Evaluation of strontium-containing hydroxyapatite as bone substitute in sheep tibiae.

With the advancement of research in biomaterials, it has been suggested that the best osteoconductivity of hydroxyapatite would be achieved if its crystal were closer to the structure, size and morphology of biological apatite, that is why nano-hydroxyapatite (nano-HA) is of great importance. current interest. Strontium ions are known to reduce bone resorption, induce osteoblastic activity and stimulate bone formation. The aim of this study was to evaluate biocompatibility and osteoconduction in surgical defects filled with nano-hydroxyapatite microspheres containing 1% strontium (nano-SrHA), stoichiometric nano-HA microspheres (nano-HA) compared to the clot (control) . Four Santa Inês sheep, weighing an average of 32 kg, were anesthetized and submitted to three 2 mm diameter perforations in the medial face of the tibia. The surgical defects were filled with blood clot, microspheres of Sr-HA 1% and microspheres of HA. After 30 days the samples were drawn (6 mm), decalcified, processed for inclusion in paraffin and stained with hematoxylin and eosin (HE) for histological evaluation with light microscopy. All groups revealed bone neoformation from the periphery to the center of the defect, with the nano-SrHA group being less intense among those studied. Presence of a discrete mononuclear inflammatory infiltrate in all experimental groups. Giant foreign body cells were only observed in the HA group. Areas of bone neoformation were observed in close contact with both biomaterials. According to the results obtained, microspheres of HA and SrHA 1% are biocompatible and have osteoconductive properties.With the advancement of research in biomaterials, it has been suggested that the best osteoconductivity of hydroxyapatite would be achieved if its crystal were closer to the structure, size and morphology of biological apatite, that is why nano-hydroxyapatite (nano-HA) is of great importance. current interest. Strontium ions are known to reduce bone resorption, induce osteoblastic activity and stimulate bone formation. The aim of this study was to evaluate biocompatibility and osteoconduction in surgical defects filled with nano-hydroxyapatite microspheres containing 1% strontium (nano-SrHA), stoichiometric nano-HA microspheres (nano-HA) compared to the clot (control) . Four Santa Inês sheep, weighing an average of 32 kg, were anesthetized and submitted to three 2 mm diameter perforations in the medial face of the tibia. The surgical defects were filled with blood clot, microspheres of Sr-HA 1% and microspheres of HA. After 30 days the samples were drawn (6 mm), decalcified, processed for inclusion in paraffin and stained with hematoxylin and eosin (HE) for histological evaluation with light microscopy. All groups revealed bone neoformation from the periphery to the center of the defect, with the nano-SrHA group being less intense among those studied. Presence of a discrete mononuclear inflammatory infiltrate in all experimental groups. Giant foreign body cells were only observed in the HA group. Areas of bone neoformation were observed in close contact with both biomaterials. According to the results obtained, microspheres of HA and SrHA 1% are biocompatible and have osteoconductive properties

Early osseointegration driven by the surface chemistry and wettability of dental implants

Objective The objective of this study was to investigate the impact of two different commercially available dental implants on osseointegration. The surfaces were sandblasting and acid etching (Group 1) and sandblasting and acid etching, then maintained in an isotonic solution of 0.9% sodium chloride (Group 2). Material and Methods X-ray photoelectron spectroscopy (XPS) was employed for surface chemistry analysis. Surface morphology and topography was investigated by scanning electron microscopy (SEM) and confocal microscopy (CM), respectively. Contact angle analysis (CAA) was employed for wetting evaluation. Bone-implant-contact (BIC) and bone area fraction occupied (BAFO) analysis were performed on thin sections (30 μm) 14 and 28 days after the installation of 10 implants from each group (n=20) in rabbits' tibias. Statistical analysis was performed by ANOVA at the 95% level of significance considering implantation time and implant surface as independent variables. Results Group 2 showed 3-fold less carbon on the surface and a markedly enhanced hydrophilicity compared to Group 1 but a similar surface roughness (p>;0.05). BIC and BAFO levels in Group 2 at 14 days were similar to those in Group 1 at 28 days. After 28 days of installation, BIC and BAFO measurements of Group 2 were approximately 1.5-fold greater than in Group 1 (

Cytocompatibility and biocompatibility of nanostructured carbonated hydroxyapatite spheres for bone repair

Objective The aim of this study was to investigate the in vitro and in vivo biological responses to nanostructured carbonated hydroxyapatite/calcium alginate (CHA) microspheres used for alveolar bone repair, compared to sintered hydroxyapatite (HA). Material and Methods The maxillary central incisors of 45 Wistar rats were extracted, and the dental sockets were filled with HA, CHA, and blood clot (control group) (n=5/period/group). After 7, 21 and 42 days, the samples of bone with the biomaterials were obtained for histological and histomorphometric analysis, and the plasma levels of RANKL and OPG were determined via immunoassay. Statistical analysis was performed by Two-Way ANOVA with post-hoc Tukey test at 95% level of significance. Results The CHA and HA microspheres were cytocompatible with both human and murine cells on an in vitro assay. Histological analysis showed the time-dependent increase of newly formed bone in control group characterized by an intense osteoblast activity. In HA and CHA groups, the presence of a slight granulation reaction around the spheres was observed after seven days, which was reduced by the 42nd day. A considerable amount of newly formed bone was observed surrounding the CHA spheres and the biomaterials particles at 42-day time point compared with HA. Histomorphometric analysis showed a significant increase of newly formed bone in CHA group compared with HA after 21 and 42 days from surgery, moreover, CHA showed almost 2-fold greater biosorption than HA at 42 days (two-way ANOVA,

Alvéolo dentário de ratos wistar como modelo experimental - 10 anos de experiência

Objetivo: o objetivo deste trabalho é mostrar a experiência adquirida com esse modelo experimental, relatando a técnica, vantagens, desvantagens e indicações através das cirurgias experimentais realizadas para implantação de diversos biomateriais osseocondutora em alvéolo dentário de ratos Wistar, em pesquisas durante os últimos 10 anos. Resultados (Revisão): o uso de biomateriais como substitutos ósseos em alternativa aos enxertos autógenos continua sendo de grande discussão na comunidade científica. Apesar dos enxertos autógenos serem considerados padrão ouro para reconstruções, oferecendo as propriedades necessárias para que o processo de regeneração ocorra, estes apresentam restrições como limitação de quantidade, aumento da morbidade, além da imprevisibilidade do grau de bioabsorção no período cicatricial. Diversas propriedades devem ser determinadas para assegurar ao biomaterial a sua competência e seu adequado uso em humanos. No intuito de avaliar a capacidade osseocondutora, bioabsorção e a eficiência carreadora dos biomateriais substitutos ósseos, o modelo experimental de alvéolos dentários em ratos vem se mostrando eficaz, de acordo com as diretrizes do Programa 3Rs. Todas as cirurgias foram realizadas nas instalações do Núcleo de Animais de Laboratório (NAL) do Laboratório de Experimentação Animal (LEA) em parceria com a faculdade de Medicina Veterinária da Universidade Federal Fluminense. Conclusão: os Ratos Wistars são excelentes modelos animais devido às semelhanças fisiológicas com humanos, boa disponibilidade, fácil manipulação e possibilidade de padronização do modelo experimental. Ao longo dos 10 anos de experiência, a utilização do modelo experimental permitiu o desenvolvimento e comprovação de novos biomateriais como substitutos ósseos

A hidroxiapatita contendo zinco a 0,5% como substituto ósseo: caracterização físico-química e análise normatizada da biocompatibilidade

O zinco é conhecido por apresentar um papel relevante no crescimento e no desenvolvimento humano, tem efeitos estimulatórios na formação do osso in vitro e in vivo e um efeito inibitório na reabsorção óssea in vitro. As apatitas biológicas apresentam baixa cristalinidade e contém substituições catiônicas e aniônicas na estrutura do cristal, por essas razões a sua composição difere da hidroxiapatita estequiométrica. Mudanças na composição da hidroxiapatita é motivo de estudos com a finalidade de melhorar a resposta do tecido ósseo após a implantação. O objetivo deste estudo foi de investigar o efeito da zincoapatita 0,5% em comparação com a hidroxiapatita (grupo controle) no reparo ósseo em tíbias de coelhos. Os cilindros (2x6 mm) de ambos os materiais foram produzidos de acordo com a especificação da International Organization for Standardization. Esse projeto foi aprovado pelo Comitê de Ética do Hospital Universitário Antônio Pedro-195/06. Quinze coelhos Branco da Nova Zelândia foram submetidos à anestesia geral e duas perfurações (2 mm) foram feitas em cada tíbia para a implantação de dois cilindros de zincoapatita (tíbia esquerda) e dois cilindros de hidroxiapatita (tíbia direita). Após 1, 2 e 4 semanas, os animais foram mortos e um fragmento de cada tíbia com cilindro foi removido, desmineralizado e cortes de 6 μm de espessura foram realizados e corados com Hematoxilina e Eosina para a análise histomorfométrica. O segundo bloco de cada tíbia foi coletado, incluído em resina e cortado (30 μm e 200 μm) paralelo ao longo eixo do implante com um disco diamantado de precisão. As amostras com ≅200 μm de espessura foram analisadas por Microfluorescência de Raios X com Radiação Síncroton e Espectroscopia de Infravermelho. As amostras de ≅30 μm foram analisadas em microscopia de luz (campo claro e luz polarizada). Na Microscopia Eletrônica de Varredura, foram utilizados os blocos de resina metalizados e para a Microscopia Eletrônica de Transmissão cortes de ≅70-90nm foram realizados. A análise histomorfométrica mostrou que após 28 dias o grupo zincoapatita mostrou maior área de osso neoformado (p<0,05). As análises de Fluorescência de Raios X, Absorção Atômica e Microfluorescência de Raios X confirmaram a presença do zinco nas amostras experimentais de hidroxiapatita contendo zinco, mas em dose inferior a dose teórica inicial. A Microscopia Eletrônica de Varredura e Transmissão mostraram heterogeneidade na superfície dos cilindros e nos grãos, respectivamente. A difração de Raios X evidenciou uma diminuição da cristalinidade da zincoapatita e o aparecimento de uma nova fase na zincoapatita após o processo de sinterização. A realização dos procedimentos normatizados facilitou o planejamento, execução e a análise comparativa dos resultados. As propriedades químicas e físicas dos biomateriais foram alteradas após a incorporação do zinco e da implantação. Ambos os materiais são biocompatíveis e osteocondutores e não houve diferença entre os materiais no reparo ósseo aos 28 diasZinc is known to play a relevant role in growth and development, it has stimulatory effects on in vitro and in vivo bone formation and an inhibitory effect on in vitro osteoclastic bone resorption. The inorganic component of the bone tissue is nonstoichiometric apatite; changes in the composition of hydroxyapatite (HA) are subject of studies in order to improve the tissue response after implantation. The objective of this study was to investigate the effect of 0.5% zinc-containing hydroxyapatite (ZnHA) in comparison to hydroxyapatite (HA, control group), on osseous repair of rabbit’s tibia. Cylinders (2X6mm) of both materials were produced according to the specification of the International Organization for Standardization (ISO). Ethics Commission on Teaching and Research in Animals approved this project (HUAP-195/06). Fifteen White New Zealand rabbits were submitted to general anesthesia and two perforations (2mm) were made in each tibia for implantation of ZnHA cylinders (left tibia) and HA cylinders (right tibia). After 1, 2 and 4 weeks, the animals were killed and one fragment of each tibia with the cylinder was collected, demineralized and 6-μm thick semi-serial sections were done for histomorphometric analysis. The second fragment of each tibia was collected and embedded in a methacrylate-based resin and cut into slices (~30 μm and ~200 μm thickness), parallel to the implant’s long axis with a precision diamond saw. The specimens with ~30 μm thickness were analyzed by light microscopy (bright field and polarized microscopy). For the Scanning Electron Microscopy and Transmission Electron Microscopy it was used an entire metalized resin block and slices with ≅70-90nm, respectively. The histomorphometric analysis revealed after 28 days that the zinc containing hydroxyapatite group showed greater area of new bone formation (p<0,05). The X-Ray Fluorescence, Atomic Absorption Spectroscopy and X-Ray Microfluorescence confirmed the presence of zinc in the experimental ZnHA specimens, however in lower quantity than the theoretical dose. The TEM and SEM analysis showed heterogeneous grains and cylinders surface, respectively. The Xray diffraction showed a decrease of ZnHA crystallinity and a new phase (CaZnTCP) was formed after the thermal treatment. The accomplishment of the standard procedures helped the planning, execution and the comparative analysis of the results. The chemical and physical properties of the biomaterials were modified after its implantation and the incorporation of zinc. Both materials are biocompatible and promote osteoconduction and no difference was found between the materials in bone repair238f