Alteration of the Thrust Force Versus Number of Drill Bit Usage in Cortical Bone Drilling

Background: Bone drilling is a common step in orthopedic surgery. Thrust force is one of the most important parameters that can influence the quality of bone drilling. The number of drill bit usage has some limitations and it can affect the quality of bone drilling. Objectives: The aim of this study was to investigate the limitations of drill bit usage number to increase the bone drilling quality. Materials and Methods: Two mid-diaphysis sections of male human cadaveric femora were prepared. Five orthopedic drill bits were used to identify the effects of the usage number. An orthopedic hand piece was attached to the dynamic testing machine. The spindle speed and feed rate of the drill bits were 900 rpm and 0.5 mm/s, respectively. Drill bit usage of 0, 20, 40, 60 and 80 were prepared for scanning electron microscopy (SEM). SEM images were taken to illustrate physical changes on the cutting surfaces of the drill bit. Results: There was an increase in the thrust force by increasing the number of drill bits usage. Irreversible physical damages were observed in drill bit point angle, frank face, and flutes of drill bits. Conclusions: The number of drill bits usage has limitation. Drill bits that are similar to the ones of the current study are better to be used no more than 55 times.