In-vitro assessment of bone viability with different implant drill speeds.

The success of implant osseointegration is clearly impacted by the heat produced throughout the implant osteotomy site preparation. Bone necrosis of the implant bed should be prevented to maintain a stable osseointegration process. The objective of this experiment was to validate the impact of implant drill speed on the bone from the point of view of heat generation; a second objective was to evaluate viability of the osteotomised implant sites in rabbits histologically. Twenty healthy adult rabbits, were randomly categorised into 4 groups; 3 bony osteotomies in the 3 mm, 3.5 mm and 4 mm diameters of the femur were made in each rabbit. Variable speeds were used for the 3 diameters as follow: Group I: speed 1000 rpm, Group II: speed 1500 rpm, Group III: speed 2000 rpm. A combination of speed 2000 rpm for the small diameter drills and the last large diameter with speed 1000 rpm was used in Group IV. The temperature changes were recorded. After the operation, the rabbits were euthanised and the bony samples were taken for histological evaluation. In group III and Group IV, histological analysis demonstrated more bone viability compared to other groups. Furthermore, heat analysis revealed significant differences between group III, Group IV and the other groups with less heat produced with greater speeds compared with lower speeds. Drilling with higher speed in dense bone with irrigation produces less heat and maintains more bone viability compared with lower speed. In addition, increased drill diameter with the same speed or with increased speed generates less heat compared with smaller diameters.