BSP and BAX Immunohistochemical analysis: Calvaria vs Iliac Crest Graft

Objectives: In this study was evaluated by immunohistochemical analysis the activity of molecules involved in the process of bone remodeling during the integration period (T1) and at a distance of 10 years (T2) of extraoral autologous bone grafts from two different donor sites: calvaria and iliac crest. Methods: Calvaria and Iliac Crest bone grafts were used to fill bone defects in edentulous sites. Specimens from the donor sites were withdrawn at the moment of grafts insertion (T0), and from regenerated sites four months (T1) and ten years (T2) after grafting. Samples at different experimental times were processed in order to investigate the levels of expression of Bone Sialoprotein (BSP) and pro-apoptotic molecule BAX by immunohystochemical analysis. Moreover was investigated the number of apoptotic cells by the Tunel analysis. Results: In our study, it was possible to evaluate that BSP and BAX were significantly more expressed in samples T1 compared to that observed in samples T0. The higher level of BSP in samples T1 indicates an intense activity of osteoblast differentiation and mineralization of the extracellular matrix; while the highest levels of BAX indicate an increase in apoptosis associated with remodeling. In T2 samples their expression return to levels comparable to that recorded in specimens from the donor sites. Moreover, in any samples from sites treated with calvaria grafts, all the investigated molecules showed higher levels of expression than in samples from sites regenerated with iliac crest bone grafts. Conclusions: These data confirm that calvaria and iliac crest bone graft, because of its biomechanical characteristics, but also biomolecular intrinsic qualities, is the most suitable to realize bone grafts since it shows, several years later insertion, complete integration with host tissue.