Novel in vivo method for evaluation of healing around implants in bone

A material implanted in bone is always inserted into coagulating blood. Protein and cell interactions during this initial implantation time will govern later healing. Many studies have focused on the tissue surrounding implants. We have developed a method for evaluation of healing around implants in bone by studying cells adhering to the implant surface. Hydrophilic titanium discs were inserted into rat tibiae. Samples were retrieved after 1, 2, 4, and 8 days of implantation and were analyzed by fluorescence microscopy techniques and scanning electron microscopy. Both proliferating and apoptotic cells were found on the surface. Generally, cells closest to the implant surface were nonviable whereas cells in the fibrin network a distance from the surface were viable. Bone morphogenetic protein-2 (BMP-2) is an osteogenic substance. An increase in BMP-2-positive cells was seen during the implantation period, and a population of large BMP-2-positive cells appeared on the surface after 4 days of implantation. The method developed here is a suitable tool for rapid evaluation of the initial healing around implant material.