The ever increasing global demand for materials has placed aluminium as the world’s second most used metal, with world annual production currently >24 million tons. Consequently, the global alumina industry is perpetually striving to meet demands in conjunction with research, development and implementation of more efficient and sustainable processes and practises. Of specific concern for many proponents within the industry is that increased alumina production inadvertently results in increased Bayer Process-derived alkaline solid and liquid waste loads. Furthermore, in-house power generation at all Australian alumina refineries contributes to acid gas emissions, particularly SOx and NOx, both of which have environmental and anthropogenic impacts of global concern. The focus of this work is SO2 emission. SOx emission control measures can be achieved before, during or after combustion; the latter is termed flue gas desulphurisation (FGD). Commercially available FGD systems are dominated by once-through wet processes whereby the flue gas passes up through an absorbtion tower. The most favourable medium for industrial use is seawater, followed by limestone, and in some cases, a combination of both. However, the ever-increasing stringency of environmental emission legislation continues to inflict tighter controls on power production and is forcing industry to investigate alternative cost-effective FGD mediums. Therefore much research is currently dedicated to the utilisation of high volume, alkaline waste streams over manufactured sorbents. Modern environmental engineering approaches to waste product minimisation, neutralisation and/or reuse have lead to many new processes which change the view of many materials from waste product to environmental resource. Subsequently, this work examines the application of an isolated Bayer Process waste product, tricalcium aluminate hexahydrate (TCA6), as a FGD medium. Initial research assessed the dissolution behaviour and performance of the proposed medium with sulphuric acid, followed by batch reactor trials with a simulated flue gas. Data derived from this research indicated the suitability of TCA6 as a FGD medium and was subsequently applied to a preliminary model and proposed design parameters required for further pilot scale investigations. This work provides strong support for an economically viable and more sustainable approach to FGD for the alumina industry.

The ever increasing global demand for materials has placed aluminium as the world’s second most used metal, with world annual production currently >24 million tons. Consequently, the global alumina industry is perpetually striving to meet demands in conjunction with research, development and implementation of more efficient and sustainable processes and practises. Of specific concern for many proponents within the industry is that increased alumina production inadvertently results in increased Bayer Process-derived alkaline solid and liquid waste loads. Furthermore, in-house power generation at all Australian alumina refineries contributes to acid gas emissions, particularly SOx and NOx, both of which have environmental and anthropogenic impacts of global concern. The focus of this work is SO2 emission. SOx emission control measures can be achieved before, during or after combustion; the latter is termed flue gas desulphurisation (FGD). Commercially available FGD systems are dominated by once-through wet processes whereby the flue gas passes up through an absorbtion tower. The most favourable medium for industrial use is seawater, followed by limestone, and in some cases, a combination of both. However, the ever-increasing stringency of environmental emission legislation continues to inflict tighter controls on power production and is forcing industry to investigate alternative cost-effective FGD mediums. Therefore much research is currently dedicated to the utilisation of high volume, alkaline waste streams over manufactured sorbents. Modern environmental engineering approaches to waste product minimisation, neutralisation and/or reuse have lead to many new processes which change the view of many materials from waste product to environmental resource. Subsequently, this work examines the application of an isolated Bayer Process waste product, tricalcium aluminate hexahydrate (TCA6), as a FGD medium. Initial research assessed the dissolution behaviour and performance of the proposed medium with sulphuric acid, followed by batch reactor trials with a simulated flue gas. Data derived from this research indicated the suitability of TCA6 as a FGD medium and was subsequently applied to a preliminary model and proposed design parameters required for further pilot scale investigations. This work provides strong support for an economically viable and more sustainable approach to FGD for the alumina industry.

The ever increasing global demand for materials has placed aluminium as the world’s second most used metal, with world annual production currently >24 million tons. Consequently, the global alumina industry is perpetually striving to meet demands in conjunction with research, development and implementation of more efficient and sustainable processes and practises. Of specific concern for many proponents within the industry is that increased alumina production inadvertently results in increased Bayer Process-derived alkaline solid and liquid waste loads. Furthermore, in-house power generation at all Australian alumina refineries contributes to acid gas emissions, particularly SOx and NOx, both of which have environmental and anthropogenic impacts of global concern. The focus of this work is SO2 emission. SOx emission control measures can be achieved before, during or after combustion; the latter is termed flue gas desulphurisation (FGD). Commercially available FGD systems are dominated by once-through wet processes whereby the flue gas passes up through an absorbtion tower. The most favourable medium for industrial use is seawater, followed by limestone, and in some cases, a combination of both. However, the ever-increasing stringency of environmental emission legislation continues to inflict tighter controls on power production and is forcing industry to investigate alternative cost-effective FGD mediums. Therefore much research is currently dedicated to the utilisation of high volume, alkaline waste streams over manufactured sorbents. Modern environmental engineering approaches to waste product minimisation, neutralisation and/or reuse have lead to many new processes which change the view of many materials from waste product to environmental resource. Subsequently, this work examines the application of an isolated Bayer Process waste product, tricalcium aluminate hexahydrate (TCA6), as a FGD medium. Initial research assessed the dissolution behaviour and performance of the proposed medium with sulphuric acid, followed by batch reactor trials with a simulated flue gas. Data derived from this research indicated the suitability of TCA6 as a FGD medium and was subsequently applied to a preliminary model and proposed design parameters required for further pilot scale investigations. This work provides strong support for an economically viable and more sustainable approach to FGD for the alumina industry.

O crescimento de células em arcabouços tridimensionais porosos tem se tornado progressivamente ativo na engenharia de tecidos. Os arcabouços guiam o crescimento celular, sintetizam uma matriz extracelular e outras moléculas biológicas, e facilitam a formação de tecidos e órgãos funcionais. Um cimento deste tipo pode ser preparado misturando um sal de fosfato de cálcio com uma solução aquosa para que se forme uma pasta que possa reagir à temperatura corporal dando lugar a um precipitado que contenha hidroxiapatita (Ca10(PO4)6(OH)2). A similaridade química e morfológica entre este biomaterial e a parte mineral dos tecidos ósseos permite a osteocondução, sendo o cimento substituído por tecido ósseo novo com o tempo e com a vantagem de não desencadear processos inflamatórios e de corpo estranho, com eventual expulsão do material implantado. O objetivo do presente trabalho foi a obtenção e caracterização de suportes tridimensionais para a engenharia de tecido, com o uso de matérias-primas nacionais, por meio da utilização de microesferas de parafina como corpos geradores de poros. As microesferas foram produzidas por suspensão em solução aquosa de poli (álcool vinílico) (PVA) e sulfato de sódio (Na2SO4). Foram analisadas as fases presentes no cimento sintetizado e após a reação de cura do mesmo, a variação do tamanho de partícula e da resistência mecânica com o tempo de moagem. Foi analisada a porosidade dos suportes e a forma de extração da parafina daqueles que a utilizaram na sua formação. O tamanho de poro dos suportes gerados com a variação da quantidade de fase líquida ficou aquém do tamanho considerado ideal para o crescimento de tecido ósseo. A porosidade dos arcabouços fabricados com esferas de parafina foi observada por microscopia eletrônica de varredura (MEV), e seu comportamento foi analisado a partir de ensaios in vitro em solução SBF (simulated body fluid) e em cultura de células. A utilização de esferas de parafina permitiu a formação de poros com tamanho tal que possibilitam potencialmente o crescimento tecidual e celular. / The growth of cells in three-dimensional porous scaffolds has been extensively studied for use in tissue engineering. They guide grow of cells, synthesize extra cellular matrix and other biological molecules, and facilitate the formation of functional tissues and organs. Bone cements has been developed for biomedical applications for a decade approximately. This kind of cement can be prepared mixing a calcium phosphate salt with aqueous solution forming a paste that can react at body temperature generating a hydroxyapatite precipitated (Ca10(PO4)6(OH)2). The chemical and morphological similarity between the cement composition and the mineral part of the bones allows osteoconduction in the tissue with replacement of cement by new bone formed with the advantage to not unchain inflammatory processes and of strange body. The objective of this work was the use of the α-TCP cement for making these scaffolds, through the variation of the amount of liquid phase in the cement and of the use of paraffin spheres as pore source. These spheres were produced by suspension in water solution of poly (vinyl alcohol) and sodium sulphate (Na2SO4). The phases had been analyzed in the synthesized cement and after the reaction of cure of cement, beyond variation of the particle size and the resistance mechanics with the milling time. It was analyzed the porosity of the scaffolds and the extraction of the paraffin in that supports. The pore size of the supports generated with the variation of the amount of liquid phase was on this side of the size considered ideal for the bone tissue growth. The porosity of scaffolds manufactured with paraffin spheres was observed by Scanning Electron Microscopy (SEM), and its behavior was analyzed from test in vitro in SBF solution (simulated body fluid). The use of paraffin spheres allowed the formation of pores size able to permit tissue growth.

Este trabalho teve como objetivo avaliar as propriedades biológicas de cimentos experimentais a base de resina metacrilato contendo α-tricálcio fosfato (α-TCP) ou hidroxiapatita nanoparticulada (HAp) in vitro e in vivo. Para isto, os cimentos experimentais foram avaliados e comparados com AH Plus (AHP). Na etapa in vitro, os materiais foram mantidos em contato com meio de cultura por 24 horas, coletados e avaliados na concentração de 10%. Células-tronco da papila apical humana (SCAPs) foram submetidas aos ensaios de viabilidade brometo de 3-(4,5-dimetiltiazólio)-2,5-difenil tetrazólio (MTT) e sulfurodamina B (SRB) no período de 24 horas; e a bioatividade foi avaliada pela atividade da enzima fosfatase alcalina (ALP) e deposição de nódulos mineralizados pelo corante vermelho de Alizarina (AR), nos períodos de 1, 5, 10 e 15 dias. Na etapa in vivo, os materiais foram inseridos em tubos de polietileno e colocados no tecido subcutâneo de ratos para avaliação da reação inflamatória, sendo utilizado um tubo vazio como controle e avaliados os períodos de 7, 30 e 90 dias; para avaliação da deposição óssea, os cimentos α-TCP e AHP foram inseridos em cavidades confeccionadas no fêmur de ratos, sendo utilizada uma cavidade vazia como controle e avaliados os períodos de 30 e 90 dias. Para o ensaio de viabilidade e ensaios in vivo, foram utilizados os testes de Kruskal-Wallis e post hoc de Dunn; para avaliação da bioatividade in vitro foram utilizados os testes ANOVA e post hoc de Tukey (P < 0.05). HAp e AHP não apresentaram diferenças estatísticas entre si em ambos os ensaios de citotoxicidade (P> 0,05) e o α-TCP apresentou menor resultado de viabilidade no teste MTT, sendo estatisticamente diferente dos outros (P <0,05). Os ensaios de bioatividade demonstraram aumento na atividade da ALP em todos os grupos (P < 0.05). Observou-se semelhança entre os grupos no primeiro período (P > 0.05), AHP apresentou menores valores em 5 dias (P < 0.05), α-TCP apresentou os maiores valores em 10 dias (P < 0.05), e em 15 dias este cimento foi superior ao AHP (P < 0.05). AR mostrou aumento na quantidade de depósitos mineralizados após 5 dias (P < 0.05). Não houve diferença entre os grupos em 1 dia (P > 0.05), α-TCP, HAp e controle foram semelhantes aos 5 dias (P > 0.05), e em 10 e 15 dias, α-TCP apresentou os maiores valores, sendo diferente dos outros cimentos (P > 0.05). Na avaliação da resposta inflamatória in vivo, observou-se diminuição da inflamação e aumento de fibras colágenas em todos os grupos. Em 7 dias, α-TCP e HAp mostraram resultados semelhantes ao controle CT (P>0.05) e diferentes do AHP (P < 0.05), que foi o único grupo a apresentar células-gigantes neste período. Na avaliação da deposição óssea, houve aumento na deposição de 30 para 90 dias nos grupos α-TCP e controle (P < 0.05), e estes grupos apresentaram resultados semelhantes em 90 dias (P > 0.05), diferindo do AHP (P < 0.05). Conclui-se que a associação de fosfatos de cálcio à resina metacrilato apresentou bons resultados de biocompatibilidade e bioatividade in vitro e in vivo, apresentando potencial para serem utilizados como cimentos obturadores na prática clínica. / This study aimed to evaluate the biological properties of experimental sealers containing α-tricalcium phosphate (α-TCP) or nanoparticulate hydroxyapatite (HAp) in a methacrylate resin-base in vitro and in vivo. For this, the experimental sealers were evaluated and compared with AH Plus (AHP). At the in vitro assays, the materials were kept in contact with culture medium for 24 hours, collected and evaluated at concentrations of 100% and 10%. Stem cells from human apical papilla (SCAPs) were submitted to 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and sulfurodamine B (SRB) viability assays for 24 hour; and bioactivity was evaluated by alkaline phosphatase enzyme activity (ALP) and deposition of mineralized nodules by Alizarin Red staining (AR), for 1, 5, 10 and 15 days. At in vivo assays, the materials were inserted in polyethylene tubes and placed in subcutaneous tissue of rats to evaluate the inflammatory reaction, using an empty tube as control and evaluating the periods of 7, 30 and 90 days; to evaluate bone deposition, α-TCP and AHP cements were inserted into cavities made in the femur of rats, using an empty cavity as control and evaluating the periods of 30 and 90 days. For viability and in vivo assays, Kruskal-Wallis and Dunn’s post hoc tests were used; for bioactivity, ANOVA and Tukey's post hoc tests were used (P < 0.05). HAp and AHP did not presented statistical differences from each other in both citotoxicity assays (P > 0.05), and α-TCP presented a lower viability result in MTT assay, being statistically different from the other sealers (P < 0.05). The bioactivity assays showed an increase in ALP activity for all groups (P < 0.05). Similar results were found between the groups at the first period (P > 0.05), AHP had the lowest values at 5 days (P < 0.05), α-TCP presented the highest values at 10 days (P < 0.05), and at 15 days, this sealer’s values were higher than AHP (P < 0.05). AR showed an increase in the amount of mineralized deposits after 5 days for all sealers (P < 0.05). No difference between groups were found at 1 day (P > 0.05), α-TCP, HAp and control were similar at 5 days (P > 0.05), and at 10 and 15 days, α-TCP presented the highest values, being different of the other sealers (P > 0.05). Regarding the evaluation of the inflammatory response in vivo, there was a decrease in inflammation and increase of collagen fibers in all groups. At 7 days, α-TCP and HAp showed similar results to the control (P > 0.05) and different from AHP (P < 0.05), which was the only group to present giant cells in this period. In the evaluation of bone deposition, there was an increase in deposition from 30 to 90 days for α-TCP and control groups (P < 0.05), and these groups presented similar results in 90 days (P > 0.05), differing from the AHP (P < 0.05). It was concluded that the association of calcium phosphates and methacrylate resin showed good biocompatibility and bioactivity results in vitro and in vivo, presenting potential to be used as endodontic sealers in clinical practice.

Orientador(a): Prof(a). Dr(a). Juliana Marchi / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2016. / A osteomielite e uma inflamacao ossea frequente em traumas diversos, causada por um organismo infectante. O tratamento convencional e o debridamento do osso infectado e dos tecidos moles adjacentes, associado a administracao de antibiotico via sistemica. Este estudo caracterizou o sistema injetavel a base de poloxamer 407 (PL407) . sozinho ou combinado com poloxamer 188 (PL188) . incorporado com o antibiotico teicoplanina e diferentes composicoes de ¿À-TCP (¿À-TCP) dopados com magnesio e/ou zinco, proposto como uma alternativa para o tratamento de osteomielite associada a reparacao ossea. As formulacoes foram caracterizadas por analise estrutural, determinacao da temperatura de transicao sol-gel, avaliacao do perfil de dissolucao das formulacoes e de liberacao da teicoplanina in vitro, e caracterizacao biologica in vitro. Os resultados mostraram que a adicao dos fosfatos tricalcicos e da teicoplanina nao alteraram a reversibilidade termica dos poloxamers, mas a teicoplanina diminuiu as temperaturas de transicao sol-gel. As formulacoes mantiveram uma das caracteristicas vantajosas dos poloxamer: a capacidade de serem injetados na forma liquida na temperatura ambiente e gelificacao proxima a temperatura corporea, ou seja, no local de tratamento. Todas as formulacoes apresentaram baixos valores de tamanho de particulas e reducao da polidispersao apos a adicao da teicoplanina, resultando em formulacoes mais homogeneas. Os fosfatos tricalcicos e a teicoplanina interferiram na agregacao micelar, alterando a entalpia de formacao de micelas e conferindo alta carga de superficie negativa, esta conferindo maior estabilidade ao coloide por repulsao eletrostatica. As formulacoes apresentaram total dissolucao apos 24 horas em contato com o meio de dissolucao e a liberacao da teicoplanina segue o modelo de Higuchi. As formulacoes nao sao citotoxicas e sao positivas para a migracao, proliferacao e diferenciacao celular osteogenica de celulas-tronco de polpa dentaria humana (hDPSCs). Todas as formulacoes apresentaram alta inibicao do crescimento de cepas Gram-positivas, principalmente Staphylococcus aureus, principal agente causador da osteomielite. Os resultados indicaram que as formulacoes a base de poloxamer 407 e 188 (20%:5%, peso/peso) sao promissoras para o carreamento de bioativos, podendo contribuir para um novo material adequado para o tratamento da osteomielite associada a regeneracao ossea. / Osteomyelitis is a inflammation of bone very often in several traumas, caused by an infecting organism. The conventional treatment is the infected bone and adjacente soft tissue debridement, associated with the systemic administration of antibiotic. This study characterized the injectable system based in poloxamer 407 (PL407) - alone or in combination with poloxamer 188 (PL188) - incorporated with the antibiotic teicoplanin and different compositions of â-TCP (â-TCP) doped with magnesium and/or zinc for osteomyelitis treatment associated with bone repair. The formulations were characterized by structural analysis, determination of the sol-gel transition temperature, evaluation of the in vitro dissolution and teicoplanina release profile, and in vitro biological characterization. The results showed that the tricalcium phosphate and teicoplanin did not change the thermal reversibility of poloxamers, but teicoplanin decreased sol-gel transition temperature. The formulations remained one of the advantageous features of poloxamer: the ability to be injected in liquid form at room temperature and near body temperature gelation, in other words, gelation at the treatment site. All formulations showed lower particle size values and decreased of polydispersity after addition of teicoplanin, resulting in more homogeneous formulations. Tricalcium phosphate and teicoplanin interfered in micellar aggregation by changing the micelle formation enthalpy and confering high load negative surface, this resulting in more colloid stability by electrostatic repulsion. The formulations showed complete dissolution after 24 hours in contact with the dissolution medium and teicoplanin release profile follows the Higuchi model. The formulations are non-cytotoxic and are positive for cell migration, proliferation and osteogenic differentiation of human dental pulp stem cells (hDPSCs). All formulations showed high inhibition of the Gram-positive strains growth, particularly Staphylococcus aureus, the most common organism seen in osteomyelitis. The results indicated the poloxamer 407 and 188 based formulations (20%:5%, w/w) are promising to be a bioactive carrier and can contribute to a new material suitable for the osteomyelitis treatment associated with bone regeneration.

O crescimento de células em arcabouços tridimensionais porosos tem se tornado progressivamente ativo na engenharia de tecidos. Os arcabouços guiam o crescimento celular, sintetizam uma matriz extracelular e outras moléculas biológicas, e facilitam a formação de tecidos e órgãos funcionais. Um cimento deste tipo pode ser preparado misturando um sal de fosfato de cálcio com uma solução aquosa para que se forme uma pasta que possa reagir à temperatura corporal dando lugar a um precipitado que contenha hidroxiapatita (Ca10(PO4)6(OH)2). A similaridade química e morfológica entre este biomaterial e a parte mineral dos tecidos ósseos permite a osteocondução, sendo o cimento substituído por tecido ósseo novo com o tempo e com a vantagem de não desencadear processos inflamatórios e de corpo estranho, com eventual expulsão do material implantado. O objetivo do presente trabalho foi a obtenção e caracterização de suportes tridimensionais para a engenharia de tecido, com o uso de matérias-primas nacionais, por meio da utilização de microesferas de parafina como corpos geradores de poros. As microesferas foram produzidas por suspensão em solução aquosa de poli (álcool vinílico) (PVA) e sulfato de sódio (Na2SO4). Foram analisadas as fases presentes no cimento sintetizado e após a reação de cura do mesmo, a variação do tamanho de partícula e da resistência mecânica com o tempo de moagem. Foi analisada a porosidade dos suportes e a forma de extração da parafina daqueles que a utilizaram na sua formação. O tamanho de poro dos suportes gerados com a variação da quantidade de fase líquida ficou aquém do tamanho considerado ideal para o crescimento de tecido ósseo. A porosidade dos arcabouços fabricados com esferas de parafina foi observada por microscopia eletrônica de varredura (MEV), e seu comportamento foi analisado a partir de ensaios in vitro em solução SBF (simulated body fluid) e em cultura de células. A utilização de esferas de parafina permitiu a formação de poros com tamanho tal que possibilitam potencialmente o crescimento tecidual e celular. / The growth of cells in three-dimensional porous scaffolds has been extensively studied for use in tissue engineering. They guide grow of cells, synthesize extra cellular matrix and other biological molecules, and facilitate the formation of functional tissues and organs. Bone cements has been developed for biomedical applications for a decade approximately. This kind of cement can be prepared mixing a calcium phosphate salt with aqueous solution forming a paste that can react at body temperature generating a hydroxyapatite precipitated (Ca10(PO4)6(OH)2). The chemical and morphological similarity between the cement composition and the mineral part of the bones allows osteoconduction in the tissue with replacement of cement by new bone formed with the advantage to not unchain inflammatory processes and of strange body. The objective of this work was the use of the α-TCP cement for making these scaffolds, through the variation of the amount of liquid phase in the cement and of the use of paraffin spheres as pore source. These spheres were produced by suspension in water solution of poly (vinyl alcohol) and sodium sulphate (Na2SO4). The phases had been analyzed in the synthesized cement and after the reaction of cure of cement, beyond variation of the particle size and the resistance mechanics with the milling time. It was analyzed the porosity of the scaffolds and the extraction of the paraffin in that supports. The pore size of the supports generated with the variation of the amount of liquid phase was on this side of the size considered ideal for the bone tissue growth. The porosity of scaffolds manufactured with paraffin spheres was observed by Scanning Electron Microscopy (SEM), and its behavior was analyzed from test in vitro in SBF solution (simulated body fluid). The use of paraffin spheres allowed the formation of pores size able to permit tissue growth.

Made available in DSpace on 2014-12-17T14:57:44Z (GMT). No. of bitstreams: 1 AndreaCSC.pdf: 2806475 bytes, checksum: a164123a8cfe29ac9b333a265d0521fa (MD5) Previous issue date: 2007-09-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The tricalcium phosphate ceramics has been widely investigated in the last years due its bioresorbable behavior. The limiting factor of the application of these materials as temporary implants is its low strength resistance. The tricalcium phosphate presents an allotropic transformation &#946;&#8594;&#945; around 1250 ?C that degrades its resistance. Some studies have been developed in order to densify this material at this temperature range. The objective of this work is to study the influence of the addition of magnesium oxide (MgO) in the sintering of &#946;-TCP. The processing route was uniaxial hot pressing and its objective was to obtain dense samples. The samples were physically characterized through density and porosity measurements. The thermal behavior was studied through dilatometric, thermal differential and thermogravimetric analysis. The mechanical properties were characterized by three point flexure test and Vickers microhardness measurements, analyzed of the microstructure. The addition of magnesium oxide doesn t cause an improvement of the mechanical strength in relation to material without additive. / As cer?micas de fosfato de c?lcio (&#946;-TCP) t?m sido intensamente investigadas nos ?ltimos anos devido as suas caracter?sticas bio - absorv?veis. Um fator limitante da aplica??o destes materiais em implantes tempor?rios ? a sua baixa resist?ncia mec?nica. O tricalciofosfato apresenta uma transforma??o alotr?pica &#946;&#8594;&#945; em torno de 1250 ?C, o que degrada significativamente sua resist?ncia mec?nica. V?rios estudos t?m sido realizados com o intuito de densificar este material nesta faixa de temperatura. O objetivo desse trabalho ? estudar a influ?ncia da adi??o do aditivo (MgO) na sinteriza??o do &#946;-TCP. O m?todo de processamento utilizado foi prensagem uniaxial a quente, teve por objetivo obter corpos densos. As amostras foram caracterizadas por meio de medidas de porosidade aparente e densidade aparente e termicamente por dilatometria, an?lise termogravim?trica e t?rmica diferencial. Os corpos sinterizados foram caracterizados mecanicamente por resist?ncia a flex?o em 3 pontos, microdureza Vickers e an?lise da microestrutura. A adi??o do ?xido de magn?sio n?o ocasionou melhoria na resist?ncia mec?nica em rela??o ao material sem aditivo

Este trabalho teve como objetivo avaliar as propriedades biológicas de cimentos experimentais a base de resina metacrilato contendo α-tricálcio fosfato (α-TCP) ou hidroxiapatita nanoparticulada (HAp) in vitro e in vivo. Para isto, os cimentos experimentais foram avaliados e comparados com AH Plus (AHP). Na etapa in vitro, os materiais foram mantidos em contato com meio de cultura por 24 horas, coletados e avaliados na concentração de 10%. Células-tronco da papila apical humana (SCAPs) foram submetidas aos ensaios de viabilidade brometo de 3-(4,5-dimetiltiazólio)-2,5-difenil tetrazólio (MTT) e sulfurodamina B (SRB) no período de 24 horas; e a bioatividade foi avaliada pela atividade da enzima fosfatase alcalina (ALP) e deposição de nódulos mineralizados pelo corante vermelho de Alizarina (AR), nos períodos de 1, 5, 10 e 15 dias. Na etapa in vivo, os materiais foram inseridos em tubos de polietileno e colocados no tecido subcutâneo de ratos para avaliação da reação inflamatória, sendo utilizado um tubo vazio como controle e avaliados os períodos de 7, 30 e 90 dias; para avaliação da deposição óssea, os cimentos α-TCP e AHP foram inseridos em cavidades confeccionadas no fêmur de ratos, sendo utilizada uma cavidade vazia como controle e avaliados os períodos de 30 e 90 dias. Para o ensaio de viabilidade e ensaios in vivo, foram utilizados os testes de Kruskal-Wallis e post hoc de Dunn; para avaliação da bioatividade in vitro foram utilizados os testes ANOVA e post hoc de Tukey (P < 0.05). HAp e AHP não apresentaram diferenças estatísticas entre si em ambos os ensaios de citotoxicidade (P> 0,05) e o α-TCP apresentou menor resultado de viabilidade no teste MTT, sendo estatisticamente diferente dos outros (P <0,05). Os ensaios de bioatividade demonstraram aumento na atividade da ALP em todos os grupos (P < 0.05). Observou-se semelhança entre os grupos no primeiro período (P > 0.05), AHP apresentou menores valores em 5 dias (P < 0.05), α-TCP apresentou os maiores valores em 10 dias (P < 0.05), e em 15 dias este cimento foi superior ao AHP (P < 0.05). AR mostrou aumento na quantidade de depósitos mineralizados após 5 dias (P < 0.05). Não houve diferença entre os grupos em 1 dia (P > 0.05), α-TCP, HAp e controle foram semelhantes aos 5 dias (P > 0.05), e em 10 e 15 dias, α-TCP apresentou os maiores valores, sendo diferente dos outros cimentos (P > 0.05). Na avaliação da resposta inflamatória in vivo, observou-se diminuição da inflamação e aumento de fibras colágenas em todos os grupos. Em 7 dias, α-TCP e HAp mostraram resultados semelhantes ao controle CT (P>0.05) e diferentes do AHP (P < 0.05), que foi o único grupo a apresentar células-gigantes neste período. Na avaliação da deposição óssea, houve aumento na deposição de 30 para 90 dias nos grupos α-TCP e controle (P < 0.05), e estes grupos apresentaram resultados semelhantes em 90 dias (P > 0.05), diferindo do AHP (P < 0.05). Conclui-se que a associação de fosfatos de cálcio à resina metacrilato apresentou bons resultados de biocompatibilidade e bioatividade in vitro e in vivo, apresentando potencial para serem utilizados como cimentos obturadores na prática clínica. / This study aimed to evaluate the biological properties of experimental sealers containing α-tricalcium phosphate (α-TCP) or nanoparticulate hydroxyapatite (HAp) in a methacrylate resin-base in vitro and in vivo. For this, the experimental sealers were evaluated and compared with AH Plus (AHP). At the in vitro assays, the materials were kept in contact with culture medium for 24 hours, collected and evaluated at concentrations of 100% and 10%. Stem cells from human apical papilla (SCAPs) were submitted to 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and sulfurodamine B (SRB) viability assays for 24 hour; and bioactivity was evaluated by alkaline phosphatase enzyme activity (ALP) and deposition of mineralized nodules by Alizarin Red staining (AR), for 1, 5, 10 and 15 days. At in vivo assays, the materials were inserted in polyethylene tubes and placed in subcutaneous tissue of rats to evaluate the inflammatory reaction, using an empty tube as control and evaluating the periods of 7, 30 and 90 days; to evaluate bone deposition, α-TCP and AHP cements were inserted into cavities made in the femur of rats, using an empty cavity as control and evaluating the periods of 30 and 90 days. For viability and in vivo assays, Kruskal-Wallis and Dunn’s post hoc tests were used; for bioactivity, ANOVA and Tukey's post hoc tests were used (P < 0.05). HAp and AHP did not presented statistical differences from each other in both citotoxicity assays (P > 0.05), and α-TCP presented a lower viability result in MTT assay, being statistically different from the other sealers (P < 0.05). The bioactivity assays showed an increase in ALP activity for all groups (P < 0.05). Similar results were found between the groups at the first period (P > 0.05), AHP had the lowest values at 5 days (P < 0.05), α-TCP presented the highest values at 10 days (P < 0.05), and at 15 days, this sealer’s values were higher than AHP (P < 0.05). AR showed an increase in the amount of mineralized deposits after 5 days for all sealers (P < 0.05). No difference between groups were found at 1 day (P > 0.05), α-TCP, HAp and control were similar at 5 days (P > 0.05), and at 10 and 15 days, α-TCP presented the highest values, being different of the other sealers (P > 0.05). Regarding the evaluation of the inflammatory response in vivo, there was a decrease in inflammation and increase of collagen fibers in all groups. At 7 days, α-TCP and HAp showed similar results to the control (P > 0.05) and different from AHP (P < 0.05), which was the only group to present giant cells in this period. In the evaluation of bone deposition, there was an increase in deposition from 30 to 90 days for α-TCP and control groups (P < 0.05), and these groups presented similar results in 90 days (P > 0.05), differing from the AHP (P < 0.05). It was concluded that the association of calcium phosphates and methacrylate resin showed good biocompatibility and bioactivity results in vitro and in vivo, presenting potential to be used as endodontic sealers in clinical practice.

O crescimento de células em arcabouços tridimensionais porosos tem se tornado progressivamente ativo na engenharia de tecidos. Os arcabouços guiam o crescimento celular, sintetizam uma matriz extracelular e outras moléculas biológicas, e facilitam a formação de tecidos e órgãos funcionais. Um cimento deste tipo pode ser preparado misturando um sal de fosfato de cálcio com uma solução aquosa para que se forme uma pasta que possa reagir à temperatura corporal dando lugar a um precipitado que contenha hidroxiapatita (Ca10(PO4)6(OH)2). A similaridade química e morfológica entre este biomaterial e a parte mineral dos tecidos ósseos permite a osteocondução, sendo o cimento substituído por tecido ósseo novo com o tempo e com a vantagem de não desencadear processos inflamatórios e de corpo estranho, com eventual expulsão do material implantado. O objetivo do presente trabalho foi a obtenção e caracterização de suportes tridimensionais para a engenharia de tecido, com o uso de matérias-primas nacionais, por meio da utilização de microesferas de parafina como corpos geradores de poros. As microesferas foram produzidas por suspensão em solução aquosa de poli (álcool vinílico) (PVA) e sulfato de sódio (Na2SO4). Foram analisadas as fases presentes no cimento sintetizado e após a reação de cura do mesmo, a variação do tamanho de partícula e da resistência mecânica com o tempo de moagem. Foi analisada a porosidade dos suportes e a forma de extração da parafina daqueles que a utilizaram na sua formação. O tamanho de poro dos suportes gerados com a variação da quantidade de fase líquida ficou aquém do tamanho considerado ideal para o crescimento de tecido ósseo. A porosidade dos arcabouços fabricados com esferas de parafina foi observada por microscopia eletrônica de varredura (MEV), e seu comportamento foi analisado a partir de ensaios in vitro em solução SBF (simulated body fluid) e em cultura de células. A utilização de esferas de parafina permitiu a formação de poros com tamanho tal que possibilitam potencialmente o crescimento tecidual e celular. / The growth of cells in three-dimensional porous scaffolds has been extensively studied for use in tissue engineering. They guide grow of cells, synthesize extra cellular matrix and other biological molecules, and facilitate the formation of functional tissues and organs. Bone cements has been developed for biomedical applications for a decade approximately. This kind of cement can be prepared mixing a calcium phosphate salt with aqueous solution forming a paste that can react at body temperature generating a hydroxyapatite precipitated (Ca10(PO4)6(OH)2). The chemical and morphological similarity between the cement composition and the mineral part of the bones allows osteoconduction in the tissue with replacement of cement by new bone formed with the advantage to not unchain inflammatory processes and of strange body. The objective of this work was the use of the α-TCP cement for making these scaffolds, through the variation of the amount of liquid phase in the cement and of the use of paraffin spheres as pore source. These spheres were produced by suspension in water solution of poly (vinyl alcohol) and sodium sulphate (Na2SO4). The phases had been analyzed in the synthesized cement and after the reaction of cure of cement, beyond variation of the particle size and the resistance mechanics with the milling time. It was analyzed the porosity of the scaffolds and the extraction of the paraffin in that supports. The pore size of the supports generated with the variation of the amount of liquid phase was on this side of the size considered ideal for the bone tissue growth. The porosity of scaffolds manufactured with paraffin spheres was observed by Scanning Electron Microscopy (SEM), and its behavior was analyzed from test in vitro in SBF solution (simulated body fluid). The use of paraffin spheres allowed the formation of pores size able to permit tissue growth.