Autogenous onlay bone grafts to the mandible : an experimental evaluation of graft cellularity and embryonic origin

The aim of this study is to compare, with regard to volume maintenance and viability of the grafted bone, three different types of autogenous bone grafts. The three types of autografts with different embryonic origin and cellularity are; cancellous endochondral, cortical endochondral and cortical membranous bone.The endochondral bone was harvested from the ilium and the membranous bone from the cranium, of New Zealand White rabbits. The grafts were applied to the mandible in an onlay fashion and were stabilized by a titanium mesh. The control group consisted of a blood clot under the titanium mesh.Micro CT and histologic analysis were performed at 6 and 12 weeks after grafting. The cortical membranous bone graft had a greater volume of bone compared to both endochondral groups. The difference in volume between the two endochondral groups was not statistically significant. These results suggest a role for the embryonic origin of bone in the volume maintenance of the grafts.The osteoblast and osteoblast counts were used to assess the viability of the grafts. The cancellous endochondral group had the highest number of cells followed by the cortical endochondral and then the cortical membranous. The cortical bone grafts seem to be less viable compared to the cancellous group