Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 235-253) Also available online.

Thesis (doctoral)--Lund University, 1993. / Added t.p. with thesis statement inserted.

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Dr. J. Carson Meredith. Part of the SMARTech Electronic Thesis and Dissertation Collection.

The thesis describes a study of the modifications of orthopaedic Ti-based substrates using nanomaterials, and the evaluation of their biocompatibility for further use as implant material, with the aim to develop new, biocompatible β-Ti/CNT composite materials. Traditionally, CNTs require the presence of a transition metal catalyst such as Fe, Ni, Co, for successful growth. Different aspects of a catalyst-assisted CVD MWCNTs growth on various Ti-based substrates including bulk, thin films and 3D porous scaffolds, have been investigated. Low concentrations of catalyst were deposited using spin coating on titanium substrates of various forms and shapes. A strong influence of the surface topography was observed. In contrast, no effect of the elemental composition of the substrate could be detected. To evaluate the biocompatibility of the newly created materials, cell culture studies using fetal human osteoblasts (fHobs) were performed. It was shown that β-Ti/MWCNTs samples possess good initial osteoblast attachment, but no long-term osteoblast activity. Hence the biocompatibility of isolated (i.e. without a Ti substrate) MWCNTs was studied, using MWCNT carpets and various types of MWCNTs buckypapers. All the samples revealed very low cell activity. While β-Ti/MWCNTs samples did not exhibit good biocompatibility, alternative β-Ti/TiC samples were synthesized with a simple CVD method and revealed good osteoblast response with increased mineralization. Moreover, good corrosion resistance and mechanical properties of β-Ti/TiC samples have been reported. Finally, successful method for non-catalytic CVD MWCNTs growth on Ti substrates was developed for the first time, thereby excluding potentially toxic catalysts from the implant material. CVD was performed with acetylene precursor on bulk titanium substrates etched with Piranha solution, which generated an appropriate surface to foster MWCNTs growth. A combination of the change in the surface roughness, improved hydrophilicity, and elemental composition of the surface as a result of the Piranha etching is likely to be responsible for the successful formation of MWCNTs.

No description available.

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Submitted by Suelen Simões Amaral (suelensimoes@live.com) on 2018-05-16T18:24:52Z No. of bitstreams: 1 Amaral_SS_Dissertacao.pdf: 1299570 bytes, checksum: f6d0db234b66c92f7344ce7348080127 (MD5) / Approved for entry into archive by Silvana Alvarez null (silvana@ict.unesp.br) on 2018-05-16T23:30:55Z (GMT) No. of bitstreams: 1 amaral_ss_me_sjc.pdf: 1299570 bytes, checksum: f6d0db234b66c92f7344ce7348080127 (MD5) / Made available in DSpace on 2018-05-16T23:30:55Z (GMT). No. of bitstreams: 1 amaral_ss_me_sjc.pdf: 1299570 bytes, checksum: f6d0db234b66c92f7344ce7348080127 (MD5) Previous issue date: 2018-05-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo do trabalho foi analisar in vitro o comportamento de osteoblastos MG-63 em contato com membranas reabsorvíveis porosas de poli (ácido lático) (PLA) e policaprolactona (PCL), incorporadas com fibras cerâmicas de silicato de cálcio (CaSiO3), visando aplicação na regeneração óssea guiada. Foram utilizados seis grupos experimentais, a partir da concentração do teor de CaSiO3, PLA P; PLA + 5% CaSiO3; PLA + 10% CaSiO3; PCL P; PCL + 5% CaSiO3; PCL + 10% CaSiO3, e o grupo controle. Foram avaliadas viabilidade celular, genotoxicidade; produção de proteína total, atividade de fosfatase alcalina e formação matriz mineralizada. Bem como, a influência das membranas poliméricas na redução de biofilmes monotípicos de Enterococcus faecalis quando associadas ou não a solução de gluconato de clorexidina a 0,12%. Os dados foram analisados por ANOVA e Tukey (p<0.05%). Os resultados mostraram que nenhum grupo experimental foi citotóxico, mas os grupos PCL P, PLA 5%, PLA P e PCL 10% apresentaram maior viabilidade celular com diferença estatística dos grupos PCL 5% e PLA 10% (p<0.05). No teste de genotoxicidade os grupos experimentais não foram genotóxicos, já que apresentaram números de micronúcleos semelhantes ou menores ao grupo controle (p>0.05). Todos os grupos experimentais apresentaram proteína total e atividade de fosfatase alcalina semelhante estatisticamente ao controle (p>0.05) e permitiram a formação de matriz mineralizada. Com relação à redução de biofilme, os grupos experimentais PCL P e PCL 10% apresentaram maior redução de biofilme para Enterococcus faecalis com diferença estatística (p<0.05) do PCL 5% e do controle. Nos grupos experimentais de PLA, todas as membranas promoveram maior redução de biofilme com diferença estatística (p<0.05) do grupo controle. Entretanto quando os grupos experimentais de PCL, bem como de PLA foram tratados com gluconato de clorexidina, observou-se redução do biofilme em todos os grupos, sem diferença estatística do grupo controle (p>0.05). Concluiu-se que as membranas poliméricas são biomateriais adequados para o uso em regeneração óssea guiada. Da mesma maneira, pareceram contribuir para a osteogênese e redução de biofilme de Enterococcus faecalis. / The objective of this study was to analyze the behavior of MG-63 osteoblasts in contact with poly (lactic acid) (PLA) and polycaprolactone (PCL) porous resorbable membranes, incorporated with calcium silicate ceramic fibers (CaSiO3), aiming application in bone regeneration guided in periapical lesions. Six experimental groups were used, from the concentration of CaSiO3, PLA P; PLA + 5% CaSiO3; PLA + 10% CaSiO3; PCL P; PCL + 5% CaSiO3; PCL + 10% CaSiO3, and the control group. Cell viability, genotoxicity; total protein production, alkaline phosphatase activity and mineralized matrix formation. As well as the influence of polymer membranes on the reduction of monotypic biofilms of Enterococcus faecalis when associated with 0.1% chlorhexidine gluconate solution. Data were analyzed by ANOVA and Tukey (p <0.05%). The results showed that no experimental group was cytotoxic, but the PCL P, PLA 5%, PLA P and PCL 10% groups presented higher cell viability with a statistical difference between PCL 5% and PLA 10% (p <0.05). In the genotoxicity test, the experimental groups were not genotoxic, since they had similar or smaller numbers of micronuclei to the control group (p> 0.05). All experimental groups presented total protein and alkaline phosphatase activity statistically similar to the control (p> 0.05) and allowed the formation of mineralized matrix. Regarding the biofilm reduction, the PCL P and PCL 10% experimental groups showed a higher biofilm reduction for Enterococcus faecalis with a statistical difference (p <0.05) in PCL 5% and control. In the PLA experimental groups, all membranes promoted a higher biofilm reduction with a statistical difference (p <0.05) in the control group. However, when the PCL and PLA groups were treated with chlorhexidine gluconate, biofilm reduction was observed in all groups, with no statistical difference in the control group (p> 0.05). It was concluded that the polymer membranes are biomaterials suitable for use in guided bone regeneration. In the same way, they appeared to contribute to the osteogenesis and biofilm reduction of Enterococcus faecalis.

Orientador: Mario Roberto Vizioli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-07-27T11:24:17Z (GMT). No. of bitstreams: 1 Ramos_MabelPhilipps_M.pdf: 4905002 bytes, checksum: f8a62f9d47dd3b1915a675f55703713f (MD5) Previous issue date: 2000 / Resumo: O retratamento é a primeira opção para os casos de insucesso da terapia endodôntica. Para que possa ser realizado, é preciso remover o material obturador pré-existente no canal radicular. O uso de solventes facilita este procedimento, além de evitar a ocorrência de acidentes. Um dos requisitos desejáveis é de não serem agressivos aos tecidos periapicais. Sendo assim, a proposta deste estudo foi de avaliar o potencial irritante destes solventes e comparar seus efeitos sobre o tecido subcutâneo de ratos. Para isto, 12 animais foram utilizados, recebendo quatro tubos de polietileno. Três preenchidos com Fibrinol embebido em cada uma das substâncias-teste, ou seja, clorofórmio, eucaliptol e óleo de laranja e um tubo preenchido apenas com Fibrinol que serviu de controle. Os animais foram sacrificados após 4, 7, 11 e 15 dias, com remoção dos tecidos dorsais que continham os tubos. Após processamento laboratorial das peças incluídas em glicol metracrilato, foram realizados cortes de 3 m m de espessura, corados com hematoxilina e eosina e analisados em microscopia óptica. Os resultados obtidos demonstraram que o óleo de laranja foi o solvente menos irritante. Subjetivamente não foi encontrada diferença entre o poder irritante do eucaliptol e do clorofórmio. Sendo assim, acreditamos que o óleo de laranja possa ser a alternativa mais adequada para a desintegração do material obturador durante o retratamento endodôntico / Abstract: Re-treatment is the first option in case of failure of the endodontic therapy. To enable this process, it is essential to remove the pre-existing filling material of the root canal. The use of solvents facilitates this procedure and helps to avoid accidents. One of the properties required from these solvents is non-aggression to periapical tissues. The aim of this study is, therefore, to evaluate the harmful potential of these solvents and compare their effect on subcutaneous tissue of rats. Twelve rats were used to carry out the experiment. Four polyethylene tubes were implanted in each animal, and these tubes were filled with Fibrinol imbibed in one of the test-substances, which were chloroform, eucalyptol, and orange oil. The fourth tube was filled only with Fibrinol and was used as a control. Animals were killed 4, 7, 11 and 15 days after implant procedures, and dorsal tissues contained in the implants were removed. After laboratory processing of the specimens, which were immersed in metacrylate glycol, three 3 mm-wide sections were made. These sections were stained with hematoxylin and eosin, and analyzed through microscopy. The results showed that the least harmful solvent was the orange oil. Subjectively, no difference was found between the harmful potential of eucalyptol and chloroform. We therefore believe that the orange oil may be the most appropriate alternative for disintegration of filling material during endodontic re-treatment / Mestrado / Mestre em Radiologia Odontológica

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