1 Orthodontic Department, School of Dentistry, Hamadan University of Medical Sciences, Iran

2 Postgraduate student, Department of Orthodontics, Hamedan dental faculty



background and aims: Cone-beam computed tomography (CBCT) is becoming established as a superior radiographic technique to conventional radiography in orthodontics. However cephalometric analysis in conventional lateral cephalograms (LC) is still an important tool in treatment planning. The aim of this study was to compare cephalometric measurements performed on conventional cephalograms with those on CBCT generated images.
Method and materials: 24 patients with both LC and volumetric CBCT imaging (Newtom 3G) were selected. Generated Lateral cephalograms (GLC) were produced from related DICOM files in Dolphin 3D. cephalometric analysis, consisted of fifteen angular measurements and fifteen linear measurements (Dolphin V.11.2) were performed on both LCs and GLCs. Paired T-Test was used to compare differences in measurements between the two image modalities. 
Results: According to paired t-test results no statistically significant differences were found between the two set of measurements except Articular Angle, Gonial Angle (Ar-Go-Me) and Ramus Height (Ar-Go) (P<0.05). Since in all cases the interval between LC and CBCT imaging was short (3.5 months ± 2) and treatment has began after CBCT imaging, neither growth nor treatment was the cause of these differences. It could be supposed that the technical positioning errors in LCs of some patients might be the cause. 
Conclusions: LC could successfully be replaced by GLC. Since we can select the best orientation of the skull before generating GLC from CBCT DICOM files, GLC could be more reliable than LC.