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Title A Smaller Voxel Size to the Cutoff of 0.150mm3 Provides More Precise Volumetric Measurements of Bony Periodontal Defects in CBCT Scans
Clinical Question In CBCT scans of the jaws, is a smaller voxel size more precise when measuring bony periodontal defects as compared to a larger voxel size?
Clinical Bottom Line For patients receiving CBCT scans for periodontal defects, a smaller voxel size generally assists in more precise volumetric measurements. Voxel sizes below 0.150mm3 do not demonstrate increased precision, so smaller voxel scans with higher radiation exposure are not suggested.
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 25900235Kolsuz/201512 dry skulls with 14 dehisences, 13 fenestrations, 8 tunnels, and 16 controlsLaboratory study
Key resultsKappa coefficients were between 0.978 and 0.973 for the 0.08 mm3 images and between 0.751 and 0.737 for the 0.160 mm3 images. There were higher kappa coefficients for smaller voxel sizes than for larger voxel sizes. When comparing different voxel settings on both the Planmeca ProMax 3D and the Morita 3D Accuitomo, voxel sizes smaller and larger than 0.150mm3 had the most statistical significance according to the t-test (p , 0.05), thus the cut-off point for overall detection of bony defects. When comparing defect types, including furcations, dehisiences, tunnels, and fenestrations, statistical analysis demonstrated similar results with the same cut-off point of 0.150mm3.
#2) 30284102 Tayman/201866 periodontal defects (17 furcations, 18 dehiscences, 16 fenestrations, and 15 three wall defects) in dry human mandiblesLaboratory study
Key resultsHeight measurements with CBCT (2.85 ± 0.73 mm for 0.2 mm voxel and 2.91 ± 0.78 mm for 0.075 mm voxel) were both lower than manual measurements (3.44 ± 1.14mm). Width measurements (1.71 ± 0.85 mm for 0.2 mm voxel and 1.65 ± 0.73 mm for 0.075 mm voxel) were both similar to manual measurements (1.70 ± 0.72 mm). Depth measurements in CBCT (3.07 ± 2.07 mm for 0.2 mm voxel and 2.93 ± 1.88 mm for 0.075 mm voxel) were similar to manual measurements (3.09 ± 2.01 mm). Volume measurements taken with CBCT demonstrated more accuracy as the voxel size decreased with statistical significance (p < 0.001). Thus, linear measurements of periodontal defects in CBCT are generally similar to manual measurements. If volumetric evaluation of bony defects is required, then a smaller voxel size of CBCT may be more accurate.
Evidence Search ("Cone-Beam Computed Tomography"[Mesh]) AND ("Periodontal Diseases/diagnostic imaging"[MAJR]) AND periodontal defect AND voxel size AND ("Humans"[Mesh])
Comments on
The Evidence
Kolsuz’s study used artificially created bone defects, which do not have the same irregular, less defined borders as in vivo periodontal defects. However, a variety of different defects were created, and some teeth were left without defects as controls. The study utilized a gold standard when testing all the subjects. Two trained and experienced oral and maxillofacial radiologists acted as observers. Results demonstrated strong interrater reliability. Limitations of the study include the use of only two CBCT systems, the lack of fixed field-of-view sizes between the machines, and use of artificially created defects. Tayman’s paper evaluated artificially created defects as well. An adequate spectrum of different defects were fabricated. The Tayman study did evaluate accuracy of 3D volumetric measurements, not just accuracy of linear measurements. Both the linear measurements and the volumetric measurements were compared to respective gold standards (manual measurements and micro-CT measurements). Limitations of the study include the use of only two CBCT systems, no non-defect sites, and no mention of a kappa statistic. The study calibrated the two selected observers, but it did not calculate interrater reliability.
Applicability In a patient with periodontal disease receiving a CBCT scan, utilizing a smaller voxel size would assist in more precise detection of periodontal defects. A smaller voxel size would provide more precise volumetric measurements. However, Kolsuz’s study suggests that a voxel size smaller than 0.150mm3 does not assist in further precision. Considering the principle of ALARA, a patient receives more radiation if a smaller voxel scan is taken. If the voxel size smaller than 0.150mm3 is not beneficial for measurements of periodontal defects, then ALARA is more reasonably achieved.
Specialty/Discipline (Oral Medicine/Pathology/Radiology)
Keywords CBCT, voxel size, periodontal defects, furcations, fenestrations, dehiscences
ID# 3478
Date of submission: 11/23/2021spacer
E-mail tsu@uthscsa.edu
Author Laura Tsu
Co-author(s) Shatha Alshehri
Co-author(s) e-mail alshehris@uthscsa.edu
Faculty mentor/Co-author Hassem Geha
Faculty mentor/Co-author e-mail geha@uthscsa.edu
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