Heat reduction during bone drilling using a two-stage drilling strategy

Thermal damage during bone drilling remains a significant concern in orthopaedic and dental surgeries. Excessive heat generation at the bone-drill interface can result in thermal necrosis and compromise implant stability. While several strategies have been proposed to mitigate intraoperative thermal injury, however, quantitative evaluations of staged drilling techniques remain limited. This study investigates the efficacy of a two-stage drilling strategy in reducing heat generation during cortical bone drilling. The approach involves creating an initial (pre-drilled) hole, followed by final enlargement to the target diameter (pilot hole). A validated three-dimensional dynamic elastoplastic finite element (FE) model was developed to simulate the bone drilling process and compare the bone temperature of conventional single-stage versus two-stage drilling techniques. Thermal analyses were conducted incorporating variations in the pre-to-pilot hole diameter ratio, feed force, and drill rotational speed. Simulation results indicated that a diameter ratio of 0.78 reduced peak bone temperatures by up to 12 °C compared to single-stage drilling. Further reductions in thermal accumulation were observed with increased feed forces of 40 N and 60 N. Increasing drill rotational speed from 800 to 2000 rpm decreased peak cortical bone temperatures from 57 °C to 43 °C. These findings demonstrate that the two-stage drilling strategy may mitigate thermal bone damage. The two-stage approach provides a practical solution to enhance thermal safety during implant site preparation.