Thermal performance of modified surgical drill margins during bone drilling: An experimental, numerical, and optimization case study.

Excessive heat generation during bone drilling causes thermal osteonecrosis, posing a significant risk in orthopedic and dental procedures. While various aspects of drill design have been studied, the specific influence of margin geometry remains underexplored in the context of thermal engineering. This study integrates drilling simulation, experimental validation, and statistical optimization to evaluate the thermal impact of drill margin width (Mw) and height (Mh) during cortical bone drilling. A validated thermo-mechanical model was developed using commercial software DEFORM-3D. The simulation results were validated with experimental bone drilling with small temperature prediction errors (2.4% and 8.0%). Key thermal metrics (maximum temperature (Tmax), osteonecrosis diameter (OD), and osteonecrosis depth (OH)) were optimized using a central composite design (CCD) of response surface methodology (RSM) and desirability-based multi-objective optimization. Results revealed that Mw had the most significant second-order influence on Tmax (47.2%), while Mh dominated OD (41.1%) and OH (47.8%). The optimal drill margins (Mh = 0.05 mm and Mw = 0.22 mm), which achieved a desirability score of 0.985, could reduce Tmax by up to 44.8°C, which is below the osteonecrosis threshold. This work highlights drill margins as a critical yet previously underutilized design variable, offering an alternative pathway for the thermally optimized development of surgical tools and next-generation robotic-assisted drilling systems.