Implant Drill Characteristics: Thermal and Mechanical Effects of Two-, Three-, and Four-Fluted Drills

Purpose: Avoiding excessive trauma-thermal or otherwise-during dental implant site preparation is considered critical to implant success; overheating is considered to be a major cause of bone necrosis. Studies evaluating thermal and mechanical effects of implant drill design are limited, and effects of flute design have not been accounted for. The purpose of this study was to compare heat generation and cutting efficiency associated with two-, three-, and four-fluted implant drills to investigate the optimal number of flutes. Materials and Methods: Two-, three-, and four-fluted dental implant drills with identical point, relief, and rake angles and otherwise standard dimensions were evaluated. Real-time temperature changes while drilling artificial bone were recorded using an infrared thermal imager. Cutting efficiency was assessed as the drilling time to a 15-mm depth under constant load using a specially designed recording system. Each drill variation was examined 20 times. A one-way analysis of variance was used for statistical analysis. Results: Mean temperature increases amounted to 8.3°C, 10.8°C, and 15.1°C for two-, three-, and four-fluted drills, respectively; temperatures significantly increased (P .001) with an increased number of flutes. Mean drilling time serving as a measure of cutting efficiency amounted to 2.6, 2.5, and 2.5 seconds for the two-, three-, and four-fluted drills, respectively. A trend of cutting efficiency increasing or decreasing according to the number of flutes was not observed. Differences in cutting efficiency among the three drill variations were statistically significant (P = .015). The cutting efficiency of the three-fluted drill was superior to that of the two-fluted drill (P = .016). Conclusion: Within the limitations of the study, a two-fluted drill would be preferred for osteotomy preparation due to its level of heat generation, whereas a three-fluted drill showed favorable cutting efficiency. Keywords: cutting efficiency, drill geometry, frictional heat, implant drill design