Objectives: The objective of this study was to evaluate the effect of drill-bone contact area on bone temperature during osteotomy preparation.
Material and methods: Conventional triflute Ø3.6 mm drills were modified with the intent to reduce frictional heat induction. The peripheral dimensions of the drill were reduced 0.15, 0.35 and 0.5 mm to evaluate the effect of surface area on induction of frictional heat between the drill and bone/cutting debris (parameter A). Also, the lateral cutting surface of the drill was set to 0.1, 2 and 7.5 mm to estimate heat induced by direct function of the drill (parameter B). A non-modified triflute drill (parameter A: 0 mm; parameter B: 15 mm) served as control. Thus, nine drills with different A/B combinations vs. one control were tested in artificial bone. Real-time temperature changes (during drilling and withdrawing) were assessed using an infrared thermal imager. Each drilling procedure was performed up to 20 times. Thermal image data were transferred to a PC for simultaneous analysis.
Results: Mean temperature changes for all modified drill combinations were smaller than for the control (P<0.001). The effects of parameters A and B were statistically significant (P<0.001). There was a significant interaction effect between the two parameters (P<0.001) showing that the effect of parameter A on the mean temperature changes is different depending on the values of parameter B. As the dimensions of parameter B decreased, the temperature change during drilling also decreased. However, a tendency for the temperature to increase or decrease by parameter A was not observed.
Conclusions: Within the limitations of this pilot study, the observations herein suggest that reduction in contact area between the drill and bone reduces heat induction. Further studies to optimize drill/bone contact dimensions are needed.
© 2010 John Wiley & Sons A/S.