Factors influencing the differences between three-dimensional measurement with cephalometric analysis and cone-beam computed tomography

This study aimed to elucidate the factors influencing the differences between three-dimensional (3D) measurements taken with cone-beam computed tomography (CBCT) and cephalometric analysis.The ANB angle, a measure of the anteroposterior relationship between the maxilla and mandible, was selected as the object for this study.However, conventional cephalometric indices may not accurately evaluate measurements using 3D analysis on CBCT.Measurements were obtained from the laboratory data of 37 adults with no congenital diseases and no additional X-ray exposure at that time.No exposure occurred during the study.A paired-samples t-test (=0.05) was performed to compare measurements taken with CBCT and cephalometric analysis.We applied multiple linear regression and step-wise methods to investigate factors influencing the differences between the ANB angle on CBCT (3D ANB) and conventional cephalometric analysis (two-dimensional [2D] ANB).The difference in ANB angles (3D ANB-2D ANB) was -1.09 (standard deviation=1.58,range=6.20).The results of the multiple linear regression and step-wise methods showed that the smaller the SNA in the cephalometric analysis, the larger the 3D ANB-2D ANB.Thus, the plot of point A in cephalometric analysis may be different from that in CBCT.This result supports the hypothesis that conventional cephalometric indices cannot be used for evaluation during 3D analysis.Furthermore, we demonstrated a relationship between conventional cephalometric analysis and 3D CBCT analysis of the ANB angle.These results suggest points for consideration when constructing a new 3D analysis index.