Comparison of tooth angulations on CBCT to those on conventional panoramic and panoramic-like images in different head orientations

Abstract

BackgroundThe purpose of this study was to compare cone-beam computed tomography (CBCT) to conventional panoramic and panoramic-like radiography with regard to the accuracy of angulation measurements between the long axes of adjacent teeth using different head orientations. MethodsThis cross-sectional study used pretreatment records from 30 orthodontic patients who had undergone concurrent (interval, <6 months) CBCT imaging in a 12-in field of view and conventional panoramic radiography. Three panoramic-like images were constructed on each CBCT scan: 1) ideal head position (0°); 2) head rotated upward (+10°); and 3) head rotated downward (−10°). The upper and lower right central and lateral incisors as well as the upper and lower right premolars were selected on each image. The angles between adjacent teeth on frontal and lateral views on CBCT were measured and compared to the corresponding angles on the panoramic views. ResultsInterdental angles on CBCT imaging were significantly greater compared with those on panoramic (P ≤ 0.001) and panoramic-like (P ≤ 0.003) imaging in the upper and lower anterior areas. At +10° on panoramic-like imaging, the interdental angles between the upper central and lateral incisors tended to be decreased significantly compared with those on CBCT. Other sites did not show significant variations. ConclusionsIn the present study, the anterior teeth showed more parallelism on panoramic imaging (conventional or panoramic-like) compared with CBCT. In contrast, the posterior region showed no differences between CBCT and radiography. Interdental angles in the anterior region of panoramic like image are more close to CBCT measurements when head oriented ideally or slightly downward.