Reliability of Digital Versus Conventional Cephalometric Radiology: A Comparative Evaluation of Landmark Identification Error

The purpose of this study was to determine whether direct digital lateral cephalometric radiographs are of equal value in diagnosis and treatment planning as conventional cephalometric radiographs by investigating differences in landmark identification on direct digital and conventional cephalometric radiographs. An evaluation of precision and the distribution of landmark identification error at each cephalometric landmark was undertaken. Ten observers, all orthodontists or postgraduate orthodontic residents, identified 19 landmarks twice on 6 digital images and 6 conventional cephalometric films obtained from the records of 6 patients at the University of Alabama School of Dentistry Graduate Orthodontic Clinic. Patient records selected were of adults with existing pretreatment conventional cephalometric films and posttreatment direct digital cephalometric images on file. Landmark identification recordings were transferred into a standardized coordinate system, adjusted for magnification differences, and evaluated separately along both the x- and the y-coordinates. Statistically significant differences in landmark identification error were found along the x-coordinate for A point (Apt) and along the y-coordinate for anterior nasal spine (ANS) and condylion (Co). These statistically significant differences, as well as those found to be not statistically significantly different, were all below 1 mm, indicating that even the statistically significant differences between the two methods of image acquisition were unlikely to be of clinical significance. Each landmark exhibited its own unique pattern of landmark identification error, the magnitude and distribution of which must be taken into consideration when selecting landmarks for use in cephalometric analysis or when interpreting these analyses for diagnostic or treatment planning purposes. The results of the present study indicate similar precision and reproducibility in landmark identification using both direct digital images and conventional lateral cephalometric head films.