The aim of this work was to investigate the immunohistochemical and histologic patterns occurring in samples obtained from sites reconstructed with calvarial bone graft, 4 months (T1) and 10 years (T2) after grafting, in comparison to those observed in samples from the calvaria taken from the donor sites at the moment of withdrawal for the grafting (T0).
Samples underwent immunohistochemical analysis for bone sialoprotein, matrix metalloproteinases 2 and 9, vascular endothelial growth factor, and Bax expressions; terminal-deoxynucleotidyl-transferase-mediated dUTP nick end-labeling analysis to evaluate the number of apoptotic samples; and morphologic evaluation after hematoxylin and eosin staining.
The expression levels of all the investigated molecules, such as the apoptotic cells' count, showed a significant (P < 0.05) increase in T1 samples, that is, 4 months after grafting, although their expression levels recorded after 10 years seemed to be comparable to those in the native bone. Moreover, at observation under the light microscope, T1 samples showed a nonuniform morphology, with mineralized areas surrounded by connective tissues where blood vessels could be distinguished. On the other hand, T0 and T2 samples showed a similar aspect, characterized by uniform areas of mineralized extracellular matrix with cavities containing osteocytes.
These data suggest that, after approximately 4 months, it is possible to highlight stronger remodeling phenomena, accompanied by new bone formation and new blood vessel proliferation, which are necessary to the host tissue for graft integration. On the contrary, these phenomena could not be observed in samples obtained after a long period (T2), which reveal a morphologic and an immunohistochemical pattern comparable to that recorded in calvarial native bone (T0).