Estudo imunoistoquímico, tomográfico e histológico sobre a remodelação de enxertos ósseos onlay. Parte II (Calota Craniana) / Immunoshistochemical, tomographic and histological study on onlay bone grafts remodeling. Part II - Calvarial bone

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Several studies have discussed factors that govern the longevity of onlay bone grafts. However, little information has been made available on molecular events that occur over time. Cranial bone grafts have been reported to produce greater responses compared to other donor regions in maxillofacial reconstructions, but necessary scientific verification was still lacking. The objectives of this study are (1) to study the morphological pattern of cranial onlay bone grafts and compare them to the biological events through immunohistochemical responses, and (2) to establish the effects of perforations on maintaining the volume and bone density of the receptor bed. Sixty New Zealand White rabbits were submitted to cranial onlay bone grafts of the mandible. In thirty rabbits, the receptor bed was perforated (perforated group), while for the remaining specimens the bed was kept intact (non-perforated group). Six animals from each group were culled at 5, 7, 10, 20 and 60 days after surgery. Histological cuts from the grafted area were prepared for immunohistochemical and histological analyses. During the immunohistochemical evaluation, markers were found for proteins Osteoprotegerin (OPG), Receptor Activator of Nuclear Factor-ß ligand (RANKL), Alkaline Phosphatase (ALP), Osteopontin (OPN), Vascular Endothelial Growth Factor (VEGF), Tartrate-Resistant Acid Phosphatase (TRAP), Type I Collagen (COL I) and Osteocalcin (OC). The tomography examination (CT scan) was conducted after surgery and at culling. The histological findings revealed that the perforations contributed to higher bone deposition during the initial stages at the graft-receptor bed interface, accelerating the incorporation process. The results of the CT scan showed lower resorption for the perforated group (P≤0.05), and both groups showed high bone density rates at 60 days. This set of evidence is corroborated by the immunohistochemical results, which showed more markers of proteins associated with revascularization and osteogenesis (VEGF, OPN, TRAP and ALP) in the perforated group. These findings indicate that the bone volume of cranial dome grafts is better maintained when the receptor bed is perforated, probably resulting from more effective graft revascularization and greater bone deposition.

ASSUNTO(S)

revascularização Óssea immunohistochemistry bone revascularization enxerto Ósseo de calota craniana imunoistoquímica calvarial bone grafts computerized tomography tomografia computadorizada

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