مشخصات پژوهش

Background: The 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. Methods: This 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 (þ10
); 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. Results: Interdental 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 þ10
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. Conclusions: In 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.
2014 World Federation of Orthodontists. 1. Introduction The importance of establishing appropriate axial inclinations with near-parallel roots has been frequently emphasized in the orthodontic literature [1,2]. This parallelism is of prime importance for o