Influence of basis images and skull position on evaluation of cortical bone thickness in cone-beam CT

Publication date: Available online 14 February 2017
Source:Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Author(s): Monikelly do Carmo Chagas Nascimento, Solange Maria de Almeida Boscolo, Francisco Haiter- Neto, Emanuela Carla dos Santos, Ivo Lambrichts, Ruben Pauwels, Reinhilde Jacobs
ObjectivesTo assess the influence of the number of basis images and the orientation of the skull on the evaluation of cortical alveolar bone in cone-beam CT (CBCT).Study DesignEleven skulls with a total of 59 anterior teeth were selected. CBCT images were acquired using four protocols, by varying the rotation of the tube-detector arm and the orientation of the skull (protocol 1: 360⁰/0⁰; protocol 2: 180⁰/0⁰; protocol 3: 180⁰/90⁰; protocol 4: 180⁰/180⁰). Observers evaluated the cortical bone as absent, thin, or thick. Direct observation of the skulls was used as the gold standard. Intra- and inter-observer agreement as well as agreement of scoring between the three bone thickness classifications were calculated using the kappa statistic. The Wilcoxon signed-rank test was used to compare the four protocols.ResultsFor lingual cortical bone, protocol 1 showed no statistical difference from the gold standard. Higher reliability was found in protocol 3​​ for absent (k=0.80) and thin (k=0.47) cortices, while for thick cortical bone, protocol 2 was more consistent (k=0.60). In buccal cortical bone, protocol 1 obtained the highest agreement for absent cortices (k=0.61), while protocol 4 was better for thin (k=0.38), and protocol 2 for thick cortical plates (k=0.40).ConclusionNo consistent effect of the number of basis images or head orientation for visual detection of alveolar bone was detected, except for lingual cortical bone, for which full rotation scanning showed improved visualization.



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