Imaging of root canal fillings:: a comparison of subjective image quality between limited cone-beam CT, storage phosphor and film radiography

Aim To compare the subjective quality of limited cone-beam computed tomography (LCBCT), storage phosphor plate (SPP) and F-speed film images for the evaluation of length and homogeneity of root fillings. Methodology Root canals of 17 extracted permanent mandibular incisor teeth were filled. With the teeth placed in their jaws, images were obtained with Accu-I-Tomo LCBCT, Digora((R)) Optime image plate system and F-speed film using exposure parameters yielding 'clinically' acceptable density and contrast. Three radiologists and three endodontists independently rated the quality of all images in respect to homogeneity and the length of root fillings using a 3-graded scale. Evaluations were undertaken in two sessions. In the first, the coronal LCBCT images were not included. In the second, both coronal and sagittal LCBCT images were rated along with F-speed film and SPP images. Results were compared using the Friedman test (P < 0.05). Pair-wise comparisons of systems were completed using the Wilxocon signed-ranks test (P < 0.05). Kappa was used to measure interobserver agreement. Results Digora images were rated superior, consecutively followed by F-speed films and LCBCT images, for the evaluation of both homogeneity and length of root fillings in both the evaluation sessions (P < 0.05). Kappa ranged from slight to moderate for the length evaluation of root fillings and from poor to fair for the evaluation of homogeneity of root fillings. Conclusion Image quality of storage phosphor images was subjectively as good as conventional film images and superior to LCBCT images for the evaluation of both homogeneity and length of root fillings in single-rooted teeth.