Evaluation of a method to predict positioning errors in orthopantomography using cephalography

Introduction: Various radiographic examinations are used to diagnose diseases and determine treatment plans, and the quality of radiographic images affects diagnostic accuracy. This study assessed the relationship between orthopantomography and cephalometric analysis in predicting positioning errors before orthopantomography.
Methods: This study evaluated four human head phantom types and included 300 patients aged ≥18 years who underwent orthopantomography. The correlation between the Frankfort horizontal plane and occlusal plane angles in the orthopantomogram was analyzed. The occlusal plane angle at a Frankfort horizontal plane of 0° was estimated using a linear approximation formula. Frankfort horizontal plane and occlusal plane angles were measured on the cephalograms, and their differences were analyzed for correlation with the occlusal plane angle at a Frankfort horizontal plane of 0° in the corresponding orthopantomograms. The cephalogram’s condylar plane–corpus line angle was also compared with orthopantomogram measurements.
Results: Frankfort horizontal and occlusal plane angles demonstrated a strong negative correlation (r < −0.9) in phantom studies and moderate negative correlation (r < −0.4) in clinical orthopantomograms. In the phantoms, the occlusal plane at a Frankfort horizontal of 0° in the orthopantomogram strongly correlated with the difference between the Frankfort horizontal and condylar plane–corpus line angles in the cephalogram.
Conclusion: Adjusting patient positioning based on individual skeletal differences and angles may reduce positioning errors and improve image quality. Cephalogram analysis could help determine an appropriate Frankfort plane angle for each patient when acquiring orthopantomograms.
Implications for practice: Integrating cephalometric analysis into positioning protocols enhances radiographic accuracy, reduces retakes, and improves diagnostic reliability in clinical positioning. This research could improve image quality by identifying reference indicators for orthopantomography by incorporating data from images other than cephalograms, such as computed tomography and magnetic resonance imaging.