Visualization of the superior and inferior borders of the mandibular canal: a comparative study using digital panoramic radiographs and cross-sectional computed tomography images.

To evaluate the visibility of the superior and inferior borders of mandibular canal using panoramic radiography (PR) and cross-sectional computed tomography (CT) images.Digital panoramic images and cross-sectional CT images of 100 patients were evaluated. The mandibular canal was divided into 4 areas of equal width (1-4), from anterior to posterior. The visibility of the superior and inferior borders was assessed using a 5-point visibility scoring system, with lower scores for worse visibility.For both modalities, the superior border showed significantly lower score than the inferior border in all areas. For the superior border, areas 1, 2, and 3 all showed significantly lower scores than area 4 for PR, whereas only area 1 showed a lower score than area 4 for CT.The visibility of the superior border was very poor on panoramic images. The use of cross-sectional CT images remarkably improved this poor visualization.