Usefulness of a novel density measurement drill for evaluating cancellous bone density: correlation between CT value and drilling torque value in bovine ribs.

Purpose: The study aimed to examine the usefulness of a novel density measurement drill for evaluating cancellous bone density by examining the correlation between computed tomography (CT)-based Misch bone density classification and drilling torque value.

Methods: Bovine ribs were used as the drilling sites for implant placement. Multidetector CT (MDCT) was performed after contrast materials were attached to the drilling sites. CT value within the region of interest (ROI) on MDCT scan was measured and classified according to the Misch classification (D1 to D5). Drilling torque value was measured using a novel measurement drill. Next, histomorphometric analysis of the drilling site was performed to assess bone density, expressed as percentage of bone area within ROI.

Results: MDCT showed the presence of D2 (n = 87), D3 (n = 92), D4 (n = 133), and D5 (n = 52) at the measurement sites, however, no sites were classified as D1. The drilling torque values were 11.2 ± 3.2 Ncm for D2, 7.8 ± 3.3 Ncm for D3, and 3.0 ± 1.2 Ncm for D4, and 1.4 ± 0.6 Ncm for D5, with significant differences. A positive correlation was observed between CT value and drilling torque value (r = 0.99). Histomorphometric analysis revealed a positive correlation between drilling torque value and bone area ratio (r = 0.97).

Conclusions: The results of this limited study demonstrated the usefulness of the direct and objective cancellous bone density evaluation method using a novel measurement drill. This evaluation method will be informative for subsequent treatment decisions.