Morphological And Immunohistochemical Evaluation Of A Resorbable Equine-Derived Bone Substitute. ORAL PRESENTATION

Objectives: The aim of the study was to evaluate, by morphological and immunohistochemical analyses, the in vivo bone regeneration obtained through a resorbable equine-derived particulate biomaterial, and to compare it with autologous bone from calvaria used for the same purpose. Methods: Patients needing pre-prosthetic rehabilitation of the posterior maxilla were treated with sinus lifting using an equine-derived particulate biomaterial (Group 1) or with onlay graft plus sinus lifting through autologous bone of the calvaria (Group 2), according to the severity and the morphology of the bone defect. Bone specimens were withdrawn from regenerated sites six months after grafting; the behavior of the different grafts was tested by histological and immunohistochemical analysis, with attention to the OPG/RANKL ratio and to the expression of proteins involved in the graft integration process, such as TGFβ1, VEGF, BSP, and SPARC. Results: Morphological analysis reveals remnant granules of biomaterial in Group 1 in parallel to a good integration between autologous bone graft and host tissue. TGFβ1 expression does not show any significant difference in the two groups. OPG/RANKL ratio and VEGF expression appear higher in Group 1, while the expression of BSP and SPARC is higher in Group 2. Conclusions: Our results show that both grafts have a close integration with the host tissue, associated with a comparable clinical performance. However, at the same experimental time, autologous graft triggers a more intense regenerative process, driven by the OPG/RANKL/RANK intracellular signaling system, and an active phase of bone remodeling, as showed by elevated BSP and SPARC expression, probably ensuring a better primary stability of the implant and a high predictability of implant-prosthetic rehabilitation