EVALUATION OF THE INFLUENCE OF THE UNIT AND SKULL ROTATION ON CORTICAL BONE THICKNESS MEASUREMENTS IN CONE BEAM COMPUTED TOMOGRAPHY IMAGES

Objectives: The aim of this study was to assess the influence arc rotation and the influence of different positions of the skull on evaluating of cortical bone in CBCT images. Methods: Fifty-nine anterior teeth were selected for evaluation of the cortical bone. Images were made on Accuitomo 170 CBCT. Four protocols regarding to arc rotation and position of skull were made (protocol 1: 3600/00; protocol 2: 1800/00; protocol 3: 1800/900; protocol 4: 1800/1800) in standard mode. Three trained and calibrated observers evaluated the cortical bone as: absent, thin and thick cortical bone in sagittal sections. Results: The results showed that only protocol 1 for lingual cortical bone, showed no statistical difference between images and gold standard. For lingual cortical bone, higher reliability values were observed in protocol 3 for absent (k=0.80) and thin (k=0.47) cortex, while for thick cortical bone, protocol 2 was more consistent (k=0.60). In buccal cortical bone, protocol 1 obtained the best correlation value for absent (K=0.61), while protocol 4 was better for thin (k=0.38), and protocol 2 for thick cortex (k=0.40). Conclusions: When teeth are present, visual detection of alveolar bone showed inaccurate on CBCT images, except for lingual cortical bone in total rotation of the arc (the X ray beam source). Visualization of buccal cortical bone remained most challenging. In addition, when the cortical bone thickness was thinner more difficult the diagnosis was.status: publishe