Accuracy and landmark error calculation using cone-beam computed tomography-generated cephalograms

Objective: To evaluate systematic differences in landmark position between cone-beam computed tomography (CBCT)-generated cephalograms and conventional digital cephalograms and to estimate how much variability should be taken into account when both modalities are used within the same longitudinal study. Materials and Methods: Landmarks on homologous cone-beam computed tomographic- generated cephalograms and conventional digital cephalograms of 46 patients were digitized, registered, and compared via the Hotelling T ² test. Results: There were no systematic differences between modalities in the position of most landmarks. Three landmarks showed statistically significant differences but did not reach clinical significance. A method for error calculation while combining both modalities in the same individual is presented. Conclusion: In a longitudinal follow-up for assessment of treatment outcomes and growth of one individual, the error due to the combination of the two modalities might be larger than previously estimated. (Angle Orthod. 2010;80:286-294.)