Effect of implant surface roughness and loading on peri-implant bone formation

Background: Critical factors for the establishment of osseointegration are the implant surface microtopography and the local mechanical environment. The present study evaluated the bone response around a turned (T) and a roughened (R) implant for either an unloaded or a well-controlled loaded situation. Methods: Bone chambers were installed in the tibia of 20 rabbits. In each of the chambers, two identical displacement-controlled loading experiments were performed: 30 mu m for 400 cycles at 1 Hz, three times a week for 9 weeks versus 0-mu m implant displacement. A linear mixed model and a logistic mixed model with alpha = 5% were set to study the significant effect of the surface texture on the peri-implant bone response in the unloaded (T-0 mu m versus R-0 mu m) and the loaded (T-30 mu m versus R-30 mu m) mode. Results: Results indicated no microtopographic dependence of the bone response further away from the implant in unloaded and loaded conditions. For a load-free implant, osseointegration seemed to occur with a higher incidence at a roughened compared to a turned implant surface. In the presence of loading, the topographic dependency of the osteogenic activity at the interface was overruled by the loading-related bone response, revealing no significant differences in osseointegration incidence between T and R. Conclusion: A predominant effect of the interfacial mechanical environment over the implant surface characteristics on the differentiating cell population is suggested.