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Browsing by Author "Figueiredo, MH"

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  • Biological response to a bioactive glass coated implant: experimental data
    Publication . Judas, F; Figueiredo, MH; Cabrita, SM; Piedade, AP; Proença, A
    A biomaterial constituted by a metallic titanium alloy (TiAl6V4) coated with a bioglass layer (Na2O (7-24%), K2O (2-8%), CaO (9-20%), Al2O3 (0.1-2%), MgO (0.1-2%), SiO2 (46-53%) and P2O5 (4-8%) was implanted in the cancellous bone of adult rabbit knee, in orthotopic situation, under conditions of mechanical stability. The animals were sacrificed after 30 (Group I), 90 (Group II), and 180 (Group III) days postoperatively. The bone pieces, containing the samples under investigation, were studied using radiographs, optical microscopy, scanning electron microscopy and electron probe micro-analysis. Radiologically, osteointegration of the implant surface was observed in all cases at the 180th day after the surgery. A new bone formation was observed in the animals of Group I and the specimens observed after 90 days of the surgery (Group II) presented a higher amount of new bone tissue. At the 180th day, the bioglass coating of the metallic titanium alloy was not detected and a total contact between the metallic surface and the new bone tissue was observed. The incorporation of the bioglass layer into the bone matrix occurred without interposition of non mineralized tissues and without the presence of inflammatory cells. These results strongly suggest that the studied ceramic coating material of the metallic implant is bioactive, biocompatible, bioresorbable, and possess osteoconductive properties.
    2005Book part Open access Show more
  • Incorporation of impacted morselized bone allografts in rabbits
    Publication . Judas, F; Figueiredo, MH; Cabrita, AS; Proença, A
    Morselized bone allografts have been used for the treatment of bone stock loss in orthopedic revision surgery with encouraging results. However, several parameters can influence the graft incorporation including the processing treatments. This experimental work used a cavitary bone defect in 90 rabbits to evaluate the sequence of incorporation of three different kinds of morselized bone allografts: uncryopreserved cancellous bone, freeze-dried cancellous bone, and totally demineralized cortical bone each of which were prepared in accordance with our rigid protocol. Revascularization and remodeling of the transplanted bone grafts were evident upon histological evaluation. Bone apposition and bone resorption resulted in a mixture of graft and new bone. Mineralized cancellous grafts showed great osteoconductive capacity, whereas demineralized cortical grafts showed an intense osteoinductive capacity and a weak osteoconductive capacity. In a general evaluation, cryopreserved cancellous bone grafts showed superior biological efficacy for reconstruction of experimental bone defects, closely followed by freeze-dried cancellous bone grafts, and, finally, by demineralized cortical bone grafts. These results validate our protocol for the processing and preservation of these three kinds of bone grafts.
    2005Journal article Open access Show more