Effects of Asymmetric Oscillatory Drilling on Bone Densification, Heat Generation, and Implant Stability.

Purpose: Achieving optimal implant site preparation is crucial for successful osseointegration, particularly in low-density bone. Excessive heat generation during drilling can compromise bone vitality, leading to impaired healing, delayed osseointegration or implant failure. This study evaluates the effects of an oscillatory drilling technique on bone densification, heat generation, and implant stability.

Materials and methods: An in vitro study was conducted using pig rib segments to simulate low-density bone. Drilling protocols were performed usin three techniques: clockwise cutting (CW), counterclockwise densifying (CC), and oscillatory movement (OM) at 60° clockwise/240° counterclockwise. Drilling was performed with automated handpiece handling under controlled conditions. Thermal changes were recorded using a laser thermometer and infrared imaging, and bone densification was assessed using micro-CT analysis. The final insertion torque (IT) was measured to determine the primary stability and removal torque was recorded to access the stability loss for each implant.

Results: The CC and OM groups demonstrated significantly higher bone volume, intersection surface, and reduced trabecular separation compared to the CW group (p < 0.05). Although the CC group exhibited the highest temperature increase, all final temperatures remained below the critical threshold of 47°C. Infrared imaging showed overall less heat retained within the body of the drill in CW group compared to CC and OM. OM drills exhibited lower heat generation than the CC group with temperature peak approximately 5 mm above the drill tip. The OM and CC groups showed significantly higher IT than the CW group (p < 0.05). Implant removal revealed a stability reduction of 27.8±10.2%, 24.8±13.6%, and 20.2±8.2% for CW, CC and OM groups, respectively (p > 0.05).

Conclusions: Oscillatory movement during implant site preparation enhanced bone densification, improved primary stability, and maintained safe thermal levels. These findings suggest that oscillatory movement could serve as a promising alternative to conventional drilling techniques, particularly in low-density bone. Further studies are needed to explore its clinical applicability and long-term outcomes.