Accuracy of cone-beam computed tomography at different resolutions assessed on the bony covering of the mandibular anterior teeth

Introduction: The aim of this study was to determine the accuracy of cone-beam computed tomography (CBCT) with different voxel resolutions. Measurements were made of the bony covering of the mandibular anterior teeth because this region is crucial in orthodontic treatment planning. Methods: CBCT data at 2 resolutions (0.125-mm and 0.4-mm voxels) were collected from 8 intact cadaver heads. The vertical position of the mucogingival junction was clinically assessed. After removal of the gingiva, vertical and horizontal bony measurements were taken, and the buccal alveolar bone margin was determined. Anatomic bony measures were compared with the CBCT measures, and the correlation of the mucogingival junction measures to the buccal alveolar bone margin measures was evaluated. Results: Bony measures obtained with CBCT were accurate and differed only slightly from the physical findings. The mean differences, ranging from -0.13 to +0.13 mm, were statistically not significant, but the limits of agreement showed discrepancies in the measurements as large as 2.10 mm, depending on measurement and resolution. Buccal alveolar bone margin measurements correlated with the mucogingival junction measurements (P < 0.001). On average, the mucogingival junction was 1.67 mm more apical than the buccal alveolar bone margin (CI 95%, 1.35-1.98 mm). Conclusions: CBCT renders anatomic measures reliably and is an appropriate tool for linear measurements. Presence of soft tissue as well as different voxel size affect the precision of the data. A customized resolution protocol must be chosen according to the accuracy needed. However, even the 0.125-mm voxel protocol does not depict the thin buccal alveolar bone covering reliably, and there is a risk of overestimating fenestrations and dehiscences. The mucogingival junction appears to follow the buccal alveolar bone margin in a parallel line. (Am J Orthod Dentofacial Orthop 2012;141:41-50)