Multistepped Drill Design for Single-Stage Implant Site Preparation: Experimental Study in Type 2 Bone

Purpose: To evaluate an experimental multistepped drill for single-stage implant site preparation by means of real- time analysis of thermal variations during and postdrilling, and by implant stability evaluation. Materials and Methods: Temperature and time were recorded in real time by paired microprobe thermocouples during simulated osteotomy in type 2 bone similes at the cortical and cancellous zones. Three different drilling groups with a new multistepped drill design were compared: Control ( 2- mm diameter pilot drill + 3.3- mm three- stepped drill + 4.1- mm three- stepped drill); Test A ( 3.3- mm three- stepped drill); and Test B ( 4.1- mm three- stepped drill). Implants were inserted, and implant stability was evaluated with the Perio Test Value ( PTV). Two- way anova was used to test the independent effects of osteotomy and implant diameter on temperature and stability. Results: All the drills induced thermal changes without significant differences between groups ( p >.05). Drilling in cortical bone produced significant increase of the temperatures in a range of 1.8 +/- 1 0.9 degrees C compared with drilling in cancellous bone ( p <.05). Delta T temperatures were significantly higher for test groups in cortical and cancellous bone ( p <.05);Delta T10 for all groups showed a reduction of the temperature in a range of 1.7 +/- 1 0.3 degrees C without significant differences between groups ( p >.05); the mean time to accomplish drilling was significantly longer in the control group ( p <.05); test groups took 10 +/- 1 0.3 seconds less to reach the required drilling depth. PTV values were higher in test groups compared with controls ( p <.05). Conclusions: The multistepped drills used for single- stage implant site preparation _ Increase temperature as in comparison with a conventional incremental protocol; _ Induce the temperature increment in cortical bone compared with the cancellous bone; _ Reduce drilling time when a multistepped drill is used alone; and _ Increase implant stability twofold compared with a conventional incremental protocol.