A Estomatite protética associada a Candida (EPC) acomete a mucosa bucal em contato com próteses removíveis e, clinicamente, caracteriza-se por eritema com diferentes graus de inflamação. Esta doença é considerada de etiologia multifatorial, isto é, uma associação de fatores como trauma, falta de higienização, uso contínuo da prótese, hipersensibilidade ao material usado na dentadura, diabetes, terapia imunossupressora e infecção por fungo, como diferentes espécies de Candida. Os principais fatores de virulência deste fungo são a formação de hifas, dimorfismo, alterações fenotípicas, aderência, persistência, sinergismo com as bactérias, interferências com o sistema de defesa do hospedeiro e a produção de enzimas hidrolíticas. Dentre as enzimas hidrolíticas, a proteinase aspartil secretada (SAP) é uma das mais importantes para a patogenia de C. albicans, sendo nociva para o tecido epitelial e para o sistema imune do hospedeiro. Não está totalmente compreendida a real penetração do fungo nos tecidos e sua correlação com a presença da SAP, na doença estomatite protética. Essa dificuldade de avaliação pode ser justificada pelas divergências intrínsecas e extrínsecas observadas em muitos aspectos, como diferentes costumes, hábitos sociais, estado emocional e fisiológico. A utilização de um modelo experimental em animais poderá minimizar essas divergências e fornecer condições mais padronizadas para o experimento. Neste trabalho, foram avaliadas, quantitativamente, a expressão gênica das enzimas SAP-2, SAP-5 e SAP-9, presentes no biofilme formado na superfície interna das placas acrílicas superiores de ratos e, microscopicamente, a invasão do fungo no tecido epitelial do palato. Para isso, foram selecionados 49 ratos Wistar, com 90 dias de vida, pesando em média 300g, os quais foram divididos em 3 grupos: Controle, Placa/Candida e Placa, acompanhados durante 2, 4 e 6 dias. Os resultados demostraram que, em 4 dias de uso da placa acrílica contaminada, houve, em alguns ratos, sinais clínicos de inflamação no palato duro; microscopicamente, hiperplasia epitelial, hiperqueratinização, invasão fúngica nas camadas superficiais do revestimento epitelial, microabscessos de Munro e hiperplasia papilar; e maior percentual de neutrófilos no Grupo Placa/Candida em relação aos Grupos Controle e Placa. Também no quarto dia de uso da placa acrílica superior, no Grupo Placa/Candida, o biofilme formado na sua superfície interna apresentou a mais alta expressão gênica relativa das enzimas SAP-2, SAP-5 e SAP-9 que os períodos de 2 e 6 dias de uso. Assim, a invasão fúngica no revestimento epitelial do palato duro pode estar correlacionada com a alta expressão de RNAm das SAPs -2, -5 e -9. / Denture stomatitis (D.S.) affects the oral mucosa in contact with removable dentures, and clinically characterized by erythema with varying degrees of inflammation. This disease is considered a multifactorial etiology, with a combination of factors such as trauma, lack of hygiene, continuous use of stents, hypersensitivity to the material used for dentures, diabetes, immunosuppressive therapy and fungal infection, such as different species of Candida. The main virulence factors of the fungus are the formation of hyphae, dimorphism, phenotypic changes, adherence, persistence, synergism with bacteria, interference with the host defense system and the production of hydrolytic proteins. Among the hydrolytic proteins, the secreted aspartyl proteinase (SAP) is one of the most important in the pathogenesis of C. albicans. SAP is harmful to both the epithelial tissue and to the host\'s immune system. It is not fully understood the real penetration of the fungus in the epithelium tissue and its correlation with the presence of SAP, in denture stomatitis. This difficulty in evaluation can be justified by the intrinsic and extrinsic differences observed in many aspects, different customs, social`s habits, emotional and physiological state. Using an experimental animal model may minimize these differences and provide more standardized conditions for the experiment. In the present work, the aim was to evaluate quantitatively the gene expression of enzymes SAP-2, SAP-5 and SAP-9 of the biofilm formed in internal surface of rat`s upper acrylic plates, and to analysis microscopically, the fungal invasion in palatal epithelial tissue. 49 Wistar rats were selected, 90 days old, weighing on average 300g. They were divided into three groups: Control Group, Plate/Candida and Plate, follow by 2, 4 and 6 days of the use of the plates. The results demonstrated, in four days of use of the acrylic plate, clinical signs of inflammation in the hard palate; microscopically epithelial hyperplasia, hyperkeratinization, fungal invasion in the superficial layers of the epithelial lining, Munro`s microabscess and papillary hyperplasia; and higher percentage of neutrophils in the Plate/Candida Group, compared to Control and Plate Groups. In the period of 4 days, the relative gene expression of the SAPs-2, -5 and -9 in biofilm also showed to be higher in Plate/Candida Group, compared with the periods of 2 and 6 days. Thus, the fungal invasion in the epithelial lining of the hard palate may be correlated with high mRNA expressionn of SAPs -2, -5 e -9.

En 1997 Stuard L. Fischman a dit « Certainement on mange bien, on parle bien, on a l'air bien et on « sent frais » - mais on a aussi la plaque dentaire, la gingivite et les caries dentaires. Le lecteur peut déterminer les progrès réalisés en réfléchissant à son état de santé bucco-dentaire personnel! ». Vingt ans plus tard cette affirmation reste valide. L'acte le plus commun d'hygiène buccale est de se nettoyer les dents par brosse à dents, eau et dentifrice. Le rôle principal de la brosse à dents et du dentifrice est d'éliminer le biofilm dentaire responsable des maladies buccales. Il est largement admis que le biofilm dentaire est éliminé au moyen de particules de nettoyage trouvés dans la composition du dentifrice. Puisque le mécanisme des particules nettoyantes est couramment supposé abrasif, la recherche sur le nettoyage des dents a été principalement conduite du point de vue « abrasif », elles sont ainsi appelées « particules abrasives ». Néanmoins, le nettoyage des dents est un processus complexe impliquant plusieurs mécanismes (biochimiques, physico-chimiques et mécaniques), chacun activé par des facteurs à la fois internes (comme l'environnement oral individuel et les habitudes individuelles d'hygiène buccale) et externes La conception de la brosse à dents et la composition de dentifrice). Ce travail a commencé à partir de l'idée que le nettoyage des dents ne peut pas être réduit à un processus d'abrasion; par conséquence, afin d'acquérir une connaissance plus profonde du comportement réel des particules nettoyantes, il est nécessaire de comprendre la contribution de chaque mécanisme d'action impliqué. Un système biomimétique a été développé pour reproduire la brosse à dents, l'émail dentaire, la pellicule exogène acquise et le dentifrice (une suspension simplifiée à base de silice). Le système a été analysé d'un point de vue tribologique, en adoptant la théorie du « troisième corps » et en utilisant différentes techniques expérimentales (spectroscopie infrarouge, microscopie à force atomique, la microscopie électronique à balayage). On a déterminé la contribution de la mécanique et de la physico-chimie de la surface de l'émail dentaire, de la chimie du dentifrice et de la mécanique de la brosse à dents. Les résultats ont montré que la pellicule exogène acquise biomimétique n'a pas été rayée pendant le nettoyage des dents, mais plutôt lissée ou enlevée, ce qui suggère que l'abrasion n'est pas le mécanisme «gouvernant» du processus de brossage des dents. En effet, un mécanisme de «lubrification fractionnée» est supposé intervenir, favorisant la formation des agglomérats de silice supportent la charge normale dans des zones de contact localisées. L'efficacité du processus de nettoyage des dents est censée être contrôlée par la taille des agglomérats de silice, qui dépend à son tour de la mécanique et la physico-chimie de la surface de l’émail dentaire, de la chimie du dentifrice et de la mécanique de la brosse à dents. / In 1997, Stuart L. Fischman wrote “We certainly eat well, speak well, look fine and ‘smell fresh’—but we also have plaque, gingivitis and dental caries. The reader can determine how much progress has been made by reflecting on his or her personal oral health status!” Two decades later, this affirmation is still valid. The most common act of oral hygiene is to clean one’s teeth via toothbrush, water, and dentifrice. The main role of toothbrush and dentifrice is to remove the dental biofilm responsible for oral diseases. Over the years, several studies have focused on improving toothbrushing techniques, toothbrush design, and dentifrice composition, often leading to conflicting results. It is largely accepted that dental biofilm is removed by means of cleansing particles, which can be found in many dentifrice compositions. Since the mechanism of the cleansing particles is commonly believed to be abrasive, research on teeth cleaning has been mainly conducted from an ‘abrasive’ point of view, so much so that cleansing particles are frequently referred to as ‘abrasive particles’. Nonetheless, teeth cleaning is a complex process involving several mechanisms (bio-chemical, physico-chemical, and mechanical), each one activated by factors that are both internal (such as individual oral environment and individual oral hygiene habits) and external (such as toothbrush design and dentifrice composition). This work started from the idea that teeth cleaning cannot be reduced to an abrasion process; consequently, in order to gain deeper knowledge about the actual behavior of the cleansing particles, it is necessary to understand the contribution of each mechanism involved. A biomimetic system was developed to reproduce toothbrush, dental enamel, acquired enamel pellicle, and dentifrice (modeled as a silica-based slurry). The system was analyzed from a tribological point of view, adopting the ‘third-body approach’ and employing different experimental techniques such as infrared spectroscopy, atomic force microscopy, and environmental scanning electron microscopy. The contribution of the dental enamel surface mechanics and physico-chemistry, of the dentifrice chemistry, and of toothbrush mechanics was assessed. Results showed that the biomimetic acquired enamel pellicle was not scratched during teeth cleaning, but rather smoothened or removed, suggesting that abrasion is not the governing mechanism of the toothbrushing process. Indeed, a ‘fractionated lubrication’ mechanism is believed to take part, promoting the formation of silica agglomerates that bear normal load at localized contact areas. The effectiveness of the teeth cleaning process is believed to be controlled by the size of the silica agglomerates, which in turn depends on dental enamel surface mechanics and physico-chemistry, dentifrice chemistry, and toothbrush mechanics.

Orientador: Alberto Noriyuki Kojima / Coorientador: Eduardo Shigueyuki Uemura / Banca: Alfredo Mikail Melo Mesquita / Banca: Rubens Nisie Tango / Resumo: O primeiro contato de alunos de graduação com a disciplina de Prótese Parcial Fixa ocorre em aulas teóricas e posteriormente em práticas laboratoriais. Na teoria os docentes utilizam de diversas formas para elucidar um preparo de Prótese Parcial Fixa, fotos e vídeos no passo a passo, guias de silicone, guias de redução, marcações coloridas e até mesmo demonstrações ao vivo. Utilizam- se desses métodos a fim de formar um conceito e fixar uma imagem de um preparo ideal obedecendo aos princípios mecânicos e biológicos das reduções estruturais em prótese fixa. O presente estudo teve como objetivo avaliar as principais dificuldades dos alunos de graduação nos preparos coronários em Prótese Parcial Fixa e sugerir ferramentas de ensino para auxiliar aluno e professor, a elucidar e calibrar os alunos nos desgastes coronários. Participaram da pesquisa ao todo 87 alunos matriculados do 3° ano integral, dos anos 2017 e 2018 da disciplina de Prótese Parcial Fixa, da graduação em Odontologia do ICT. Foi desenvolvido um aplicativo de celular com um banco de dados dos principais preparos coronários e com a possibilidade de comparação do preparo finalizado através de fotos. Também foram desenvolvidas, aplicadas e validadas 02 metodologias: Um manequim com esquema de cores que auxiliou o aluno a visualizar os preparos coronários e uma demonstração prática projetada comparou os métodos de ensino teórico e prático. 78,2% dos alunos relatam a quantidade de redução como a principal dificuldade. O... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The first contact of undergraduate students with the discipline of Partial Fixed Prosthesis occurs in theory classes and later in laboratory practices. In theory, teachers use a variety of ways to elucidate a Fixed Partial Prosthesis preparation, step-by-step photos and videos, silicone guides, reduction guides, color markers and even live demonstrations. These methods are used to form a concept and to fix an image of an ideal preparation obeying the mechanical and biological principles of the structural reductions in fixed prosthesis. The present study had as objective to evaluate the main difficulties of undergraduate students in coronary arteries in Fixed Partial Prosthesis and to suggest teaching tools to help students and teachers to elucidate and calibrate students in coronary wear. A total of 87 enrolled students from the 3rd full year, from the years 2017 and 2018 of the discipline of Partial Fixed Prosthesis, from the graduation in Dentistry from the ICT participated in the research. A cellular application was developed with a database of the main coronary preparations and the possibility of comparing the finished preparation with photos. Two methodologies were also developed, applied and validated: a color design mannequin that helped the student to visualize the coronary preparations and a practical demonstration designed to compare the methods of theory and practical teaching. 78.2% of the students report the amount of reduction as the main difficulty. The method ... (Complete abstract click electronic access below) / Mestre

Ce travail permet, d'une part, de mieux appréhender l'étude du bruit magnétique des machines asynchrones et, d'autre part, de présenter une méthode permettant de le réduire en injectant un faible courant harmonique.<br />Le premier chapitre expose le phénomène, fait une synthèse des relations mécaniques et acoustiques existantes et les confronte avec des expériences pratiques.<br />Une méthode de calcul des harmoniques d'induction présents dans l'entrefer est développée dans le deuxième chapitre, ils sont responsables des forces de Maxwell à l'origine du bruit. Les relations obtenues sont valables pour un moteur à rotor bobiné ou à cage et permettent la détermination des harmoniques de courant rotorique et statorique. Elles sont comparées à celles données par d'autres auteurs qui négligent certains termes.<br />Les applications numériques présentées dans le troisième chapitre soulignent l'importance d'un phénomène qualifié de résonance de denture, responsable de courants rotoriques harmoniques importants et de bruit magnétique. Elles montrent également la validité de la théorie en comparant les résultats aux relevés pratiques.<br />Le dernier chapitre expose le principe de réduction active du bruit magnétique. Il consiste à injecter un faible courant harmonique créant une force qui s'oppose à celle à l'origine du bruit. Plusieurs montages sont proposés, permettant l'injection d'un courant supplémentaire dans une machine alimentée par le réseau. L'étude expérimentale permet de valider le procédé.

Four denture base materials of poly(methyl methacrylate) (QC-20, Pladent-20, Hygenic, and Optilon-399) were prepared by convention water bath and microwave-energy cured methods. While the resin was in the dough stage, it was packed into two molds (65 mm ¡¦15 mm ¡¦10 mm) in the fiber reinforced plastic flask. The variation of temperature with time was recorded by two thermocouples during the microwave heating at 80, 160, and 240 watts, respectively. Microwave polymerization was carried out in the same equipment. The microwave flask containing the same size of resin blocks were processed at 80, 160, 240, and 560 watts for 15, 10, 7, and 2 min, separately. Then each flask was turned over, and cured an additional 2 min at 560 watts. In the case of water-bath method, the resin in the dough stage was packed in the Brass flask, and then cured at 70¢J for 9 hours. Ten specimens were prepared for each condition studied. The surface hardness, porosity, flexural properties and solubility of both process conditions were evaluated. The samples were sectioned by microtome and stained 2 % Osmiun tetroxide, then the morphology of Optilon-399 was observed by using TEM (Transmission electron microscopy) at 160 KV. The result indicate that the flexural strength for Optilon-399 specimens prepared by water-bath method was 20 MPa higher than that prepared in microwave oven, however, there were no obvious difference between the samples cured at different power. Phase separation in two different sizes was observed in all of the Optilon-399 specimens. The larger domain was with 0.18 mm~0.67 mm diameter has dispersed rubber phase surrounded by a rubber periphery. The smaller domain with 0.1 mm diameter is rich with rubber phase. The size and distribution of the larger domain were correlated with the microwave power and curing time. The sample cured by water-bath has the largest average domain diameter (0.395¡Ó0.068 mm). In the specimens prepared by microwave method, the domain size decreased with increasing power. In additions, the domain size varied across the specimen. The size difference between the largest and the smallest domain for specimens cured at 80W was 0.03 mm, and that for specimens cured at 560W was 0.05 mm. This indicated that the larger the power watt was, the higher the morphology difference was.

In this study, the thermal and mechanical properties of poly(ethylenetheraphthalate) (PET)-thermotropic liquid crystal polyester (TLCP), mixtures and poly(methyl methacrylate) (PMMA)-TLCP mixtures were studied. The curing of PMMA-TLCP mixtures was done by heat, gamma radiation and microwave. The amount of TLCP in mixtures was % 0.5, 2 and 5 TLCP by weight. TLCP was synthesized by melt-acidolysis system, and PET-TLCP mixtures were prepared by using lab scale batch mixer. PMMA samples were prepared according to denture manufacturer&rsquo / s procedure. The characterization of polymer samples and mixtures were carried by FT-IR, NMR, DSC, DMA, tensile, impact, three point bending tests and light microscopy. The mixing of TLCP with PMMA yielded heterogeneous dispersions. This was observed from light micrographs. The mechanical and rheological properties of all polymers were not positively affected by inclusion of TLCP. It is also worthwhile to note that weakening of PET-TLCP mixtures were due to the thermal degradation as the thermal age of the mixtures is much higher.

Background Surface treatments and irregularities in the surfaces may affect the fracture of ceramics. The effects of various treatments on the surface texture of different types of ceramic cores/substructures was therefore qualitatively, quantitatively and numerically evaluated. Since fractures in ceramics are not fully understood, the fracture behavior in dental ceramic core/substructures was also studied using both established laboratory methods and newly developed numerical methods. Methods The surfaces of dental ceramic cores/substructures were studied qualitatively by means of a fluorescence penetrant method and scanning electron microscopy, quantitatively evaluated using a profilometer and also numerical simulation. In order to study fracture in zirconia-based fixed partial denture (FPD) frameworks, fractographic analysis in combination with fracture tests and newly developed two-dimensional (2D) and three-dimensional (3D) numerical modeling methods were used. In the numerical modeling methods, the heterogeneity within the materials was described by means of the Weibull distribution law. The Mohr–Coulomb failure criterion with tensile strength cut-off was used to judge whether the material was in an elastic or failed state. Results Manual grinding/polishing could smooth the surfaces on some of the types of dental ceramic cores/substructures studied. Using the fluorescence penetrant method, no cracks/flaws apart from milling grooves could be seen on the surfaces of machined zirconia-based frameworks. Numerical simulations demonstrated that surface grooves affect the fracture of the ceramic bars and the deeper the groove, the sooner the bar fractured. In the laboratory tests the fracture mechanism in the FPD frameworks was identified as tensile failure and irregularities on the ceramic surfaces could act as fracture initiation sites. The numerical modeling codes allowed a better understanding of the fracture mechanism than the laboratory tests; the stress distribution and the fracture process could be reproduced using the mathematical methods of mechanics. Furthermore, a strong correlation was found between the numerical and the laboratory results. Conclusion Based on the findings in the current thesis, smooth surfaces in areas of concentrated tensile stress would be preferable regarding the survival of ceramic restorations, however, the surfaces of only some of the ceramic cores/substructures could be significantly affected by manual polishing. The newly developed 3D method clearly showed the stress distribution and the fracture process in ceramic FPD frameworks, step by step, and seems to be an appropriate tool for use in the prediction of the fracture process in ceramic FPD frameworks.

Thesis (M.S.)--University of Michigan, 1984.

Thesis (M.S.)--University of Michigan, 1982.

Thesis (M.S.)--University of Michigan, 1979.