CRANIAL VERSUS ILIAC ONLAY BONE-GRAFTS IN THE FACIAL SKELETON - A MACROSCOPIC AND HISTOMORPHOMETRIC STUDY

We compared autologous bicortical iliac and cranial bone grafts onlaid to the facial skeleton in 60 adult New Zealand rabbits to evaluate th e initial phase of incorporation of these grafts. The animals were dis tributed in two equal groups in which either cranial or iliac grafts w ere harvested and fixated, devoid of their periosteum, in direct conta ct with the nasal bone with micro screws. Each of these two groups wer e then subdivided into three groups, which corresponded to the three t imes the animals were killed: 18 days, 30 days, and 60 days. The graft s were measured in their linear dimensions and weighed before fixation and after harvesting when the animals were killed. Undecalcified hist ological sections were prepared, and histomorphometric parameters of b one formation (bone volume, osteoid volume, surface thickness, and ost eoblastic surface) and resorption (osteoclastic surface and eroded sur face) were measured. The results confirmed those of previous studies i n that cortical grafts maintained their volumes to a greater extent th an their cancellous counterparts, indicating that the remodeling proce ss may be uncoupled in the transplanted iliac grafts. It is postulated that the significant decrease in mechanical stimulus that the cancell ous grafts undergo determines this imbalance in the remodeling activit y, which results in greater bone resorption than formation and thus th e decreased volume.