Investigation of drilling and necrosis zone performance of split point drills in surgical cortical bone drilling

The surgical bone drilling process is unavoidable in orthopedic, traumatological and dental applications for screw, plate and implant placement procedures. The mechanical and thermal effects generated during this process have a direct impact on both surgical success and post-operative recovery. The high axial forces, torque, and local temperature increases that occur during drilling can lead to serious clinical complications such as microcrack formation, thermal necrosis, implant loosening, and delayed bone healing. Therefore, optimizing the cutting tool geometry in bone drilling processes is one of the important focal points of current research. In this study, cortical bone drilling processes performed using split point drills with different geometric parameters and standard drills were investigated. The drilling force, torque, and thermal necrosis formation during drilling were simulated using the finite element method (FEM), and the obtained data were modelled using artificial neural networks (ANN). A high level of compatibility was achieved between the ANN model and the FEM results, with training and test correlation coefficients and mean error rates calculated as 0.99998, 0.99502 and 1.84%, respectively. The results showed that split point drills provided significantly lower drilling forces compared to standard drills. The combination of optimum design parameters, namely a 115-degree splitting angle, 0.25 mm split point web thickness, and 7-degree gashing rake angle, resulted in a 46.8% lower drilling force, 4.6% lower torque, and 5.2% lower thermal necrosis compared to the standard drill. These findings demonstrate that split point drill geometry offers significant advantages in surgical bone drilling applications.