluded from the study.
Multislice CT images made with an MDCT scanner (Philips Ingenuity, Philips Systems, Cleveland, OH, USA) for the cranium for any reason in our hospital were scanned retrospectively. Reconstruction images of 0.5 mm thickness were created from the source images of 3 mm thickness. Multipanar reconstruction and 3D volume rendering (VR) images were obtained from 0.5 mm thick thin sections with a workstation. The distance of the foramen mandible to the determined places on the mandible was measured on the 3D images obtained and the data were analyzed. All measurements were made in the presence of a radiologist and repeated twice.
We measured the closest distance from the upper edge of the foramen mandible to the incisura mandible and the distance from the foramen mandible to the anterior border of mandibular ramus. We measured the distance between the foramen mandible and the mandiblar notch [Figure 1]. We measured the distance from the anterior border of mandibular ramus to the posterior border of mandibular ramus and the distance from the foramen mandible to the occlusal plane.

Figure 1: The distance between the foramen mandible and the mandiblar notch.

Data analyzes were performed using the Statistical Package for the Social Sciences (SPSS) version 20.0. The data obtained for statistical analysis were evaluated with descriptive statistics (arithmetic mean, median, standard deviation, percentage distributions). The mean between groups was evaluated with the Shapiro Wilk test. The Mann Withney U Test was used when comparing the mean of two independent groups. The Pearson test was used to evaluate the correlation of two continuous data. The results were evaluated at the 95% confidence interval, and the significance was evaluated at the p<0.05 level.

102 people aged between 18 and 36 with a mean age of 26.08 were included in our study. 36 (35.29%) of the individuals were female and 66 (64.71%) were male. There was no significant difference between the measurements in the comparison of the right and left foramen mandible (p>0.05). There was no significant difference between the measurements in the male-female comparison  [Table 1].

MF: foramen mandible, MI: incisura mandible, MRA: anterior border of mandibular ramus, MRP: posterior border of mandibular ramus, OP: occlusal plane, MN: mandibular notch
Table 1: Mean values of measurement sites and ratios in all patients.

Correct localization of the mandibular foramen is important during anesthesia of the inferior alveolar nerve [3,4]. However, there is still some controversy over the anatomical definition of the mandibular ramus, particularly with regard to the mandibular foramen [5].
Various methods (dry skull, radiography, computed tomography, etc.) have been used in the literature to locate the foramen mandible. There are some limitations in the studies of determining the position of the foramen mandible with the dry skull, such as unknown age and gender, uncertain anatomical locations, and mandibular tooth loss, which may affect the reliability of the study [6]. Panoramic radiographs are a preferred method over dry bone studies with easy accessibility and wide field of view. However, the ghost image and overlapping anatomical structures due to the angle may affect the image quality, making it difficult to identify vital structures [7]. Measurements using three-dimensional computed tomography show greater accuracy in identifying landmarks. However, it should be noted that this method is taken with devices that emit more radiation doses. In our study, we evaluated three-dimensional computed tomography images by scanning archives in order to obtain better measurement results.
The distance of the foramen mandible and the anterior border of the mandibular ramus can be used as a reference for the length of the needle to be inserted into the soft tissue. Park and Lee [8] compared this distance with computed tomography and found the average values as 19.41 mm. In our study we found this distance 13.5 mm in female, 14.8 mm in male. There was no significant difference in gender comparisons in the measurements in our study (p >0.05).
Kang et al. [9] reported the distance between the occlusal plane and the mandibular foramen as 3.8 mm. In our study, the mean distance was 15.8mm in male and 11.9 mm in female. In our study, there was no statistically significant difference between groups, which is consistent with the literature.
In conclusion, computed tomography images were a useful method to provide measurements of mandibular foramen position for block anesthesia of the inferior alveolar nerve.

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Corresponding Author: Rukan Karaca, Department of Radiology, Malatya Training and Research Hospital, Malatya, Turkey.

Copyright: © 2021 All copyrights are reserved by Karaca R, published by Coalesce Research Group. This This work is licensed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.