Optimizing cone beam computed tomography (CBCT) protocol for visualization of thin bone

Abstract

Background

Cone beam computed tomography (CBCT) has various dental applications, but discrepancies exist between direct measurements and measurements from CBCT images, particularly in assessing thin alveolar bone. Limited research has investigated the impact of CBCT scan protocols on measurement accuracy for thin bone.

Objectives

The objective of this study was to optimize CBCT scanning protocols for measuring thin alveolar bone.

Study Design

CBCT scans (Morita Accuitomo 170), were performed using different fields of view (4 × 4, 6 × 6 or 10 × 10 cm), voxel size (80 or 200 um), and acquisition time (17 or 30.8 seconds). Two reference holes per tooth were placed in 8 pig mandibles (32 teeth, 64 sites). Following protocol scanning, specimens underwent sectioning, decalcification, and staining. Bone width and height were measured from CBCT and histology slides at each site (buccal and lingual of each tooth). Two observers performed CBCT measurements independently. Histomorphometric measurements were determined by consensus among three observers and used as the gold standard. Agreement between measurements was assessed by Bland-Altman plots.

Results

After processing, only 37 viable sites remained. The mean measurement of bone width and height from histologic slides was 1.6 mm and 7.07 mm, respectively. The mean differences between all CBCT measurements and gold standard measurements ranged from 0.04 mm to 0.21 mm. The mean difference between CBCT protocols ranged from 0.005 mm to 0.10 mm. For CBCT measurements, the interobserver agreement was excellent (the intraclass correlation coefficient was 0.95).

Conclusion

We found that the differences between CBCT protocols were smaller than the differences between any CBCT and histomorphometric measurements. The mean differences between histological and CBCT measurements for different protocols were not clinically significant. We concluded that modifying CBCT scan protocols did not significantly impact the accuracy of CBCT scans.