Dissertations / Theses on the topic 'Prosthesis Materials'

While mechanical, homograft and bio-prosthetic valves have been used in patients for many decades and have made significant improvements in patient morbidity, there is still a distinct need to overcome their limitations. Recently, emerging elastomer heart valves have been shown to be able to better re-create the flow physics of native heart valves, resulting in preferable hemodynamic responses. Unfortunately, elastomers such as silicone are prone to structural failure, which drastically limits their applicability towards the development of valve prosthesis. In order to produce a mechanically more robust silicone substrate, we reinforced it with graphene nanoplatelets (GNPs). Cytotoxicity and hemocompatibility tests revealed that the incorporation of GNPs did not adversely affect cell proliferation or augment adhesion of platelets on the surface of the composite materials. The ECM valves showed good hydrodynamic properties and favorable acute performance compared to a commercially available valve. We conclude that both the Graphene reinforce silicone and the ECM is useful and warrants further evaluation as aortic valve substitutes.

The Cold Spray (CS) is a novelty technique for the production of coatings within the field of Thermal Spray. The use of low work temperatures (under the melting point of the material) is what makes it different from the other conventional spraying techniques. CS is an ideal technique to spray materials that are sensitive to temperature, such as nanostructured and amorphous materials, or sensitive to the oxygen, as could be titanium. These characteristics may be specially promising within the field of biomedical coatings. Compared to the conventional processes, it would allow to produce coatings in a more cost-effect and environmental friendly way. The research is mostly focused on the obtaining of highly rough Commercial Pure Titanium (CP-Ti) and Calcium Phosphate (CP) coatings by CS for joint prosthesis application. An exhaustive development of coating parameter optimization has been developed and the different deposition mechanisms for each feedstock powder were analyzed as well. The mechanical and biological properties of the optimal coatings were evaluated consequently. The mechanical testing (e.g. Tensile and shear strength test and Taber test), was performed on the optimized CP-Ti coating overcoming the ASTM standard specifications for joint, shoulder and knee prosthesis; CP-Ti coating showed good bonding between particles as well with the substrate. The used of coarse titanium particles provided high roughness (Ra=40±12 µm and Rz=235±44 µm) that shows an increase in cell viability, proliferation and differentiation as well as mineralization, in comparison with a low-roughness titanium surface obtained by Sand Blasted (SB).Afterwards, additional surface modification procedures were investigated to obtain nanotextured surfaces on the as-sprayed CS titanium coatings to evaluate their in-vitro response for comparison. The anodic oxidation treatment leads to a TiO2 Nanotube (NT) layer with a pore diameter between 50-100 nm and a roughness of Ra=36.8±4.6 nm, whereas the alkaline treatment leads to a nanosurface of Ra=1.2±0.2nm, composed by very fine porosity <100nm. The nanotextured treatments lead to an increase of cell viability in comparison with the as-sprayed CP-Ti coating as well as high cell differentiation due to its nanofeatures. On the other hand, Hydroxyapatite (HA) coatings were well-deposited by CS without amorphization. Two different HA powders were used as feedstock, a sintered HA powder with a crystalline microstructure, and agglomerate HA feedstock powder with a nanocrystalline microstructure. Both powders show different deposition by CS according to their microstructure; particle deposition of sintered HA powder occurred by slight void collapse and dynamic fragmentation followed by cracking and crushing and reduction in crystal size by plastic deformation mechanisms, whereas agglomerate HA powder a consolidation between particles is caused by the tamping effect produced by the continuous impact of incoming particles onto the already adhered ones, leading to coating build up. Although sintered HA coatings show high cell differentiation, agglomerated HA coatings result in higher cell viability and proliferation, as well as a more homogeneous cell deposition along the coating; agglomerate HA coatings were compared to HA coatings obtained by conventional techniques (e.g. Plasma Spray), and an increase of cell viability and proliferation were observed according to the crystalline HA percentage (CS>PS). To sum up, CS has shown to be suitable to produce metallic and ceramic coatings for joint applications, especially those dealing with materials that are sensitive to the temperature and oxygen. The non-microstructural changes from the feedstock powder to the coatings leads to a big advantage in CS to obtain customized coatings.
La Proyección Fría o también conocida por el nombre de Cold Spray (CS), es una técnica muy novedosa para la obtención de recubrimientos en el ámbito de la proyección térmica. El uso de bajas temperaturas de trabajo (siempre por debajo del punto de fusión del material) es lo que la hace diferente respecto al resto de técnicas convencionales, ya que la hace ideal para depositar materiales sensibles a la temperatura (ej. Materiales nanoestructurados y amorfos) o reactivos al oxígeno (ej. Titanio). Además tiene un gran potencial a nivel económico y ambiental por ser un proceso eficiente y respetuoso con el medio ambiente. La investigación se basa principalmente en la obtención de recubrimientos de titanio rugoso y fosfato cálcico mediante proyección fría, donde se han estudiado los diferentes mecanismos de deposición de las materias primas y se ha elaborado un estudio a nivel mecánico y biológico. Además, se han realizado tratamientos adicionales sobre los recubrimientos de titanio para obtener superficies nanotexturizadas y poderlas comparar in vitro. El uso de partículas gruesas de titanio facilita la obtención de grandes rugosidades superficiales en los recubrimientos de titanio, mejorando así la viabilidad y proliferación celular, al igual que la diferenciación y mineralización celular, en comparación a superficies con bajas rugosidades (como las superficies de titanio granalladas). Aun así, los tratamientos de nanotexturización, tales como el anodizado (donde se obtuvieron nanotubos de TiO2 con un diámetro entre 50-100nm) y el tratamiento alcalino (en el cual se obtuvieron porosidades <100nm), promovieron aún más la respuesta celular de los recubrimientos de titanio en los aspectos previamente mencionados. Por otra parte, los recubrimientos de hidroxiapatita (HA), se depositaron por CS sin ninguna amorfización. También se observó que el proceso de obtención de la HA influía en la deposición de la partícula. La deposición de una HA sinterizada ocurre mediante el colapso de poros y fragmentación dinámica de la partícula, reduciendo así el tamaño de cristal por mecanismos de deformación plástica. Por el otro lado, el polvo de HA obtenido mediante aglomeración, se deposita mediante la compactación y consolidación entre partículas, pudiendo hacer crecer la capa. In vitro, la HA sinterizada da una mayor diferenciación celular, mientras que la HA aglomerada da una mayor viabilidad y proliferación celular. Los recubrimientos de HA aglomerada fueron comparados con los que actualmente se producen por proyección de plasma, y se observó una mejor respuesta celular en los recubrimientos obtenidos por CS debido a que no ofrece cambios microestructurales en el polvo de partida. Para resumir, el CS es una técnica idónea para la producción de recubrimientos metálicos y cerámicos para prótesis articulares, especialmente con materiales sensibles a la temperatura y al oxígeno. Al no producirse un cambio microestructural en el recubrimiento durante el proceso de su obtención, permite la elaboración de recubrimientos personalizados.

The aim of this researchis to use advanced materials and state of the art Finite Element Analysis to produce a novel acetabular cup prosthesis. An investigation into current static and fatigue testing procedures for acetabular cup prostheses has identified current strengths and weakness and proposes a cheap, fast method that is closer to anatomical loading conditions. The current trend of performing Total Hip Replacements(THR) on younger patients incurs an increasing number of revisions. Therefore, prolonging the life of a THR is of paramount importance and is the principal goal of this study. With this trend comes a new set of design goals driven by higher patient expectations of their THR. Younger patients not only require increased longevity from their prosthesis but also increased performances so as to be able to undertake more strenuous everyday activities, such as sports. Historically, the main objective of THR was to relieve pain and increase quality of life in the elderly and was not intended for young active patients. Previous research proposes that the acetabularcup design has far more impact on long-term survival of the THR than the femoral component. Optimising the acetabular cup prosthesis produces a highly complex problem where many of the individual design factors have massive impact on the system. A main aim is to develop a material or combination of materials to optimise the stress distribution in the system without sacrificing the service life of the THR. Of the 800,000 hip replacements carried out annually, many of the current acetabular cups have some form of polyethylene bearing surface. However, polyethy lenewear debris is seen as a major contributing factor to bone resorption and hence prosthesis loosening. Changes in stress values, even caused by initial primary fixation during the operation, can result in stresses being transferred in an unrealistic manner. The effect is that the bone grows to differing thickness and strengths. This is known as remodelling. For optimisation of the acetabular cup, the properties of the natural hip must be retained by minimising both remodelling and bone resorption. The present research, with collaboration from Orthodynamics Ltd., has produced novel composite acetabular cup prostheses with a ceramic on ceramic bearing surface that should last longer and perform better, thus reducing the necessity for costly and debilitating revisions later on in life. In addition, the use of the proposed novel anatomically orientated mechanical testing methods gave fast,cheap results and could also allow further research into fatigue failure of alumina bearing couples in THR.

Statement of Problem There are limited studies evaluating the effect of a cyclic load on interim fixed prosthetic materials and its effect on flexural strength. Purpose of Study 1) To verify the flexural strength of previously studied interim fixed prosthetic materials. 2) To establish the flexural strength of new, advanced generation and untested interim fixed prosthetic materials. 3) To determine the effect of cyclic load on the flexural strength of interim fixed prosthetic materials. Materials and Methods Bar-type specimens of Caulk Temporary Bridge Resin, VitaVM CC, Protemp 3 Garant and Radica were fabricated according to International Standards Organization 4049 and American National Standards Institute/American Dental Association specification 27. After being stored in distilled water for 10 days, specimens were divided into Noncycled and Cycled Groups. The Noncycled Group specimens were fractured under a 3-point loading in a Bose Electroforce 3300 testing instrument at a crosshead speed of 0.75 mm/min. Cycled Groups specimens underwent a 6-12 Newton 3 Hertz cyclic load for 20,000 cycles in a Bose Electroforce 3300 testing instrument. Immediately following completion of the cycles, the specimens were fractured under a 3-point loading. Maximal loads to fracture in Newtons were recorded and mean flexural strengths were calculated (n = 20 per group). Comparisons were made with analysis of variance and Tukey's Multiple Comparison Test. Results Noncycled (NC) and Cycled (C) groups order of mean flexural strengths (MPa) from lowest to highest mean were as follows: Caulk (Noncycled - 53.83; C - 60.02), Vita VM CC (NC - 65.96; C - 66.83), Protemp 3 Garant (NC - 75.85; C - 77.18), and Radica (NC - 106.1; C - 115.96). In the Noncycled and Cycled groups, Radica was statistically superior when compared to all materials and Protemp 3 Garant was statistically superior to Caulk Temporary Bridge Resin. There was no statistically significant difference between the material's flexural strengths before and after cycles. Conclusion Within the limitations of this study, 20,000 cyclic loads of 6-12 Newtons at 3 Hertz did not have a significant effect on the flexural strength of interim fixed prosthetic materials. Radica demonstrated significantly superior flexural strength over other materials tested.

Orientador: Eulália Maria Martins da Silva
Banca: Wirley Gonçalves Assunção
Banca: Paulo Henrique dos Santos
Banca: Osvaldo Luiz Bezzon
Banca: Paulo Martins Ferreira
Resumo: Os protocolos estabelecidos numa técnica de fundição objetivam compensar a contração de solidificação da liga metálica e obter estruturas metálicas fundida com adequada adaptação cervical. A técnica de fundição rápida tem demonstrado ser uma alternativa, mas há dúvidas sobre como os revestimentos se expandem. Este estudo comparou as expansões de presa, térmica e total de três revestimentos odontológicos perante os procedimentos realizados em técnicas de fundição convencional e rápida. Na primeira parte desse estudo, determinaram-se as curvas das expansões resultantes da reação exotérmica de presa (n=5/revestimentoXtécnica), juntamente com as curvas de temperaturas que permitiram determinar o pico da exotermia e o intervalo médio requerido por cada revestimento para atingí-lo e; na segunda parte, aferiu-se a expansão térmica (n=3/revestimento). Para a análise estatística, utilizou-se o ANOVA e o Teste de Tukey (p<0,05). O maior valor médio de temperatura durante a presa foi determinado para o revestimento Micro Fine 1700 (88oC), que não diferiu estatisticamente do Heat Shock (80,3oC) e o menor, para o All Therm (67oC). O Micro Fine 1700 foi o que atingiu seu pico máximo de temperatura mais precocemente (5,8min), seguido pelo Heat Shock (16,4min) e o All Therm (18,8min), sendo todos diferentes entre si (p<0,05). Pôde-se constatar que os três revestimentos avaliados atingiram seus respectivos picos de temperatura num tempo menor ou igual a 20 minutos. Quanto à expansão de presa, para os revestimentos fosfatados foi muito menor no tempo de 20 minutos (tempo de espera para presa na técnica de fundição rápida) em comparação ao que se obteve com 60 minutos; o que não ocorreu, estatisticamente, para o revestimento cerâmico Micro Fine 1700. Só o revestimento cerâmico Micro Fine 1700 apresentou sua expansão de presa estabilizada aos 20 minutos.
Abstract: The protocols established in casting techniques aimed to compensate the solidification contraction of metallic alloy and to get casting metallic structures with accurate marginal fit. The accelerated casting technique has demonstrated to be an alternative, but some doubts regarding investment expansion remains. This study compared the curves of temperatures resultant setting expansion and expansions of setting, thermal and total of three dental investments before the conventional and accelerated casting techniques. In the first part of this study, the curves of the resultant expansion of the setting exothermic reaction (n=5/investment) were determined, together with the curves of temperatures. Based on theses temperatures curves either the maximum exothermic setting reaction temperature, and the mean time interval required for each investment were calculated. In the second part, thermal expansion (n=3/investmentXtechnique) was analyzed. ANOVA and Tukey Test were used as a statistic analysis at 5% level of significance. Micro Fine 1700 investment showed the highest temperature values during the setting (88oC), and did not differ significantly from the Heat Shock (80.3oC) (p>.05). All Therm exhibited lower values (67oC) that differed from the two other investments (p<.05). Micro Fine 1700 reached the maximum exothermic setting reaction temperature first (5.8min), followed by Heat Shock (16.4min) and All Therm (18.8min) (p<.05). It can be evidenced that the three investments had reached their temperature peak until 20 minutes. The setting expansions of the phosphate bonded investments were very lower in the time of 20 minutes (wait time for setting in the accelerated casting technique) in comparison to 60 minutes. However, this difference did not occur to Micro Fine 1700 ceramic investment (p>.05). Analyzing thermal expansion, only Heat Shock showed statistic difference regarding technique factor.
Doutor

Orientador: Luiz Felipe Valandro
Coorientador: Marco Antonio Bottino
Banca: João Paulo Barros Machado
Banca: Guilherme de Siqueira Ferreira Anzaloni Saavedra
Resumo: O objetivo deste estudo foi avaliar o efeito do desgaste com broca diamantada, o envelhecimento (degradação em baixa temperatura) e espessura do material cerâmico no comportamento mecânico de uma cerâmica Y-TZP. Para este estudo, 240 espécimes foram fabricados em formato de disco, de acordo com a norma ISO 6872: 2008 para resistência à flexão biaxial de amostras de cerâmica (N = 120, com dimensões de 0,5 mm de espessura x 15 mm de diâmetro; N = 120 com a dimensão 1,0 milímetros de espessura x diâmetro 15 mm). Os espécimes foram divididos aleatoriamente em 8 grupos (n = 30), de acordo com três fatores em estudo: 'desgaste' em 2 níveis (com e sem desgaste com broca diamantada), o envelhecimento em 2 níveis (com e sem envelhecimento) e da espessura da cerâmica também em 2 níveis (0,5 a 1,0 mm). O desgaste foi realizado com uma broca diamantada montada em um motor de baixa rotação associado a um contra-ângulo multiplicador de velocidade (T2 REVOR R170, Sirona, Bensheim, Alemanha), sob constante irrigação de água. O envelhecimento foi simulado em uma autoclave à temperatura de 134 °C, durante um período de 20 horas, sob pressão de 2 bar. Após o desgaste e envelhecimento, análises de rugosidade e topográficas foram realizadas e análises de transformação de fase por difração de raios-X. Os dados coletados foram submetidos à análise de Weibull. O desgaste promoveu um aumento da rugosidade, enquanto que o envelhecimento em autoclave não afetou estatisticamente a rugosidade da superfíc... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The goals of this investigation were to evaluate the effects of grinding with diamond bur and aging (low temperature degradation) on the mechanical behavior of a fullcontour Y-TZP ceramic with two thicknesses. Y-TZP shaped-disc specimens (Zirlux FC, Ardent Dental) were manufactured with thickness of 0.5 mm and 1.0 mm (both with 15 mm in diameter). The specimens from every thickness were randomly assigned into 4 groups, according to two factors: 'grinding' on 2 levels (with and without grinding with diamond bur), aging in 2 levels (with and without aging). Grinding was performed with a diamond bur mounted in a slow speed rotation motor associated with a counter-angle speed multiplier hand-piece, under constant watercooling. Low temperature aging was performed in an autoclave at 134°C temperature, for a period of 20h, under 2 bar of pressure. After grinding and aging, roughness analyzes were performed on a surface roughness tester and 3D digital optical profilometer; topographic analysis were made in a scanning electron microscope; phase transformation analysis by X-ray diffraction. Biaxial flexural strength tests were performed in the universal testing machine. Specific statistical analyses were carried out (Weibull analysis for the strength data). Grinding promoted an increase in roughness, while aging in autoclave did not affect statistically the surface roughness. Also, grinding and aging lead to higher values of m-phase content, although, grinding lead to a decrease in the material susceptibility to a new phase transformations during aging (after aging, as-sintered condition resulted in higher m-phase content compared with ground). Independent on the zirconia's thickness, aging in autoclave and grinding led to an increase in characteristic strengths. Within the limits of this study, it was observed that: grinding and low ...(Resumo completo, clicar acesso eletrônico abaixo)
Mestre

Orientador : Guilherme Elias Pessanha Henriques
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo:A utilização das ligas de metais não nobres para metalocerâmica tem aumentado com o passar do tempo devido às propriedades mecânicas e baixo custo das mesmas. O titânio tornou-se popular devido à sua excelente biocompatibilidade e propriedades mecânicas favoráveis. Apesar de tais vantagens, as informações sobre a influência dos ciclos de cocção das cerâmicas na dureza Vickers e resistência à tração são escassas. O objetivo do presente estudo foi: 1) avaliar a influência do ciclo de cocção da cerâmica (Vitatitankeramic) na dureza Vickers, bem como na resistência à tração (resistência à tração máxima, resistência à tração na ruptura e alongamento) do titânio comercialmente puro grau 2 fundido; 2) determinar o modo de falha nas superfícies fraturadas por meio de inspeção visual e caracterização por imagens obtidas com microscopia eletrônica de varredura (MEV). A dureza com penetrador Vickers foi medida em corpos-de-prova fundidos em formato de disco (3mm de espessura e 6mm de diâmetro) com carga de 9,08N e 5 segundos (HV1) de tempo de permanência. Os corpos-de-prova foram divididos nos seguintes grupos (n=5): DIN (sem ciclo de cocção), DBO (ciclo do ERQGHU), DOP (ciclos do ERQGHU+opaco), DDE (ciclos do ERQGHU+opaco+dentina) e DGL (ciclos do ERQGHU+opaco+dentina+JOD]H). Para o teste de resistência à tração foram utilizados corpos-de-prova de acordo com a norma E8M da ASTM e especificação número 5 da A.D.A. O teste foi realizado em uma máquina de ensaios mecânicos (MTS 810) com velocidade de deslocamento do atuador de 1mm/min. Os grupos (n=10) para o teste de resistência à tração foram divididos em TIN (sem ciclo de cocção), TBO (ciclo do ERQGHU), TOP (ciclos do ERQGHU+opaco), TDE (ciclos do ERQGHU+opaco+dentina) e TGL (ciclos do ERQGHU+opaco+dentina+JOD]H). A análise de falha foi feita por avaliação macroscópica visual e caracterização com MEV para determinar o modo predominante de fratura. Os valores originais de dureza Vickers e resistência à tração foram submetidos ao teste de análise de variância e as médias comparadas pelo teste de Tukey com 5% de nível de probabilidade. Os valores médios de dureza Vickers foram: 187,00±5,91 para DIN, 206,44±3,37 para DBO, 199,55±3,15 para DOP, 202,05±1,78 para DDE e 207,10±6,87 para DGL, com diferença significativa apenas entre o grupo DIN e os outros grupos submetidos aos ciclos de cocção da cerâmica. Os valores médios de 20 resistência máxima à tração (MPa) foram 494,05±54,4 para TIN, 511,28±51,76 para TBO, 505,46±44,76 para TOP, 481,99±68,66 para TDE e 493,13±33,17 para TGL. Os valores médios de resistência à tração na ruptura (MPa) foram: 409,24±58,5 para TIN, 411,45±42,62 para TBO, 407,06±35,83 para TOP, 390,26±55,96 para TDE e 395,5±26,35 para TGL. Os valores médios de alongamento (mm) foram: 3,07±1,04 para TIN, 3,01±0,93 para TBO, 2,72±0,44 para TOP, 3,05±0,86 para TDE e 2,72±0,89 para TGL. Não foram encontradas diferenças significativas nos grupos quanto à resistência máxima à tração, resistência à tração na ruptura e alongamento. A dureza Vickers após os ciclos de cocção da cerâmica exibiu diferença significativa em relação ao grupo DIN. A resistência à tração máxima, resistência à tração na ruptura e alongamento não foram influenciados pelos ciclos de cocção de forma significativa. A fratura dúctil foi predominante em todos os grupos, com presença de dimples na superfície de fratura
Abstract: The application of base metal alloys in metal-ceramic crowns has increased in the past because of their mechanical properties and low cost. Titanium has become popular due to its excelent biocompatibility and favorable mechanical properties. Despite its advantages, information about the influence of porcelain firing cycle on the Vickers hardness and tensile strenght is scarce. The aim of this study was: 1) to evaluate the porcelain firing cycle (Vitatitankeramic) influence on Vickers hardness and tensile strength, ultimate tensile strength and elongation of cast grade 2 commercially pure titanium; 2) to determine the mode of failure in fractured surfaces by macroscopic visualization and characterisation by scanning electron microscope (SEM) images. The hardness was measured with Vickers hardness tester in cast disc specimens (3mm in thickness and 6mm in diammeter) with 9,08 N of load and 5 seconds (HV1) for maintenance time. The specimens were divided into the following groups (n=5): DIN (without firing cycle), DBO (bonder cycle), DOP (bonder + opaque), DDE (bonder+opaque+dentin cycles) and DGL (bonder+opaque+dentin+glaze cycles). For the tensile test, specimens according with the ASTM E8M and specification 5 A.D.A. were used. The test was performed in a mechanical testing machine (MTS 810) with a crosshead speed of 1mm/min.. For tensile test the groups (n=10) were divided into TIN (without firing cycle), TBO (bonder cycle), TOP (bonder + opaque), TDE (bonder+opaque+dentin cycles) and TGL (bonder+opaque+dentin+glaze cycles). The failure analysis was made by visual inspection and characterisation with SEM to determine the predominant fracture mode. The original values of Vickers hardness and tensile strength were subjected to analysis of variance and the mean values were subjected to Tukey's test set at 5% probability level. The mean values of Vickers hardness were: 187.00±5.91 to DIN, 206.44±3.37 to DBO, 199.55±3.15 to DOP, 202.05±1.78 to DDE and 207.10±6.87 to DGL, with significant difference only between the DIN and the other groups submitted to the firing cycles. The mean values of tensile strength (MPa) were 494.05±54.4 to TIN, 511.28±51.76 to TBO, 505.46±44.76 to TOP, 481.99±68.66 to TDE and 493.13±33.17 to TGL. The ultimate tensile strength (MPa) mean values were: 409.24±58.5 to TIN, 411.45±42.62 to TBO, 407.06±35.83 to TOP, 390.26±55.96 to TDE and 395.5±26.35 to TGL. The values of elongation values (mm) were: 3.07±1.04 to TIN, 3.01±0.93 to TBO, 2.72±0.44 to TOP, 3.05±0.86 to TDE and 2.72±0.89 to TGL. No significant differences were found among groups regarding the tensile strength, ultimate tensile strength and elongation. The Vickers hardness after porcelain firing cycles was significantly different of DIN group. However, the tensile strength, ultimate tensile strength and elongation were not influenced by porcelain firing. Ductile fractures were predominant in all the experimental groups with the presence of dimples
Doutorado
Materiais Dentarios
Doutor em Materiais Dentários

Orientador: Alexandre Brait Landulpho
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Este estudo analisou comparativamente a adaptação marginal antes e após a cimentação de copings metálicos e de alumina, no sistema In-Ceram, em preparos sobre dentes bovinos, utilizando dois tipos de cimento. Sessenta incisivos bovinos foram fixados em resina acrí­lica ativada quimicamente e as porções coronárias foram preparadas para coroa total, utilizando pontas diamantadas tronco cÃ'nica no 4103 com paredes axiais com expulsividade de 8o e término cervical em ombro. Trinta coroas foram confeccionadas para cada tipo de coping. Após, os copings foram adaptados sobre os preparos com carga estática de 9 Kgf por 1 minuto e a discrepância marginal foi medida com microscópio de mensuração (STM). Em seguida, os copings foram removidos e 15 amostras de cada tipo de coping foram cimentados sobre os dentes com cimento de fosfato de zinco (SS White, Petrópolis, RJ. Brasil) e 15 com cimento resinoso (Rely X ARC 3M/ESPE Divisão Dental â?¿ Brasil), aplicou-se uma carga estática de 9 Kgf por 7 minutos e novamente a discrepância marginal foi medida. Os resultados foram submetidos à  Análise de Variância e ao Teste de Tukey (5%) e indicaram que os dois tipos de copings apresentaram desajuste cervical após a cimentação estatisticamente superior ao desajuste cervical antes da cimentação, para os dois cimentos. O sistema In-Ceram apresentou valores de desajuste cervical estatisticamente superior quando cimentados com cimento resinoso. Nenhuma diferença estatá­stica foi observada entre os dois tipos de copings quando cimentados com cimento de fosfato de zinco
Abstract: The purpose of this study was to evaluate the marginal fit before and after cementation of metal and aluminium oxide In-Ceram copings, on bovine teeth preparation using two kinds of cement. Sixty bovine incisors were embedded in resin and the coronal portions of the teeth were prepared to receive complete crowns usin a 4103 diamond bur under refrigeration with 8o of tapering and right shoulder. Thirty crowns were fabricated for each coping. The crowns were then seated on the teeth with 9 Kgf static loads for 1 minute and the marginal discrepancy was mensured using a microscopic (STM). Afterwards, the copings were removed and fifteen samples of each coping were luted on the teeth with zinc phosphate (SS White/Esp, Petrópolis, RJ. Brasil) and resin cement (Rely X ARC 3M/ESPE Divisão Dental â?¿ Brasil), applied 9 Kgf static loads for 7 minutes and the marginal discrepancy was mensured again. Data were submitted to analysis of variance and TukeyÂ's test (5%); results showed that the two copings had cervical fits after cementation statistically higher than those before cementation, concerning both cements. The In-Ceram system showed statistically higher values for the cervical fits when resin cement was used. No statistically significant difference was found between the copings concerning cements with zinc phosphate
Mestrado
Protese Dental
Mestre em Clínica Odontológica

O objetivo deste estudo foi analisar a força de retenção de dois cimentos resinosos utilizados na técnica de cimentação passiva para implantes osseointegráveis, Panavia F e RelyX U100, avaliando essa propriedade na sua aplicação em espécimes de três tipos de diferentes metais, NiCr (Verabond 2, Aalba Dental), NiCrTi (Tilite Ômega, Talladium) e Titânio (Ti c.p., grau 2, Realum), submetidos ou não à termociclagem. Noventa e seis cilindros calcináveis (Conexão Sistemas de Próteses) foram encerados de forma padronizada, fundidos (32 cilindros em cada tipo de liga) e cimentados sobre cilindros de titânio (Conexão Sistemas de Próteses). Os corpos-de-prova foram distribuídos em 12 grupos (n = 8) de acordo com o tipo de liga, cimento e ciclagem térmica. Todos os espécimes foram submetidos a imersão em água destilada a 37º C por 24 horas, entretanto apenas metade deles a um ensaio de termociclagem em uma máquina de simulação de ciclos térmicos MSCT-3 por 5000 ciclos durante 30 dias. Todos os corpos-de-prova foram submetidos a ensaios de tração em uma máquina de ensaios mecânicos EMIC-DL2000 (velocidade = 5mm / min e célula de carga = 500 Kgf ). A análise estatística evidenciou resistência de união à tração do cimento RelyX U100 superior ao cimento Panavia F, independente do tipo de metal utilizado, com médias de até 71,18 Kgf e 55,08 Kgf respectivamente. O ensaio de termociclagem não exibiu interferência na resistência de união de ambos cimentos.
The aim of this study was to analyze the bond strength of two resin cements used in the passive cementation technique for osseointegrated implants, Panavia F and RelyX U100, evaluating this property on its application in specimens of three different metal types, NiCr (Verabond 2, Dental Aalba), NiCrTi (Tilite Omega, Talladium) and Titanium (Ti c.p., degree 2, Realum), submitted or not to termocycling assay. Ninety six calcined cylinders (Conexão Sistemas de Próteses) had been waxed of standardized form, casted (32 in each type of league) and cemented on titanium cylinders (Conexão Sistemas de Próteses). The specimens were distributed enter 12 groups (n = 8) in accordance with the type of metal, cement and thermocycling. All specimens were submitted to an immersion in distilled water at 37ºC for 24 hours, however only half of them to a termocycling assay in a simulation thermal cycles machine MSCT-3 for 5000 cycles during 30 days. All specimens were submitted to a tensile test in a mechanical test machine EMIC-DL2000 (speed = 5mm/min and cell load = 500Kgf). The statistics analysis evidenced tensile strength of the RelyX U100 cement greater than Panavia F cement independent of the metal league type used with averages until 71,18 Kgf and 55,08 Kgf respectively. The termocycling assay did not show interference in the tensile strength of both cements.

As próteses sobre implantes apresentam alto índice de sucesso, mas ainda existem relatos de complicações técnicas e mecânicas, principalmente em relação à adaptação e desaperto de parafusos. Técnicas CAD/CAM foram desenvolvidas tentando melhorar adaptação e passividade, e hoje existem vários materiais e sistemas como opção de trabalho. A proposta deste estudo foi avaliar, por meio de leitura em microscópio, a adaptação de próteses de três elementos sobre dois implantes confeccionadas em diferentes materiais, por diferentes técnicas, antes e após a queima de cerâmica. Também foi verificado se o método/material utilizado, assim como o grau de adaptação influenciariam no comportamento das peças frente a um ensaio de fadiga mecânica. Foram formados 5 grupos de 10 amostras (n=10). Após leituras, prensagem de cerâmica e ensaio de fadiga, os dados foram submetidos aos testes ANOVA e Tuckey-Kramers. As médias de desajuste vertical pré e pós aplicação da cerâmica (μm), quando ambos parafusos apertados foram para G1: Estruturas fundidas em Co-Cr com cilindros calcináveis (26,03 ± 18,4) e (36,5 ± 9) G2: Estruturas sobrefundidas em liga de Co-Cr, utilizando cilindros com base de Co-Cr (4,86 ± 5) e (10,5 ± 6); G3: Estruturas fundidas em liga de Co-Cr, associadas à técnica do cilindro cimentado (0 ± 0)e (0 ± 0); G4: Estruturas usinadas em Co-Cr CAD/CAM (0 ± 0) e (2,7 ± 2);G5: Estruturas usinadas em Zircônia CAD/CAM (14,87 ± 9) e (15,2 ± 8). Para a condição de medida com apenas um dos lados apertado, pré e pós cerâmica, do lado parafusado, os resultados foram para G1: 9,63 ± 1 e 34,8 ± 8; G2: 2,37 ± 5 e 11,9 ± 9; G3: 0 ± 0 e 0 ± 0; G4: 0 ± 0 e 3,4 ± 3; G5: 17,69 ± 1 e 20,8 ± 9. Para a condição de medida com apenas um dos lados apertado, pré e pós cerâmica, do lado desparafusado, os resultados foram para G1: 124,22 ± 37 e 129,8 ± 37; G2: 64,79 ± 47 e 80,6 ± 46; G3: 12,34 ± 17 e 2,1 ± 3; G4: 3,54 ± 5 e 17,6 ± 8; G5: 37,77 ± 25 e 42,4 ± 19. O torque de desaperto (Ncm) dos parafusos protéticos foi verificado antes e após ensaio de fadiga com 300.000 ciclos. Os valores médios encontrados foram respectivamente: G1: 5,80 ± 1,23 e 4,11 ± 1,16; G2: 6,30 ± 1,00 e 3,32 ± 0,87; G3: 5,63 ± 1,05 e 3,30 ± 1,46; G4: 7,24 ± 1,05 e 3,44 ± 1,62; G5: 7,75 ± 1,25 e 6,78 ± 1,18. Os grupos CC, Co-Cr CAD/CAM e Zi, apresentaram os melhores resultados quanto ao ajuste vertical, seguidos pelo grupo Co-Cr e calcinável. Os grupos CC, Co-Cr e Co-Cr CAD/CAM apresentaram perda de torque dos parafusos protéticos após oensaio de fadiga mecânica. O grupo Zi teve menor perda de torque entretodos grupos, comparando antes e após o teste de fadiga. Nenhum dos grupos apresentou perda de torque suficiente para que a prótese perdesse estabilidade da junção.
The implant-supported prostheses present a high success rate, but there are still reports of technical and mechanical complications, mainly regarding adaptation and loosening of screws. CAD/CAM techniques have been developed trying to improve adaptation and passivity, and today there are many options of materials and systems to work with. The purpose of this study was to evaluate, by microscope, fitting of three elements prostheses retained by two implants, made of different materials, different techniques, before and after ceramic firing. It was also verified if the method/material used, as well as the degree of adjustment would influence on the behavior of the prostheses after a fatigue test. Five groups of ten specimens were formed (n = 10). After reading, ceramic pressing and fatigue test data were submitted to ANOVA and Tukey-Kramer\'s tests. The mean vertical misfit pre and post application of ceramic (μm), whit both screws tightened to G1: Structures casted in Co-Cr with castable cylinders (26.03 ± 18.4) and (36.5 ± 9) G2: Structures casted in Co-Cr, with Co-Cr basis cylinder (4.86 ± 5) (10.5 ± 6); G3: Structures casted in Co-Cr associated with the cemented cylinder technique (0 ± 0) and (0 ± 0); G4: Machined structures in Co-Cr CAD/CAM (0 ± 0) and (2.7 ± 2), G5: Structures machined in zirconia CAD/CAM (14.87 ± 9) and (15.2 ± 8). To the measurement condition of only one side tighted, pre and post ceramic, on the tightned side, the results were G1: 9.63 ± 1 and 34.8 ± 8; G2: 2.37 ± 5 and 11.9 ± 9; G3: 0 ± 0 and 0 ± 0; G4: 0 ± 0 and 3.4 ± 3; G5: 17.69 ± 1 and 20.8 ± 9. To the measurement condition of only one side tightened, pre and post ceramic, on the untightened side, the results were in G1: 124.22 ± 37 and 129.8 ± 37; G2: 64.79 ± 47 and 80.6 ± 46; G3: 12.34 ± 2.1 and 17 ± 3; G4: 5 ± 3.54 and 17.6 ± 8; G5: 37.77 ± 25 and 42.4 ± 19. The loosening torque of the prosthetic screws (Ncm) was checked before and after fatigue test to 300,000 cycles. The mean values were: G1: 5,80 ± 1,23 e 4,11 ± 1,16; G2: 6,30 ± 1,00 e 3,32 ± 0,87; G3: 5,63 ± 1,05 e 3,30 ± 1,46; G4: 7,24 ± 1,05 e 3,44 ± 1,62; G5: 7,75 ± 1,25 e 6,78 ± 1,18. CC groups, Co-Cr CAD/CAM and Zi, showed the best results regarding vertical adjustment, followed by the Co-Cr group and castable. CC groups, Co-Cr and Co-Cr CAD/CAM presented loss of torque after fatigue test. The Zi group showed less loss of torque among all groups, comparing before and after fatigue test. None of the groups showed enough loosening to loose joint stability.

Le thème central de cette thèse est la conception d’actionneurs doux à partir de matériaux intelligents et d’une prothèse de main robotique souple. Notre approche prends en compte les différents points qui peuvent influer sur le développement d’une stratégie d’actionnement ou d’un muscle artificiel : i) Les mécanismes et la fonctionnalité de la main humaine afin d’identifier les exigences fonctionnelles pour une prothèse de main robotique en matière de préhension. ii) L’analyse et l’amélioration des mécanismes de la main robotique pour intégrer un comportement souple dans la prothèse. iii) L’évaluation expérimentale de la prothèse de main robotique afin d’identifier les spécifications du système d’actionnement nécessaire au fonctionnement cinématique et dynamique du robot. iv) Le développement et la modélisation d’une stratégie d’actionnement utilisant des matériaux intelligents.Ces points sont abordés successivement dans les 4 chapitres de cette thèse1. Analyse du mouvement de la main humaine pour l’identification des exigences technologiques pour la prothèse de main robotique.2. Conception et modélisation de la prothèse de main robotique à comportement souple.3. Evaluation mécatronique de la prothèse de main.4. Conception d’un muscle artificiel basé sur des matériaux intelligents
In the field of robotic hand prosthesis, the use of smart and soft materials is helpful in improving flexibility, usability, and adaptability of the robots, which simplify daily living activities of prosthesis users. However, regarding the smart materials for artificial muscles, technologies are considered to be far from implementation in anthropomorphic robotic hands. Therefore, the target of this thesis dissertation is to reduce the gap between smart material technologies and robotic hand prosthesis. Five central axes address the problem: i)identification of useful grasping gestures and reformulation of the robotic hand mechanism, ii) analysis of human muscle behavior to mimic human grasping capabilities, iii) modeling robot using the hybrid model DHKK-SRQ for the kinematics and the virtual works principle for dynamics, iv) definition of actuation requirements considering the synergy between prehension conditions and robot mechanism, and v) development of a smart material based actuation system.This topics are addressed in four chapters:1. Human hand movement analysis toward the hand prosthesis requirements2. Design and modeling of the soft robotic hand ProMain-I3. Mechatronic assessment of Prosthetic hand4. Development of an artificial muscle based on smart materials

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Os protocolos estabelecidos numa técnica de fundição objetivam compensar a contração de solidificação da liga metálica e obter estruturas metálicas fundida com adequada adaptação cervical. A técnica de fundição rápida tem demonstrado ser uma alternativa, mas há dúvidas sobre como os revestimentos se expandem. Este estudo comparou as expansões de presa, térmica e total de três revestimentos odontológicos perante os procedimentos realizados em técnicas de fundição convencional e rápida. Na primeira parte desse estudo, determinaram-se as curvas das expansões resultantes da reação exotérmica de presa (n=5/revestimentoXtécnica), juntamente com as curvas de temperaturas que permitiram determinar o pico da exotermia e o intervalo médio requerido por cada revestimento para atingí-lo e; na segunda parte, aferiu-se a expansão térmica (n=3/revestimento). Para a análise estatística, utilizou-se o ANOVA e o Teste de Tukey (p<0,05). O maior valor médio de temperatura durante a presa foi determinado para o revestimento Micro Fine 1700 (88oC), que não diferiu estatisticamente do Heat Shock (80,3oC) e o menor, para o All Therm (67oC). O Micro Fine 1700 foi o que atingiu seu pico máximo de temperatura mais precocemente (5,8min), seguido pelo Heat Shock (16,4min) e o All Therm (18,8min), sendo todos diferentes entre si (p<0,05). Pôde-se constatar que os três revestimentos avaliados atingiram seus respectivos picos de temperatura num tempo menor ou igual a 20 minutos. Quanto à expansão de presa, para os revestimentos fosfatados foi muito menor no tempo de 20 minutos (tempo de espera para presa na técnica de fundição rápida) em comparação ao que se obteve com 60 minutos; o que não ocorreu, estatisticamente, para o revestimento cerâmico Micro Fine 1700. Só o revestimento cerâmico Micro Fine 1700 apresentou sua expansão de presa estabilizada aos 20 minutos.
The protocols established in casting techniques aimed to compensate the solidification contraction of metallic alloy and to get casting metallic structures with accurate marginal fit. The accelerated casting technique has demonstrated to be an alternative, but some doubts regarding investment expansion remains. This study compared the curves of temperatures resultant setting expansion and expansions of setting, thermal and total of three dental investments before the conventional and accelerated casting techniques. In the first part of this study, the curves of the resultant expansion of the setting exothermic reaction (n=5/investment) were determined, together with the curves of temperatures. Based on theses temperatures curves either the maximum exothermic setting reaction temperature, and the mean time interval required for each investment were calculated. In the second part, thermal expansion (n=3/investmentXtechnique) was analyzed. ANOVA and Tukey Test were used as a statistic analysis at 5% level of significance. Micro Fine 1700 investment showed the highest temperature values during the setting (88oC), and did not differ significantly from the Heat Shock (80.3oC) (p>.05). All Therm exhibited lower values (67oC) that differed from the two other investments (p<.05). Micro Fine 1700 reached the maximum exothermic setting reaction temperature first (5.8min), followed by Heat Shock (16.4min) and All Therm (18.8min) (p<.05). It can be evidenced that the three investments had reached their temperature peak until 20 minutes. The setting expansions of the phosphate bonded investments were very lower in the time of 20 minutes (wait time for setting in the accelerated casting technique) in comparison to 60 minutes. However, this difference did not occur to Micro Fine 1700 ceramic investment (p>.05). Analyzing thermal expansion, only Heat Shock showed statistic difference regarding technique factor.

Atualmente os implantes passaram a ser uma opção viável de tratamento para se obter uma adequada reabilitação oral, sendo que a estética tem se tornado um fator de grande importância na Odontologia. Os pilares em zircônia tem-se apresentado como uma boa alternativa que vem preencher o fator estético, não contemplado pelos pilares metálicos. O objetivo deste estudo foi avaliar a resistência à fratura dos pilares de zircônia personalizados e não personalizados e o efeito da ciclagem termomecânica sobre a adaptação marginal, perda de torque e resistência à cimentação destes pilares. Para avaliar a resistência à fratura, 18 implantes cone morse foram utilizados e estes foram divididos em três grupos: GZr: 6 conjuntos implantes/pilares em zircônia; GZrp: 6 conjuntos implante/pilares em zircônia personalizados e GTi: 6 conjuntos implante/pilares em titânio (controle). Os conjuntos implante/pilar foram submetidos à carga compressiva oblíqua em máquina universal de ensaios, com célula de carga de 500kgf e velocidade de 0,5mm/min, em angulação de 30°. Para avaliar os efeitos da ciclagem termomecânica foram utilizados 24 implantes cone morse e estes foram divididos em três grupos: GZr: 8 conjuntos implantes/pilares em zircônia; GZrp: 8 conjuntos implante/pilares em zircônia personalizados e GTi: 8 conjuntos implante/pilares em titânio (controle). Os pilares foram instalados com o torque recomendado pelo fabricante (15Ncm). Coroas cerâmicas foram confeccionadas para todos os grupos. A adaptação marginal das coroas foi avaliada antes e após a ciclagem termomecânica e a resistência de cimentação das coroas foi avaliada após a ciclagem termomecânica através do ensaio de tração. Os conjuntos foram submetidos a 1.000.000 ciclos mecânicos e 8.400 ciclos térmicos. A análise estatística utilizada para o teste de resistência à fratura foi Anova com teste complementar de Tukey. O Grupo GZrp apresentou resistência a fratura significantemente maior que GZr (p=0,009) e o GZr foi semelhante ao GTi. Para a análise da perda de torque e adaptação marginal foi utilizado o modelo linear de efeitos mistos. Para a adaptação marginala análise estatatística revelou haver diferença entre os grupos GZrp e GTi (após ciclagem p=,010) porém não houve diferença dentro do mesmo grupo nos diferentes tempos (antes e após ciclagem termomecânica). Para a perda de torque a análise estatística revelou não haver diferenças significantes, antes e após a ciclagem termomecânica, dentro dos grupos, porém entre os grupos houve diferenças estatísticas entre GZr e Gti antes da ciclagem . Para a análise da resistência de cimentação das coroas foi utilizado ANOVA e este revelou não haver diferenças significantes entre os grupos. Sendo assim, conclui-se que a personalização dos pilares de zircônia não afeta suas propriedades mecânicas, e que o comportamento dos pilares de zircônia é semelhante aos pilares de titânio o que viabiliza o seu uso clínico.
Now implants have been a viable option of treatment for reaching an adequate oral rehabilitation, once the aesthetic have become a factor of great importance in Dentistry. The zirconia abutments have appeared as a good alternative to fill the aesthetic factor that is not present in the metallic abutments. The aim of the present study was to evaluate the fracture strength of customized and not customized zirconia abutments and the effect of thermomechanical cycling in the marginal fit, torque loss and cementation resistance of these abutments. For fracture strength evaluation, 18 morse taper implants were used and divided into three groups: GZr: 6 sets of implants/zirconia abutments; GZrp: 6 sets of implants/customized zirconia abutments and GTi: 6 sets of implants/titanium abutments (control). The sets were submitted to compressive oblique loading in universal testing machine, with a load cell of 500kgf and 0.5mm/min speed, in a 30 degree angulation. For evaluation of the thermomechanical cycling effect, 24 morse taper implants were used and divided into three groups: GZr: 8 sets implants/zirconia abutments; GZrp: 8 sets implants/customized zirconia abutments and GTi: 8 sets implants/titanium abutments (control). The abutments were installed with the torque recommended by the manufacturer (15Ncm). Ceramic crowns were made for all groups. The marginal fit of crowns was evaluated before and after thermomechanical cycling and the cementation resistance of crowns was evaluated after thermomechanical cycling by tensile strength test. The sets were submitted to 1,000,000 mechanical cycles and 8,400 thermal cycles. The fracture strength data were statistically analyzed by ANOVA and Tukey\'s test. The GZrp group presented fracture strength statistically greater than GZr (p=.009) and GZr was similar to GTi. Marginal fit and torque loss data were analyzed by mixed linear model. In the marginal fit, significant difference was noted between GZrp and GTi (after: p=.010), but no difference was noted in the group at different times (before and after thermomechanical cycling).For torque loss, no significant difference was noted before and after thermomechanical cycling in the groups, but significant difference was noted between Gzrp and GTi after thermomechanical cycling. Cementation resistance of crowns was analyzed by ANOVA and no significant difference was noted among the groups. Thus, it was concluded that customization of zirconia abutments does not affect their mechanical properties, and the behavior of zirconia abutments is similar to titanium ones, enabling its clinical use.

Orientadores: Wander José da Silva, Altair Antoninha Del Bel Cury
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Os sistemas cerâmicos representam na odontologia uma alternativa aos metais na reabilitação protética, sendo que a zircônia é o material com melhores propriedades mecânicas. Coroas confeccionadas em zircônia sem aplicação de cerâmica de cobertura, chamadas monolíticas, têm se mostrado uma alternativa favorável para reabilitação oral, pois associam alta resistência à fratura e estética satisfatória, assim como evitam a complicação mais evidente em infraestruturas de zircônia que é a fratura da cerâmica de cobertura. A zircônia pura pode assumir 3 formas cristalográficas: monoclínica, tetragonal e cúbica, dependendo da temperatura. A união da zircônia com óxidos estabilizadores, como o óxido de ítrio (Y-TZP) faz com que a zircônia se mantenha na fase tetragonal. No entanto, a zircônia permanece metaestável e mediante relativamente baixas temperaturas, umidade e estresse uma progressiva transformação de fase de tetragonal para monoclínica pode ocorrer e afetar a resistência da mesma. Assim sendo, o presente estudo avaliou a carga à fratura e a transformação de fases da zircônia em coroas monolíticas submetidas ao envelhecimento através de testes térmicos e mecânicos. Setenta coroas monolíticas de zircônia (Y-TZP) foram cimentadas em réplicas de resina composta e separadas aleatoriamente em 5 grupos (n=14): Controle (C), sem tratamento; Envelhecimento hidrotérmico (EH), 122°C, 2 bar de pressão por 1 hora; Fadiga térmica (FT), 104 ciclos, de 5 a 55°C por 30 segundos; Fadiga Mecânica (FM), 106 ciclos, 70 N de carga, deslizamento de 1,5 mm da cúspide mesiopalatina com frequência de 1,4 Hz; e Fadiga Mecânica associada com tratamento térmico (FMT). Ao final de cada tratamento, a carga à fratura foi determinada em máquina de testes universal com célula de carga de 10KN e velocidade de 1mm/min (n=12/grupo). Avaliação de alterações de superfície e o modo e a origem da fratura foram realizadas no microscópio eletrônico de varredura. A transformação de fases foi analisada através da difração de raios X (n=2/grupo). Os dados de resistência à compressão foram analisados por Análise de variância a um fator e o nível de significância foi de 5%. Também foi realizada a distribuição de Weibull. Todas as restaurações sobreviveram aos testes de envelhecimento e não foram observadas diferenças significantes entre os tratamentos para a carga à fratura (p>0,05). O módulo de Weibull variou de 6,2 a 16,6, com diferença significativa para o grupo envelhecido pelo tratamento hidrotérmico. Falhas catastróficas com origem na superfície foram evidenciadas. Na análise da difração de raios X foi observado que houve transformação de fases, para todos os grupos, nas diferentes faces da coroa, variando entre 1,9 a 8,9%. Com base nos dados concluí-se que coroas monolíticas de zircônia evidenciam uma alta carga à fratura, confiabilidade estrutural e apresentaram baixa transformação de fase
Abstract: Nowadays, in dentistry, zirconia ceramic systems represent an alternative to metals in prosthetic treatment due to the excellent mechanical properties. Zirconia crowns made without porcelain veneering, called monolithic, have proven to be a favorable alternative to oral rehabilitation, as they associate high strength and satisfactory aesthetic, while avoiding the most known complications in zirconia prosthesis, chipping and delamination. Pure zirconia can assume three crystallographic forms: monoclinic, tetragonal and cubic depending on the temperature. The zirconia association with stabilizing oxides, such as yttrium oxide (Y-TZP), maintains the zirconia in the tetragonal phase at room temperature. Therefore, zirconia remains metastable and at low temperatures, with moisture and stress a progressive transformation of tetragonal to monoclinic phase can occur and affect its strength. The present study evaluated the fracture load and phase transformation of zirconia monolithic crowns submitted to thermal and mechanical aging tests. Seventy monolithic zirconia crowns (Y-TZP) were cemented in resin-based replica and randomly divided into 5 groups (n = 14): Control (C), no treatment; Hydrothermal aging (HA), 122°C, 2 bar for 1 hour; Thermal Fatigue (TF), 104 cycles between 5 and 55°C for 30 seconds; Mechanical Fatigue (FM) 106 cycles, with a load of 70 N sliding of 1.5 mm in mesiopalatal cusp at 1.4 Hz; Mechanical and Thermal Fatigue associated (MTF). After each treatment, the fracture load was determined in a universal testing machine with 10KN load and speed of 1mm/min (n=12/group). Surface modifications and fracture origin and mode were evaluated by scanning electron microscope. The phase transformation was analyzed by x-ray diffraction (n=2/group). The fracture load data were analyzed by one-way ANOVA at a level of 5%. Also, the Weibull distribution was performed. All restorations survived the aging tests and no significant differences were observed in between treatments (p> 0.05). There was no statistically significant difference in the mean fracture load and characteristic fracture load among the groups (p>.05). The Weibull modulus ranged from 6.2 to 16.6, with significant difference between control and hydrothermal aging groups. Catastrophic failures were observed. Phase transformation was shown at the different surfaces of the crown in all groups (1.8-8.9%). In conclusion, monolithic zirconia crowns showed high fracture load, structural reliability and low phase transformation
Mestrado
Protese Dental
Mestra em Clínica Odontológica

Various silicone elastomers have been evaluated for use in the prosthetic reconstruction of facial defects. Their strength, texture, flexibility, hardness, ease of preparation, pigment receptivity and retention, and their resistance to cleaning were compared and the data consulted when an elastomer was chosen to restore defects, improve aesthetics and reestablish the confidence of a selection of patients. Detailed case reports are provided, together with information on the adhesives or mechanical methods available for retaining the facial prosetheses. Cyanoacrylate adhesives for use on skin surfaces and as tissue adhesives have been studied in detail. A novel n-butyl 413 cyanoacrylate has been developed with a viscosity, haemostatic property and stability to make it particularly suitable for use in skin grafting and tissue repair. It has already been used with good results on patients with severe burns. An improved formulation, containing a fluorescent dye, can be precisely applied through a specially constructed foot-controlled dispenser illuminated by a fibre-optic supplying UV-light. Cyanoacrylates are already being used as tissue adhesives in place of the conventional but potentially disfiguring suture. The availability of improved, imperceptible adhesives and a precision applicator, which can be used in a modern operating theatre, will extend their effectiveness and satisfy some of the needs of Plastic, and Oral and Maxillo-Facial Surgeons. Portable applicators have potential use in battlefield and in veterinary surgery and overcome the imprecision characteristic of earlier methods.

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O objetivo do estudo foi avaliar a influência da inclinação das cúspides, do tipo de retenção e do envelhecimento mecânico na resistência à fratura de coroas metalocerâmicas implanto-suportadas. Para o ensaio estático utilizou-se seis grupos (n=10): coroas cimentadas com cúspide de inclinação padrão (CIP) de 33º ou cúspides de inclinação reduzida (CIR) de 20°, parafusadas com o orifício de acesso ao parafuso (OAP) não-restaurado com CIP ou CIR e parafusadas com OAP restaurado com CIP ou CIR. Para o efeito do envelhecimento, 4 grupos foram utilizados (n=20): cimentadas com CIP ou CIR; e parafusadas com OAP não-restaurado com CIP ou CIR, em que 50 % das amostras de cada grupo foram cicladas mecanicamente previamente ao ensaio estático. Coroas de um segundo molar inferior foram confeccionadas sobre análogos de implante hexágono externo 5.0 (Biomet 3i, West Palm Beach, FL). O ensaio estático foi realizado aplicando-se força até a fratura da porcelana e para o efeito do envelhecimento, a ciclagem foi realizada (1 x 106; 125 N; 10Hz) antes do ensaio de resistência máxima à fratura. Após análise estatística observou-se que as médias de resistência à fratura apresentaram efeito significativo para Forma de Retenção (FR) e Inclinação de cúspide (IC) (p<0,01). Para FR apenas as coroas parafusadas não apresentaram diferenças estatísticas entre si (p>0,05), porém ambas apresentaram valores estatisticamente menores do que as cimentadas. Para IC, CIP apresentaram menores valores de resistência à fratura. Após o envelhecimento mecânico foi observado efeito significativo somente para os fatores isolados Forma de Retenção e Inclinação de cúspide (p<0,01), com melhores resultados para coroas cimentadas e CIR, respectivamente. O fator Envelhecimento Mecânico (p=0,659) não apresentou efeito significativo. Diante dos resultados, conclui-se que isoladamente... (Resumo completo, clicar acesso eletrônica abaixo)
The aim of this study was evaluate the influence of cusp inclination, type of retention and mechanical aging on fracture strength of implant-supported metal-ceramic (MC) single crowns. To static test, six groups were used (n=10): cemented crowns with 33° standard cusp inclination (SCI) or with 20° reduced cusp inclination (RCI), screwed crowns with screw access hole (SAH) not restored with SCI or RCI and screwed crowns with SAH restored with SCI or RCI. To test aging effect, 4 groups were used (n=20): cemented with SCI or RCI; and screw-retained with SAH not restored with SCI or RCI, in which 50% of specimens of each group were submitted to mechanical aging previously to static test. Crowns of a lower second molar were made on the analog implant external hexagon 5.0 (Biomet 3i, West Palm Beach, FL). The cycling (1.106; 125N; 10Hz) will be performed before the fracture resistance test. The static test was performed in a universal testing machine EMIC DL2000, with load application until porcelain failure. After statistical analysis it was observed that the mean fracture resistance of porcelain showed significant effect (p<0.01), to type of retention (TR) and cusp inclination (CI), respectively. To TR, screwed crowns did not show statistical differences (p>0.05), however, both two showed statistically lower values than cemented. To CI, crowns with SCI showed lower values of fracture resistance. After mechanical aging, TR and CI showed significant effect (p<0.01), with better results to cemented crowns and RCI, respectively. The factor mechanical aging did not show significant effect (p=0.659). According to these results, it was concluded that alone, type of retention and the cusp inclination showed influence on fracture resistance of MC crowns, being cemented crowns and reduced cusps mechanically more resistant against a static and cyclic load. The mechanical aging had no significant... (Complete abstract electronic access below)

Orientador: João Neudenir Arioli Filho
Banca: Francisco de Assis Mollo Junior
Banca: Ricardo Faria Ribeiro
Resumo: O objetivo do estudo foi avaliar a influência da inclinação das cúspides, do tipo de retenção e do envelhecimento mecânico na resistência à fratura de coroas metalocerâmicas implanto-suportadas. Para o ensaio estático utilizou-se seis grupos (n=10): coroas cimentadas com cúspide de inclinação padrão (CIP) de 33º ou cúspides de inclinação reduzida (CIR) de 20°, parafusadas com o orifício de acesso ao parafuso (OAP) não-restaurado com CIP ou CIR e parafusadas com OAP restaurado com CIP ou CIR. Para o efeito do envelhecimento, 4 grupos foram utilizados (n=20): cimentadas com CIP ou CIR; e parafusadas com OAP não-restaurado com CIP ou CIR, em que 50 % das amostras de cada grupo foram cicladas mecanicamente previamente ao ensaio estático. Coroas de um segundo molar inferior foram confeccionadas sobre análogos de implante hexágono externo 5.0 (Biomet 3i, West Palm Beach, FL). O ensaio estático foi realizado aplicando-se força até a fratura da porcelana e para o efeito do envelhecimento, a ciclagem foi realizada (1 x 106; 125 N; 10Hz) antes do ensaio de resistência máxima à fratura. Após análise estatística observou-se que as médias de resistência à fratura apresentaram efeito significativo para Forma de Retenção (FR) e Inclinação de cúspide (IC) (p<0,01). Para FR apenas as coroas parafusadas não apresentaram diferenças estatísticas entre si (p>0,05), porém ambas apresentaram valores estatisticamente menores do que as cimentadas. Para IC, CIP apresentaram menores valores de resistência à fratura. Após o envelhecimento mecânico foi observado efeito significativo somente para os fatores isolados Forma de Retenção e Inclinação de cúspide (p<0,01), com melhores resultados para coroas cimentadas e CIR, respectivamente. O fator Envelhecimento Mecânico (p=0,659) não apresentou efeito significativo. Diante dos resultados, conclui-se que isoladamente... (Resumo completo, clicar acesso eletrônica abaixo)
Abstract: The aim of this study was evaluate the influence of cusp inclination, type of retention and mechanical aging on fracture strength of implant-supported metal-ceramic (MC) single crowns. To static test, six groups were used (n=10): cemented crowns with 33° standard cusp inclination (SCI) or with 20° reduced cusp inclination (RCI), screwed crowns with screw access hole (SAH) not restored with SCI or RCI and screwed crowns with SAH restored with SCI or RCI. To test aging effect, 4 groups were used (n=20): cemented with SCI or RCI; and screw-retained with SAH not restored with SCI or RCI, in which 50% of specimens of each group were submitted to mechanical aging previously to static test. Crowns of a lower second molar were made on the analog implant external hexagon 5.0 (Biomet 3i, West Palm Beach, FL). The cycling (1.106; 125N; 10Hz) will be performed before the fracture resistance test. The static test was performed in a universal testing machine EMIC DL2000, with load application until porcelain failure. After statistical analysis it was observed that the mean fracture resistance of porcelain showed significant effect (p<0.01), to type of retention (TR) and cusp inclination (CI), respectively. To TR, screwed crowns did not show statistical differences (p>0.05), however, both two showed statistically lower values than cemented. To CI, crowns with SCI showed lower values of fracture resistance. After mechanical aging, TR and CI showed significant effect (p<0.01), with better results to cemented crowns and RCI, respectively. The factor mechanical aging did not show significant effect (p=0.659). According to these results, it was concluded that alone, type of retention and the cusp inclination showed influence on fracture resistance of MC crowns, being cemented crowns and reduced cusps mechanically more resistant against a static and cyclic load. The mechanical aging had no significant... (Complete abstract electronic access below)
Mestre

A utilização do titânio em odontologia tem aumentado devido suas propriedades mecânicas, biocompatibilidade, resistência à corrosão e baixo peso específico. Entretanto, o uso do titânio em próteses ainda não é rotineiro em virtude de dificuldades no processo de fundição. Uma das maneiras de superar estas dificuldades seria através do desenvolvimento de novas ligas cujo ponto de fusão fosse inferior ao do Ti cp. O objetivo deste estudo foi avaliar as propriedades mecânicas, biológicas e microestrutura de ligas experimentais de titânio para utilização em estruturas metálicas de próteses dentárias, após fundição odontológica, comparando-as ao Ti cp. As ligas experimentais avaliadas foram Ti-5Zr(%p), Ti-5Ta(%p) e Ti-5Ta-5Zr(%p). Os corpos-de-prova foram fundidos por arco voltaico em atmosfera de argônio e injeção por vácuo-pressão. Para avaliação das propriedades mecânicas, corpos-deprova em forma de halteres foram submetidos a ensaios de tração, barras foram submetidas a ensaios de flexão para avaliação do módulo de elasticidade, e hemi-esferas e discos foram submetidos ao teste de desgaste de dois corpos, sendo o perfil das amostras avaliado antes e após o teste para cálculo da perda de altura vertical. Discos foram utilizados para avaliação da microdureza e para caracterização microestrutural. Para avaliação das propriedades biológicas, células SCC9 foram cultivadas em meio de cultura D-MEM/HF12 suplementado sobre discos e poços sem discos foram usados como controle. Após períodos de 1, 4, 7, 10 e 14 dias, foi avaliada a proliferação celular pelo método histoquímico MTT. Aos 7 dias foi avaliada a viabilidade celular após marcação com azul de Trypan e contagem em hemocitômetro. A morfologia celular foi avaliada às 2, 12 e 24 horas através da visualização, em microscópio de fluorescência por epiluminação, do citoesqueleto de actina e dos núcleos, usando, respectivamente, faloidina e DAPI. Os resultados foram submetidos a testes estatísticos e a liga Ti-5Ta apresentou resistência à tração menor que as demais e módulo de elasticidade significativamente menor do que o Ti cp, embora não diferente das demais ligas experimentais. Com relação à resistência à abrasão, as ligas experimentais apresentaram desgaste significativamente menor do que o Ti cp e a liga Ti-5Zr apresentou microdureza significativamente maior do que os demais materiais. Não houve diferença na proliferação e na viabilidade celular entre os materiais. A avaliação da morfologia celular mostrou diferença na proporção de células nos diferentes estágios de desenvolvimento nos períodos de 2 e 12 horas, mas não em 24 horas. O Ti cp apresentou microestrutura do tipo feather-like com fase α, enquanto Ti-5Zr apresentou estrutura do tipo Widmanstätten com fase α e α´. As ligas Ti- 5Ta e Ti-5Ta-5Zr apresentaram as fases α, α´, α´´ e β, com arranjos lamelar e acicular, respectivamente. Os resultados deste estudo sugerem que as ligas estudadas apresentam potencial para aplicação em próteses dentárias, uma vez que suas propriedades biológicas foram semelhantes às do Ti cp, comprovado por proliferação, viabilidade e morfologia celular; e suas propriedades mecânicas, como resistência à abrasão, microdureza e resistência à tração foram satisfatórias, ainda que o módulo de elasticidade possa e deva ser melhorado.
The use of titanium in dentistry have increased due to its mechanical properties, biocompatibility, corrosion resistance and density. However, titanium has not been routinely used because of the difficulties related to casting technique. One of the options to solve these difficulties would be to develop new titanium alloys whose melting point was lower than cp Ti. So, the aim of this study was to evaluate the mechanical and biological properties and microstructure of experimental titanium alloys for prosthesis frameworks, after dental casting, comparing to cp Ti. The experimental alloys evaluated were Ti-5Zr(%w), Ti-5Ta(%w) and Ti-5Ta-5Zr(%w). The samples were cast by voltaic arc in argon atmosphere and vaccum/pressure injection. To evaluate the mechanical properties, dumbbell-shaped samples were submitted to tensile test, slab-shaped were submitted to flexure for modulus of elasticity evaluation, and stylus tips and disks were submitted to two-body wear test, evaluating the profile of the samples before and after the test to calculate vertical height loss. Disks were used for microhardness evaluation and microstructural observation. For the biological properties evaluation, SCC9 cells were cultured in D-MEM/HF12 supplemented on the disks and wells without disks were used as control. After 1, 4, 7, 10 and 14-day period, cell proliferation was measured by MTT method. After 7 days, cell viability was evaluated after Trypan blue marking and counting in a hemacytometer. Cell morphology was evaluated in 2, 12 and 24-hour periods examining, in fluorescence microscope under epifluorescence, actin cytoskeleton and cell nuclei, using, respectively, phalloidin and DAPI. The results were submitted to statistical analysis and Ti-5Ta alloy presented ultimate tensile strength lower than the others and modulus of elasticity statistically lower than cp Ti, but no different to the other experimental alloys. In relation to wear resistance, the experimental alloys presented wear significantly lower than cp Ti and the Ti-5Zr alloy presented microhardness greater than other materials. Cell morphology evaluation showed difference in the proportion of cells in the different stages in 2 and 12-hour periods, but not in 24. The cp Ti presented feather-like structure with α phase while Ti-5Zr presented a Widmanstätten structure with α and α´ phases. The Ti-5Ta and Ti-5Ta-5Zr alloys presented α, α´, α´´ and β phases with lamellar and acicular structures, respectively. The results of this study suggest that the studied alloys could be applied in dental prosthesis, once their biological properties were similar to cp Ti in cell proliferation, viability and morphology; and their mechanical properties, like wear resistance, microhardness and ultimate tensile strength were ideal, although the modulus of elasticity can and should be improved.

O uso de resinas acrílicas para confecção de restaurações provisórias é bastante difundido na prática odontológica. Dois tipos de resina encontram-se comercialmente disponíveis, as de bisacrilato de metila e as de metacrilato de metila e, em decorrência das exigências funcionais e estéticas das restaurações provisórias, estes materiais devem apresentar resistência, estabilidade de cor e durabilidade. Objetivo: Verificar a resistência à flexão, a microdureza, a rugosidade superficial e a estabilidade de cor de quatro resinas para restaurações temporárias quando submetidas à termociclagem e à imersão em clorexidina. Metodologia: Foram utilizadas as resinas Luxatemp e Structur 2, a base de bisacrilato de metila, e as resinas Duralay e Alike a base de metacrilato de metila. Os corpos-de-prova (n=220) foram divididos em quatro grupos, de acordo com a marca comercial e o ensaio realizado (resistência à flexão, microdureza, rugosidade superficial e estabilidade de cor), sendo avaliados em três tempos distintos: após 24 horas da confecção, após termociclagem (2000 ciclos) e após termociclagem e imersão em clorexidina a 0,12% por 14 dias. Resultados: Os dados obtidos foram analisados com o teste ANOVA e em seguida com o teste t (p<0,05), evidenciando que a termociclagem alterou as propriedades mecânicas das resinas, diminuindo a resistencia a flexão e a microdureza, aumentando a rugosidade superficial e ocasionando alteração de cor. A clorexidina não afetou as propriedades mecânicas das resinas estudadas, porém alterou a cor das resinas de metacrilato. Conclusões: As resinas de bisacrilato apresentaram resultados superiores aos das resinas de metacrilato para todas as variáveis estudadas. A termociclagem afetou negativamente todas as resinas, apenas as resinas de bisacrilato não apresentaram alteração de cor após imersão em clorexidina.
The use of acrylic resins is quite spread in dental practice, being accomplished temporary restorations with this material during the prosthetic treatment. Two chemical groups of this material exist, bis-acryl resins and another of methacrylate resins. Aim: This study verified the flexural resistance, micro hardness, superficial roughness and the color variation of four temporary resins submitted to thermo cycling and chlorexidine immersion. Methods: Luxatemp and Structur 2, bis-acryl based resins, and, Duralay and Alike, methacrylate based resins, has been used. The specimens (n=220) were divided in four groups, in agreement with the accomplished rehearsal, being appraised in three different times: after 24 hours, after the thermo cycling (2000 cycles) and after the thermo cycling followed by the immersion in 0.12% chlorexidine solution during 14 days. The tests were accomplished to the flexural, microhardness, superficial roughness and the color variation verification in all of the experimental times. Results: The results were statistically verified with ANOVA test followed by a t-test (p<0.05). Thermo cycling decreased flexural resistance and micro hardness, increased superficial roughness and caused color variation in all studied resins. Chlorexidine immersion did not changes physicals properties of studied resins, but caused color variation in methacrylate resins. Conclusions: The bis-acryl resins obtained results superiors to the checked for the methacrylate resins in all the experimental tests. Thermo cycling manegeament affected negatively all the studied resins. Only bis-acryl resins didnt presented color variation caused by chlorexidine immersion.

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A fim de investigar a vida em fadiga, modos de falha e distribuição de tensões de restaurações ultrafinas parciais, tipo tabletop, em diferentes cerâmicas, sessenta preparos padronizados foram confeccionados em resina epóxi G10 e foram cimentadas adesivamente restaurações cerâmicas de silicato de lítio reforçado com zircônia (ZLS, Vita Suprinity- Vita Zahnfabrik), ou restaurações de cerâmica híbrida (PIC, Vita Enamic- Vita Zahnfabrik), em 0,5 ou 1 mm de espessura. O mesmo protocolo de ciclagem foi aplicado para todos os espécimes, que consistiu em 5.000 ciclos a 200 N, seguidos de 450 N ciclos até a fratura dos espécimes ou a suspensão do teste após 1,5 x 106 ciclos. A carga axial foi realizada com uma freqüência de 4 Hz no equipamento Biocycle V2 (Biopdi, São Carlos, SP), com amostras imersas em água. A presença de falhas e/ou fraturas foi verificada a cada 2,5 x 105 ciclos e a análise de sobrevivência foi realizada com o número de ciclos em que cada espécime falhou. Os espécimes foram avaliados usando estereomicroscópio e microscopia eletrônica de varredura (MEV). Após a tabulação de dados, foram realizados Kaplan-Meier e Mantel-Cox (Teste Log Rank), seguindo de comparação múltipla aos pares, todos com nível de significância de 5% e análise de Weibull. Através da análise tridimensional de elementos finitos, a distribuição de tensões máximas principais (TMP) nas tabletop oclusais posteriores foram avaliados comparando diferentes tipos de substrato (G10, esmalte/dentina, esmalte), espessuras e materiais cerâmicos. As restaurações de silicato de lítio reforçadas com zircônia com 0,5 mm de espessura (ZLS.5) apresentaram menor resistência à fadiga em comparação com restaurações cerâmicas híbridas de 1,0mm (PIC1), e ambas foram similares a outras restaurações (PIC.5 e ZLS1); X2 = 11,2; df = 3; p = 0,0107 <0,05). Os grupos ZLS apresentaram defeitos aleatórios que culminaram com a fratura, ao passo que os grupos PIC apresentaram defeitos que aumentaram com a fadiga mecânica após algum tempo sob ciclagem. As imagens do estereomicroscópio mostram falhas radiais observadas devido à translucidez do material, não houve danos causados pelo aplicador de carga. A distribuição de TMP foi semelhante para os diferentes tipos de substrato, mas o maior módulo de elasticidade mostrou uma concentração de tensão ligeiramente menor. É favorável o uso de PIC em espessura delgada, com resistência à fadiga semelhante à restaurações de ZLS mais espessas.
To investigate the fatigue life, failure modes and stress distribution of partial ultrafine restorations for posterior teeth in different ceramics, sixty standard tabletop preparations in epoxy resin G10 received lithium silicate based zirconia reinforced (ZLS, Vita Suprinity- Vita Zahnfabrik), or hybrid ceramic (PIC, Vita Enamic- Vita Zahnfabrik), restorations in .5 or 1 mm thickness bonded using resin cement. The same cycling protocol was applied for all specimens that consisted of 5.000 cycles at 200 N followed by 450 N cycles until the specimens’ fracture or the suspension of the test after 1.5 x 106 cycles. Axial load was carried out with a 4 Hz frequency in Biocycle V2 equipment (Biopdi, São Carlos, SP), with samples immersed in water. Presence of cracks and/or fractures was checked with every 2,5 x 105 cycles and the survival analysis was performed using the number of cycles in which each specimen failed. All specimens were evaluated using stereomicroscope and scanning electron microscopy (SEM). After data tabulation, Kaplan-Meier and Mantel-Cox (Log Rank test) analysis were performed, followed by multiple pairwise comparison, all with a significance level of 5%, and Weibull analysis. Through tridimensional finite element analysis, stresses distribution and maximum principal stresses in the posterior occlusal veneers were evaluated comparing different types of substrate (G10, enamel/dentin, enamel), thicknesses and ceramic materials. Zirconium-reinforced lithium silicate restorations with 0.5 mm thickness (ZLS.5) showed lower fatigue strength compared to 1.0 mm hybrid ceramic restorations (PIC1), and both were similar to other restorations (PIC.5 and ZLS1) (Log-Rank test, X2 = 11.2; df = 3; p = 0.0107<0.05). ZLS groups presented random defects that culminated with the fracture, whereas PIC groups presented defects that increased with the mechanical fatigue after some time under cycling. Stereomicroscope images show radial cracks observed due to the translucency of the material, there was no damage caused by applicator. TMP distribution was similar for the different substrate types, but the highest modulus of elasticity showed slightly lower stress concentration. PIC is favorable to be used in thin thickness with similar fatigue strength to thicker ZLS restorations.

As restaurações provisórias no tratamento reabilitador oral são de suma importância. Por isso é preocupante que os materiais utilizados para a execução das mesmas sejam críticos com relação à sua resistência e longevidade, principalmente, quando estas são executadas em tratamentos prolongados e/ou em espaços desdentados extensos. O objetivo deste trabalho foi avaliar em 4 grupos reforçados, compostos por 9 espécimes cada um, a resistência e o modo de fratura, de uma resina acrílica poli(metilmetacrilato) auto-polimerizável (Dencor® - Clássico®, São Paulo, SP, Brasil) utilizada para restaurações provisórias quando reforçada com fibras de vidro (Fibrante® e Interlig® - Angelus®, Londrina, PR, Brasil), fibras de aramida (Kevlar® - Du Pont®, USA) y fio ortodôntico ∅ 0, 7mm. E um grupo controle sem nenhum tipo de reforço, com a mesma quantidade de corpos de prova. A análise dos resultados (ANOVA, p < 0,05), para o teste de resistência, mostrou haver diferença estatística entre os grupos. O teste de Tukey encontrou que os grupos reforçados, aqueles que alcançaram maior média de resistência à fratura foram os que utilizaram a fibra de vidro trançada pré-impregnada com resina composta foto-polimerizável, Interlig® (1083 N); a fibra de vidro unidirecional préimpregnada com dimetacrilato de glicol, Fibrante® (1022 N) e a fibra de poli(aramida) unidirecional sem pré-impregnação, Kevlar® 29, aumentando em 26%, 22% e 17%, respectivamente, esta resistência em relação ao grupo controle (800 N), não havendo diferença estatística significante entre eles. O grupo reforçado com fio de aço com ∅ 0,7 mm (871 N) apareceu em seguida com uma resistência somente 8% maior e semelhante àquela apresentada pelo grupo controle sem reforço. A análise das fraturas concorreu com a elaboração de um novo sistema de classificação dividindo-as em quatro tipos: Ausente, Parcial, Total Não Separada e Total Separada. As fraturas dos espécimes reforçados foram consideradas mais favoráveis ocorrendo, predominantemente, os tipos Ausente e Parcial.
Provisional restorations are of ultimate importance in the oral rehabilitation treatment. Thus, clinicians have to bear in mind that materials used for their fabrication are critical due to its longevity and strength, when these are done for longterm therapy and/or large edentulous spaces. The aim of this work was to evaluate the flexural resistance and fracture mode of an auto-cure polymethylmetacrilate resin (Dencor® - Classico® , Sao Paulo, SP, Brasil) used for provisional restorations and reinforced with four materials. Samples were divided in four groups of nine each, as the following: glass fiber (Fibrante® and Interlig® Angelus®, Londrina, PR, Brasil), aramide fibers (Kevlar® Du Pont®, USA), and orthodontic wire ∅ 0,7mm. one group whitout reinforcement served as control. Data was submitted to statistical analysis with one-way ANOVA (p<.05) test. Results showed statistically significant difference among the groups. Tukeys test showed that glass-fiber Interlig® exhibited the greatest value of flexural strength (1083 N); followed by unidirectional glycol dimetacrylate glass-fiber Fibrante® (1022 N) and aramid fiber Kevlar® (966 N). These values represent 26%, 22% and 17% in relation to the control group (800 N), being non statistically significant difference observed among them. The group with ∅ 0,7mm orthodontic wire (871 N) had a resistance only 8% higher and similar of that of control group without reinforcement. Fracture analysis was conducted by the following scale: absence, partial, complete without separation, and complete with separation. Fracture modes observed on reinforced samples were considered more favorable, with types absent and partial seeing more frequently.

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The adaptation precision of metallic structures to implant abutments is a very questionable subject and the scientific literature lacks about the alloy that shows an adaptation closer to the ideal. This study had the proposal of: evaluating the vertical marginal misfit levels (in μm) using a digital microscope of one-piece and after laser welding metallic structures of total fixed implant supported prosthesis casted in Nickel-Chrome, Nickel-Chrome-Titanium-Molibidenium and Palladium-Silver alloys and commercially pure Titanium, over two different kinds of abutments and, also, associate the misfit results observed at the one-piece structures phase with the data obtained after the laser welding treatment. After the fabrication of two master models, 40 pre-fabricated copings for both Estheticone and Micro-Unit type abutments were used at the survey. Eight metallic structures were casted with Ni-Cr, Ni-Cr-Ti-Mo, Pd-Ag and Ti-c.p., being two structures for each alloy. The vertical misfit values concerning the relation of the metallic structures and implant abutments from all alloys and on both stages one-piece and after laser welding were tabulated and then submitted to statistical tests. The values were exposed to the ANOVA and the significant statistic means were compared by the Tukey test considering a 5% significance value (p<0.05), as well as the standard deviation. The results evidenced that the one-piece structures showed misfit, but the mean values did not present statistic significant differences. The material (alloys) analysis showed that the Ti-c.p. did not show discrepant mean values, but the same did not occur with the other alloys. The comparison between all alloys showed no significant statistical differences, and, the Pd-Ag alloy (control group) showed the higher misfit mean values at the one-piece phase. The relation between the one-piece and after laser welding phases showed the presence of statistic significant values, based on the mean values (onepiece= 0.0953 μm / laser welding=0.0452 μm) and the marginal vertical misfit after laser welding appeared significantly decreased.
A precisão da adaptação das infra-estruturas sobre pilares de implantes é objeto de inúmeros questionamentos e a literatura ainda é carente em relação à liga que possa apresentar adaptação próxima do ideal. Assim, esta pesquisa teve como propósitos: avaliar os níveis de desajustes marginais verticais (em μm) por meio de microscópio mensurador digital das infra-estruturas metálicas em monobloco e após soldagem a laser de próteses totais fixas fundidas em ligas de Níquel-Cromo, Níquel-Cromo-Titânio-Molibidênio, Paládio-Prata e Titânio Comercialmente Puro assentadas sobre dois tipos diferentes de pilares de implantes e, ainda, correlacionar os resultados obtidos dos níveis de desajustes das infra-estruturas monobloco com os das infra-estruturas pós-soldagem (a laser). A partir de dois modelos-mestre, foram enceradas 40 amostras sobre copings pré-fabricados de pilares de implantes tipo Estheticone e Micro-Unit (Conexão Sistema de Prótese-SP). Obteve-se oito infra-estruturas metálicas a partir da fundição das ligas Ni-Cr, Ni-Cr-Ti-Mo, Pd-Ag e Ti-c.p., sendo duas infraestruturas para cada liga. Os valores correspondentes às leituras das distâncias verticais (em !m) da relação infra-estruturas metálicas e pilares de implantes de todas as amostras das diferentes ligas metálicas utilizadas e das etapas monobloco e soldagem a laser foram tabulados e, em seguida, aplicado os testes estatísticos. Os valores foram sujeitos à análise de variância e as médias com diferenças estatísticas significativas foram comparadas pelo teste de Tukey com nível de significância 5% (p<0,05), bem como o desvio padrão. Os resultados evidenciaram que nas infra-estruturas em monobloco (sem solda), houve a presença de desajuste, porém os valores médios não apresentaram diferenças estatísticas significativas. Na avaliação do material empregado (ligas) verificou-se que as infra-estruturas em Ti-c.p. não apresentaram valores médios discrepantes, o que não ocorreu com as infra-estruturas obtidas com as demais ligas. Na comparação de todas as ligas utilizadas, os seus valores médios não apresentaram diferenças estatísticas significativas e a liga de Pd-Ag (Grupo Controle) foi a que apresentou valor médio de maior desajuste nas estruturas em monobloco. Na correlação das infra-estruturas monobloco e pós-soldagem (a laser), evidenciou-se a existência de diferenças estatísticas significativas, baseado nos valores médios (monobloco 0,0953μm / solda a laser 0,0452μm), sendo o desajuste marginal vertical para a infra-estrutura com solda a laser, significativamente menor.

Em próteses sobre implantes, o recobrimento oclusal com materiais pouco rígidos como os acrílicos, é por vezes utilizado por supostamente reduzir a carga transmitida ao osso, entretanto não existe um consenso na literatura sobre a sua efetividade. O objetivo deste trabalho foi comparar, por análise fotoelástica e dinâmica, a transmissão de forças após a ação de cargas sobre próteses unitárias sobre implantes em função dos materiais protéticos. Confeccionou-se um modelo em resina fotoelástica com anatomia semelhante à região de pré-molares inferiores, contendo um implante de hexágono interno de 3,75 x 11,5 mm. Foram elaboradas três tipos de próteses em materiais com rigidez decrescente: 1- Metálica (alta rigidez); 2- Resina composta (rigidez moderada), 3- Com um disco de EVA interposto com h=2,5 mm (baixa rigidez). Por meio de um polariscópio circular, observou-se qualitativamente a tensão gerada no modelo durante a aplicação de forças axiais de 100 N, em regime compressivo, sobre cada tipo de prótese. Para a análise dinâmica, realizou-se um modelamento físico de cada um dos três sistemas implante-prótese com modelos de Voigt. A partir daí, uma representação matemática dos sistemas foi deduzida e resolvida, levando em consideração as propriedades mecânicas dos diferentes materiais testados, como o módulo de elasticidade (E), o coeficiente elástico (k) e a constante de amortecimento (c). Para representar uma carga mastigatória fisiológica, foi aplicado um pulso de força senoidal com duração de 0,25 s e intensidade máxima de 100 N, segundo a expressão ()) 8 cos( . 50 50 t t f π −=. Observou-se na análise fotoelástica que após a aplicação de 100N, surgiram tensões na região apical e na cervical dos implantes, com intensidade e localização similares entre os três tipos de prótese. A análise dinâmica mostrou que a força de 100N aplicada na prótese é totalmente transmitida ao implante instantaneamente. Os resultados das análises concordam entre si e mostram que não é possível amortecer as forças mastigatórias por meio dos materiais oclusais.
Less rigid oclusal materials such as acrylic resins are often used in prosthesis over implants because they are supposed to diminish the loads transferred to the bone; however there is no scientific evidence to support this theory. The objective of this work was to compare by photoelastic and dynamic analysis the load transfer after oclusal loads over single prosthesis over implants, varying the oclusal materials. A photoelastic model was created, with an anatomy similar to an inferior premolar region. An internal hexagon implant (3,75 x 11,5 mm) was put in this model. Three different types of prosthesis were constructed with decrescent stiffness: 1- Metallic (higher stiffness); 2- Composite resin (moderate stiffness); 3- With an EVA disc interposed (fewer stiffness). By means of a circular polariscope, the stress generated in the model with a compressive axial load of 100 N, was observed for each prosthesis. For the dynamic analysis, a physical modeling of each implant-prosthesis was carried out with Voigt models. After that, a mathematical representation of the systems was deduced and solved, taking into account the mechanic properties of the different materials, like the elastic modulus (E), the elastic coefficient (k) and the damping constant (c). To represent a physiologic masticatory load, a senoidal force was applied, during 0,25 s and maximum load of 100 N, by the expression ()) 8 cos( . 50 50 t t f π −=. With the photoelastic analysis, it was observed that stresses were generated at the apical and cervical regions of implants, with similar intensity and patterns between the three types of prosthesis. The dynamic analysis, showed that the loads applied over the prosthesis are transferred to the implant instantaneously. The results of both anaylis are in agreement that it is not possible to damp masticatory loads by means of occlusal materials.

Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Scott, David; Committee Member: Kurtis, Kimberly; Committee Member: Work, Paul. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Os biopolímeros surgem como materiais alternativos no atendimento aos requisitos de desempenho que a área médica tem exigido para implantes ósseos. Nesse contexto o polímero poliuretano derivado de óleo de mamona (Ricinus communis) tem obtido lugar de destaque. Mesmo assim, esse material, considerado um biopolímero regenerador ósseo, ainda necessita de investigação mecânica consistente para uma aplicação de forma confiável. No entanto, há uma grande dificuldade em se prever o comportamento mecânico das estruturas fabricadas por biopolímeros. Diante desse fato, o presente projeto de pesquisa visa através de ensaios experimentais em amostras padronizadas para ensaios de tração e compressão, bem como, ensaios normalizados para próteses de quadril, adquirir propriedades de material adequadas para a implementação dos modelos computacionais, assim como dados de comportamento mecânico sob solicitação. De posse desses dados, através do método dos elementos finitos, são realizadas simulações computacionais com o objetivo de verificar a capacidade do modelo de material de Drucker-Prager representar o comportamento mecânico do biopolímero. Este modelo é aplicado inicialmente na simulação dos ensaios de tração e compressão e posteriormente nas simulações das próteses em biopolímero, onde carregamentos mais complexos estão presentes. Os resultados obtidos nas simulações são analisados e discutidos para fins de validação do uso deste modelo de material em estruturas fabricadas com o biopolímero.
Biopolymers have been widely used as alternative materials to attend the performance requirements that medical area has demanded to bone implants. In this way, the Castor Oil Polyurethane (Ricinus communis) has taken a distinct place. Nevertheless, this material, considered bone constructive, still needs a consisting mechanical investigation for a reliable application, despite the great difficulty to predict the mechanical behavior of biopolymer structures. Face this fact, this work intends through experiments in normalized specimens for tensile and compressive tests, as well as normalized tests for hip implants, to obtain material properties and mechanical behavior data required to implement computational models of the hip prosthesis. Using the finite element method, computational simulations are carried out to verify the capability of Drucker-Prager material model to represent the biopolymer mechanical behavior. This model is first applied in tensile and compressive tests simulations, and further in prosthesis biopolymer simulations, where more complex loadings are present. The results of these simulations are analyzed and discussed in order to validate the use of this material model in biopolymers structures.

For many years, the biggest issue that causes discomfort and hygiene issues for patients with lower limb amputations have been the interface between body and prosthetic, the socket. Often made of an inflexible, solid polymer that does not allow the residual limb to breathe or perspire and with no consideration for the changes in size and shape of the human body caused by changes in temperature or environment, inflammation, irritation and discomfort often cause reduced usage or outright rejection of the prosthetic by the patient in their day to day lives. To address these issues and move towards a future of improved quality of life for patients who suffer amputations, Loughborough University formed the Next Generation Prosthetics research cluster. This work is one of four multidisciplinary research studies conducted by members of this research cluster, focusing on the area of Computer Aided Design (CAD) for improving the interface with Additive Manufacture (AM) to solve some of the challenges presented with improving prosthetic socket design, with an aim to improve and streamline the process to enable the involvement of clinicians and patients in the design process. The research presented in this thesis is based on three primary studies. The first study involved the conception of a CAD criteria, deciding what features are needed to represent the various properties the future socket outlined by the research cluster needs. These criteria were then used for testing three CAD systems, one each from the Parametric, Non Uniform Rational Basis Spline (NURBS) and Polygon archetypes respectively. The result of these tests led to the creation of a hybrid control workflow, used as the basis for finding improvements. The second study explored emerging CAD solutions, various new systems or plug-ins that had opportunities to improve the control model. These solutions were tested individually in areas where they could improve the workflow, and the successful solutions were added to the hybrid workflow to improve and reduce the workflow further. The final study involved taking the knowledge gained from the literature and the first two studies in order to theorise how an ideal CAD system for producing future prosthetic sockets would work, with considerations for user interface issues as well as background CAD applications. The third study was then used to inform the final deliverable of this research, a software design specification that defines how the system would work. This specification was written as a challenge to the CAD community, hoping to inform and aid future advancements in CAD software. As a final stage of research validation, a number of members of the CAD community were contacted and interviewed about their feelings of the work produced and their feedback was taken in order to inform future research in this area.

The purpose of this study was to evaluate the incidence of corrosion and fretting in 48 retrieved titanium-6aluminum-4vanadium and/or cobalt-chromium-molybdenum modular total hip prosthesis with respect to alloy material microstructure and design parameters. The results revealed vastly different performance results for the wide array of microstructures examined. Severe corrosion/fretting was seen in 100% of as-cast, 24% of low carbon wrought, 9% of high carbon wrought and 5% of solution heat treated cobalt-chrome. Severe corrosion/fretting was observed in 60% of Ti-6Al-4V components. Design features which allow for fluid entry and stagnation, amplification of contact pressure and/or increased micromotion were also shown to play a role. 75% of prosthesis with high femoral head-trunnion offset exhibited poor performance compared to 15% with a low offset. Large femoral heads (>32mm) did not exhibit poor corrosion or fretting. Implantation time was not sufficient to cause poor performance; 54% of prosthesis with greater than 10 years in-vivo demonstrated none or mild corrosion/fretting.

Orientador: Marcelo Ferraz Mesquita
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O afrouxamento dos parafusos protéticos é frequentemente encontrado nos exames de rotina e pode causar complicações. Assim, métodos para sua prevenção devem ser desenvolvidos. O objetivo neste estudo foi avaliar a influência do retorque de parafusos protéticos (titânio ou ouro) na estabilidade de próteses totais implantossuportadas com diferentes níveis de adaptação (passiva ou desadaptada), após simulação da função mastigatória por meio de ciclagem mecânica (6 meses, torque de afrouxamento, reaperto dos parafusos + 6 meses de simulação; ou 1 ano de simulação e torque de afrouxamento). No capítulo 1, 10 próteses mandibulares implantossuportadas e 20 modelos foram confeccionados para duas condições de adaptação: passiva (adaptada) e não-passiva (desadaptada). Também foram avaliadas duas técnicas de aperto em função da aplicação de retorque e materiais do parafuso: 1) sem retorque + parafusos de titânio; 2) sem retorque + parafusos de ouro; 3) com retorque + parafusos de titânio; e, 4) com retorque + parafusos de ouro. Para a técnica de aplicação de retorque, os parafusos foram apertados (10 Ncm) e após 10 minutos, reapertados (10 Ncm). O torque de afrouxamento dos parafusos foi mensurado por meio de torquímetro digital de precisão após simulação de 1 ano da função mastigatória. Os dados foram submetidos à análise de variância (ANOVA) em 2 fatores seguido pelo teste complementar de Tukey em (?=0,05). Os fatores adaptação e técnica de aperto (retorque e tipo de parafuso), e a interação entre os fatores foram estatisticamente significantes. O desajuste diminui o torque de afrouxamento. A aplicação do retorque aumentou a estabilidade da conexão dos parafusos, independente da adaptação ou material dos parafusos. No capítulo 2, próteses passivas e não-passivas foram fabricadas de modo semelhante ao capítulo 1. O torque de afrouxamento foi mensurado após 2 condições de simulação de uso clínico: 1) 6 meses / torque de afrouxamento / reaperto / mais 6 meses / torque de afrouxamento; 2) 1 ano de simulação / torque de afrouxamento. Foram utilizados parafusos de titânio e ouro. O teste estatístico foi similar ao capítulo 1. O fator tempo de ciclagem e condição de uso (nível de ajuste e tipo de parafuso), bem como a interação desses fatores influenciaram os valores de torque de afrouxamento (p<0,05). Após 6 meses + 6 meses de simulação de uso clínico, os parafusos de titânio apresentaram maiores valores de torque de afrouxamento quando comparados aos parafusos de ouro, para o mesmo nível de adaptação. Após 1 ano de simulação de uso clínico, ambos materiais dos parafusos em próteses passivas apresentaram valores mais elevados que em próteses não-passivas. Dessa forma podemos concluir que a desadaptação reduz o torque de afrouxamento dos parafusos e que o retorque após 10 minutos consegue estabilizá-los. Parafusos de titânio apresentaram maior estabilidade que parafusos de ouro após 6 meses de simulação devido a sua menor deformação plástica. Quando o tempo de ciclagem foi analisado, parafusos de titânio apresentaram menor estabilidade após 1 ano de simulação devido à perda de torque frente à desadaptação, necessitando acompanhamento mais criterioso para que mantenham sua estabilidade
Abstract: The prosthesis screw loosening is often found at routine examinations and may cause complications. Therefore, methods to prevent them must be developed. The objective of this study was to evaluate the influence of retorque application on joint stability of prosthetic screws (titanium or gold) in implant-supported dentures under different fit levels (passive or misfit), after masticatory function simulated by means of mechanical cycling (6 months, loosening torque, screws retightening and another 6 months of simulation; or 1 year of simulation). In the first chapter, 10 mandibular implant-supported dentures and 20 cast models were fabricated to two fit levels: passive fit and misfit. Two tightening techniques were also evaluated according to the retorque application and screws material: 1) without retorque + titanium screws; 2) without retorque + gold screws; 3) retorque + titanium screws; and 4) retorque + gold screws. The screws were tightened 10 Ncm and retightened to 10 Ncm after 10 min. The screw joint stability was measured after a one-year clinical function simulation using a digital torque meter. Data were analyzed statistically by ANOVA/Tukey's test (?=0.05). The factors of fit level and tightening technique and the interaction between the factors were statistically significant. The misfit decreases the loosening torque. The retorque application increased joint stability independent of fit level or screw material. In the chapter 2, passive and misfit dentures were fabricated as in chapter 1. The loosening torque was measured after two conditions of clinical use simulating: six months / torque loosening / retightening / further six months / loosening torque; and one year of simulation / loosening torque. Titanium and gold screws were used. The statistical analysis was similar to the first chapter. Therefore, the factor cycling time and condition use (fit level and screw type) as well the interaction between the factors influenced the loosening torque values (p<0.05). After six months another six months of masticatory function simulated, the titanium screws showed higher loosening torque than did gold screws for the same fit level. After one year of clinical use simulation, both material screws in passive dentures showed higher loosening torque values than did misfit dentures. Thus we can conclude that the misfit decreases the loosening torque and retorque application increased joint stability. The stability of titanium screws was higher than gold screws after 6 months of simulation, due to its lower plastic deformation. When the cycling time was analyzed, titanium screws were less stable after 1 year of simulation due to loss of torque in misfit presence, requiring more careful monitoring to maintain stability
Doutorado
Protese Dental
Doutor em Clínica Odontológica

Children born with congenital heart valve defects require open-heart surgery to implant an artificial replacement valve. These valves are unable to grow with the developing child and need replacing every 5 years. Tissue engineered heart valves, capable of growing with the patient, would alleviate the need for repeat surgery. I hypothesize chitosan and collagen possess advantageous qualities as scaffolding for a tissue engineered heart valve. This study evaluated chitosan and collagen hydrogels as potential scaffold materials. Chitosan scaffolds had suitable pore size/distribution and scaffold strength; however, they were unable to sustain cell attachment or viability. Collagen gels were assessed for compaction, mechanical properties and expression of matrix metalloproteases in the presence or absence of biochemical and mechanical stimuli. Pressure increased the remodeling potential. This was augmented further in the presence of TGF-β. In conclusion, both materials have potential as scaffolding substrate in a tissue engineered heart valve.

The development of small diameter tissue engineered blood vessels (TEBVs) with low thrombogenicity, low immunogenicity, suitable mechanical properties, and a capacity to remodel to their environment could significantly advance the treatment of coronary and peripheral artery disease. Despite significant advances in the field of tissue engineering, autologous vessels are still primarily utilized as grafts during bypass surgeries. However, undamaged autologous tissue may not always be available due to disease or prior surgery. TEBVs lack long-term efficacy due to a variety of types of failures including aneurysmal dilations, thrombosis, and rupture; the mechanisms of these failures are not well understood. In vitro mechanical testing may help the understanding of these failure mechanisms. The typical mechanical tests lack standardized methodologies; thus, results vary widely. The overall goal of this study is to develop novel experimental and mathematical models to study the mechanical properties and failure mechanisms of TEBVs. Our results suggest that burst pressure tests, the current standard, are not sufficient to assess a TEBVs’ suitability as a coronary substitute; creep and/or cyclic loading tests are also required. Results from this model can help identify the most insightful experiments and quantities to be measured – ultimately reducing the overall number of experimental iterations. Improving the testing and characterization of TEBVs is critically important in decreasing the time necessary to validate the mechanical and functional responses of TEBVs over time, thus quickly moving TEBVs from the benchtop to the patient.

La durabilité à long terme des prothèses articulaires repose sur leur résistance vis-à-vis de la corrosion et leur comportement à l'usure. Quels que soient les matériaux utilisés, des produits de dégradation (ions métalliques et débris d’usure) se forment, du fait de la corrosivité des fluides corporels et de la biomécanique des articulations. Généralement, ces produits sont associés aux complications post-opératoires et en conséquence, leurs effets constituent des préoccupations cliniques critiques. A cet égard, la tribocorrosion est une considération sérieuse dans la performance des prothèses articulaires. Ce travail vise à contribuer à l'amélioration de la compréhension des mécanismes de dégradation d’un alliage de CoCrMo, utilisé en tant que prothèse articulaire, en appréhendant le couplage de charges mécaniques et l’activité cellulaire. Cette thèse a été entreprise selon une approche itérative, qui débute par l’étude du comportement électrochimique du milieu physiologique simulé, propice à la culture cellulaire (le RPMI-1640). L’alliage métallique et les cellules ont successivement été ajoutés au système d’étude. Les essais ont révélé que l'oxydation du CoCrMo est accélérée en présence d'espèces carbonées et de composés organiques, et que les cellules interviennent sur la libération d’ions métalliques. Un dispositif de biotribocorrosion a été développé dans le but d’évaluer l’influence des produits de dégradation sur le métabolisme cellulaire. Cette étude multidisciplinaire exhaustive a combiné des techniques expérimentales d’électrochimie, de biologie et de tribologie, afin de souligner l'importance de la chimie de surface du biomatériau sur sa résistance à la tribocorrosion et son caractère cytotoxique. Finalement, une méthodologie expérimentale a été proposée dans ce travail, en vue de mieux comprendre l’interaction entre les fluides physiologiques simulés et les biomatériaux
The long-term durability of joint replacements is based on their corrosion resistance and wear behavior. Whatever the materials used, degradation products (metal ions and wear debris) are formed due to the aggressiveness of body fluids and the biomechanics of the joints. Generally, these products are associated with post-operative complications and, as a result, their effects are critical clinical concerns. In this respect, tribocorrosion is a serious consideration in the performance of joint replacements. This work aims to contribute to the improvement of the understanding of the degradation mechanisms of a CoCrMo alloy, used as a joint prosthesis, by understanding the coupling of mechanical loads and cellular activity. This thesis has been structured according to a progressive approach, which begins with the study of the electrochemical behavior of a simulated physiological environment conducive to cell culture (RPMI-1640). Metal alloys and cells were successively added to the study system. The tests revealed that the oxidation of CoCrMo is accelerated in the presence of carbonaceous species and organic compounds, and that the cells are involved in the release of metal ions. A biotribocorrosion device has been developed to evaluate the influence of degradation products on cellular metabolism. This comprehensive multidisciplinary study combined experimental techniques from electrochemistry, biology and tribology to highlight the importance of biomaterial surface chemistry on tribocorrosion resistance and cytotoxicity. Finally, an experimental methodology was proposed in this work, in order to better understand the interaction between simulated physiological fluids and biomaterials

Orientadores: Cecília Amélia de Carvalho Zavaglia, Carmen Gilda Barroso Tavares Dias
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: A coesão de um grupo de profissionais de diversas áreas onde haverá troca de informações para a concretização de um biomaterial é fator decisivo para reunir todos os requisitos necessários de caracterizações físicas, químicas e biológicas e assim garantir biocompatibilidade e biofuncionalidade, associadas à interação entre o tecido vivo e o biomaterial. Scaffold biodegradável que combina a bioatividade de hidroxiapatita (HA) e a degradabilidade ajustável de matriz de poliuretano (PU) obtido a partir do PVAl foi desenvolvido nesta pesquisa e submetido à caracterizações morfológicas, mecânicas e biológicas. Este novo tipo de scaffold não é tóxico, apresenta interconexão de poros e microporos nas paredes dos poros, boa resistência mecânica e boa ativação de crescimento celular, propriedades que satisfazem as exigências do uso clínico. As análises através de microscopia eletrônica de varredura mostram além da conexão de poros as nanopartículas de hidroxiapatita distribuídas de maneira uniforme na matriz do bionanocompósito. Os valores médios de resistêcia à compressão da matriz e do bionanocompósito foram próximos de 60 MPa tanto para PVAl-PU como para PVAl-PU/HA com 25% de HA, e 105 MPa PVAl-PU/HA com 33% de HA. Após 24 horas de implante o biomaterial PVAl-PU/HA já apresentou em observação por MEV, detalhe de células aderidas, sugestivas provavelmente de células de fibroblasto, espraiamento com formação de uma camada celular compacta e homogênea e após 14 dias do implante foi observada a interação do biomaterial com as camadas do tecido subcutâneo e a invasão do crescimento celular pelos poros interconectados do scaffold. Portanto o scaffold desenvolvido neste trabalho é indicado com expectativas promissoras para implantes ósseos
Abstract: The cohesion of a group of professionals from many areas, exchanging information to concretize a bio material, is a crucial factor to gather all of the requirements of physical, chemical, and biological characterization and therefore ensure biocompatibility and bio functionality, associated to the interaction of the living tissue and the biomaterial. In this research it was developed and subjected to morphological, mechanical and biological characterization, a biodegradable scaffold that combines the bioactivity of hydroxyapatite (HA) and the adjustable degradability of polyurethane matrix (PU) obtained from the PVA1. This new kind of Scaffold is non toxic, has interconnected pores and micropores at the pore's wall, great mechanical resistance and great cellular growing activation. These properties meet the clinical use requirements. The scanning electronic microscopy analysis shows, beside the pore connection, the hydroxyapatite microparticles arranged evenly in the bionanocomposite. The medium values of compression resistance of the matrix and of the bionanocomposite were close to 60 MPa for PVA1-PU well as PVA1-PU/HA with 25% of HA, and 105 MPa PVA1-PUH/HA with 33% of HA. After 24 hours of insertion, the biomaterial PVA1-PU/HA presented as seen in MEV observation, adherent cells, probably coming from fibroblast cells, spreading with a cellular compact and homogeneous layer and, after 14 days of the insertion, it was observed the biomaterial interaction with the layers of the subcutaneous tissue and the invasion of the cellular growing through the scaffold's interconnected pores. Therefore, the osseous scaffold is indicated with promissing expectations to implants
Doutorado
Materiais e Processos de Fabricação
Doutora em Engenharia Mecânica

Thesis: S.B., Massachusetts Institute of Technology, Department of Architecture, 2003.
Cataloged from PDF version of thesis.
Includes bibliographical references (unnumbered pages 41-42).
The thesis is based on physical interactivity between a user's physical body and the built environment. The relationship between body and architecture is challenged by the demands and desires for adaptability and interactivity, however material and construction methods of architecture have changed little to address these concerns. By allowing the user to become an instigator and an active controller for organizing space and program. Architectural elements are enabled with flexibility and mutability, in terms of its skin and program, which are activated by the user. The first investigation explores three joints within the body and documents, analyses and transforms these joints into an architectural abstraction. Then the concept of collapsed and interactive skin is applied to a design proposal for the fagade for the Art Interactive Gallery. The fagade engages pedestrians visually as well as physically. The final component of the thesis redefines the program of a fitting room as a physically transformable and socially interactive fagade condition activated by the body's own movements. Throughout the research, the thesis has focused on the process of manipulating materials to create composite skin and structural conditions to further investigate the relationship between the body and architecture.
by Soohyun Chang.
S.B.

U uvodnom delu doktorske disertacije opisane su osnovne konvencionalne metode otiskivanja, kao i modifikovane tehnike koje se koriste u savremenoj implant protetici. Prikazana je specifičnost biomehanike implantno nošenih i poduprtih nadoknada u odnosu na biomehaniku nadoknada retiniranih prirodnim zubima. Akcenat je stavljen na kompleksnost problematike postizanja apsolutno pasivnog naleganja nadoknade na nosač implanta (abatment), sa posebnim osvrtom na uticaj same procedure otiskivanja implanata i angulacije implanata na tačnost naleganja. Detaljno su opisani i svi ostali faktori koji mogu da utiču na tačnost radnih modela pri izradi nadoknada na implantima, pozivajući se na aktuelne podatke iz literature i naučno opravdanje za potrebe istraživanja. Cilj rada je bio ispitati uticaj metode otiskivanja, angulacije implanata i vrste otisnog materijala na tačnost definitivnog radnog modela za izradu implantno nošenih zubnih nadoknada. Eksperiment je obavljen u in vitro uslovima. Istraživanje je bazirano na ispitivanju tačnosti otiskivanja pomoću tri različite metode otiskivanja (direktne, indirektne i modifikovane „splint“ metode), dve vrste elastičnih otisnih materijala (adicionog silikona i polietra) i uticaja dve različite grupe implanata (anguliranih od 20° i paralelnih implanata) na tačnost otiskivanja. Master (referentni) model je isplaniran tako da simulira čest klinički slučaj parcijalne bezubosti gornje vilice (klasa Kenedi I), koji je osim dva ugrađena angulirana implanta sa jedne, i dva paralelna implanta sa druge strane, podrazumevao i prisustvo brušenih zuba, pripremljenih za prihvatanje keramičkog mosta u frontalnoj regiji. Otiskivanje zuba i implanata vršeno je istovremeno i drugi deo istraživanja je obuhvatao ispitivanje uticaja primenjene metode i materijala na tačnost otisnutih površina zuba. Time je prošireno polje istraživanja i omogućeno donošenje zaključka o pravoj indikaciji metode i materijala za otiskivanje konkretnog kliničkog slučaja. Kompletna metodologija izrade master i definitivnih radnih (replika) modela, kao i sama procedura otiskivanja, izvedena je po najsavremenijim principima istraživanja, uz upotrebu instrumenata i materijala vodećih svetskih proizvođača. Za potrebe analize odstupanja implanata i zuba na replica modelima u odnosu na referentni, modeli su podvrgnuti optičkoj 3D (trodimenzionalnoj) digitalizaciji pomoću dva savremena laboratorijska skenera koje karakteriše izuzetna tačnost skeniranih površina. Prvo je digitalizovan master model za potrebe dobijanja nominalne geometrije, a nakon toga 30 replika modela, za potrebe uporedne geometrijske analize. Analiza je vršena pomoću najnovijeg specijalizovanog softverskog programa, primenom metode CAD-inspekcije (eng. Computer-Aided Design). Geometrijska analiza odstupanja brušenih zuba (patrljaka) izvedena je tehnikom preklapanja odnosno superpozicije (eng. bestfit) realne geometrije (na replika modelu) sa nominalnom geometrijom (na master modelu). Za razliku od analize patrljaka, za potrebe geometrijske analize odstupanja implanata kreiran je lokalni koordinatni sistem za svaki analizirani implant, pomoću specijalnih abatmenta upotrebljenih za digitalizaciju i uvozom 3D modela implanata iz CAD biblioteke proizvođača. Odstupanja su analizirana u odnosu na centar baze implanta (odstupanje od centra) i u odnosu na centralnu osu implanta (ugao odstupanja), što je omogućilo tačno prostorno orijentisanje implanata na replika modelima u poređenju sa referentnim. Ova metodologija je originalna, jer je u odnosu na metodologije koje su do sada korišćene u svrhu prostorne orijentacije implanata, uvođenjem novih parametara u analizu, omogućila tačnije defi nisanje prostornog odstupanja analiziranih implanata. Rezultati dobijeni u istraživanju doveli su do zaključka da metoda otiskivanja i vrsta otisnog materijala utiču na tačnost otiskivanja implanata. Takođe, angulacija implanata od 20° ima veći uticaj na tačnost definitivnih radnih modela u poređenju sa paralelnim angulirana implanta sa jedne, i dva paralelna implanta sa druge strane, podrazumevao i prisustvo brušenih zuba, pripremljenih za prihvatanje keramičkog mosta u frontalnoj regiji. Otiskivanje zuba i implanata vršeno je istovremeno i drugi deo istraživanja je obuhvatao ispitivanje uticaja primenjene metode i materijala na tačnost otisnutih površina zuba. Time je prošireno polje istraživanja i omogućeno donošenje zaključka o pravoj indikaciji metode i materijala za otiskivanje konkretnog kliničkog slučaja. Kompletna metodologija izrade master i definitivnih radnih (replika) modela, kao i sama procedura otiskivanja, izvedena je po najsavremenijim principima istraživanja, uz upotrebu instrumenata i materijala vodećih svetskih proizvođača. Za potrebe analize odstupanja implanata i zuba na replika modelima u odnosu na referentni, modeli su podvrgnuti optičkoj 3D (trodimenzionalnoj) digitalizaciji pomoću dva savremena laboratorijska skenera koje karakteriše izuzetna tačnost skeniranih površina. Prvo je digitalizovan master model za potrebe dobijanja nominalne geometrije, a nakon toga 30 replika modela, za potrebe uporedne geometrijske analize. Analiza je vršena pomoću najnovijeg specijalizovanog softverskog programa, primenom metode CAD-inspekcije (eng. Computer-Aided Design). Geometrijska analiza odstupanja brušenih zuba (patrljaka) izvedena je tehnikom preklapanja odnosno superpozicije (eng. bestfit) realne geometrije (na replika modelu) sa nominalnom geometrijom (na master modelu). Za razliku od analize patrljaka, za potrebe geometrijske analize odstupanja implanata kreiran je lokalni koordinatni sistem za svaki analizirani implant, pomoću specijalnih abatmenta upotrebljenih za digitalizaciju i uvozom 3D modela implanata iz CAD biblioteke proizvođača. Odstupanja su analizirana u odnosu na centar baze implanta (odstupanje od centra) i u odnosu na centralnu osu implanta (ugao odstupanja), što je omogućilo tačno prostorno orijentisanje implanata na replika modelima u poređenju sa referentnim. Ova metodologija je originalna, jer je u odnosu na metodologije koje su do sada korišćene u svrhu prostorne orijentacije implanata, uvođenjem novih parametara u analizu, omogućila tačnije definisanje prostornog odstupanja analiziranih implanata. Rezultati dobijeni u istraživanju doveli su do zaključka da metoda otiskivanja i vrsta otisnog materijala utiču na tačnost otiskivanja implanata. Takođe, angulacija implanata od 20° ima veći uticaj na tačnost definitivnih radnih modela u poređenju sa paralelnim implantima. Time su potvrđene radne hipoteze doktorske disertacije. „Splint“ metoda otiskivanja i adicioni silikon izdvojili su se kao najtačniji pri otiskivanju implanata. Kombinacije „splint“ metode sa adicionim silikonom i polietrom i otvorene metode sa adicionim silikonom dale su bolje rezultate pri otiskivanju anguliranih implanta, dok je u grupi paralelnih implanata zaključeno da metoda i materijal ne utiču na tačnost otiskivanja. „Splint“ i otvorena metoda i adicioni silicon pružili su najtačnije otiske brušenih zuba. „Splint“ metoda u kombinaciji sa adicionim silikonom dala je najmanja ukupna odstupanja pri otiskivanju implanata i zuba zajedno. Prezentovana studija je specifi čna, kako po izboru zadatog kliničkog slučaja I uporednoj analizi tačnosti istovremenog otiskivanja implanata i zuba, tako i po samoj metodologiji analiza odstupanja implanata, te predstavlja originalni doprinos naučnoj i stručnoj javnosti.
The introductory part of the PhD-theses describes fundamental conventional impression methods, as well as modified techniques used in modern-day implant prosthetics. The biomechanics specificity of the implant supported prosthesis in relation to the biomechanics of natural-teeth retained prosthetics is showed. The emphasis is on the issue’s complexity at accomplishing the absolute passive fit of the prosthesis onto the abutment, with particular regard to the impact of the implant impression procedure and implant angulation its elf. A detailed description is provided for all other factors which can influence the accuracy of working casts during implant-based dental prosthesis, making reference to the current data in the literature, as well as to the scientific justification for research. The aim of the study was to examine the influence of the impression method, implant angulation and type of the impression material on the accuracy of the definitive working model for production of the implant-supported dental prosthesis. The experiment was conducted in the in vitro conditions. The research is based on examining the impression accuracy by using three different impression methods (direct, indirect, as well as modifi ed “splint” method), by using two types of elastic impression materials (addition silicone and polyether), as well as the impact from two different implant groups (angled at 20°, and parallel ones). Master (referential) model was planned to simulate a common clinical case of the upper jaw partial edentulism (Kennedy 1st class), which apart from the two angulated implants on one side, and two parallel implants on the other, also presupposed presence of milled teeth, prepared to accept ceramic dental bridge in the frontal region. Impression of teeth and implants was conducted simultaneously, and second part of the research encompassed examination of the applied method’s and material’s impact onto accuracy of the impressed teeth surfaces. This expanded the research fi eld and enabled drawing conclusions regarding the appropriate method indication and material for impression of a particular clinical case. Complete production methodology of master and definitive working casts (replicas), as well as the impression procedure itself, were all conducted according to the cutting-edge research principles, as well as with the application of instruments and materials of leading world producers. For the purpose of the analysis of implants and teeth deviation on replica models in relation to the reference model, the models underwent optical 3D (three-dimenzional) digitalization by using two state-of-the-art laboratory scanners characterized by exceptional accuracy of scanned surfaces. First model to be digitalized was the master one, in order to obtain nominal geometry, following which 30 model replicas were scanned, for the purpose of comparative geometrical analysis. The analysis was conducted by using latest specialized software designed for CAD (Computer-Aided Design) inspection method. Geometric analysis of the milled teeth (tooth abutments) deviation was conducted by using the overlapping superposition technique (bestfit) real geometry (on the replica model) with nominal geometry (on the master model). As opposed to the teeth-stump analysis, for the purpose of geometrical analysis of implant deviations, a local coordinate system for each analyzed implant was created, by using special abutments used for digitalization and by importing 3D implant models from the manufacturer’s CAD library. Deviations were analyzed in relation to the implant base center (deviation from the center), and in relation to the implant central axis (deviation angle), which enabled accurate implant spatial orientation on the replica models in comparison the referential ones. This methodology is original, since unlike methodologies used so far for implant spatial orientation, it has enabled, through introducing new parameters into analysis, a more accurate defining of analyzed implants spatial deviation. Results obtained during research have led to the conclusion that that the impression methodology and type of the impression material influence the implant impression accuracy. Also, implant angulation of 20° has a higher impact on accuracy of definitive working models in comparison with parallel implants. This confirms the PhD-thesis working hypotheses. The “splint” impression method and addition silicone have excelled as most accurate at implant impression. Combination of “splint” methods with addition silicone and polyether and opened methods with addition silicone proved to obtain better results when impressing angulated implants, while in the group of parallel implants, it was concluded that the method and material do not infl uence the impression accuracy. The “splint” and the open method and addition silicone provided most accu rate imprints of ground teeth. The “splint” method in com bination with addition silicone provided the least over all deviation at impression of implants and teeth together. The presented study is a specifi c one, both in terms of selection of the given clinical case and comparative analysis of the simultaneous impression of teeth and implants, but also in terms of the methodology itself used to analyze implant deviation, which in its own right represents an original contribution to the scientific and expert public.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Objectives: (1) Compare the effects of grinding on a Y-TZP ceramic executed by diamond discs and diamond burs (with similar grit sizes) in the micromorphology of surface, phase transformation (t®m), flexural strength and structural reliability (Weibull analysis), (2) evaluate the effect of LTD (low-temperature degradation) in the outcomes mentioned above. Methods: Three hundred and sixty discs (15mm x 1,2 mm) of Y-TZP were made according to ISO 6872 2008 for flexural strength determination on ceramic materials and sintered according to the manufacturer`s instructions, than they were divided into groups according to two factors in study: surface treatment - 5 levels (without treatment, extra-fine diamond bur, 600-grit diamond disc, coarse diamond bur and 120-grit diamond disc) and LTD on 2 levels (with and without). For grinding with diamond discs a polishing machine was employed, while for grinding with diamond burs a device was employed to assure the perpendicularity between diamond tip and abrading surface, that way the abrasion movements and the applied pressure were standardized. The LTD was induced in an autoclave at 134ºC under 2 bar for 20 hours. Results: Our findings support that LTD although promoted increase in mphase content and micromorphological alterations did not promoted decrease in zirconia s mechanical properties, grinding at a first moment did not affected too, but when ground Y-TZP was submitted to the LTD effects, the defects introduced by grinding could be detrimental to the material`s resistance. From a methodological point of view, diamond discs should not be employed to simulate clinical abrasion performed with diamond burs on Y-TZP ceramics. Conclusion: Thus grinding of zirconia should be avoided and when it was really necessary tools with low grit sizes should be employed.
Objetivos: (1) Comparar os efeitos do desgaste da cerâmica Y-TZP gerados por lixas e pontas diamantadas (com granulações semelhantes) na micromorfologia da superfície, na transformação de fase (t®m), na resistência à flexão biaxial e confiabilidade estrutural (análise de Weibull), (2) Avaliar o efeito da LTD nos desfechos citados acima. Métodos: Trezentos e sessenta discos (15 mm x 1,2 mm) de Y-TZP foram confeccionados segundo as instruções da ISO 6872 2008 para ensaios de flexão em material cerâmico e sinterizados de acordo com as recomendações do fabricante, posteriormente foram divididos em grupos, de acordo com dois fatores em estudo: tratamento de superfície da cerâmica - 5 níveis (sem tratamento, disco de granulação 120, ponta diamantada de granulação super grossa, disco de granulação 600, ponta diamantada extra fina) e LTD - 2 níveis (sem e com). Para abrasão com lixas de diferentes granulações foi utilizada uma politriz, enquanto que para a abrasão com as pontas diamantadas foi utilizado um dispositivo que garantiu a perpendicularidade da ponta diamantada à superfície da amostra, padronizando os movimentos de abrasão e a pressão aplicada. A LTD foi realizada em autoclave sob 134° C à 2 bar por 20 horas. Resultados: Nossos achados suportam que a LTD embora promovesse aumento de fase monoclínica e alterações micromorfológicas não causou perda de propriedades mecânicas da zircônia, o desgaste em primeiro momento também não promoveu, mas quando esta superfície foi submetida aos efeitos da LTD, os defeitos introduzidos pelo desgaste podem ser prejudiciais a resistência do material. Sob um ponto de vista metodológico o uso de discos diamantados não deve ser empregado para simular o desgaste executado clinicamente com pontas diamantadas. Conclusão: Dessa forma o desgaste da superfície da zircônia deve ser evitado e quando necessário deve ser realizado com instrumentos de menor granulação.

Neural prosthetics are used to replace or substantially augment remaining motor and sensory functions of neural pathways that were lost or damaged due to physical trauma, disease, or genetics. However, due to poor spatial signal resolution, neural prostheses fail to recapitulate the intimate, precise interactions inherent to neural networks. Designing materials and interfaces that direct de novo nerve growth to spatially specific stimulating elements is, therefore, a promising method to enhance signal specificity and performance of prostheses such as the successful cochlear implant (CI) and the developing retinal implant. In this work, the spatial and temporal reaction control inherent to photopolymerization was used to develop methods to generate micro and nanopatterned materials that direct neurite growth from prosthesis relevant neurons. In particular, neurite growth and directionality has been investigated in response to physical, mechanical, and chemical cues on photopolymerized surfaces. Spiral ganglion neurons (SGNs) serve as the primary neuronal model as they are the principal target for CI stimulation. The objective of the research is to rationally design materials that spatially direct neurite growth and to translate fundamental understanding of nerve cell-material interactions into methods of nerve regeneration that improve neural prosthetic performance. A rapid, single-step photopolymerization method was developed to fabricate micro and nanopatterned physical cues on methacrylate surfaces by selectively blocking light with photomasks. Feature height is readily tuned by modulating parameters of the photopolymerizaiton including initiator concentration and species, light intensity, separation distance from the photomask, and radiation exposure time. Alignment of neural elements increases significantly with increasing feature amplitude and constant periodicity, as well as with decreasing periodicity and constant amplitude. SGN neurite alignment strongly correlates with the maximum feature slope. Neurite alignment is compared on unpatterned, unidirectional, and multidirectional photopolymerized micropatterns. The effect of substrate rigidity on neurite alignment to physical cues was determined by maintaining equivalent pattern microfeatures, afforded by the reaction control of photopolymerization, while concomitantly altering the composition of several copolymer platforms to tune matrix stiffness. For each platform, neurite alignment to unidirectional patterns increases with increasing substrate rigidity. Interestingly, SGN neurites respond to material stiffness cues that are orders of magnitude higher (GPa) than what is typically ascribed to neural environments (kPa). Finally, neurite behavior at bioactive borders of various adhesion modulating molecules was evaluated on micropatterned materials to determine which cues took precedence in establishing neurite directionality. At low microfeatures aspect ratios, neurites align to the pattern direction but are then caused to turn and repel from or turn and align to bioactive borders. Conversely, physical cues dominate neurite path-finding as pattern feature slope increases, i.e. aspect ratio of sloping photopolymerized features increases, causing neurites to readily cross bioactive borders. The photopolymerization method developed in this work to generate micro and nanopatterned materials serves as an additional surface engineering tool that enables investigation of cell-material interactions including directed de novo neurite growth. The results of this interdisciplinary effort contribute substantially to polymer neural regeneration technology and will lead to development of advanced biomaterials that improve neural prosthetic tissue integration and performance by spatially directing nerve growth.

L'objectif de cette thèse est de développer de nouveaux textiles biomimétiques pour réaliser des prothèses vasculaires au comportement mécanique proche de celui de l'aorte native, afin de limiter les problèmes post-opératoires observés actuellement. Afin d'établir le cahier des charges, un modèle de comportement de l'AA inspiré d'un modèle multicouches a été ajusté sur des essais biaxiaux de la littérature réalisés sur des échantillons d'AA excisés, pour trois groupes d'âge distincts. Ce modèle a ensuite été implémenté dans un code de calculs par éléments finis afin de simuler le comportement mécanique de l'aorte saine soumise à un ensemble de sollicitations mécaniques, tant à l'échelle du matériau (traction uni et biaxiale, flexion) qu'à celle de la structure (gonflement avec pré-élongation, flexion, compression diamétrale). Dans un second temps, des essais de caractérisation couplés à des mesures par imagerie ont été mis en œuvre sur des prothèses du commerce, avec les mêmes conditions limites et de chargement que les simulations numériques. Ces essais ont permis d'identifier les écarts de comportement mécanique entre les prothèses actuelles et l'aorte native. Afin de pallier à cela, la dernière partie de ce travail a été consacrée au développement de nouveaux textiles biomimétiques, i.e mimant le comportement mécanique de l'aorte native ainsi que ses principales caractéristiques histologiques (« ondulation » et « orientations de fibres privilégiées»), réalisables à l'échelle industrielle par technologie « tricot maille jetée ». Dans un premier temps, le comportement mécanique de plusieurs multifilaments en PET avec différents titres, nombres de filaments et différentes textures, a été étudié après plusieurs traitements (thermique…). Ceci a permis de sélectionner un fil en particulier pour la réalisation des textiles. Par la suite, une première optimisation des paramètres de fabrication (armure, densité de mailles, jauge) a été réalisée pas-à-pas à travers plusieurs campagnes de réalisations et de caractérisations de tricots plans en sollicitation uniaxiale et biaxiale. Enfin, des premiers essais de mise en forme tubulaire ont été réalisés à partir des textiles optimisés. Deux procédés de mise en forme ont été développés : tubes cousus / tubes tramés. La production de « tubes tramés » continus est une technologie innovante à notre connaissance, et prometteuse. Le comportement mécanique des tubes réalisés a été caractérisé en gonflement pour une première évaluation. Plus spécifiquement, l'effet des procédés appliqués sur les textiles médicaux (lavage, traitement thermique, enduction) a été testé sur des échantillons de tube tramé et de textiles plans. Ces premiers essais ont montré qu'en pilotant les paramètres de ces différents traitements et plus particulièrement ceux du traitement thermique, il est possible de moduler le comportement mécanique des tricots afin qu'il s'approche au mieux de celui de l'AA
This thesis aims at developing new biomimetic textiles to design vascular prostheses with a mechanical behavior close to the one of the host aorta, in order to reduce current post-operative problems. To define the ideal target properties, a AA mechanical model was chosen, based on a multi-layered model from the literature. The model parameters were adjusted on biaxial tensile data reported in the literature, performed on excised AA samples for three different age groups. Then, this model was implemented in a finite element code in order to simulate the mechanical behavior of the healthy aorta submitted to various mechanical loadings, both at the material's scale (uni- and biaxial tensile tests, bending) and at the structure's scale (inflation with prestretch, bending, diametric compression). Secondly, several commercial prostheses were characterized using dedicated experimental devices combined with image recordings. The prostheses were tested under the same boundary and loading conditions as the ones used in the numerical simulations. These tests showed that the actual prostheses are not fully mechanically compatible with the host aorta. In order to solve this problem, the last part of this work was dedicated to the design of new biomimetic textiles, i.e. mimicking the healthy aorta's mechanical behavior and main histologic properties (“wavy fibres” and “preferred fiber orientations”), which can be produced industrially using “warp knitting” technology. Firstly, the mechanical behavior of several PET yarns made of different titers, filament numbers and textures were characterized after several treatments (thermal, etc.). This step enabled to identify one specific yarn to produce the biomimetic textiles. Then, a first optimization of the manufacturing parameters (weave, gauge, density, etc.) was made step by step by means of several textile production and planar tests (uni- and biaxial tensile tests). Finally, several trials were conducted to design tubular structures from the optimized textiles. Two shaping methods were developed: sewed tubes / weaved tubes. The continuously “weaved tubes” production is an innovative and promising technology as far as we know. The mechanical behavior of the new tubes was characterized using inflation tests for a first assessment. More specifically, the effect of the treatments usually applied on medical textiles (cleaning, thermal treatment, coating) was tested on weaved tubes and planar textiles samples. By adjusting the parameters of the several processes - and mostly those of thermal treatments – it was possible to adjust the textiles' mechanical behavior in order to make it the closest to the AA's one