Dissertations / Theses on the topic 'Dental materials Denture Liners'

Orientador: Marcelo Ferraz Mesquita
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Este trabalho teve como objetivo comparar a resistência da união entre bases resilientes (Dentuflex, Ufi-Gel e Eversoft) e resina acrílica (QC-20), submetidas ou não à termociclagem. Foram utilizadas 60 amostras divididas em 6 grupos de variáveis, com 10 repetições cada. Para a confecção das amostras, foram utilizadas matrizes metálicas incluídas em mufla, cujo molde impresso na silicona de condensação e no gesso foi preenchido com resina acrílica. Após polimerizadas, as amostras foram unidas duas a duas em seu eixo longitudinal por uma base resiliente. Em seguida, metade das amostras foi levada ao termociclador MCT2 AMM Instrumental onde foram realizados 3000 ciclos de 1 minuto em água à 5° C '+ ou -'1° C) e 1 minuto em água a 65° C ( '+ ou -'1°C). A outra metade das amostras foi armazenada em água à 37° C durante 24 horas. Após cada período, as amostras foram submetidas a um tracionamento no equipamento EMIC-DL500MF com velocidade de 5mm/minuto. Os dados obtidos foram submetidos à análise estatística pelo Teste de Tukey, ao nível e 5% de probabilidade e as amostras foram analisadas quanto ao tipo de falha ocorrida. O material Dentuflex apresentou os maiores valores de resistência à tração, independentemente do tratamento recebido, apresentando diferença estatística em relação aos demais materiais. O material Eversoft quando termo ciciado apresentou superioridade estatística em relação ao material Ufi-Gel. Para os materiais Dentuflex e Eversoft, a termociclagem aumentou os valores de resistência à tração, apresentando diferença estatística em relação ao controle, entretanto, para o material Ufi-Gel, o comportamento não foi alterado
Abstract: The purpose of this study was to compare the tensile bond strength between soft-liners (Dentuflex, Ufi-Gel and Eversoft) and the acrylic resin (QC-20), submitted or not to the thermal cycling (of 1 minute in water at 5°C and 1 minute in water at 65°C). Twenty samples were made of each soft-liner. Half of each group received thermal cycling, and the other half, did not. For making the samples, metal matrixes were invested in flasks, the molds was packed with acrylic resin and a spacer was used to divided tbe samples in the middle. After the resin curing, the spacer was taken out and the acrylic resins were joint with soft-liner material. Half of the samples were submitted to 3.000 thermal cycles, and the other half, were not. Afterwards, the samples were submitted to the tensile bond strength test in a universal testing machine (EMIC-DL500MF) with a crosshead speed of 5 mm/min. The results, after Tukey test at 5% of probability, showed that the highest values were obtained to the Dentuflex (3:32 MPa), and the lowest values were observed with Ufi-Gel (0.18 MPa), both when submitted to the thermal cycling. According to the results it was observed that: the Dentuflex material presented the highest values of tensile bond strength, independent of the received treatment, presenting statistical differences related to the Eversoft and Ufi-Gel. The Eversoft material when submitted to the thermal cycling presented values statistically higher than the Ufi Gel. For the Dentuflex and Eversoft materials, the thermal cycling increased the tensile bond strength values presenting statistical differences related to the no cycled, and for the Ufi-Gel the behavior was not altered.
Mestrado
Protese Dental
Mestre em Odontologia

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Este estudo avaliou o efeito de tratamentos da superfície de união e de materiais reembasadores na resistência ao impacto de uma resina para base de prótese. Corpos-de-prova foram confeccionados com a resina Lucitone 550 (60x6x2 mm) e reembasados (2 mm) com o mesmo material (L) ou com as resinas para reembasamento imediato Tokuso Rebase (TR) e Ufi Gel Hard (UH). Para o material L, as superfícies de união permaneceram sem tratamento (L/L/ST) ou foram tratadas com o monômero da resina L (metil metacrilato) for 180 segundos (L/L/M). Quando o reembasamento foi realizado com os reembasadores imediatos, os tratamentos de superfície consistiram de aplicação dos agentes adesivos fornecidos pelos fabricantes (L/TR/A - diclorometano e L/UH/A - diclorometano e 2-hidroxietil metacrilato) ou tratamento com o monômero da resina L seguido pelos adesivos (L/TR/MA e L/UH/MA). Corpos-de-prova do material L intacto (60x6x4 mm) também foram confeccionados para se determinar a resistência ao impacto dessa resina. Um total de 140 corpos-de-prova foi confeccionado, sendo 20 para cada condição experimental. Para metade dos corpos-de-prova, os entalhes foram realizados na largura, na superfície correspondente ao material reembasador, com profundidade de 0,8 mm, permanecendo 3,2 mm de material intacto (E1). Para os corpos-de-prova restantes, o entalhe foi realizado na espessura, envolvendo tanto o material reembasador como a resina de base, com profundidade de 1,2 mm (E2), permanecendo 4,8 mm de material intacto. Todos os entalhes, em forma de V, foram realizados na área central do comprimento dos corpos-de-prova. O teste utilizado foi do tipo Charpy, com pêndulo de 0,5 J e distância de 50 mm entre os suportes. Os resultados (kJ/ m2) de cada entalhe foram analisados, separadamente, utilizando-se ANOVA e teste de...
This study evaluated the effect of surface treatments and reline materials on the impact strength of a denture base acrylic resin. Specimens were made using Lucitone 550 resin (60x6x2 mm) and relined (2 mm) with the same material (L) or with the hard chair-side reline resins Tokuso Rebase (TR) and Ufi Gel Hard (UH). For material L, the bond surfaces remained untreated (L/L/ST) or were wetted with resin L monomer (methyl methacrylate) for 180 seconds (L/L/M). When the relining was made with the hard reline materials, the surface treatments consisted of coating with the bonding agents supplied by the manufacturers (L/TR/A - dichloromethane and L/UH/A - dichloromethane and 2-hydroxyethyl methacrylate) or wetting with the resin L monomer followed by bonding agents application (L/TR/MA and L/UH/MA). Material L intact specimens (60x6x4 mm) were also made to determine the impact strength of the bulk resin. A total of 140 specimens were made, 20 for each experimental condition. Half of the specimens were notched across the width to a depth of 0.8 mm, leaving an effective depth under notch of 3.2 mm (E1). For the remaining specimens, the notch was cut across the thickness to a depth of 1.2 mm (E2) leaving an effective depth under notch of 4.8 mm. All the V-notches were machined at the midpoint of the length of the specimens. Impact tests were carried out on a Charpy type pendulum impact tester (0.5 J pendulum; distance between supporting points - 50 mm). Results (kJ/ m2) from each notch depth were analyzed separately using one-way ANOVA and Tukey's HSD tests (a = .05). No significant differences were noted among the mean impact values of L (1.39 kJ/ m2), L/L/ST (1.28 kJ/ m2) and L/L/M (1.20 kJ/ m2) specimens with the E1 notch (P>.05). Similar results were observed (P>.05) for the specimens with the E2 notch (L - 1.00 kJ/ m2; L/L/ST - 0.93 kJ/ m2; ...(Complete abstract, click electronic access below)

Orientador: Ana Lucia Machado
Banca: Ana Cláudia Pavarina
Banca: Luiz Antonio Pessan
Resumo: Este estudo avaliou o efeito de tratamentos da superfície de união e de materiais reembasadores na resistência ao impacto de uma resina para base de prótese. Corpos-de-prova foram confeccionados com a resina Lucitone 550 (60x6x2 mm) e reembasados (2 mm) com o mesmo material (L) ou com as resinas para reembasamento imediato Tokuso Rebase (TR) e Ufi Gel Hard (UH). Para o material L, as superfícies de união permaneceram sem tratamento (L/L/ST) ou foram tratadas com o monômero da resina L (metil metacrilato) for 180 segundos (L/L/M). Quando o reembasamento foi realizado com os reembasadores imediatos, os tratamentos de superfície consistiram de aplicação dos agentes adesivos fornecidos pelos fabricantes (L/TR/A - diclorometano e L/UH/A - diclorometano e 2-hidroxietil metacrilato) ou tratamento com o monômero da resina L seguido pelos adesivos (L/TR/MA e L/UH/MA). Corpos-de-prova do material L intacto (60x6x4 mm) também foram confeccionados para se determinar a resistência ao impacto dessa resina. Um total de 140 corpos-de-prova foi confeccionado, sendo 20 para cada condição experimental. Para metade dos corpos-de-prova, os entalhes foram realizados na largura, na superfície correspondente ao material reembasador, com profundidade de 0,8 mm, permanecendo 3,2 mm de material intacto (E1). Para os corpos-de-prova restantes, o entalhe foi realizado na espessura, envolvendo tanto o material reembasador como a resina de base, com profundidade de 1,2 mm (E2), permanecendo 4,8 mm de material intacto. Todos os entalhes, em forma de V, foram realizados na área central do comprimento dos corpos-de-prova. O teste utilizado foi do tipo Charpy, com pêndulo de 0,5 J e distância de 50 mm entre os suportes. Os resultados (kJ/ m2) de cada entalhe foram analisados, separadamente, utilizando-se ANOVA e teste de ...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This study evaluated the effect of surface treatments and reline materials on the impact strength of a denture base acrylic resin. Specimens were made using Lucitone 550 resin (60x6x2 mm) and relined (2 mm) with the same material (L) or with the hard chair-side reline resins Tokuso Rebase (TR) and Ufi Gel Hard (UH). For material L, the bond surfaces remained untreated (L/L/ST) or were wetted with resin L monomer (methyl methacrylate) for 180 seconds (L/L/M). When the relining was made with the hard reline materials, the surface treatments consisted of coating with the bonding agents supplied by the manufacturers (L/TR/A - dichloromethane and L/UH/A - dichloromethane and 2-hydroxyethyl methacrylate) or wetting with the resin L monomer followed by bonding agents application (L/TR/MA and L/UH/MA). Material L intact specimens (60x6x4 mm) were also made to determine the impact strength of the bulk resin. A total of 140 specimens were made, 20 for each experimental condition. Half of the specimens were notched across the width to a depth of 0.8 mm, leaving an effective depth under notch of 3.2 mm (E1). For the remaining specimens, the notch was cut across the thickness to a depth of 1.2 mm (E2) leaving an effective depth under notch of 4.8 mm. All the V-notches were machined at the midpoint of the length of the specimens. Impact tests were carried out on a Charpy type pendulum impact tester (0.5 J pendulum; distance between supporting points - 50 mm). Results (kJ/ m2) from each notch depth were analyzed separately using one-way ANOVA and Tukey's HSD tests (a = .05). No significant differences were noted among the mean impact values of L (1.39 kJ/ m2), L/L/ST (1.28 kJ/ m2) and L/L/M (1.20 kJ/ m2) specimens with the E1 notch (P>.05). Similar results were observed (P>.05) for the specimens with the E2 notch (L - 1.00 kJ/ m2; L/L/ST - 0.93 kJ/ m2; ...(Complete abstract, click electronic access below)
Mestre

Orientador: Rafael Leonardo Xediek Consani
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Forças aplicadas por próteses totais a implantes submersos durante o período deosseointegração podem, em alguns casos, levar ao insucesso clínico. Até o momento não existe trabalho na literatura que quantifique e/ou verifique a distribuição das forças mastigatórias em implantes submersos durante a ação mastigatória de próteses totais convencionais usadas provisoriamente durante o período de osseointegração. Dessa forma, neste trabalho foram avaliadas as tensões geradas no tecido ósseo subjacente a implantes recém-colocados, em diferentes situações, durante a ação mastigatória em próteses totais convencionais provisórias inferiores, por meio da metodologia dos elementos finitos. Com software de modelagem 3-D (SolidWorks 2010, SolidWorks Corp., Concord, Massachusetts, EUA) foram confeccionados modelos tridimensionais de mandíbula simulando diferentes situações clínicas: (1) implantes submersos, próteses totais convencionais e próteses reembasadas com diferentes materiais reembasadores macios; (2) diferentes níveis de altura de exposição dos cicatrizadores (submerso, nível gengival, 1,5 mm exposto no meio bucal); e (3) diferentes espessuras e comparação entre reembasamento na base da prótese inteira ou somente na região dos implantes. As análises foram realizadas em software específico (ANSYS Workbench 12, Ansys Inc., Canonsburg, Pennsylvania, EUA) e para cada modelo foram simuladas duas situações, com aplicação de carga mastigatória em canino inferior direito (35N) e primeiro molar inferior direito (50N). Todas as análises foram realizadas em tensão máxima principal, em MPa. Os resultados obtidos demonstraram que o reembasamento da prótese com material macio reduziu a concentração de tensões no tecido ósseo peri-implantar, sendo a concentração de tensão diretamente relacionada com a maciez do material. Os cicatrizadores submersos foram os que apresentaram menor valor de concentração de tensões. A espessura e área de reembasamento estão relacionadas à transmissão de tensões ao osso peri-implantar, quando o reembasamento da região dos implantes com espessura de 3 mm apresentou melhores resultados. Comparando-se os resultados mostrados nas diferentes simulações conclui-se que a situação que promoveu menor concentração de tensões no osso peri-implantar foi com implantes submersos, reembasamento realizado somente na região dos implantes, espessura de 3 mm e material macio.
Abstract: Forces applied to submerged implants from complete dentures during the osseointegration period can, in some cases, lead to clinical failure. To date there is no study in the literaturethat quantifies and/or verifies the stress distribution of occlusal forces in submerged implants during the masticatory function of conventional complete dentures used on an interim basis during the period of osseointegration. Thus, this study evaluated the stresses in the bone adjacent to newly placed implants during the masticatory function in conventional complete dentures through the finite element methodology. Using a 3-D modeling software (SolidWorks 2010, SolidWorks Corp., Concord, Massachussets, EUA) it were made tridimensional models of a mandible simulating different clinical situations: (1) submerged implants, conventional complete dentures and relined ones with different soft liner materials; (2) different height levels of exposure to the oral environment (submerged, gingival level and 1.5mm of exposure to the oral environment); and (3) different thickness and comparation between relining the entire base or only in the region near the implants. The analysis were made in a specific software (ANSYS Workbench 12, Ansys Inc., Canonsburg, Pennsylvania, EUA) and for each model it were simulated two situations with masticatory load in inferior right canine (35N) and inferior right first molar (50N). All the analysis were made in maximum principal stress, in MPa. The obtained results showed that relined dentures with soft liner material reduced the stress concentration in the peri-implant bone tissue, being the stress concentration directly related to the softness of the material. Submerged implants presented the lowest values of stress concentration in the peri-implant bone tissue. The thickness and the area of reline are related to the transmission of stress to the peri-implant bone tissue, when relining the denture only in the region of the implants with a 3-mm thick layer of soft liner material presented better results. Comparing the results obtained from the different simulations it is possible to conclude that the situation which promoted fewer stress concentration in the peri-implant bone was with submerged implants, relining made only in the implants region, thicker layer (3 mm) of reline and softer material.
Doutorado
Protese Dental
Doutor em Clínica Odontológica

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Dental Technology in the Faculty of Health and Wellness Sciences at the Cape Peninsula University of Technology, 2012
Statement of problem It is well documented that water sorption and water solubility by auto-polymerizing resins have a negative impact on their physical properties and may lead to harmful tissue reactions. The presence of residual monomer is often identified as the main cause for adverse tissue reactions. To optimize the polymerization reaction, the use of the proper powder/liquid ratio is recommended in the fabrication of a dental appliance. It is also recommended that a dental appliance should be soaked in water for at least 24 hours before delivery to a patient, in order to reduce the possible adverse effect. For auto-polymerizing resins, associated with higher residual monomer levels than heat-cured resins, soaking the appliance at elevated temperatures (65ºC for 60 minutes), would reduce the residual monomer content more efficiently than at room temperature. This requires additional processing conditions from the technician or dentist. Changing the powder/liquid ratios, deliberately or not, may modify the residual monomer content of the final product. A relationship exists between the levels of residual monomer and water sorption. Also, residual monomer leaching into the oral fluids may lead to adverse effects such as, oral tissue irritation or a delayed hypersensitivity reaction. Aim of the study The aim of this study was to evaluate the effect of different powder/liquid ratios and different water temperatures on the levels of sorption and solubility of an auto-polymerizing resin material used for denture bases. The null-hypothesis tested was that there is no difference in sorption and solubility among groups of specimens made from an auto-polymerizing resin material soaked in water at different temperatures and/or fabricated with different powder/liquid ratios. Material and methods Specimens were made from cold-cure pour-type denture base resin (Type 2, Class 2) using different powder/liquid ratios and soaked at different soaking temperatures. One group of specimens fabricated with the manufacturer’s recommended powder/liquid ratio and soaked in water at 37ºC, served as the control group for both experiments. Custom-made stainless steel moulds were used to fabricate resin disks, with a diameter of 50mm and a thickness of 0.5mm. For the temperature-controlled experiment, identical specimens were prepared and stored in distilled water at 37ºC; 45ºC; 55ºC and 67ºC. For the ratio-controlled experiment, the ratios were increased incrementally for each group, starting with a 10% increase, followed by a 15%; 20% and 25% increase in monomer. Water sorption and solubility were tested in accordance with ISO Standard 1567 (1999). Specimens were weighed before and after water immersion, and desiccation. Water sorption and solubility were calculated using the difference in wet and dry mass and the volume of the specimens. The water sorption and solubility results were analyzed by means of analysis of variance. For multiple comparisons, Bonferroni simultaneous confidence intervals (α=0.05) were applied. Results For the ratio-controlled experiment, water sorption mean values varied from 24.148 μg/mm3 to 25.1333 μg/mm3. Statistically significant differences in mean values were found between the following groups: 0%-10%; 0%-15%; 0%-25%; 10%-20%; 15%-20% and 20%-25% ratio groups (P<.0001). Water solubility mean values varied from 0.616μg/mm3 to 0.932μg/mm3. Statistically significant differences in mean values were found between the following groups: 0%-15%; 0%-20%; 0%-25% and 10%-25% and 20%-25% ratio groups (P<.0001). For the temperature-controlled experiment, water sorption mean values varied from 24.185μg/mm3 to 26.434μg/mm3. Statistically significant differences in mean values were found between the following groups: 37ºC-45ºC; 37ºC-55ºC; 37ºC-67ºC; 45ºC-67ºC and 55ºC-67ºC temperature-controlled experiments (P<.0001). Water solubility mean values, for the same experimental groups, varied from 0.616μg/mm3 to 2.752μg/mm3. Statistically significant differences in mean values were found among all the 6 pairs of groups (P<.0001). Despite statistical differences, the water sorption and water solubility values of the tested resin for both experiments and all groups were within the ISO Standard 1567 (1999) specification limits. Conclusion For the ratio-controlled experiment, there was an inverse relationship between the mean sorption and solubility values with an increase in liquid in the mixture: low water sorption levels are associated with high solubility levels. The lower water sorption and higher solubility results for more fluid mixtures could be related to initial and residual high monomer content characteristic of auto-polymerizing materials. These higher levels of free monomer are consequently released upon immersion in water; hence the higher water solubility levels. For the temperature-controlled experiment, a higher soaking temperature resulted in an increase in water solubility levels. The higher solubility levels could be attributed to the higher soaking temperatures causing higher or faster monomer diffusion from the resin material. Except for the 67ºC group, sorption is also lower with higher temperatures. It may be assumed that an additional polymerization process takes place and a subsequent more inaccessible polymer matrix is produced. For the 67ºC group, thermal expansion may explain the higher sorption level. Clinical Implications In terms of the sorption and solubility results, this auto-polymerizing pour-type resin may be used as a denture base resin. Even though statistical differences were demonstrated, the material satisfies the ISO 1567 (1999) requirements not only for auto-polymerizing but also for heat-polymerizing resins. Therefore, within limits, the mixture may be prepared more fluidly in order to improve flow of the material, without negatively affecting its sorption and solubility properties. Because solubility is higher at higher soaking temperatures, this property can be used to minimize monomer content of the appliance. Therefore, it is recommended that the dental appliance be soaked in warm water, below 67ºC, prior to delivery to the patient.

Orientador: Marcelo Ferraz Mesquita
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Este trabalho teve como objetivo avaliar o efeito da escovação mecânica e termociclagem sobre dureza e rugosidade superficiais de três materiais reembasadores resilientes considerados definitivos, dois à base de silicone, um auto (Sofreliner MS) e outro termopolimerizável (Molloplast-B), além de um à base de resina acrílica autopolimerizável (Dentuflex). Para a confecção das amostras, foram utilizadas matrizes de silicone polimerizado por reação de condensação incluídas em muflas, obtendo um molde impresso no gesso posteriormente preenchido com os materiais resilientes. Foram confeccionadas 60 amostras, submetidas à leitura de rugosidade superficial num rugosímetro SURFCORDER SE 1700 (Kosaka Laboratory) e à leitura de dureza num durômetro Shore A (GS ¿ 709 Teclock, Osaka, Japão). Em seguida as amostras foram separadas em dois grupos, onde metade foi submetida ao ensaio de termociclagem numa máquina MSCT ¿ 3 PLUS regulada em 2.000 ciclos com banhos alternados de 60 segundos a 5±1oC e 55±1oC e a outra metade ao ensaio de escovação mecânica numa máquina MSEt, seguida de termociclagem. O ensaio de escovação foi executado sob carga estática de 200 g, com movimentos lineares, totalizando 30.000 ciclos, onde uma solução de dentifrício contendo água era liberada a cada 1 minuto sobre as amostras. Após os ensaios, foram executadas novas leituras de dureza e rugosidade superficial. Os valores obtidos foram submetidos à análise de variância em parcelas subdivididas no tempo, seguida do teste de Tukey em nível de 5% de significância. O material Dentuflex apresentou os maiores valores médios de rugosidade e dureza iniciais, seguidos do Molloplast-B e Sofreliner MS. Após termociclagem, os materiais Dentuflex e Sofreliner MS apresentaram aumento estatisticamente significante da dureza. Após escovação, o material Dentulfex apresentou diminuição nos valores de rugosidade e o Sofreliner MS aumento, ambos estatisticamente significantes. Após a escovação seguida de termociclagem, todos os materiais apresentaram valores de rugosidade estatisticamente semelhantes entre si, provavelmente devido ao polimento do material Dentuflex, abrasão do Sofreliner MS e preservação das características do Molloplast-B
Abstract: The aim of this study was to evaluate the effect of mechanical brushing and thermocycling on hardness and roughness of three resilient definitive lining materials: 1) auto (Sofreliner MS), 2) heat-polymerized (Molloplast-B) silicone bases; and 3) auto-polymerized plasticized acrylic resin (Dentuflex). To prepare the samples, silicone rubber matrixes were made and placed in a flask to obtain a cast pressed mold, and then filled with resilient lining materials, handled according to the manufacturer¿s directions. All samples were submitted to surface roughness readings in a roughness readings machine (SURFCORDER SE 1700 ¿ Kosaka Laboratory) and hardness readings in a Shore A durometer (GS ¿ 709 Teclock, Osaka, Japan). After the readings, the samples were assigned into 6 groups of 10 each, half of which were submitted to thermocycling treatment in a thermal cycler machine (MSCT ¿ 3 PLUS) for 2.000 cycles at temperatures ranging from 5±1oC to 55±1oC and a 60-second dwell time. The other half was submitted to a mechanical brushing simulation in an MSEt brushing machine followed by thermocycling. The samples were submitted to 30.000 strokes with linear brushing movements, under a 200 g static load pressure. Toothpaste solution was injected every one-minute break. Then new readings of hardness and roughness were done, and the values were submitted to variance analysis test followed by Tukey test, with 5% of significance. Dentuflex showed the highest initial values for both roughness and hardness, followed by Molloplast-B and Sofreliner MS. After thermocycling, Dentuflex and Sofreliner-MS showed a statistically significant increase in hardness values. After mechanical brushing, Dentuflex showed a decrease and Sofreliner MS an increase in roughness values. After mechanical brushing followed by thermocycling, all materials showed similar roughness values (statistically significant), probably due to the Dentuflex polished surface, the Sofreliner MS abrasion and the remained features of the Molloplast-B
Mestrado
Protese Dental
Mestre em Clínica Odontológica

Orientador: Marcelo Ferraz Mesquita
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo deste trabalho foi avaliar o efeito da escovação mecânica e de agentes de limpeza sobre as características superficiais de materiais reembasadores resilientes. Foram utilizados os materiais Luci Sof (Dentsply), Molloplast-B (Dentax) e Sofreliner (Tokuyama), os agentes de limpeza Hipoclorito de Sódio a 0,5% (Medicinallis-Fármacia de Manipulação-SP-BR) e Efferdent (Warner-Lamber Co-EUA), a escova dental extra macia Johnson & Johnson Reach Professional (Johnson & Johnson Industrial LTDA.) e dentifrício Sorriso Dentes Brancos (Kolynos do Brasil). Foram confeccionadas 30 amostras de cada material, a partir da moldagem do dispositivo porta matriz da máquina de ensaio de escovação mecânica, com 25mm de comprimento X 14mm de largura X 3mm de espessura. Dez amostras de cada material foram submetidas à escovação mecânica e 20 imersas em agente de limpeza. A escovação mecânica foi realizada na máquina MSEt (Máquina de Simulação de Escovação), com velocidade de 5 movimentos por segundo (20.000 ciclos). Foram utilizados 2 agentes de limpeza: 1) Hipoclorito de Sódio a 0,5% a 37 + 1ºC, durante 20 minutos; 2) Efferdent, a 37 + 1ºC, durante 15 minutos. Após as imersões, as amostras foram lavadas e imersas em água destilada, a 37 ± 1ºC, pelo período restante das 24 h. Esse processo foi repetido 8 vezes por dia, durante 90 dias (720 ciclos). A rugosidade superficial, dureza Shore A e observação em microscópio eletrônico de varredura foram avaliadas antes e após os métodos de higienização. A rugosidade foi avaliada em rugosímetro Surfcorder SE 1700 (Kosaka ¿ Laboratory Ltda.); o ensaio de dureza Shore A em durômetro modelo GS-709 (Teclock-Japão), com aplicação de carga de 10N durante 1 segundo; a microscopia eletrônica de varredura em microscópio modelo JSM 5600 PV (JEOL-Japão), onde foi observada a morfologia superficial de amostras representativas de cada tratamento. Os resultados obtidos foram submetidos aos Testes de Wilcoxon-Mann-Whitney e de Kruskal-Wallis (5%). A escovação aumentou significantemente os valores de rugosidade dos materiais. Luci Sof (Ra=0,74m), Molloplast-B (Ra=1,28m) e Sofreliner (Ra=3,18m) apresentaram diferença estatisticamente significante entre si. O tratamento em Efferdent promoveu diminuição significante dos valores de rugosidade de Luci Sof e Sofreliner. Após o tratamento, os materiais não apresentaram diferença estatisticamente significante entre si (Luci Sof Ra=0,32m; Molloplast-B Ra=0,32m; Sofreliner Ra=0,36m). A imersão em Hipoclorito promoveu diminuição significante os valores de rugosidade dos materiais. Luci Sof (Ra=0,29m) e Molloplast-B (Ra=0,27m) e Molloplast-B e Sofreliner (Ra=0,17m) não apresentaram diferença estatisticamente significante entre si. A escovação diminuiu os valores de dureza significantemente de Molloplast-B (35,10), mas não alterou esses valores de Luci Sof (43,80) e Sofreliner (27,10). Após a escovação, os materiais apresentaram diferença estatisticamente significante entre si. A imersão em Efferdent diminui significantemente os valores de dureza dos materiais. Após o tratamento, Molloplast-B (25,70) e Sofreliner (25,75) não apresentaram diferença estatisticamente significante entre si, mas diferiram de Luci Sof (36,65). A imersão em Hipoclorito diminui significantemente os valores de dureza de Molloplast-B e Sofreliner, e não alterou para Luci Sof. Após o tratamento, Molloplast-B (28,85) e Sofreliner (26,00) não apresentaram diferença estatisticamente significante entre si, mas diferiram de Luci Sof (43,80). A escovação mecânica foi o tratamento que promoveu os maiores valores de rugosidade superficial para todos os materiais avaliados. Após a escovação, todos apresentaram valores estatisticamente diferentes entre si, na ordem crescente: Luci Sof, Molloplast-B e Sofreliner. Os tratamentos de imersão promoveram a diminuição dos valores de rugosidade superficial apresentados pelos materiais Luci Sof e Molloplast-B, e elevação para o material Sofreliner quando imerso em Efferdent. A escovação diminuiu o valor mediano de dureza do material Molloplast-B. Após a escovação, todos apresentaram valores estatisticamente diferentes entre si, na seguinte crescente: Sofreliner, Molloplast-B e Luci Sof. A imersão em Efferdent promoveu diminuição significativa dos valores de dureza para todos os materiais. A imersão em Hipoclorito de Sódio promoveu diminuição significativa dos valores de dureza dos materiais Sofreliner e Molloplast-B
Abstract: The aim of this study was to evaluate the influence of mechanical brushing and denture cleansers on the surface properties of soft lining materials. Three soft liners, Luci Sof (Dentsply), Molloplast-B (Dentax), and Sofreliner (Tokuyama), two denture cleansers Efferdent (Warner-Lamber Co- EUA), and 0,5% alkaline hypochlorite preparation, the Reach Professional toothbrush (Johnson & Johnson) and the dentifrice Sorriso Dentes Brancos (Kolynos do Brasil) were used. Thirty specimens of each soft liner material were prepared by molding the specimen container appliance of the brushing machine, measuring 25mm long, 15mm wide and 3mm thick. Ten specimens of each material were submitted to the mechanical brushing assay, and 20 specimens of each material immersed into the solution of each denture cleanser. The mechanical brushing assay was conducted on the MSEt plus machine, at a rate of 5.0 strokes per second (20.000 cycles). Two denture cleansing approaches were used: 1) specimens immersed in 0.5% alkaline hypochlorite preparation at 37 ± 1 ºC for 20 minutes; 2) specimens immersed in Efferdent at 37 ± 1 ºC for 15 minutes. The specimens were then washed thoroughly with tap water, and immersed into distilled water, for the remainder of the 24 h period, at 37 ± 1 ºC. This procedure was repeated 8 times a day, during 90 days (720 cycles). The specimens were evaluated before and after the cleansing procedures. The surface roughness was evaluated in a profilometer SE 1700 (Kosaka ¿ Laboratory), and the Shore A hardness in a microdurometer GS-709 (Teclock, Japan) with a penetrating load of 10N for 1 second. The observation of superficial morphology from representative specimens of each method of cleanser were observed using a scanning electron microscope JSM 5600 PV model (JEOL-Japan). All numeric data were subjected to Wilcoxon-Mann-Whitney and Kruskal-Wallis tests at the 5% level. The mechanical brushing assay increased significantly the roughness mean values for all materials. The mean values for Luci Sof (Ra=0.74m), Molloplast-B (Ra=1.28m) and Sofreliner (Ra=3.18m) were statistically different after the brushing assay. The Efferdent treatment decreased the roughness mean values of Luci Sof and Sofreliner significantly, but not for Molloplast-B. After the treatment, no differences in the mean values were observed among the materials (Luci Sof Ra=0.32m; Molloplast-B Ra=0.32m; Sofreliner Ra=0.36m). The Hypochlorite treatment decreased the roughness mean values of all materials significantly. After the treatment, neither Luci Sof (Ra=0.29m) and Molloplast-B (Ra=0.27m) nor Molloplast-B and Sofreliner (Ra=0.17m) showed statistically significant differences. The brushig assay decreased the hardness mean values significantly only for Molloplast-B. After the assay, no statistically significant differences were observed for Luci Sof (43.80), Molloplast-B (35.10) and Sofreliner (27.10). The Efferdent treatment decreased the hardness mean values significantly for all materials. After the treatment, mean values of Molloplast-B (25.70) and Sofreliner (25.75) were not statisticaly different, but they differed from that of Luci Sof (36.65). The Hypochlorite treatment decreased the hardness mean values of Molloplast-B and Sofreliner. After the treatment, mean values of Molloplast-B (28.85) and Sofreliner (26.00) were not statisticaly different, but they differed from that of Luci Sof (43.80). The mechanical brushing assay increased the roughness mean values for all materials significantly, from smoothest to roughest in the following order: Luci Sof, Molloplast-B, and Sofreliner. The denture cleansers decreased the roughness mean values of Luci Sof and Molloplast-B, and increased this values for Sofreliner in Efferdent. The mechanical brushing decreased the hardness mean value of Molloplast-B, and after this treatment, all materials showed statistical significantly differences, from smoothest to hardest in the following order: Sofreliner, Molloplast-B, and Luci Sof. The Efferdent treatment decreased the hardness mean values for all materials significantly. The Hypochlorite treatment decreased the hardness mean values for Sofreliner and Molloplast-B significantly
Mestrado
Protese Dental
Mestre em Clínica Odontológica

Orientador: Marcos Yutaka Shiino
Coorientador: Alberto Noriyuki Kojima
Banca: Vinícius Anéas Rodrigues
Banca: Vivian Silveira dos Santos Bardini
Resumo: A introdução da zircônia na Odontologia deu-se pela necessidade de melhores propriedades mecânicas dos materiais cerâmicos, pois com a crescente demanda estética, os cerâmicos tornaram-se materiais de largo uso, devido às suas propriedades estéticas e mecânicas. Em busca dessas propriedades, vários estudos analisaram a taxa de sobrevivência de restaurações zircônia-porcelana, relatando como uma das causas de falha a fratura precoce da porcelana de cobertura e o aumento significativo nos relatos clínicos de lascamento da porcelana de recobrimento aplicada sobre "coping" de zircônia. Diante desse problema, o objetivo deste trabalho foi determinar a tensão de falha no lascamento a partir de casos de clínicos e experimentais pertinentes a esse fenômeno em próteses fixas livres de metal .Foram coletados dados de artigos dos últimos 15 anos, por meio das bases de dados Pubmed e Google Schoolar, sendo selecionados para essa revisão os que obtiveram melhor abordagem do assunto, dando ênfase às possíveis causas de falhas nas restaurações cerâmicas dos casos clínicos e os ensaios realizados, visando um melhor entendimento desse fenômeno, via análise quantitativa e qualitativa, para melhor utilização e aproveitamento desse material na Odontologia. Para determinação da tensão de falha, foi empregada a mecânica da fratura linear elástica e determinado o fator de correção da trinca com base nas dimensões da trinca.Com a presente pesquisa, nota-se que amplitude de tensão influencia no proce... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The introduction of zirconia in dentistry was due to the need for better mechanical properties of ceramic materials, because of an increasing aesthetic demand. Ceramics became widely used materials due to their aesthetic and mechanical properties. Aiming at these properties, several studies have analyzed the survival rate of zirconia-porcelain restorations, reporting as one of the causes of failure. Early porcelain fracture coverage and a significant increase in clinical reports of veneering porcelain applied over "coping "of zirconia. In view of this problem, the objective of this work was to determine the failure causes of chipping from clinical and experimental cases associated to this phenomenon in fixed metal free prostheses. Data from articles of the last 15 years were collected through the Pubmed and Google Schoolar databases. Those who obtained the best approach to the subject were selected for this analysis, emphasizing the possible causes of failures in the ceramic restorations of the clinical cases and the tests performed. Aiming for a better understanding of this phenomenon, via quantitative and qualitative analysis, to better use this material in dentistry. To determine the failure causes, linear elastic fracture mechanics were used and the crack correction factor was determined based on the crack dimensions. With the present research, it is noticed that stress amplitude influences in the fracture process, although it has not pointed exactly the cause of the frac... (Complete abstract click electronic access below)
Mestre

Orientador: Marcelo Ferraz Mesquita
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo deste trabalho foi avaliar e comparar o desempenho de um material reembasador resiliente à base de resina acrílica (Eversoft com ou sem adição de citrato à composição), submetido ou não ao envelhecimento (termociclagem), sobre as propriedades de deformação permanente e resistência à tração da união com resina acrílica (QC-20®). Para a realização dos ensaios foram confeccionadas 80 amostras, metade para cada ensaio, separadas por composição e submetidas ou não à termociclagem, totalizando 8 grupos. Para o ensaio de tração, foram utilizadas matrizes retangulares de 10mm2 de secção transversal e um espaçador de 3mm de espessura para padronizar o espaço para a base resiliente, cujo molde impresso no silicone polimerizado por reação de condensação foi preenchido com resina acrílica e material resiliente. A resina acrílica foi incluída com o espaçador e após a polimerização, o espaçador foi removido, as amostras de resina acrílica retiradas do molde e realizado o acabamento. As amostras de resina acrílica retornaram ao molde, e no lugar do espaçador, os materiais resilientes foram prensados e termopolimerizados de acordo com as instruções dos fabricantes. Para o ensaio de deformação permanente, foram utilizadas matrizes cilíndricas de 12,7mm de diâmetro e 19mm de altura, cujo molde impresso no silicone foi preenchido com material resiliente. Metade das amostras de cada ensaio foi levada ao termociclador MSCT-3 PLUS, onde foram realizados 3.000 ciclos de 1 minuto de imersão em água a 5±1ºC e 1 minuto a 55±1ºC. A outra metade foi armazenada em água numa estufa a 370C durante 24 horas. As amostras foram submetidas ao ensaio de tração no equipamento EMIC-DL500MF com velocidade de 5 mm/minuto. As amostras foram avaliadas visualmente quanto ao tipo de ruptura ocorrida, e amostras representativas de cada tipo foram analisadas através de microscopia eletrônica de varredura em microscópio modelo JSM 5600 PV (JEOL, Japão). As amostras do estudo de deformação permanente foram ensaiadas em um aparelho mecânico recomendado na especificação no18 da American Dental Association (A.D.A.). Todos os dados obtidos foram submetidos à análise de variância em esquema fatorial 2x2 e as médias comparadas pelo Teste de Tukey, em nível de significância de 5%. Em relação aos valores médios de resistência à tração da união dos materiais não submetidos à termociclagem, o Eversoft com citrato ¿ Experimental apresentou menor valor (0,39 MPa), porém sem diferença estatística com o Eversoft sem citrato ¿ Eversoft® (0,44 MPa). Houve aumento dos valores médios de resistência à tração da união quando submetido à termociclagem para o Eversoft® (0,46 MPa) e Experimental (0,55 MPa), sendo estatisticamente significativo apenas para o material Experimental Em relação aos tipos de fratura, para ambos materiais não submetidos à termociclagem, predominaram rupturas coesivas (80%); e quando submetidos à termociclagem, foram observadas rupturas adesivas para o material Experimental (80%) e adesivas e mistas (40% e 50%, respectivamente) para o Eversoft®. Em relação à deformação permanente, os valores médios obtidos para os materiais Eversoft® e Experimental não submetidos à termociclagem (1,06% e 1,82%, respectivamente) diferiram estatisticamente quando submetidos à termociclagem (1,36% e 1,98 %, respectivamente). A termociclagem não afetou a resistência à tração da união para o material Eversoft®, enquanto o Experimental apresentou elevação no valor médio de resistência à tração da união, com diferença estatística significativa. A termociclagem elevou os valores médios de deformação permanente para ambos materiais. Independentemente do tratamento, o material resiliente Experimental apresentou o valor médio mais elevado para deformação permanente
Abstract: The aim of this study was to evaluate and compare the effect of citrate added or not to a composition of acrylic-based soft liner (Eversoft) on its permanent deformation and bond strength with acrylic resin (QC-20®). Eighty samples were used to carry out the two assays containing 40 specimens each: 2 materials (Eversoft® and Eversoft + citrate) and 2 treatments (with and without thermocycling) totaling 8 groups of 10 specimens each. For the tensile test, rectangular specimens with a 10x10mm2 cross sectional area were prepared for each acrylic resin and soft liner. Acrylic resin specimens were prepared by investing brass dies with a 3mm thick spacer in a denture flask. The dies and spacers were invested in silicone rubber. All dies and the spacer were machined to the same dimensions to standardize acrylic resin and soft liner shape. Specimens were made by processing soft liner against acrylic resin blocks according to the manufacturers¿ directions. For the permanent deformation, the specimens were prepared by investing brass dies (12.7 x 19.0 mm) in a denture flask and the model impressed was filled up with a soft liner. Half of the specimens of each assay were thermocycled using the MSCT-3 Plus with cycles of 1 minute in water at 5±1ºC and 1 minute in water at 55±1ºC, totaling 3000 cycles. The other half was stored in water at 370C for 24h. For the tensile test, the specimens were submitted to a bond strength testing machine (EMIC DL-500 MF) at the crosshead speed of 5mm/minute. Samples were visually evaluated as to the types of rupture observed in this study. The Scanning Electron Microscope JSM 5600 PV (JEOL, Japan) was used to analyze the representative samples. Permanent deformation was measured with an instrument described in the American Dental Association (A.D.A.) - specification number18. The data were submitted to a 2-way analysis of variance and the Tukey test (5%). The bond strength test, without thermocycling, revealed a lower mean value (0.39 MPa) for the group Eversoft with citrate - Experimental; however, no statistically significant difference was observed for the group Eversoft without citrate - Eversoft® (0.44 MPa). Thermocycling did not affect the bond strength regarding Eversoft® (0.46 MPa); however, Experimental presented a higher mean value (0,55 MPa) ¿ statistically significant. Both materials, without thermocycling, presented cohesive failures (80%). When submitted to thermocycling, 80% of adhesive failures were observed for Experimental, and 40% of adhesive and 50% of a combined mode of failures for Eversoft®. In relation to the permanent deformation, Eversoft® and Experimental, not submitted to thermocycling, presented mean values (1.06% and 1.82%, respectively) differing statistically from those submitted to thermocycling (1.36% and 1.98%, respectively). Thermocycling did not affect the bond strength regarding Eversoft®; however, Experimental presented a higher mean value. Thermocycling had a deleterious effect on the permanent deformation of both materials. Regardless of treatment, statistically significant difference was observed for Experimental group, showing the highest permanent deformation permanent value
Mestrado
Protese Dental
Mestre em Clínica Odontológica

Orientador: Marcelo Ferraz Mesquita
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Este trabalho teve como objetivo avaliar comparativamente o efeito do envelhecimento por termociclagem na absorção, solubilidade e dureza em dois materiais reembasadores resilientes considerados de longa duração, um à base de silicone autopolimerizável (Sofreliner MS) e outro à base de resina acrílica termopolimerizável (Super-soft). As amostras foram confeccionadas a partir de matrizes metálicas com formato circular medindo 45 mm de diâmetro X 1 mm de espessura (absorção e solubilidade) e 45 mm de diâmetro X 3 mm espessura (dureza). As matrizes foram incluídas em mufla metálica, obtendo um molde impresso no silicone posteriormente preenchido com os materiais resilientes. Foram confeccionadas 40 amostras, metade para mensuração de absorção de água e solubilidade e outra metade para dureza Shore A, mensurada num durômetro GS ¿ 709 Teclock, Osaka, Japão. Em seguida as amostras foram submetidas ao ensaio de termociclagem numa máquina MSCT ¿ 3 PLUS, regulada em 2.000 ciclos com banhos alternados de 60 segundos a 5±1oC e 55±1oC. Após os ensaios, foram efetuadas novas leituras de dureza Shore A e avaliação quanto à absorção de água e solubilidade. Os valores obtidos foram submetidos ao teste de Shapiro ¿ Wilks para avaliação da normalidade dos dados, seguida da aplicação do teste t de Student. Os resultados de absorção de água e solubilidade apresentaram diferença estatisticamente significante para ambos os materiais, sendo respectivamente 2,69 ± 0,16% e 1,59 ± 0,24% para o material Super ¿ soft e 1,41 ± 0,21% e 0,01 ± 0,1% para o Sofreliner MS (p<0,05). Para o ensaio de dureza Shore A, os valores apresentados antes e após termociclagem foram de 64 e 30 unidades pelos materiais Super ¿ soft e Sofreliner MS, respectivamente, não diferindo estatisticamente considerando os materiais isoladamente (p>0,05). Comparando cada material separadamente antes e após a termociclagem, ambos apresentaram diferença estatisticamente significante entre si (p<0,05). O material Sofreliner MS apresentou menores valores de absorção de água, solubilidade e dureza Shore A. Desse modo, concluiu-se dentro dos limites deste estudo que aparentemente este material deva apresentar melhor comportamento quando utilizado clinicamente
Abstract: The aim of this study was to evaluate the effect of thermocycling on sorption, solubility and Shore A hardness of two resilient definitive lining materials: 1) auto-polymerized silicone base (Sofreliner MS); and 2) heat-polymerized plasticized acrylic resin (Super - soft). To prepare the samples, twenty aluminium matrixes were made (ten for sorption and solubility and ten for Shore A hardness) placed in a flask order to obtain a cast pressed mold, and then filled with resilient lining materials, handled according to the manufacturer¿s directions. The hardness samples were submitted for readings in a Shore A durometer (GS ¿ 709 Teclock, Osaka, Japan). After the readings, the samples were submitted to thermal cycling treatment in a thermal cycler machine (MSCT ¿ 3 PLUS) for 2.000 cycles at temperatures ranging from 5±1oC to 55±1oC and a 60-second dwell time. After thermal cycling new readings of hardness were done, and the values of sorption and solubility calculated by Kasanji & Watkinson equation. The values were submitted to Shapiro ¿ Wilks analysis followed by Student test, with 5% of significance. Sorption and solubility showed statistical significance for both materials (2,69 ± 0,16 and 1,59 ± 0,24 for Super ¿ soft and 1,41 ± 0,21 and 0,01 ± 0,1 for Sofreliner MS) (p<0,05). For Shore A hardness the thermal cycling showed no effect for both materials (64 for Super ¿ soft and 30 for Sofreliner MS) (p>0,05). Sofreliner MS showed the lower values for sorption, solubility and Shore A hardness. Withing the limitations of this in vitro study Sofreliner MS showed best properties
Doutorado
Protese Dental
Doutor em Clínica Odontológica

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O câncer da região de cabeça e pescoço é uma doença muito prevalente no Brasil, e as principais formas de tratamento são a cirurgia acompanhada ou não da radioterapia e quimioterapia. Perdas parciais ou totais de osso maxilar podem comprometer seriamente a fisiologia bucal causando sequelas como comunicações buconasosinosal. Neste caso, podese optar como forma de tratamento pela reabilitação protética com a aplicação de implantes osseointegrados. A literatura odontológica tem mostrado inúmeros trabalhos que avaliam a distribuição de forças com a finalidade de recolher melhores subsídios para o planejamento de próteses bucomaxilofaciais, que ainda é pouquíssimo explorada. Dentre os métodos utilizados, o da fotoelasticidade tem sido aceito, especialmente por permitir uma análise fiel da distribuição de forças. Assim, a proposta deste trabalho foi verificar a tendência de distribuição de forças e estresse, através do método fotoelástico, que incidem sobre diferentes tipos de sistemas de retenção em implantes (o’ring, barra clipe e o’ring/barra clipe) associado a próteses obturadoras palatinas implantoretidas e também em próteses obturadoras mucossuportadas (sem implante), utilizandose ou não de silicone com reembasamento direto (Sofreliner). O conjunto (prótese e modelo fotoelástico) foi posicionado em polariscópio circular e recebeu aplicação de carga de 100 N a velocidade de 10 mm/s no primeiro molar de cada prótese. Após as aplicações de carga houve a formação franjas correspondentes à tensão registrada. Então, as imagens foram transferidas para um computador e analisadas no programa ADOBE Photoshop. Ao se comparar os três sistemas de retenção das próteses obturadoras palatinas implantoretidas com a prótese mucossuportada (sem implantes), podese observar que as tensões foram distribuídas de forma mais homogênea...
The head and neck cancer is a very prevalent disease in Brazil and the main treatment is the surgery with or without radiation therapy and chemotherapy. Partial or total bone maxillary defects could involve seriously oral physiology causing consequences as buconasosinosal communications. In this case could be applied other option of treatment as prosthetic rehabilitation associated with osseointegrated implants. Scientific literature demonstrated countless studies that evaluate the force distribution with the aim to provide better subsidies for the planning of bucomaxillofacial prostheses, which still have few researches. Between the methodologies, the photoelastic method has been accepted; especially by allow an accurate analysis of the force distribution. Thus, the aim of this study was to verify the tendency of force distribution and the stress on different types of retention system (o’ring, clip bar and o’ring/clip bar) associated with palatal obturator prostheses with implant retention and conventional obturator prostheses (without implants), with or without silicone soft lining(Sofreliner), by means of photoelastic method. The set (prosthesis and photoelastic model) was located in circular polariscope and was applied a load of 100 load N at 10 mm/s on the first molar of each prostheses. After the load applications was registered the tension fringes. The images was transferred to a computer and analyzed at ADOBE Photoshop software. When compared the three retention systems of the palatal obturator prostheses and mucosupported prostheses (without implants), it can be observed that the stress was distributed more homogeneous and in lesser amount that the conventional prostheses, when compared to the other prostheses that presented implants and retention systems. With relation to stress distribution in the different retention systems, the bar clip... (Complete abstract click electronic access below)

U uvodnom delu doktorske disertacije opisuje se kompleksnost problematike korišćenja polimera za bazu zubne proteze, sa osvrtom na njihove opšte osobine, stepen biokompatibilnosti i njihove mehaničke karakteristike. Detaljno je opisana problematika ispitivanja stomatoloških materijala i napravljeno je poređenje i korelacija između in vitro i in vivo načina ispitivanja biokompatibilnosti. Drugi deo obuhvata ispitivanje čvrstoće polimera za bazu zubne proteze i analizu uticaja osobina materijala u odnosu na biološku sredinu u kojoj obavljaju svoju funkciju, i u odnosu na sile kojima su tokom funkcije materijali izloženi. Cilj doktorske disertacije je utvrđivanje stepena biokompatibilnosti i mehaničkih karakteristika toplopolimerizujućih, hladnopolimerizujućih i termoplastičnih akrilata za bazu zubne proteze. Istraživanje je obuhvatilo 3 komercijalna materijala iz grupe akrilata, koji se razlikuju po hemijskom sastavu i načinu polimerizacije. Ispitivanje biokompatibilnosti rađeno je u in vitro i in vivo uslovima. Ispitivanje na ćelijskim kulturama obuhvatalo je dve ćelisjke linije (MRC 5 i L929) sa dva načina kontakta između ćelija i materijala (direktan, indirektan) i dva načina određivanja biološkog ishoda (MTT test, Agar difuzioni test). Istraživanje urađeno in vivo obuhvatalo je test subkutane implantacije, na animalnom modelu pacova, i test iritacije oralne sluzokože na animalnom modelu hrčka. Oba testa rađena su u skladu sa standardom ISO 10993. Cilj in vivo istraživanja bio je ispitivanje reakcije tkiva na implantirani materijal, računajući i završnu integraciju ili dezintegraciju implantiranog materijala. Prednost in vivo istraživanja nalazi seu analizi uticaja materijala na sterilno živo tkivo, uz praćenje imunološke reakcije, kao dopuna prethodnom istraživanju na ćelijskim kulturama. Dopunski deo in vivo ispitivanja biokompatibilnosti određen je prema kliničkoj upotrebi ispitivanih materijala, zbog čega je odabran test oralne iritacije sluzokože. Sluzokoža bukalne kesice sirijskog hrčka sastoji se od pločasto slojvitog epitela sa orožavanjem, što je predstavljao dobar model za ispitivanje polimera za bazu zubne proteze, pošto zubna proteza naleže na sluzokožu nepca i rezidualnog alveolarnog grebena koja takođe orožava. Drugi deo disertacije obuhvatao je ispitivanje mehaničkih karakteristika, pri čemu su urađeni test zatezne čvrstoće, test savojne čvrstoće, test čvrstoće loma i mikrotvrdoće, uz dopunsku analizu pratećih parametara. Rezultati ispitivanja biokompatibilnosti pokazali su da su testovi biokompatibilnosti osetljivi na upražnjeni metodološki postupak. Ispitivanjem na ćelijskim kulturama nisu utvrđene značajne razlike u citotoksičnosti između toplopolimerizujućih, hladnopolimerizujućih i termoplastičnih akrilata. Takođe, rezultati su se razlikovali u odnosu na tip ćelijske kulture i način provere biološkog ishoda, što se slaže sa prethodnim navodima o kompleksnoj problematici njihovog međusobnog poređenja. Ispitivanjem biokompatibilnosti subkutanom implantacijom praćen je inflamatorni odgovor tkiva u vremenskom intervalu od 90 dana. Reakcija organizma na implantirani materijal posmatrana je kroz ćelijske i tkivne parametre, u skladu sa ISO 10993. Dodatno je urađena i analiza hrapavosti implantiranih materijala. Histološkom analizom utvrđena je razlika u inflamatornom odgovoru u odnosu na korišćeni materijal, kao i prema vremenskom intervalu implantacije. Test oralne iritacije sluzokože nije se pokazao kao dovoljno senzitivan za ispitivanje ovih vrsta materijala. Ispitivanjem mehaničkih karakteristika utvrđene su razlike između toplopolimerizujućih, hladnopolimerizujućih i termoplastičnih akrilata. Najveći stepen čvrstoće utvrđen je kod toplopolimerizujućih akrilata dok je najveća konzistentnost rezultata bila u grupi termoplastičnih akrilata. Prezentovano istraživanje predstavlja prvu detaljnu analizu biokompatibilnosti i mehaničkih karaktestistika polimera za bazu zubne proteze.
The introduction describes the complexity of use of denture base materials, with regard to their general characteristics, biocompatibility and mechanical properties. Issues related to the testing of dental materials is described in detail and comparison is made between in vitro and in vivo methods of biocompatibility testing. The second part further covers the determination of strength of previously used materials, in relation to biological environment in which their function is conducted and in relation to the influence of masticatory forces which can contribute to their mechanical failure. The aim of the presented research was to assess the degree of biocompatibility and mechanical properties of cold curing, hot curing and thermoformed denture base materials. The research included three denture base materials, which differed according to their chemical composition and polymerization protocols. The biocompatibility testing was carried out in in vitro and in vivo conditions. The in vitro experiments covered two different cell lines (MRC 5 human lung fibroblasts and L929 mouse fibroblasts) with two types of contact (direct, indirect) and two different types of quantification of biological outcome (MTT assay and Agar overley test). The in vivo assessment of biocompatibility covered the subcutaneous implantation test, on the animal model of Wistar rat, and oral mucosa irritation test, on the animal model of sirian hamster. Both tests were conducted according to the ISO 10993. The aim of the in vivo investigation was to evaluate tissue reactions to the implanted materials, including the final integration or disintegration of the tested materials. The advantage of in vivo investigation included the possibility of monitoring the materials influence on living tissues, with the analysis of imunological response as an addition to the previously conductedresearchon cell cultures. The supplemental part of in vivo investigation was chosen according to the clinical use of the tested materials, which included the oral mucosa irritation test.The mucosa of hamster buccal pouch consists of stratified squamos epithelium, which is considered to be an adequate replacement for the human denture supporting tissues, which also consist of the same type of epithelium. The second part of thesis includes the determination of mechanical properties of denture base materials. It consists of four types of tests: tensile strength test, bending strength test, fracture toughness test and microhardness tests, followed by the analysis of corresponding parameters. The results of the biocompatibility tests showed that the biological outcome of the applied method is highly depended on the methodological procedure. The investigation conducted in vitro, on two different cell lines, did not show significant difference in cytotoxicity between hot curing, cold curing and thermoformed denture base materials. Also, the results were influenced by the type of cell culture and the evaluation method of biological outcome, which agrees with the previous allegations about the complexicity of their mutual comparison. The subcutaneous implantation test covered the inflammatory response in the time period of 90 days. The organism reaction to the implanted material was determined through the cell and tissue parameters of organism response, evaluation of which was conducted according to the ISO 10993. Additionally, the surface roughness of the implanted specimens of materials was also measured. The inflammatory response of the ogranism was influenced by the type of the implanted material and the time interval of implantation. The oral mucosa irritation test has proven not to be sufficiently sensitive for testing of this type of materials. Testing of the mechanical properties od denture base materials, revealed the difference between the cold curing, hot curing and thermofomed denture base materials. The highest strength was observed in hot curing materials, while the highest consistency of the results was observed in thermoformed resins. The presented investigation presents the first detail analysis of the biocompatibility and mechanical properties of the denture base materials, and as such presents a novelty in the field of dental materials characterization.

Reembasadores resilientes temporários contendo fármacos antifúngicos foram sugeridos como um tratamento adjunto para estomatite protética. No entanto, antes de utilizar clinicamente estes reembasadores modificados em humanos, é importante avaliar a sua biocompatibilidade em modelos animais. Este estudo avaliou a biocompatibilidade in vivo de um reembasador resiliente temporário para base de prótese (Trusoft) modificado por agentes antimicrobianos em suas mínimas concentrações inibitórias (MCIs) para biofilme de Candida albicans. Dispositivos acrílicos intra-orais (DIOs) foram confeccionados individualmente para 60 ratos Wistar. Os ratos foram divididos em 6 grupos (n=5): 3 grupos controle (Negativo: sem DIO; Geral: DIO sem reembasamento; Positivo: DIO reembasado com Trusoft sem fármacos) e 3 grupos experimentais (DIOs reembasados com Trusoft modificados por fármacos em suas respectivas MCIs: 0,032 g de nistatina, 0,064 g de diacetato de clorexidina e 0,128 g de cetoconazol). Os ratos com ou sem os DIOs foram eutanasiados após 7 e 14 dias de avaliação. A análise histopatológica qualitativa foi realizada comparando-se fotomicrografias de secções histológicas, que foram obtidas utilizando um microscópio óptico que abrangeu transversalmente a região intermolares. As alterações morfológicas no epitélio e queratina foram analisadas quantitativamente através da realização de planimetria computadorizada. Os dados quantitativos foram analisados utilizando ANOVA 2-fatores e teste de Tukey (=0,05). A análise quantitativa mostrou que apenas o grupo com DIO contendo cetoconazol diminuiu significativamente a espessura e a área do estrato córneo em comparação com os outros grupos (p<0,05), que não apresentaram diferenças significativas entre si (p>0,05). Estes resultados estiveram de acordo com os obtidos para análise qualitativa. A incorporação de MCIs de nistatina e diacetato de clorexidina no Trusoft não induziram alterações histopatológicas na mucosa palatina de ratos, sugerindo a biocompatibilidade in vivo deste protocolo para o tratamento de estomatite protética.
Temporary resilient denture liners containing antifungal drugs have been suggested as an adjunct treatment for denture stomatitis. However, before clinically using these modified liners in humans, it is important to assess their biocompatibility in animal models. This study evaluated the in vivo biocompatibility of a temporary soft denture liner (Trusoft) modified by antimicrobial agents at their minimum inhibitory concentrations (MICs) for biofilm formation by Candida albicans. Methods: Acrylic intraoral devices (IODs) were individually made for 60 Wistar rats. The rats were divided into the following 6 groups (n=5): 3 control groups (Negative: without IOD; General: IOD without relining; Positive: IOD relined with Trusoft without drugs) and 3 experimental groups (IOD relined with Trusoft modified by drugs at MICs: 0.032 g for nystatin, 0.064 g for chlorhexidine diacetate, and 0.128 g for ketoconazole). The rats with or without the IODs were sacrificed after 7 or 14 days of evaluation. Histopathological qualitative analysis was performed by comparing photomicrographs of histological sections, which were obtained using an optical microscope that transversely covered the inter-molar region. Morphological changes in the epithelium and keratin were quantitatively analyzed by performing computerized planimetry. Quantitative data were analyzed using 2-way ANOVA and Tukey\'s test (=0.05). Quantitative analysis showed that only the group with IOD containing ketoconazole significantly decreased the thickness and area of the stratum corneum compared with the other groups (p<0.05), which showed no significant differences between each other (p>0.05). These results were in accordance with those obtained for qualitative analysis. Incorporation of MICs of nystatin and chlorhexidine diacetate in Trusoft did not induce histopathological changes in the palatal mucosa of rats, suggesting the in vivo biocompatibility of this protocol for treating denture stomatitis.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O objetivo deste estudo foi avaliar o efeito de três tratamentos superficiais na resistência de união de um cimento resinoso a três cerâmicas dentais: Duceram Plus (DP), IPS Empress II (IPS) e In-Ceram Alumina (INC), e analisar a topografia superficial dessas cerâmicas submetidas aos mesmos tratamentos superficiais. Para o teste de resistência de união foram confeccionadas 18 amostras de cada material (7,5mm de diâmetro x 3,0mm de espessura), incluídas em resina acrílica e polidas até lixa nº 600. As amostras foram divididas em três grupos: a) jateamento com partículas de óxido de alumínio de 50 æm; b) condicionamento com ácido fluorídrico 10%; c) associação de a e b. As amostras foram lavadas e secas. A área de adesão da cerâmica foi delimitada com matriz metálica perfurada (5,0mm de diâmetro e 3,0mm de espessura). Foi aplicado silano, adesivo e cimento resinoso Variolink II, fotoativado por 40 segundos. As amostras receberam 1000 ciclos térmicos de 5 a 55°C. O ensaio de cisalhamento foi realizado em máquina de ensaios MTS 810, com célula de carga de 10 kN e velocidade de 0,5 mm/min. Para a topografia superficial foram confeccionados um coping de IPS, um do INC e uma coroa de DP, seguindo as recomendações dos fabricantes. Cada coping ou coroa foi cortado com disco diamantado em quatro partes: uma delas não recebeu nenhum tratamento, e as demais receberam um dos tratamentos acima descritos. Fotomicrografias foram obtidas por meio de microscopia eletrônica de varredura e a análise foi feita de acordo com a característica da superfície. Pode-se concluir que: o tratamento associado não ofereceu vantagens em relação ao condicionamento ácido, para os materiais DP e IPS; para o INC o tratamento associado não ofereceu vantagens em relação ao jateamento. A DP e o IPS apresentaram resultados melhores em relação ao INC, independentemente dos tratamentos...
The aim of this study was to evaluate the effect of three surface treatments on the shear bond strength of a resin luting cement to three ceramics materials: Duceram Plus (DP), IPS Empress II (IPS) and In-Ceram Alumina (INC), and to assess its surface topography after these treatments. Eighteen specims were fabricated to each material (7,5 mm in diameter x 3,0 mm in thickness), embebed in acrylic resin and ground up to 600 grit. The specims were randomly divided into 3 groups of 6 specims: (a) airborne particle abrasion with 50 æm aluminum oxide; (b) 10% hydrofluoric acid etching; (c) a and b treatments. The specims were cleaned and dried. Silane, adhesive and resin luting cement Variolink were applied in 5,0 mm in diameter and 3,0 mm height to ceramic surface and then light cured. All specims were termocycled (1000, 5-55°C). The shear bond strength was then measured in a testing machine MTS 810, at a crosshead speed of 0,5 mm/min. To asses the surface topography, one coping each of IPS and INC, and a DP crown were fabricated following the manufacturer's instructions. Each coping or crown was sectioned into 4 equal parts by a diamond disk. One part didn't receive any treatment, and the others, received treatments as above described. Photomicrographs were obtained by a SEM, and the superficial characteristic was described. In conclusion, the associate treatment didn't offer advantages in relation to the acid etching, for DP and IPS; for INC the associate treatment didn't offer advantages in relation to the airborne. DP and IPS presented the best results, independently of the superficial treatments. The photomicrographs showed compatible correlation of the superficial characteristic with the bond strength values.

Orientador: José Cláudio Martins Segalla
Banca: Regina Helena Barbosa Tavares da Silva
Banca: Marcos Ribeiro Moysés
Resumo: O objetivo deste estudo foi avaliar o efeito de três tratamentos superficiais na resistência de união de um cimento resinoso a três cerâmicas dentais: Duceram Plus (DP), IPS Empress II (IPS) e In-Ceram Alumina (INC), e analisar a topografia superficial dessas cerâmicas submetidas aos mesmos tratamentos superficiais. Para o teste de resistência de união foram confeccionadas 18 amostras de cada material (7,5mm de diâmetro x 3,0mm de espessura), incluídas em resina acrílica e polidas até lixa nº 600. As amostras foram divididas em três grupos: a) jateamento com partículas de óxido de alumínio de 50 æm; b) condicionamento com ácido fluorídrico 10%; c) associação de "a" e "b". As amostras foram lavadas e secas. A área de adesão da cerâmica foi delimitada com matriz metálica perfurada (5,0mm de diâmetro e 3,0mm de espessura). Foi aplicado silano, adesivo e cimento resinoso Variolink II, fotoativado por 40 segundos. As amostras receberam 1000 ciclos térmicos de 5 a 55°C. O ensaio de cisalhamento foi realizado em máquina de ensaios MTS 810, com célula de carga de 10 kN e velocidade de 0,5 mm/min. Para a topografia superficial foram confeccionados um coping de IPS, um do INC e uma coroa de DP, seguindo as recomendações dos fabricantes. Cada coping ou coroa foi cortado com disco diamantado em quatro partes: uma delas não recebeu nenhum tratamento, e as demais receberam um dos tratamentos acima descritos. Fotomicrografias foram obtidas por meio de microscopia eletrônica de varredura e a análise foi feita de acordo com a característica da superfície. Pode-se concluir que: o tratamento associado não ofereceu vantagens em relação ao condicionamento ácido, para os materiais DP e IPS; para o INC o tratamento associado não ofereceu vantagens em relação ao jateamento. A DP e o IPS apresentaram resultados melhores em relação ao INC, independentemente dos tratamentos ...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this study was to evaluate the effect of three surface treatments on the shear bond strength of a resin luting cement to three ceramics materials: Duceram Plus (DP), IPS Empress II (IPS) and In-Ceram Alumina (INC), and to assess its surface topography after these treatments. Eighteen specims were fabricated to each material (7,5 mm in diameter x 3,0 mm in thickness), embebed in acrylic resin and ground up to 600 grit. The specims were randomly divided into 3 groups of 6 specims: (a) airborne particle abrasion with 50 æm aluminum oxide; (b) 10% hydrofluoric acid etching; (c) "a" and "b" treatments. The specims were cleaned and dried. Silane, adhesive and resin luting cement Variolink were applied in 5,0 mm in diameter and 3,0 mm height to ceramic surface and then light cured. All specims were termocycled (1000, 5-55°C). The shear bond strength was then measured in a testing machine MTS 810, at a crosshead speed of 0,5 mm/min. To asses the surface topography, one coping each of IPS and INC, and a DP crown were fabricated following the manufacturer's instructions. Each coping or crown was sectioned into 4 equal parts by a diamond disk. One part didn't receive any treatment, and the others, received treatments as above described. Photomicrographs were obtained by a SEM, and the superficial characteristic was described. In conclusion, the associate treatment didn't offer advantages in relation to the acid etching, for DP and IPS; for INC the associate treatment didn't offer advantages in relation to the airborne. DP and IPS presented the best results, independently of the superficial treatments. The photomicrographs showed compatible correlation of the superficial characteristic with the bond strength values.
Mestre

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária
Introdução: O conhecimento das características das próteses fixas metalocerâmicas e totalmente cerâmicas é fundamental para se obter uma reabilitação oral adequada, tanto para o médico-dentista como para o paciente a ser reabilitado. Na literatura científica estão descritas diversas possibilidades de tratamento e existe uma grande variabilidade de materiais e protocolos instituídos, o que dificulta a comparação e a conclusão relativa a qual das opções é efetivamente a melhor. Objetivo: Realizar uma revisão sistemática sobre avaliação dos tipos de reabilitações fixas dento-suportadas em dentes anteriores, abordando as principais propriedades e comparando de cada uma e delas. Materiais e métodos: A presente revisão bibliográfica foi baseada em informação científica publicada, recorrendo-se às seguintes bases de dados: “MEDLINE/Pubmed”, “B-On”, “EBSCO HOST” e “SCIENCE DIRECT”, através da utilização das palavras-chave: “Cerâmic crowns”; “Metalceramic crowns”; CAD-CAM”; “Fixed partial denture”; “Dental techonology”; ”Dental materials”; “Prótese parcial fixa”; “Cerâmica dentária”; “Procera”; “IPS Empress”; In-Ceram”; “Coroas dentárias”. Conclusões: Para cada situação clínica quando se está perante uma reabilitação com prótese fixa, é importante determinar os objetivos do tratamento com base num diagnóstico preciso e selecionar o tratamento mais adequado, bem como o tipo de material a utilizar, de maneira a que a estética, resistência e durabilidade estejam associadas. O estudo de novos materiais dentários tem proporcionado um melhor tratamento estético e funcional a quem recorre aos tratamentos restauradores com coroas metalocerâmicas ou totalmente cerâmicas. Assim, com o aperfeiçoamento e desenvolvimento de novas técnicas, bem como o avanço da tecnologia, podem obter-se estruturas cada vez mais semelhantes às estruturas dentárias naturais. As coroas metalocerâmicas ou totalmente cerâmicas, dão-nos a capacidade conseguir realizar a substituição de uma ou mais estruturas dentárias, quer seja por perda parcial dos dentes, usando a coroa como reforço, ou por perdas totais dos dentes, com a utilização de pontes ou implantes. No decorrer desta revisão, descreve-se e compara-se as várias propriedades de cada tipo de coroa, bem como dos materiais e técnica CAD-CAM utilizados nas suas confeções. Introduction: The knowledge of the characteristics of the fixed prosthesis PFM and all-ceramic is crucial to obtain a proper oral rehabilitation, as for medical dentist as for the patient to be rehabilitated. In the scientific literature are described several possibilities for treatment and there is a great variability in materials and protocols in place, which makes the comparison and the arrival of conclusions. Objective: Conduct a systematic review of evaluation of the types of tooth-supported fixed restorations in anterior teeth, addressing the main properties and comparing each of them and. Material and methods: The present bibliographic revision has bases in published scientific information. It was resorted to the following primary data bases: “MEDLINE/PubMed”, “B-On”, “EBSCO HOST” and “SCIENCE DIRECT”, through the following keywords: “Cerâmic crowns”; “Metalceramic crowns”; CAD-CAM”; “Fixed partial denture”; “Dental techonology”; ”Dental materials”; “Prótese parcial fixa”; “Cerâmica dentária”; “Procera”; “IPS Empress”; In-Ceram”; “Coroas dentárias”. Conclusions: For each clinical situation when one is faced with a rehabilitation with fixed prosthesis, it is important to determine the goals of treatment based on an accurate diagnosis and to select the most appropriate treatment, as well as the type of material to be used, so that the aesthetics, strength and durability are associated. The study of new dental materials has provided a better functional and aesthetic treatment to those who resort to restorative treatments crowns with metal-ceramic or all-ceramic. Thus, with the improvement and development of new techniques as well as the advancement of technology, allows us to structure increasingly similar to natural tooth structure. The ceramic-metal crowns or fully ceramic give us the ability to accomplish replacement of one or more dental structures, whether by partial loss of the teeth, using a crown reinforcement, or total loss of teeth, with the use of bridges or implants. During this revision will be described in detail the various properties of each type of crown, as well as materials and technique used in the CAD-CAM their clothing.

Among the prosthetic and implant biomaterials in the oral cavity currently exciting tremendous interest, titanium and resin are the main components of implants and dentures respectively. From their introduction in the oral cavity, a highly complex heterogeneous biofilm coats these biomaterials. The present thesis analyzes the complex relationships that are formed between one single microorganism (Candida albicans), one defence system of the oral cavity (oral peroxidases) and the two aforementioned biomaterials (titanium and resin). These biomaterials are indeed in contact with peroxidases: myeloperoxidase from neutrophils and sialoperoxidase from salivary secretions. Oral peroxidases belong to the salivary non immune innate defence mechanisms that control the oral microbial flora. In the presence of hydrogen peroxide (H2O2), they catalyze in vivo the oxidation of thiocyanate (SCN-) into hypothiocyanite (OSCN-), in vitro the oxidation of iodide (I-) into hypoiodite (OI-). In the salivary compartment and in oral biofilms, H2O2 is mainly formed by bacteria. In our investigations, H2O2 was produced by an enzyme sequence glucose (G) / glucose-oxidase (GOD). The OSCN- and OI- are antibacterial, antiviral and antifungal oxidants. Few studies have considered their action on Candida biofilms.

Candida albicans is a commensal yeast of the oral cavity which can turn parasitic when the host immune defences are weakened. This fungus forms biofilms on biomaterials within the mouth, especially on dentures, the decontamination of these prostheses is therefore essential to avoid the risk of candidosis. (Candida et prothèses dentaires. Ahariz M. Loeb I. Courtois Ph. Rev. Stomatol. Chir. Maxillofac. 111: 74-78, 2010).

In vitro, our investigations aimed to analyze the relationships between peroxidase systems and Candida. The effect of peroxidase systems (G / GOD / KI or KSCN / peroxidase) on Candida suspensions, on biofilms already formed or in formation was evaluated with various inputs of hydrogen peroxide and was studied by incorporation of enzymatic sequences in the culture media used for Candida biofilms formation. The susceptibility of Candida albicans ATCC 10231 to OSCN- versus to OI-, produced by lactoperoxidase (LPO), was studied in three different experimental models: - in a liquid culture medium – on a solid medium (with agarose gel), - in a biofilm model developed in the context of this work. The latter consisted of titanium powder suspended in Sabouraud broth contaminated with Candida albicans. The growth of Candida in the supernatant (planktonic phase) was evaluated by turbidimetry and the biomass of yeasts adherent to biomaterials (attached phase) by the tetrazolium salt MTT method. Enzymatic studies have allowed the optimization of the concentrations and activities of peroxidase systems components and the illustration of the competition between thiocyanate and iodide for lactoperoxidase. Peroxidase systems G/GOD/I-/LPO and G/GOD/SCN-/LPO prevented or limited the growth of Candida in the planktonic and attached phases on titanium powder for at least 21 days. At a dose of GOD (0.2 U / ml), the system G/GOD/I-/LPO has limited the development of planktonic and attached phases for 4 days while the system G/ GOD/SCN-/LPO has shown an inhibitory effect only in the first 2 days of incubation. (Candida albicans susceptibility to lactoperoxidase-generated hypoiodite. Ahariz M. Courtois Ph. Clinical, cosmetic and investigational dentistry; 2: 69-78, 2010).

In other experiments, peroxidase was adsorbed on titanium sheets in order to modify their surface and give them the property of inhibiting biofilm formation of Candida after addition of the enzyme substrates. Enzymatic studies and X-ray photoelectron spectroscopy (XPS) showed the adsorption of lactoperoxidase to titanium. In vivo, peroxidases are adsorbed on titanium healing abutments. (Adsorption of peroxidase on titanium surfaces: A pilot study. Ahariz M. Mouhyi J. Louette P. Van Reck J. Malevez C. Courtois P. J. Biomed. Mater. Res. 52: 567-571, 2000).

The development of the Candida biofilm was followed on titanium (powder or sheets) as well as on resin. Planktonic and attached phases have been monitored for 21 days. The presence of an exopolysaccharide matrix secreted by the yeasts has been observed with light microscopy and confirmed with fluorescence using the calcofluor method. In a series of experiments on titanium and resin sheets, an attached phase was demonstrated by the same techniques. The efficiency of the peroxidase system using iodide as a substrate was demonstrated when the enzyme was in solution and when it was preadsorbed on titanium (Candida albicans biofilm on titanium: effect of peroxidase precoating. Ahariz M. Courtois Ph. Medical Devices: Evidence and Research; 3: 33-40, 2010).

The incorporation in oral gels of other molecules present in exocrine secretions is a research direction that was also discussed: the present studies have demonstrated the in vitro benefits of peroxidase systems (with thiocyanate, chloride or especially iodide as substrates) acting in synergy with colostrum, lactoferrin and lysozyme. But the formulation of specialities that contain these natural antimicrobials is difficult to transpose in vivo as the complexity of the oral environment is very large (Denture contamination by yeasts in the elderly. Vanden Abbeele A. de Meel H. Ahariz M. Perraudin J.-P. Beyer I. Courtois P. Gerodontology; 25: 222-228, 2008).

Investigations pursued in vivo in 155 patients allowed the determination of the wild strains of Candida sp present on the fitting surface of the removable dental appliance and on the corresponding palatal mucosa. The link between the presence of yeasts and a reduced salivary flow was confirmed. These wild strains were directly grown and identified on Petri dishes (ChromAgar™ medium) from the macroscopic morphology of colonies and from additional tests (germination test in human serum, formation of chlamydoconidies on RAT medium, API™ galleries identification system ). For a period of two weeks, 14 patients accepted the daily application of a gel on the fitting surface of their denture. It was a double-blind comparison of an active gel containing the thiocyanate - lysozyme - lactoferrin - colostrum complete system with a control gel inactivated by heating. Data analysis showed a reduction in the number of colonies on the palatal mucosa by Candida sp, but not on the denture itself. By contrast, decontamination ex vivo of dentures by immersion in a bath (at room temperature or 37° C) containing either G/GOD producing H2O2 or the complete peroxidase system G/GOD/KI/L producing OI- demonstrated the efficiency of hypoiodite.

Parmi les biomatériaux prothétiques et implantaires qui connaissent actuellement un essor considérable dans la sphère orale, le titane est le composant principal des implants et la résine celui des prothèses dentaires. Dès leur introduction dans la cavité orale, un biofilm hétérogène très complexe les recouvre. Cette thèse analyse la complexité des relations qui se nouent entre un seul micro-organisme (Candida albicans), un système de défense de la cavité orale (les peroxydases orales) et les 2 biomatériaux précités (titane, résine). Ces biomatériaux sont en effet, dans le milieu oral, au contact de peroxydases: la myéloperoxydase des neutrophiles et la sialoperoxydase des sécrétions salivaires. Les peroxydases orales appartiennent aux mécanismes salivaires de défense innée non immunitaires qui contrôlent la flore microbienne orale. En présence de peroxyde d’hydrogène (H2O2), elles catalysent in vivo l’oxydation du thiocyanate (SCN-) en hypothiocyanite (OSCN-) et in vitro l’oxydation d’iodure (I-) en hypoiodite (OI-). Dans le compartiment salivaire et dans les biofilms oraux, l’H2O2 provient essentiellement des bactéries. Dans nos investigations, l’H2O2 était produit par une séquence enzymatique glucose (G) / glucose-oxydase (GOD). L’OSCN- et l’OI- sont des oxydants antibactériens, antiviraux et antifongiques. Peu d’études envisagent leur action sur les biofilms à Candida.

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Doctorat en Sciences dentaires
info:eu-repo/semantics/nonPublished

Submitted in fulfillment of the requirements for the award of the degree of Master of Health Sciences: Dental Technology, Durban University of Technology, Durban, South Africa, 2017.
The poor mechanical properties of denture base acrylic resins can cause dentures to fracture either through impact or stress fatigue. Various metal reinforcing materials such as powders, nets, plates and wires together with synthetic fibres are therefore used to improve the strength properties of denture base acrylic resins. Despite their benefits, they are difficult to apply during fabrication, are costly, non-recyclable, and not environmentally friendly. The suitability of Hibiscus sabdariffa (H. sabdariffa) as a fibre reinforcement material for denture base acrylic resins was therefore investigated. A quantitative research paradigm and a two-phased experimental research design was used. The preliminary study used Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and field emission scanning electron microscope (FE-SEM) to assess the characteristics of, and the effect of, mercerisation on H. sabdariffa fibres. In determining the suitability of H. sabdariffa fibres, fibre diameter, fibre density, moisture content and absorption were examined. The main study investigated the mechanical and physical properties of two sample groups namely: the unreinforced (control) group and the H. sabdariffa fibre-reinforced (test) group denture base acrylic resins. The flexural strength, impact strength, specific wear rate, hardness and water absorption behaviour were determined in line with ASTM D 790 and D 256, G 99, D 2583 and D 570 methods of testing, respectively. Parametric and non-parametric tests were used to analyse the mean differences (p = 0.05) between the unreinforced and the H. sabdariffa fibre-reinforced denture base acrylic resins. The preliminary study revealed that H. sabdariffa fibres favourably compared to other lignocellulosic fibres in terms of fibre diameter, fibre density, water content and absorption behaviour. In the main study, a t-test revealed that there were significant differences in flexural strength at 0oC (p < 0.0001) and at 65oC (p < 0.0025) between the two sample groups. Similarly, there were significant differences in the impact strength between the two sample groups at 0oC (p < 0.031) and at 65oC (p < 0.0001). In contrast to the 200g load, there were significant differences (p < 0.044) in the specific wear rate of the unreinforced and the H. sabdariffa fibre-reinforced denture base acrylic resins at the 500g load. The hardness values revealed no significant differences (p > 0.707) between the two sample groups. There were however, significant differences (p < 0.041) in the water absorption rate between the two sample groups. Overall, the prominent features of this study showed that H. sabdariffa fibre is a suitable reinforcement fibre material for denture base acrylic resins and is in compliance with ISO 1567: 1999. Although this study found that H. sabdariffa fibres can be used as reinforcement material for denture base acrylic resins, the results cannot be generalised to clinical conditions, therefore in vitro and in vivo investigations are recommended.
M

A research report submitted to the School of Oral Health Science, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Dentistry in the field of Prosthodontics. Johannesburg, 2013
Background: The majority of edentulous patients are unable to afford anything other than mucosa-borne complete dentures, but the conventional methods of complete denture fabrication can be lengthy and expensive. Simplified techniques have been proposed to reduce the number of clinical visits as well as the laboratory time and costs. One such technique has advocated making the final heat-cured acrylic resin denture base after the first visit, which then requires a second processing cure for the artificial teeth. This dual-cure has been reported to cause distortion of the previously cured denture base. Purpose: To measure the amount of linear and three-dimensional distortion of an acrylic resin maxillary denture base following an additional curing cycle using different processing methods. Method and Materials: A standardised method was developed for fabricating a maxillary denture base with measuring pins , as well as a standardised method for waxing an arch of teeth to the base. The pins were used to make three-dimensional measurements using a Reflex Microscope. The resins used were from the same manufacturer. Four dual cure methods of varying temperature and time were used: 1. Place flask in boiling water for 20 minutes, remove and plunge into cold water for 20 minutes; 2. Place into cold water, heat up to 70°C, leave for 1 hour, remove and bench cool; 3. Place into cold water, bring to 72°C for 8 hours and bench cool; and 4. Place in cold water, bring to the boil for 40 minutes, bench cool for 45 minutes, then plunge into cold water for 20 minutes. For each method five models were fabricated, to give a total of 20 models. Results: Although there was an overall distortion of all denture bases following a second cure, the linear and 3D differences were not statistically significant between and within the different dual cure methods tested. The mean percentage changes measured were translated into real changes in distances or angles between the pins, in order to ascertain the clinical relevance of these changes, for if they are too great, the distortion of the denture base will exceed the resilience of the mucosa as well as disrupt the peripheral seal, and the denture base will not be retentive. The largest mean change was seen in the three-dimension distance between the innermost pins in the posterior palate, but this was only 1.3mm. This also showed the worst change of all measurements, but it was still only 2.0mm. Conclusions: With the adaptive nature of the denture-supporting tissues, the changes described are unlikely to have any clinical significance. Although only one brand of denture base resin was used, it is representative of the modern rapid-cure resins, and so rapid cure methods can be advocated when a dual cure is required.

Submitted in fulfillment of the Degree of Master in Technology: Dental Technology in the Department of Dental Services Faculty of Health Sciences, Durban University of Technology, 2008.
Globally in the field of Dental Technology, polymethyl methacrylate (PMMA) resin continues to be the popular material for the fabrication of denture bases in removable prosthodontics. However, the mechanical strength of the denture base is a concern due to fractures occurring intra-orally or when accidentally dropped. The objective of this in vitro investigation was therefore to evaluate and compare the flexural strength and microstructure of stick® glass fibre and wire mesh reinforced PMMA resin after thermocycling. The selection of the materials used in this study was based primarily on their popularity and availability in South Africa. These materials were selected to ensure that the results of this study would have further implicational value in the commercial dental industry when published. This investigation was conducted by means of fabricating a total of 90 PMMA resin specimens and divided in three groups consisting of 30 specimens each. Sample groups 1 and 2 were reinforced with stick® glass fibres and wire mesh respectively. The un-reinforced sample group was the control. All 90 specimens were thermocycled in water at temperatures between 5˚C and 55˚C for 2100 cycles. The flexural strength of each specimen was tested using a universal testing machine and the microstructure of the fractured surfaces was then analysed using scanning electron microscopes (SEM). SPSS version 15.0 was used for data analysis. A p-value of <0.05 was considered as statistically significant. Data were analysed using parametric and non-parametric statistical methods. Statistically significant differences in flexural strength existed between the three sample groups (p<0.001) with the stick® glass fibre and wire mesh sample groups being significantly superior to the control. Furthermore there was a significant association between fracture modes and sample groups. Microscopic analysis revealed the presence of voids. Statistically, in terms of microstructure (% of voids present), a significant difference existed between all sample groups. With regards to surface texture of the compression and tension sides of the test specimens, significant differences existed between the three sample groups. Furthermore microscopic analysis revealed partial impregnation and distribution of the fibres to the PMMA resin matrix and un-bonding between the wire mesh and PMMA resin matrix. Statistically, the Mann-Whitney test was conducted to compare flexural strength between sample groups with and without voids. The flexural strength was higher in sample groups with voids than those without. This is an important finding from the clinical perspective because, in some structures of dentures, toughness is a desired property. Nevertheless in order to find the long-term data especially on clinical behaviour of these new fibre reinforcement systems, more studies should be conducted.

Statement of the Problem: Despite its popularity as a denture-base material, poly-methyl methacrylate exhibits inherently low resistance to impact and fatigue failure. This is reflected in the analyses of the prevalence of denture fracture which suggests that prosthesis failure remains an unsolved problem. Consequently, various approaches to improve the physical and mechanical properties of denture-base polymers have been proposed. These include incorporation of solid metal forms and various types of fibers to provide reinforcement to fracture prone areas. In recent years there has been considerable interest in glass fiber reinforcement of polymeric denture resins. Partial fiber reinforcement using glass fiber has been shown to improve the mechanical properties of removable prostheses. However, adequate impregnation of fibers often requires the use of excessive methyl methacrylate monomer which has a deleterious effect on the mechanical properties of the fiber composite material. Purpose: The aim of the present study was to determine the effect of glass fiber polysulphone composite reinforcement on the flexural characteristics of two commonly used denture-base polymers. Materials and methods: Prefabricated E-glass fiber polysulphone composite rods, ± 3mm in diameter, with a continuous, unidirectional, non-silanized fiber concentration of ± 55 vol %, were employed as strengtheners. The reinforcement was incorporated axial to the neutral axis in standardized cylindrical heat polymerizing conventional and high impact resin test specimens 6mm in diameter and 28mm in length. The two reinforced pattern groups (n = 10) were compared with unreinforced resin control groups. A three point loading test was performed in air after storage of the specimens in water at 37°C for a period of 8 weeks. The following values were measured : flexural modulus and flexural strength. The obtained data were subjected to relevant statistical analysis. Results: The flexural modulus of the glass fiber polysulphone reinforcement was 14,106 MPa and the flexural strength 546.6 MPa. The flexural modulus of conventional denture-base resin was 1746 MPa, reinforcement increased it to 2328 MPa, and the flexural strength increased from 164 MPa to 209 MPa. The flexural modulus of high impact polymer was 1684 MPa and reinforcement increased it to 2067 MPa. The flexural strength was increased from 171 MPa to 242 MPa with reinforcement. Statistical analysis using t test showed that reinforcement affected the flexural modulus and flexural strength of polymer brands (p < : 05). Conclusion: Novel glass fiber polysulphone composite reinforcement may considerably enhance the flexural properties of multi phase denture-base polymers.
Dissertation (MSc (Prosthetic Dentistry))--University of Pretoria, 2005.
Prosthodontics
unrestricted

Indiana University-Purdue University Indianapolis (IUPUI)
A provisional restoration must fulfill biologic, mechanical, and esthetic requirements. These prostheses should provide comfort, pulp protection, positional stability, occlusal function, hygiene access, esthetics, strength and retention. Methyl-methacrylate acrylic has assumed many appli¬cations in the field of restorative dentistry. However, the material still has deficiencies, such as polymerization shrinkage, pulpal damage associated with exothermic polymerization and susceptibility to fracture. Bis-GMA composites, Bis-acryl composites and visible light-cured urethane dimethacrylate resins have been developed to address these issues. The purpose of this study was to compare the mechanical properties of provisional restorations made from composite resins (Protemp Plus, Luxatemp Solar, Radica, Protemp Crown) to those made of the traditional methacrylate resins (Jet, Snap, High Impact). Six groups of samples, two groups from methacrylate and four groups from composite based materials, were fabricated. Samples from each group were evaluated for microhardness (n=10), flexural strength and flexural modulus (n=20) according to ISO 4049, and fracture toughness (n=20) according to ISO 13586. From each of the six groups, ten samples were tested for flexural strength, flexural modulus and fracture toughness and 5 samples were tested for microhardness. These tests were done after storing at 37°C in a distilled water solution for 7 days followed by thermal cycling (2500 cycles, 5-55°C, 45 s. dwell). Identical sets of samples from each group were used as controls; these were tested after storing for 24 hours in dry conditions. The results were analyzed by two-way ANOVA with material type and aging conditions as the two main variables. Significance level was set at p=0.05. For flexural strength and flexural modules, the higher values were obtained for Radica. Protemp plus (7 days) and Radica (24h) had the highest fracture toughness value. Protemp crown showed the highest surface hardness. The mechanical properties of composite resin were superior.

Uma prótese dentária total removível é um dispositivo protético artificial que substitui toda a dentição e estruturas anexas da maxila ou da mandíbula. É consensual que para se obter uma prótese total removível bem-sucedida, é necessário ter-se suporte, estabilidade e retenção. Para isso, são vários os passos importantes na elaboração das próteses, desde uma impressão preliminar adequada que permita construir as moldeiras individuais, a realização de selamento periférico da moldeira individual e impressões definitivas com detalhe e precisão ótimos. Um selamento periférico e uma extensão da prótese total removível adequados ajudam a conseguir uma “tríade de equilíbrio”, caracterizada por boa retenção, suporte e estabilidade. O objetivo deste estudo foi identificar quais as tendências atuais nas impressões em prótese total realizadas nas pós-graduações em Prostodontia na Península Ibérica; determinar quais as técnicas de impressão mais utilizadas e determinar quais os biomateriais mais frequentemente usados, através de um questionário enviado por correio eletrónico aos responsáveis de pós-graduações no âmbito da Prostodontia na Península Ibérica. O questionário consistiu em 24 perguntas, divididas em duas partes. Apesar de ter havido limitações decorrentes da falta de algumas respostas a certas perguntas, que podem ter tido influência na possível inferência estatística dos resultados deste inquérito, foi possível verificar que: em grande parte, as técnicas e materiais utilizados são semelhantes entre Portugal e Espanha. No entanto, verificou-se que existem algumas diferenças, como por exemplo o tipo de moldeira utilizada nas impressões preliminares e o material utilizado para a realização da impressão definitiva. Não sendo conhecidos estudos deste tipo na Península Ibérica, verificou-se que a grande maioria das técnicas e materiais utilizados na Península Ibérica são semelhantes aos encontrados em pós-graduações na área de Prostodontia nos EUA.
A complete denture is an artificial prosthetic device that replaces the entire dentition and associated structures of the maxilla or the mandible. There exists consensus that to obtain a successful complete denture it is necessary to have support, stability and retention. It starts from an adequate preliminary impression, that allows building the individual trays, performing peripheral sealing of the individual tray to final impressions with great detail and accuracy. A peripheral sealing and an adequate extension of removable prostheses helps to acomplish a “triad of equilibrium” characterised by good retention, support and stability. The aim of this study was to identify the current trends in impressions for complete dentures made in post-graduate programs in Prosthodontics in the Iberian Peninsula; establishing the most used impression techniques as well as establishing which biomaterials are the most frequently used, through a survey sent by e-mail to postgraduate directors in Prosthodontics in Iberian Peninsula. This survey comprised 24 questions, divided into two parts. Although there have been limitations due to the lack of some answers to certain questions, which may have had an influence on the possible statistical inference of the results of this survey, it was found that: largely, the techniques and materials used were similar both in Portugal and Spain. Nevertheless, it was found that there are some differences, such as the type of tray used in the preliminary impression and the material used for final impressions. There aren’t any studies of this kind in the Iberian Peninsula and from the academic point of view it was found that most of the techniques and materials used in the Iberian Peninsula are similar to those found in the postgraduate prosthodontic programs in the United States of America.