Heat Generation During Guided and Freehand Implant Site Preparation at Drilling Speeds of 1500 and 2000 RPM at Different Irrigation Temperatures: An In Vitro Study.

Purpose: The purpose of our study was to evaluate the impact of different irrigation fluid temperatures on intraosseous temperature increment during guided and freehand implant site preparation. Materials and Methods: Bovine rib segments were used. Temperature was detected using K-type thermocouples. The studied groups were defined as combinations of the following: drilling speed (1500, 2000 RPM), drill diameter (2.0, 2.5, 3.0, 3.5 mm), surgical method (guided, freehand), and irrigation fluid temperature (10 degrees C, 15 degrees C, 20 degrees C). The data were analysed with Kruskal-Wallis analysis of variance (ANOVA) and ANOVA, as appropriate. Results: At 1500 RPM, guided drilling with 20 degrees C irrigation fluid yielded temperature values exceeding the necrotic threshold (47 degrees C) when performed with bits of 3.0 and 3.5 mm diameters. Meanwhile, 15 degrees C irrigation managed to keep the mean increment below 8.0 degrees C at the diameter of 3.5 mm for both guided and freehand surgery. However, 10 degrees C irrigation cancelled every statistically significant difference between guided and freehand groups. At 2000 RPM and with 20 degrees C irrigation, mean peak temperatures exceeded the necrotic threshold at the diameters 3.0 and 3.5 mm (guided) and 3.5 mm (freehand). When applying 10 degrees C irrigation, though, all measurements indicated peak temperatures in the safe zone. Conclusion: Drillings at 1500 and 2000 RPM, in a guided setting, cause temperature elevations that exceed the necrotic threshold. A speed of 2000 RPM drilling may produce potentially harmful temperatures also in a freehand setting. 10 degrees C and 15 degrees C irrigation kept temperature increments in the safe zone at 2000 RPM and 1500 RPM, respectively.