Anterior Loop visibility and diameter evaluated by Cone Beam Computed Tomography and comparison with anatomic measurements: ex-vivo study

Abstract

The region between the mental foramen is erroneously considered safe to perform surgeries and is often neglected in preoperative planning. In this area, there may be anatomical variations that may influence at anesthetic technique, surgery success, and postoperative severity. The anterior loop (AL) is one of these variations located near the mental foramen. It is characterized by a route from the inferior alveolar nerve that emerges from the canal and after a short intraosseous route returns to the mental foramen. Currently, the main method of evaluation for pre-surgical images is accomplished through panoramic radiographs. However, the images are two-dimensional, moreover, there are overlapping images, especially on the midline and adjacencies, the study area of our research. Therefore other forms of assessment are necessary as the Cone Beam Computed Tomography (CBCT). It is a diagnostic imaging method that allows three-dimensional visualization of mineralized tissues with minimal distortion and reduced radiation dose and cost compared to medical CT. This new technology allows an image of the AL in three dimensions, allowing a complete study of its course and morphology. This study aims to analyze 50 dry mandibles (100 Hemi-mandibles) submitted to CBCT scan. CBCT images are obtained by i-CAT Classic with 0.25 voxel size. In the obtained images, primarily, the mental foramen will be located, and subsequently, LA presence or absence will be identified. If present, through the tool "distance" from the i-CAT Vision, its diameter will be evaluated in three standard positions: near the beginning, in the middle portion, and near its end in crossectional reformation. In panoramic reformation, it will be evaluated its vertical and horizontal extension. In the mandible, where there is positive visualization, the AL will be exposed by removing the cortical bone near to the mental foramen to confirm the finding and anatomical measurements with digital microscopy will be performed and these measurements will be compared with those obtained in CBCT. The results will be statistically analyzed using the Mann-Whitney test, p <0.05 for positive and negative indices. For the study of quantitative measures of the AL, it will be used paired t-test, p <0.05.(AU)