Infrared Thermographic Evaluation of Temperature Modifications Induced during Implant Site Preparation with Cylindrical versus Conical Drills

Background: A few studies have investigated the influence of drilling on bone healing. Many factors have been reported to influence temperature rise during surgical preparation for implant placement: drill geometry, drilling depth, sharpness of the cutting tool, drilling speed, pressure applied to the drill, use of graduated versus one-step drilling, intermittent versus continuous drilling, and use or not of irrigation. Purpose: The objective of this study was to quantify the temperature changes in cortical bone and at the apical portion of the drills during implant site preparation with a cylindrical implant drill versus a conical implant drill. Materials and Methods: Two implant drill systems were evaluated in vitro using bovine femoral cortical bone. The two implant drill systems evaluated in this study were systemA (a cylindrical drill with triple twist drills) (Bone System, Milano, Italy) and system B (a conical drill with quadruple twist drills) (Bone System). Site preparation began, and the temperature of the cortical bone and at the apical portion of the drill was measured by the infrared thermography. Results: The mean temperature produced in the cortical bone during implant preparation was 31.2 +/- 0.5 degrees C for the cylindrical drills and 29.1 +/- 0.6 degrees C for the conical drill. The mean temperature produced in the apical portion of the drill during implant site preparation was 32.1 +/- 0.7 degrees C for the cylindrical drill system and 29.6 +/- 0.6 degrees C for the conical drill. Statistically significant differences were found in the temperature measurements in the cortical bone in the two groups (p < .05). A statistically significant difference was observed for the temperature measurements in the apical portion of the drill in the two groups (p < .005). Discussion: The model system used in this work was able to evaluate the temperature in the cortical bone and in the apical portion of the drills; the temperature modifications in the apical portion of the drill seemed to be correlated to the drill geometry. The results of the present study showed that drill geometry seems to be an important factor in heat generation during implant site preparation. Conclusion: The drill geometry could explain the increased temperature in the apical portion of the drill.