Yes / Peri-implantitis remains the major impediment to the long-term use of dental implants. With increasing concern over the growth in antibiotic resistance, there is considerable interest in the preparation of antimicrobial dental implant coatings that also induce osseointegration. One such potential coating material is fluorapatite (FA). The aim of this study was to relate the antibacterial effectiveness of FA coatings against pathogens implicated in peri-implantitis to the physicochemical properties of the coating. Ordered and disordered FA coatings were produced on the under and upper surfaces of stainless steel (SS) discs, respectively, using a hydrothermal method. Surface charge, surface roughness, wettability, and fluoride release were measured for each coating. Surface chemistry was assessed using X-ray photoelectron spectroscopy and FA crystallinity using X-ray diffraction. Antibacterial activity against periodontopathogens was assessed in vitro using viable counts, confocal microscopy, and scanning electron microscopy (SEM). SEM showed that the hydrothermal method produced FA coatings that were predominately aligned perpendicular to the SS substrate or disordered FA coatings consisting of randomly aligned rodlike crystals. Both FA coatings significantly reduced the growth of all examined bacterial strains in comparison to the control. The FA coatings, especially the disordered ones, presented significantly lower charge, greater roughness, and higher area when compared to the control, enhancing bacteria−material interactions and therefore bacterial deactivation by fluoride ions. The ordered FA layer reduced not only bacterial viability but adhesion too. The ordered FA crystals produced as a potential novel implant coating showed significant antibacterial activity against bacteria implicated in peri-implantitis, which could be explained by a detailed understanding of their physicochemical properties. / This work was partially funded through WELMEC, a Centre of Excellence in Medical Engineering funded by the Wellcome Trust and EPSRC, under grant number WT 088908/Z/09/Z.

Identification of an appropriate material capable of enamel remineralization to fill a cavity after the removal of dental tissue is a new field of dental research. Elucidation of the associated factors involved in enamel defects remain in question including the mechanisms of enamel hypoplasia as well as improvement needed in our current treatment models. The purpose of this thesis is to evaluate the factors associated with enamel defects, to understand the mechanism by which they evolve, as well as look into a new method of treatment called, fluorapatite cement. This new treatment has shown promising affects to improve our current treatment to restore enamel defects, however, to find the best treatment we must understand the foundations of enamel and how defects arise. Enamel is the strongest tissue in the body because it must maintain resistance to factors such as bacterial adhesion, acidity, and temperature. Enamel defects can present as white spots, discoloration, or deep fissures in the enamel due to a disturbance that occurred during tooth oogenesis. Enamel hypoplasia provides favorable conditions for the early development of caries and the retention of plaque, which can progress and reach deep into the enamel and the dentin and cause sensitivity. Our current treatment is efficient and has been used for decades, however, requires the surrounding health enamel to be removed. This is a disadvantage and has encouraged scientists to continue researching for an effective way to remineralize enamel and avoid the loss of healthy enamel. Diseases such as coeliac disease have an influence on the formation of enamel that lead to defects. A recent study investigated if dentists can play a role in early diagnosis of diseases including coeliac disease by examining patients for enamel defects. The study discovered that there was not a significant difference in oral evaluations to determine upon early diagnosis, however, they did conclude that there was pattern in the types of defects that were found in coeliac patients. Specifically, grade I and II defects were found on the anterior teeth of coeliac patients, therefore, the study still recommends seeing the dentist for oral exams as well as supports further study. To understand the mechanism of how defects arise, scientists studied first permanent molars in children during their first three years of life with factors including, institutionalization, gender, medications, and diseases. Studies showed that females have a two-fold risk for enamel defects over males and institutionalized children have a three-to-four-fold risk of enamel defects. To improve our current treatment and avoid loss of healthy enamel and a costly procedure, scientists are looking into the use of hydroxyapatite (HA), a natural occurring mineral in our body, to create a possible new synthetic enamel called fluorapatite (FA) cement. Research analyzed fluorapatite cement compared to natural enamel and found that FA cement has a stronger resistance to acidity with a weight loss of 0.75% wt% compared to enamel with 1.2% and greater resistance to bacterial adhesion than natural enamel by three times. FA cement was also found to have more stability and higher cellular activity than hydroxyapatite. As for safety for dental application, FA cement and HA were placed in simulated body fluid to test for cytotoxicity levels, and none were present. Therefore, FA cement has a promising approach to restore enamel defects effectively and conveniently. Further research is recommended to understand the association of females and institutionalized children with enamel defects versus all children in a larger study group. The current reported results from fluorapatite cement are very promising. This cement can allow an inexpensive and more efficient method of treatment due to its abilities to remineralize enamel that even stronger than natural enamel. The recent hydroxyapatite and fluoride toothpaste products show the growing research that is being put into this idea of creating a synthetic enamel with our current mineral hydroxyapatite. This thesis supports the idea that FA cement has the potential as an alternative to current treatment for enamel defects and hopefully will be ready to undergo a clinical trial in the near future.

A l'heure actuelle les recherches de nouvelles apatites thermiquement plus stables se développent. Ainsi desdépôts à base de fluoroapatite (Ca10(PO4)6F2) ou de fluorhydroxyapatite fournissent des dépôts plus stables etplus adhérents que l'hydroxyaptite tout en étant biocompatibles. La fluoroapatite (Fap) présente non seulement despropriétés physicochimiques semblables à celles de l'os naturel mais également une bonne résistance à lacorrosion dans le milieu physiologique. La Fap et l'hydroxyapatite (Hap) sont utilisées soit sous forme de dépôt surles parties métalliques de prothèses soit toutefois comme matériaux de comblement osseux. L'utilisation de cesbiocéramiques pose quelques problèmes en raison de leur faible tenue mécanique. L'alumine a été proposée ainsipour ses bonnes propriétés mécaniques et pour sa forte affinité pour le fluor avec lequel elle donne des composéstrès stables. Des dépôts composites Al2O3-Fap et Hap-Fap ont été réalisés par projection thermique. Nous avonsfait varier dans ces composites le pourcentage de fluor. Les résultats obtenus montrent que l'ajout de Fap améliorela résistance mécanique et les propriétés tribologiques de l'Hap et contribue à l'adhésion et à la prolifération descellules osseuses pour les dépôts d'alumine. / A considerable amount of research already focused on ceramic biomaterials given their chemical stabilityand high mechanical strength. On the one hand, Fluorapatite (Fa) has recently attracted some attention as analternative to pure hydroxyapatite (Hap) as coating on metallic implants, given its chemical composition which issimilar to the bone mineral and therefore its excellent biocompatibility. On the other hand, alumina is known for itsexcellent bioinertia and is also one of the most widely investigated bioceramics. In this frame, the aim of our workwas to investigate Al2O3-Fap and Hap-Fap composite coatings deposited on stainless steel substrates usingSpraying processes (APS and SHVOF). The mechanical, micro-structural, tribological and biological (in Vitro and inVivo tests) properties of these composite coatings are determined and analysed in order to determine their possibleuse as surigical implant materials.

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2017-03-27T17:56:33Z No. of bitstreams: 1 Dissertação de Mestrado de ELIZABETH DA COSTA ANHAIA - UFF..pdf: 1042477 bytes, checksum: be29f9090248c95f72b4ed4344942f26 (MD5) / Made available in DSpace on 2017-03-27T17:56:33Z (GMT). No. of bitstreams: 1 Dissertação de Mestrado de ELIZABETH DA COSTA ANHAIA - UFF..pdf: 1042477 bytes, checksum: be29f9090248c95f72b4ed4344942f26 (MD5) / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências- Geoquímica Ambiental. Niterói, RJ / A redistribuição dos radioisótopos presentes em alguns rejeitos industriais, ao provocar aumento na radioatividade natural, representa grave problema para a saúde e para o ambiente. Na produção de ácido fosfórico, o radioisótopo 226Ra é depositado preferencialmente no fosfogesso, resíduo gerado no processo por via úmida. Atualmente, com a produção anual de cerca de 12 milhões de toneladas, há um estoque estimado de mais de 80 milhões de toneladas de fosfogesso no Brasil. O presente trabalho buscou determinar as concentrações do 226Ra presente em uma amostra de fosfogesso, determinar um método de extração eficiente, desenvolver uma metodologia para pré-concentração do 226Ra por sorção em colunas trocadoras de íons e comparar a eficiência da hidroxiapatita e da flúorapatita no seu acondicionamento, de forma a possibilitar a remediação do passivo ambiental da indústria de fertilizantes por remoção do 226Ra, principal contribuinte de radiação de meia vida longa no fosfogesso. A média das concentrações de atividade radioativa encontrada para o 226Ra, na amostra de fosfogesso estudada, foi de 168±11 Bq.kg-1, com eficiência de extração de (82±31)%. O carvão ativado apresentou desempenho (32±3)% superior ao da resina chelex-100 na pré-concentração do 226Ra. Para seu acondicionamento, tanto a hidróxiapatita quanto a flúorapatita, apresentaram resultados satisfatórios, com eficiências globais similares, de (49±24)% e de (52±28)%, respectivamente, a nível laboratorial. Se os valores encontrados fossem extrapolados para a pilha de origem, com atividade estimada em (8,4±0,6)x1010 Bq o acondicionamento, tanto na flúorapatita quanto na hidróxiapatita, poderia promover a remoção de cerca de (4,5±2,6)x1010 Bq. / The redistribution of radioisotopes found in some industrial by-products, by the increasing of the natural radioactivity, represents a serious problem for the health and for the atmosphere. The production of phosphoric acid from natural phosphate rock by the wet process gives rise an industrial by-product called phosphogypsum where the radioisotope 226Ra is preferentially deposited. There are an annual production about 12 million tons and a stock of more than 80 million tons of phosphogypsum in Brazil. The present work aims to determinate the 226Ra radioactive activity present in a phosphogypsum sample, an efficient extraction method, development of a methodology for pré-concentration of the 226Ra by sorption in exchange ions columns and compare the global efficiency of the hydroxyapatite and the fluorapatite in its packaging, in order to turn possible the removal of the 226Ra from the phosphogypsum, by-product of the fertilizers industry. As results, the average of the concentrations of radioactive activity found for the 226Ra in the phosphogypsum samples was of 168±11 Bq.kg-1, with extraction efficiency of (82±31)%. Activated charcoal presented sorption (32±3)% higher than the chelex-100 resin in the pré-concentration of the 226Ra. For its packaging, hydroxyapatite and fluorapatite, presented satisfactory results, with similar global efficiencies around (49±24)% and (52±28)%, respectively, at laboratory level. If the found values were extrapolated to the original stack, with estimated activity of (8,4±0,6)x1010 Bq the packaging, in any of both materials, could remove about (4,5±2,6)x1010 Bq.

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Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-09-21T17:41:19Z No. of bitstreams: 1 LuanaAlves.pdf: 1633592 bytes, checksum: 785a3f9aa7f3fc08d80023603f457b39 (MD5) / Made available in DSpace on 2017-09-21T17:41:19Z (GMT). No. of bitstreams: 1 LuanaAlves.pdf: 1633592 bytes, checksum: 785a3f9aa7f3fc08d80023603f457b39 (MD5) Previous issue date: 2017-07-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão / Bioactive borate glass has presented superior results then bioactive silicate glasses, when compared its conversion rates in apatite and its potential of bioactivity. In this work, new Borate glasses with the basic 60B2O3 - 4P2O5 - 18Na2O – xCaF2 – (18-xCaO), com x = 0, 5 e 10 % wt were synthesized, and investigated the influence of CaF2 addition on bioactivity of samples in vitro, in a period of 28 days in a simulator of the body fluid (SBF). This bioactivity was investigated by means of X-ray diffraction (DRX), Raman Spectroscopy, FTIR and by the measure of pH. DRX measures, prior to immersion, presented wide bands, evidencing the amorphous structure of glasses. The results of density, thermal analysis, XRD, Raman and FTIR show that the addition of CaF2, until 10 % wt, did not cause significant changes in samples network structure. The thermal stability for all samples was calculated from DSC data and all presented values up to 120°C. The results of pH of SBF solution show increase from for 24 hours, which contributes to the dissolution of the outermost layer of the glass and the precipitation of apatite. In XRD data for 60B sample soaked in SBF for 7 days, there was formation of crystalline peaks, at 26° and 32° (2ϴ), in all measures. These peaks correspond to patterns of hydroxyapatite (HA). The XRD spectra in 60B5CaF and 60B10CaF, soaked in SBF for 7 days, presented peaks in 28°(2ϴ) corresponding to fluorapatite (FA), due to the presence of CaF2 in these glasses. Raman and FTIR measurements confirmed what was measured by XRD, showing characteristic peaks of HA and FA for all the samples. Results show that the prepared samples present potential for being used as biomaterials in biomedical applications, such as orthopedics, dentistry and tissue engineering. / Vidros boratos bioativos têm apresentado resultados superiores aos vidros silicatos bioativos, quando comparamos suas taxas de conversão em apatita e seu potencial de bioatividade. Neste trabalho sintetizamos novos vidros boratos com a composição básica 60B2O3 - 4P2O5 - 18Na2O – xCaF2 – (18-xCaO), com x = 0, 5 e 10 % em massa, e investigamos a influência da adição de CaF2 na bioatividade das amostras in vitro, em um período de 28 dias, em um simulador do fluído corporal (SBF). As medidas de DRX, antes da imersão, apresentaram bandas largas, comprovando a estrutura amorfa dos vidros. E verificou-se por meio das análises de Densidade, análise térmica, DRX, Raman e FTIR, que a adição de CaF2 até 10%, em massa, não provocou grandes mudanças estruturais na amostras. Por meio da calorimetria exploratória diferencial, determinamos a estabilidade térmica dos vidros que apresentaram valores acima de 120°C. A bioatividade foi investigada por meio das técnicas de difração de raios-X (DRX), espectroscopia Raman e FTIR, e pela medida do pH da solução SBF. Os resultados obtidos mostraram que, em 24h, houve um aumento no pH da solução SBF, o que contribui para a dissolução da camada mais externa do vidro e sua conversão em apatita. Nos difratogramas (DRX) para as amostras imersas por 7 dias, houve a formação de picos cristalinos, em 26° e 32° (2ϴ), em todas as amostras medidas. Esses picos correspondem aos padrões de hidroxiapatita. A presença de CaF2 na composição das amostras imersas por 7 dias apresentou picos em 28° (2ϴ) correspondendo a fluorapatita. A intensidade destes picos apresentou um aumento em função do tempo de imersão, durante todo período estudado. As medidas de Raman confirmaram os resultados do DRX, apresentando para todas as amostras espectros característicos da hidroxiapatita em 960 cm-1 . As amostras preparadas com CaF2 apresentaram picos em 965 cm-1 , que corresponde a fluorapatita. O FTIR confirmou os resultados apresentados no DRX e Raman, em que todas as amostras apresentaram um pico centrado em 1041 cm-1 para a hidroxiapatita e 1042 cm-1 característico para a fluorapatita. Os resultados demonstram que as amostras preparadas apresentam potencial para serem usados como biomateriais em aplicações biomédicas, como ortopedia, odontologia e engenharia de tecidos.

No description available.

Die vorliegende Dissertation beschäftigt sich mit Wachstum und Aufbau von Fluorapatit-Gelatine-Nanokompositaggregaten. Diese Aggregate werden im sogenannten Doppeldiffusionsversuch biomimetisch erzeugt und ihre äußere Form bzw. Formentwicklung lässt sich anhand eines fraktalen Modells bis ins Detail nachvollziehen. Sie zeigen einen komplexen inneren Aufbau, in dem die Makromoleküle der organischen Komponente einerseits im Zentrum jeder Nanoeinheit und andererseits zu Strängen, den sogenannten Fibrillen, zusammengelagert am Aufbau der Kompositaggregate beteiligt sind. Im Fall des Kompositkeims ist die innere Architektur in hoher Detailstufe verstanden, auch wenn -- insbesondere bezüglich der späteren Wachstumsphasen -- eine Reihe ungeklärter Fragestellungen verbleibt. Ein zentrales Ergebnis der vorliegenden Arbeit bildet die Entdeckung eines weiteren Wachstumstypen, der im Vergleich zu den bekannten, fraktalen Kompositaggregaten grundsätzliche Unterschiede bezüglich des inneren und äußeren Aufbaus zeigt. Der Grund für die andersartige Formentwicklung liegt in der Versteifung der organischen Komponente durch eine vorangegangene Einlagerung von Calciumionen, wie sowohl experimentell als auch mit atomistischen Computersimulationen gezeigt werden konnte. Aufgrund der hohen Komplexität des Systems ist es bislang allerdings nicht möglich, lokale Ionen-Konzentrationen und pH-Werte vor bzw. während Nukleation und Wachstum der Kompositaggregate im Doppeldiffusionsversuch zu bestimmen. Deshalb wurde ein Ersatzversuch -- der sehr ähnlich strukturierte Aggregate erzeugt, sich aber mit rechnerischen Methoden analysieren lässt -- entworfen und untersucht. Anhand dieser Ergebnisse konnte erstmals die "Geschichte" von Fluorapatit-Gelatine-Nanokompositaggregaten detailliert nachvollzogen werden. Da über die Rolle der Gelatine beim Wachstum der Kompositaggregate nur wenig bekannt ist, wurde eine Reihe von Versuchen durchgeführt, in denen Gelatinen mit verschiedenen Molekülmassenverteilungen eingesetzt wurden. Es stellte sich heraus, dass für selbstorganisiertes und insbesondere fraktales Wachstum der Kompositaggregate lange, möglichst wenig gestörte Makromoleküle von zentraler Wichtigkeit sind. Um die Funktion der organischen Komponente für das Kompositwachstum näher zu untersuchen, wurden Oberflächen von Kompositkeimen mit rasterkraftmikroskopischen Methoden studiert. Durch Säuberung der Oberflächen konnten Austrittsstellen der organischen Komponente durch die Oberfläche der Kompositkeime identifiziert werden. Damit konnte gezeigt werden, dass die organische Komponente aus dem Inneren des Festkörpers teilweise durch die Oberfläche dringt und somit während des Wachstums weit in das Gel hineinreichen sollte. Für die mesoskopische Strukturbildung der Kompositaggregate spielen intrinsische elektrische Felder eine essenzielle Rolle. Deshalb wurde bislang eine Wirkung externer elektrischer Felder auf das Wachstum der Kompositaggregate vermutet. Im Rahmen der vorliegenden Arbeit wurde herausgearbeitet, dass es zwar zu keiner direkten Beeinflussung kommen kann, jedoch in den elektrodennahen Bereichen des Gels eine Ordnung der organischen Moleküle durch externe elektrische Felder zu erwarten ist. Dies könnte eine Wirkung auf wachsende Kompositaggregate zeigen. Da diese Effekte auch aufgrund der elektrischen Felder um die dipolaren Kompositaggregate zu erwarten sind, könnte eine ähnliche Strukturierung der Gelatine in der Nähe der wachsenden Kompositaggregate stattfinden. Insgesamt wurden in dieser Arbeit eine Reihe grundlegender Beiträge zur Erforschung der biomimetisch erzeugten Fluorapatit-Gelatine-Nanokompositaggregate geleistet. Es konnten neue Erkenntnisse zur inneren und äußeren Architektur der Kompositaggregate, zu Mechanismen der Morphogenese und deren wichtigsten Einflussgrößen sowie zum Verständnis der chemisch-physikalischen Vorgänge auf atomarer Größenskala gewonnen werden. Als besonders fruchtbar erwies sich die Verbindung von Experimenten mit theoretischen Untersuchungen, so dass dieser Weg auch in Zukunft grundlegende Erkenntnisse bei der Erforschung der Biomineralisation verspricht und weiterhin verfolgt werden sollte.

Made available in DSpace on 2015-03-26T13:51:58Z (GMT). No. of bitstreams: 1 texto completo.pdf: 568781 bytes, checksum: e6beb96802418d9a09f3cb5c6661297e (MD5) Previous issue date: 2013-08-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The use P solubilizing microorganisms are an alternative for a sustainable use of P against a backdrop of depletion of high-grade ores. Nevertheless, the chemical characteristics of rock phosphates (RP), particularly the level of toxic elements, can affect the efficiency of microbial solubilization. Fluoride (F-) released from fluorapatites has been shown to significantly inhibit P solubilization by Aspergillus niger, stimulating the search for alternatives to overcome F- toxicity. Thus, the aim of this study was to select A. niger mutants efficient at P solubilization in the presence of F-. Three selected mutants were also characterized as to their P solubilization mechanisms and the solubilization potential of different P sources. Twenty-nine mutants were obtained that presented changes in their phosphate solubilization activity in comparison to the wild type (WT). The mutant FS1-331 showed higher solubilization of Araxá RP, while FS1-555 promoted higher soluble P when grown in media with calcium phosphate supplemented with F- and in those with pure P sources. These mutants also showed higher tolerance to F- than the WT and displayed changes in the production of organic acids. The higher production of oxalic acid by FS1-331 and FS1-555 correlated with their improved capacity of Araxá RP solubilization. A mutant with decreased P solubilization capacity showed lower production of organic acids, corroborating the importance of these compounds for RP solubilization. FS1-331 was more efficient at solubilizing Araxá, Catalão, and Patos de Minas RPs than the WT and FS1-555. The variation in P solubilization capacity of the mutants obtained in this work may help clarify the RP solubilization mechanisms by A. niger. Moreover, the mutants with better performance selected in this work show potential for use in microbial RP solubilization systems with P sources rich in fluoride. / O uso dos micro-organismos solubilizadores de fosfato (P) é uma alternativa para o uso sustentável do P tendo em vista a diminuição das reservas fosfáticas de alta qualidade. As características químicas dos fosfatos de rocha (FR), em especial o nível de elementos tóxicos, podem influenciar a eficiência de solubilização microbiana. O fluoreto (F-) liberado de fluorapatitas inibi significativamente o processo de solubilização por Aspergillus niger FS1. Assim, o objetivo deste estudo foi selecionar mutantes de A. niger eficientes na solubilização de fosfato na presença de F-. Três mutantes selecionados foram também caracterizados quanto aos mecanismos de solubilização de fosfato e ao potencial de solubilização de diferentes fontes de P. Vinte e nove mutantes com alterações na solubilização de fosfato foram obtidos. O mutante FS1-331 demonstrou maior potencial de solubilização de fosfato de Araxá, enquanto que o mutante FS1-555 aumentou o P solubilizado em meio de cultura com fosfato de cálcio suplementado com F- e naqueles com fontes sintéticas de P. Os mutantes avaliados mostraram maior tolerância ao F- do que o tipo selavagem e tiveram a produção de ácidos orgânicos alterada. A maior produção de ácido oxálico pelos mutantes FS1-331 e FS1-555 relacionou-se com o melhor desempenho dessas estiprpes na solubilização de fosfato de Araxá. Um mutante com solubilização de P diminuída (FS1-375) apresentou menor produção de ácidos orgânicos quando comparado ao tipo selvagem, corroborando a importância desses compostos para o processo de solubilização de FRs. O mutante FS1-331 foi o mais eficiente na solubilização dos FRs de Araxá, Catalão e Patos de Minas. A variação na solubilização de P das estirpes fúngicas estudadas pode contribuir para a melhor compreensão do processo de solubilização de fosfatos por A. niger. Além disso, os mutantes mais eficientes obtidos apresentam alto potencial de aplicação em sistemas microbianos de solubilização de fosfatos com fontes de P ricas em fluoreto.