Reliability of using CBCT scans to derive the parameters of the facial canal

Abstract

PURPOSE : Studies have analysed the facial canal (FC) parameters using dissection or imaging technologies. To date, no studies have analysed the differences between these methods. The purpose of this study was to evaluate the reliability and accuracy of deriving the parameters from the FC on cone-beam computed tomography (CBCT) scans by comparing it to FC morphometric analyses of dissected heads. METHODS : Ten embalmed heads (n = 20) were CBCT scanned and analysed using ImageJ. Next, each FC segment was dissected. Measurements for both methods included the proximal and distal diameters and lengths for each segment, and angles of the first and second genua. RESULTS : The paired t-test indicated significant differences (p < 0.05) between the CBCT and dissected measurements for most FC segments measured. The respective dissection measurements were consistently higher than the CBCT measurements. However, the Bland-Altman plots showed agreement between the two modalities in measuring FC segments. Interobserver error values were 0.963 and 0.950 for the CBCT and dissection groups, respectively, indicating a high repeatability. CONCLUSIONS : Although the current study showed differences between the parameters of the FC derived from CBCT scans and dissected measurements, CBCT scans remain a valuable tool for non-invasive assessments. However, the differences have implications for modelling in that CBCT measurements underestimate the true size for the various segments of the FC. It is worth noting that a potential difference in segment sizes may exist between populations but will have no effect on using CBCT scans as a pre-operative assessment of the FC.