Effect of cone-beam computed tomography voxel size on detection of vertical periodontal bone defects

Objectives: Finding the best voxel size for the detection of vertical periodontal bone defects with minimum patient radiation dose is a priority. This study sought to assess the effect of cone-beam computed tomography (CBCT) voxel size on the detection of vertical bone de-fects. Materials and Methods: In this in vitro, experimental study, 31 vertical defects including 2 one-wall, 12 two-wall, and 17 three-wall defects were randomly created in the maxilla and mandible of four sheep skulls with the associated soft tissue using round and needle burs. Forty sound sites were considered as the control group. The CBCT scans were obtained from the skulls with 0.150 and 0.300 mm³ vox-el sizes and 8 x 11 cm² field of view (FOV). The images were randomly evaluated by two oral and maxillofacial radiologists and two peri-odontists, and their findings were recorded. The inter-rater observer agreement (weighted kappa), sensitivity and specificity values were calculated for each voxel size. Comparisons were made using paired t-test. Results: The two voxel sizes had no signifi-cant difference in detecting one-wall and two-wall defects (P>0.05). But the smaller voxel size was significantly superior for detecting three-wall defects (P=0.001). The inter-rater observer agreement was unfavorable (kappa < 0.6) for the detection of all three defect types. Conclusion: In general, increasing the image resolution by decreasing the voxel size in-creased the sensitivity and reduced the specificity of CBCT for detection of vertical bone defects, and is only recommended for detection of three-wall defects.