The Effect of Voxel Size on the Reliability and Reproducibility of Alveolar Bone Crest Identification on Cone Beam CT Scans

Objective: the aim of this study is to compare the reliability and reproducibility of landmarks representing the labial alveolar bone crest of maxillary and mandibular teeth using two different CBCT machines with different image resolutions and voxel size and accordingly different radiation dose.
Material & Methods: 340 landmarks representing the alveolar bone crest opposite each tooth from the central incisor up to the second molar on sixteen CBCT data sets were identified. The landmarks were located by the principle operator, and relocated by the same principle operator to evaluate the intra-observer reproducibility, then located by the second observer to evaluate the inter-observer reliability error. For testing the intra-observer reproducibility and inter-observer reliability of the landmark identification within each scanner data, the Mean Absolute error (MAE) and the Dahlberg error (DE) and Intra-class correlation coefficient tests with 95% confidence intervals were used. Independent samples t-test was used to compare the intra-observer and inter-observer error between the two scanners.
Results: The Mean Absolute Error (MAE), the Dahlberg Error (DE) and the Intra-Class Coefficient (ICC) tests showed excellent intra-observer reproducibility values in the x, y and z-axis for the Galileos scanner, with the least reproducibility in the z-axis. The same concordance was found for the Planmeca CBCT scanner, with excellent reliability in the x, y and z-axis, and the least reproducibility in the z-axis. For the inter-observer reliability testing, the same pattern was found for each CBCT scanner. Very good inter-observer reliability was found in the x, and y dimensions, while the least was found in the vertical z-dimension.
Conclusion: The Galileos and the Planmeca CBCT scanners produced comparable reliability and reproducibility for identification of alveolar bone crest landmarks. The vertical axes showed the least accurate coordinates for landmarks identification.