The Effect of Using Worn Osseodensification Drills on Bone An Ex-Vivo Study

Abstract

Introduction: The use of osseodensification drills to increase implant stability, and expand edentulous ridges is now considered mainstream. These drills are used in reverse to compact, and displace, instead of removing the bone. It is suggested to limit their use to 20 osteotomies, however, as the mode of function does not include cutting, the importance of maintaining drill sharpness is questionable. Materials and Methods: Bovine tibial plateau and ribs were used in this study. New, and worn drills were used to perform osteotomies and place implants. Wear protocol consisted of 15 cycles of sterilization, and 100 osteotomies half clockwise, and half counterclockwise. The primary outcome in this study was temperature increase, and secondary outcomes included the time to complete each osteotomy, bone expansion coronally, and apically, and primary implant stability measured with resonance frequency analysis. A non-inferiority study design was utilized, with preset clinically acceptable margins. (2.0°C, 4.0s, 0.2mm, 5 ISQ). The t-test was conducted for the outcome of temperature, and time-to-complete, whereas the non-parametric Wilcoxon Mann-Whitney test was used for the other outcomes. Results: Mean temperature increases were 10.81 (±2.09) for the new, and 10.96 (±2.61) for the worn drills. Mean time-to-complete was 14.44 (±5.43) and 14.33 (±5.12) for new and worn drills. Mean primary stability was 83.17 (±3.31) and 82.04 (±1.81) for the new and worn drills. For the outcome of expansion, mean expansion at the coronal portion was 0.47(±2.80) for the new drills, and 0.51 (±2.80) for the worn drills, whereas, for the apical portion was 0.43 (±0.33) and 0.30 (±0.16) for the new and worn drills respectively. Non-inferiority was established for temperatures increases (1.75, 95%CI: 0.013 – inf, p=0.049), for time-to-complete (1.91, 95%CI: 0.414 to inf, p=0.035), for primary stability (p<0.001), and for coronal expansion (p=0.034). The null hypothesis that there was no difference between groups was not rejected for the outcome of apical expansion (p=0.36) Discussion: Within the limitations of this study, the use of osseodensification drills in reverse may still be safe, and effective after repeated usage, in terms of expected temperature increases, time efficiency, primary stability achieved, and bone expansion.