A fundamental issue in onlay bone graft persistence is the unpredictable extent of incorporation and volumetric maintenance of the graft. The purpose of this study was to evaluate the effects on integration of onlays, with either their cancellous or cortical portion facing toward the host bed, positioned over cortical perforations at the recipient site. Tibial or femoral unicortical bone grafts were harvested from isogeneic donors and positioned subperiostally on each tibia of 22 adult Lewis rats. On the experimental side, the recipient outer cortical bone surface received multiple perforations, 0.25 mm in diameter. The contralateral side served as a control (no cortical perforations). The findings were assessed after 4 and 20 weeks using routine histologic and immunohistochemistry techniques. Cortical perforations induced a migration of the recipient bone marrow into the graft as well as a reduced size diminution. More cortical bone remodeling and marginal lamellar bone apposition were observed after orientating the cortical portion of the graft toward the recipient site. These observations may be useful clinically to improve long-term success after autogeneic bone grafting.
This study confirms that an osmotic soft tissue expander creates a surplus of periosteum and soft tissue and that new bone can be generated under a titanium mesh or bioresorbable mesh.
We aimed to evaluate a new technique for intraoral expansion of soft tissue with a self-inflatable expander in rabbits. We placed a self-inflatable soft tissue expander bilaterally in eight rabbits under the periosteum of the mandible through an extraoral approach. The expander was left to self-inflate for two weeks, after which the animals were killed and specimens collected for histological examination. The self-inflatable soft tissue expanders expanded the periosteum. There were no dehiscences or infections. Histological observations showed no signs of any inflammatory reaction and there was no evidence of bony resorption. New bone had formed at the edges of the expanded periosteum. In the control area no new bone had formed. The osmotic soft tissue expander model for intraoral soft tissue and periosteal expansion suggests a promising way of creating a surplus of soft tissue that can be used to cover bone grafts.
This study aimed to evaluate the effects on incorporation of onlay grafts after exposure of the marrow of the skull recipient bed. Tibial or femoral uni- and bicortical bone grafts were positioned subperiosteally or submuscularly in the parietal and temporal region, respectively, of 28 adult rats. The recipient bed was ground to remove the external cortical layer and expose the underlying marrow. The outcome was assessed after four, 12, and 20 weeks by routine histology and immunohistochemical labelling for various bone and cartilage proteins. Marrow exposure resulted in an explosive bone formation, prompt graft incorporation, earlier onset of bone remodelling, but also localized resorption at the host bed due to increased vulnerability to pressure. Graft height loss was similar relative to previous observations by us using the same experimental model but without exposure of the marrow. The investigated proteins were identified at various locations and with different temporal sequences; the technique contributed to a diversified appreciation of graft behaviour. The findings emphasize the essential role of the bone marrow constituents to bone graft incorporation.
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