Abstract
Introduction: This study aimed to investigate in an ex vivo model the reduction in patient radiation dose while maintaining accurate linear measurements by comparing cone-beam computed tomography (CBCT) scans taken at 360 degrees versus 180 degrees rotation, with porcine jaw specimens as a reference standard. Methods: CBCT scans of 12 sectioned porcine hemimandibles at 360 degrees and 180 degrees rotations were taken with standardized clinical exposure parameters. To assess interobserver variability, 6 assessors who were blinded to the degree of rotation took linear measurements of anatomic structures on each scan. The measurements were repeated after 2 weeks to assess intraobserver variability. Accuracy of measurement was judged against the corresponding measurements taken from the porcine jaw specimens. Results: Intraclass correlations signaled good-to-excellent intraobserver and interobserver agreement (0.65-0.98 and 0.79-0.98), respectively. Mixed regression analysis found no significant difference between the measurements from 180 degrees or 360 degrees rotations and no difference between the 2 rotations and porcine jaw specimens. Conclusions: A CBCT image sufficient to make accurate clinical measurements with a reduced radiation exposure may be obtained by using 180 degrees rotation of the CBCT tube head. (J Endod 2013;39:394-397)