The effect of micro-motion on the tissue response around immediately loaded roughened titanium implants in the rabbit

Initial osteogenesis at the implant interface is, to a great extent, determined by the implant surface characteristics and the interfacial loading conditions. The present study investigated the effect of various degrees of relative movement on the tissue differentiation around a roughened screw-shaped immediately loaded implant. Repeated-sampling bone chambers were installed in the tibia of 10 rabbits. In each of the chambers, three experiments were performed by inducing 0 (control), 30, and 90 mu m implant displacement for 9 wk. A linear mixed model and a logistic mixed model with alpha = 5% determined statistical significance. Tissue filling of the bone chamber was similar for the three test conditions. The bone area fraction was significantly higher for 90 mu m implant displacement compared with no displacement. A significantly higher fraction of bone trabeculae was found for 30 and 90 mu m implant displacement compared with the unloaded situation. The incidence of osteoid-to-implant and bone-to-implant contact was significantly higher for 90 mu m implant displacement compared with 30 and 0 mu m implant displacement. Significantly more osteoid in contact with the implant was found for the loaded conditions compared with no loading. Well-controlled micro-motion positively influenced bone formation at the interface of a roughened implant. An improved bone reaction was detected with increasing micro-motion.