Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 202-236).

Thesis (M.Sc.Dent.)--University of Adelaide, Dental School, 2004. / "April 2004" Includes bibliographical references (leaves 73-87).

Thesis (Ph.D.)--University of Melbourne, Melbourne Dental School, 2009. / Typescript. Includes bibliographical references.

Submitted by MORGANNA BORGES DE ALMEIDA SOUZA (morh_borges@hotmail.com) on 2018-08-03T02:56:51Z No. of bitstreams: 1 Influência da contaminação e das formas de limpeza na resistência de união do Cimento de Ionômero de Vidro Modificado por Resina no tecido dentinário.pdf: 2719657 bytes, checksum: 37986fa293b448d6ed156e35f1738178 (MD5) / Approved for entry into archive by Ana Paula Rimoli de Oliveira null (anapaula@foa.unesp.br) on 2018-08-03T14:18:20Z (GMT) No. of bitstreams: 1 souza_mba_me_araca_int.pdf: 2719657 bytes, checksum: 37986fa293b448d6ed156e35f1738178 (MD5) / Made available in DSpace on 2018-08-03T14:18:20Z (GMT). No. of bitstreams: 1 souza_mba_me_araca_int.pdf: 2719657 bytes, checksum: 37986fa293b448d6ed156e35f1738178 (MD5) Previous issue date: 2018-06-12 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo neste estudo foi avaliar o efeito da contaminação do tecido dentinário e dos métodos normalmente empregados na limpeza do substrato sobre a resistência de união obtida na interface cimento de ionômero de vidro modificado por resina (CIVMR)/dentina. Para tanto, os 168 dentes bovinos foram desgastados até o tecido dentinário divididos em doze grupos (n=14), de acordo com o agente contaminante e a técnica de limpeza, sendo: NN - sem contaminação (N) e sem limpeza do substrato (N); NA - sem contaminação (N) e limpeza com spray ar/água (A); NP - sem contaminação (N) e limpeza com ácido poliacrílico 26% (P); SaN - contaminação por saliva (Sa) e sem limpeza do substrato (N); SaA - contaminação por saliva (Sa) e limpeza do substrato com spray ar/água (A); SaP - contaminação por saliva (Sa) e limpeza do substrato com ácido poliacrílico 26% (P); SgN - contaminação por sangue (Sg) e sem limpeza do substrato (N); SgA - contaminação por sangue (Sg) e limpeza do substrato com spray ar/água (A); SgP - contaminação por sangue (Sg) e limpeza do substrato com ácido poliacrílico 26% (P); HN - contaminação por agente hemostático (H) e sem limpeza do substrato (N); HA - contaminação por agente hemostático (H) e limpeza do substrato com spray ar/água (A); HP - contaminação por agente hemostático (H) e limpeza do substrato com ácido poliacrílico 26% (P). Todos os espécimes foram restaurados com o material ionomérico encapsulado Riva Light Cure (SDI) e, posteriormente foram obtidos palitos de aproximadamente 1,0 x 1,0mm, submetidos ao teste de microtração antes e após a realização de 10000 ciclos ciclagem térmicos (CT). Os fragmentos foram analisados quanto ao padrão de fratura e os espécimes representativos de cada grupo levados à microscopia eletrônica de varredura a um aumento de 1.000x. Os valores foram submetidos à ANOVA dois fatores e pós-teste de Tukey para dados paramétricos e Kruskal Wallis e pós-teste Holm-Sidak para não paramétricos (α=0,05). Na análise imediata todos os grupos contaminados sem limpeza tiveram menores valores de adesão, quando comparados ao controle. Na contaminação por saliva, o grupo que não recebeu nenhuma limpeza e o grupo lavado com spray ar/água apresentaram os menores valores de resistência de união, no entanto o grupo recondicionado apresentou valores semelhantes ao controle. Analisando a contaminação por sangue no tempo imediato, os tratamentos propostos não foram tão efetivos na limpeza do substrato. Já nos grupos contaminados por hemostático o recondicionado foi semelhante ao grupo controle. Após a CT, nos grupos contaminados sem limpeza apenas o hemostático foi semelhante ao controle. Já os grupos contaminados por saliva, mantiveram o mesmo padrão da análise imediata. E os contaminados por sangue que receberam limpeza foram semelhantes ao controle, que apresentou redução significativa no seu valor diferentemente do tempo imediato. Por fim na contaminação por hemostático todos os grupos foram semelhantes entre si. Concluiu-se que os agentes contaminantes testados prejudicaram a adesão imediata do material ionomérico ao substrato dentinário. O recondicionamento do substrato foi efetivo para as contaminações de saliva e agente hemostático e que a resistência de união do material à dentina foi reduzida após o envelhecimento. / The objective of this study was to evaluate the effect of the contamination of the dentin tissue and the methods normally employed in the cleaning of the substrate on the bond strength obtained at the resin modified glass ionomer cement (RMGIC) / dentin interface. For this purpose, 168 bovine teeth were selected, which were worn to dentin tissue, and were then divided into twelve groups (n = 14), according to the contaminating agent and the cleaning technique: NN - without contamination (N) and without substrate cleaning (N); NW - no contamination (N) and spray / water cleaning (W); NP - without contamination (N) and cleaning with 26% polyacrylic acid (P); SaN - contamination by saliva (Sa) and without substrate cleaning (N); SaW - saliva contamination (Sa) and spray / water substrate cleaning (W); SaP - saliva contamination (Sa) and substrate cleaning with 26% polyacrylic acid (P); BN - blood contamination (B) and no substrate cleaning (N); BW - blood contamination (B) and cleaning the substrate with spray / water (W); BP - blood contamination (B) and substrate cleaning with 26% polyacrylic acid (P); HN - contamination by hemostatic agent (H) and without cleaning of the substrate (N); HW - hemostatic agent contamination (H) and spray / water substrate cleaning (W); HP - hemostatic agent contamination (H) and substrate cleaning with 26% polyacrylic acid (P). All specimens were restored with the Riva Light Cure (SDI) encapsulated ionomeric material and, afterwards, sticks of approximately 1.0 x 1.0mm were obtained, submitted to the microtraining test before and after performing 10000 thermal cycling (TC). The fragments were analyzed for the fracture pattern and the representative specimens of each group were taken by scanning electron microscopy at a magnification of 1000x. Values were submitted to two-way ANOVA and Tukey post-test for parametric data and Kruskal Wallis and Holm-Sidak post-test for non-parametric (α = 0.05). In the immediate analysis all the groups contaminated without cleaning had lower values of adhesion, when compared to the control. In the saliva contamination, the group that did not receive any cleaning and the group washed with air / water spray had the lowest values of bond strength, however the refurbished group presented similar values to the control. Analyzing the contamination by blood in the immediate time, the proposed treatments were not as effective in cleaning the substrate. Already in the groups contaminated by hemostatic the reconditioning was similar to the control group. After TC, in the contaminated groups without cleaning, only the hemostatic was similar to the control. The groups contaminated by saliva, however, maintained the same pattern of immediate analysis. And those contaminated by blood that received cleaning were similar to the control, which presented significant reduction in its value differently from the immediate time. Finally in hemostatic contamination all groups were similar to each other. It was concluded that the contaminating agents tested impaired the immediate adhesion of the ionomeric material to the dentin substrate. Substrate reconditioning was effective for saliva and hemostatic contaminations and the bond strength of the material to the dentin was reduced after aging. / 16/09117-6

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Orientador: Angela Cristina Cilense Zuanon / Banca: Renata Cristiane da Silva / Banca: Josimeri Hebling da Costa / Resumo: Este estudo investigou o efeito da excitação ultra-sônica na resistência máxima à tração e de união à dentina de cimentos de ionômero de vidro (CIV), após 24 horas ou 30 dias de armazenamento em água destilada à 37ºC, por meio do teste de microtração. Os materiais utilizados foram o CIV de alta viscosidade Fuji IX GP, Ketac Molar e o modificado por resina, Vitremer. Foram confeccionados 12 corpos de prova para cada material, dos quais 6 formaram o grupo controle e 6 receberam tratamento com US, por 30 segundos. Para o experimento de resistência de união à dentina, trinta e seis terceiros molares foram divididos aleatoriamente entre os grupos experimentais já descritos. Em ambos os experimentos, após o período de armazenamento, os corpos de prova foram seccionados em espécimes com área adesiva média de 0,91mm2 (± 0,1) e 0,93 mm2 (± 0,09), respectivamente para o experimento de resistência à tração e de união. Os dados foram analisados pela análise de variância com a correção de Welch (p<0,001) e teste de Tamhane (α = 0,05). O cimento Fuji IX (24 horas) apresentou aumento significativo na resistência máxima à tração e o Ketac Molar (24 horas) na resistência de união à dentina, após a aplicação do US. Os grupos controle destes materiais também apresentaram aumento da resistência após 30 dias de armazenamento. Em todos os outros grupos experimentais não houve alteração significativa após a aplicação de US ou após diferentes períodos de armazenamento. A aplicação do ultra-som aumentou a resistência máxima à tração e de união à dentina, após 24 horas de armazenamento, quando se utilizou respectivamente, os cimentos Fuji IX e Ketac Molar. / Abstract: This study investigated the GICs ultimate tensile strength and bond to dentine after ultrasonic excitation and after periods of the 24 hours and 30 days storage in distilled water at 37ºC, using microtensile test. Two high viscosity GICs, Fuji IX GP and Molar Ketac, and the resin modified GIC Vitremer were used. Twelve specimens for each material were prepared, 6 formed the control group and 6 received treatment with US, por 30 seconds. For the ultimate tensile strength experiment, a cross-sectional area of 0.91mm2 (± 0.1) in the specimens were obtained. For the tensile bond strength to dentine test, 36 third molar were selected and randomly divided into groups, with a cross-sectional area of 0.93 mm2 (± 0.09). All specimens were tested in a microtensile test machine. The data were evaluated by analysis of variance and corrected by Welch (p<0.001) and Tamhane tests (α = 0.05). Fuji IX (24 hours) had significant increase in the ultimate tensile strength and Ketac Molar (24 hours) had significant increase in the tensile strength of union to dentine, after the application of the US. The control groups of the Fuji IX and Ketac Molar had increase in the tensile strength after 30 days of storage. All the other groups, did not show significant difference neither when US application was used nor between different storage times. The ultrasound application increased the ultimate tensile strength and bond to the dentine, after 24 hours of storage, when if it used respectively, the Ketac Molar and Fuji IX cements. / Mestre

A proposta deste trabalho experimental in vitro foi avaliar se a incorporação de 1% - em peso - do alcalóide teobromina (Sigma Aldrich, Darmstadt, Alemanha) ao cimento de ionômero de vidro (CIV) convencional (GC Gold Fuji 9, GC Corp, Japão) tem a capacidade de alterar as propriedades físico-químicas desse material. Para tanto, dois grupos experimentais foram propostos: G1 - CIV convencional e G2 - CIV com adição de teobromina. Foram confeccionados 160 discos de CIV de acordo com as instruções do fabricante, utilizando matrizes circulares. Para analisar as mencionadas propriedades, os discos foram submetidos a testes específicos, de acordo com as normas da International Standard Organization (ISO) para cada uma das propriedades. Discos de 15mmx1mm de diâmetro foram utilizados para as provas de sorção (n=5) e de solubilidade (n=5), com o auxílio de balança analítica, dissecadores e estufa a 23 e 37ºC por várias semanas. O ensaio de microdureza foi realizado em amostras (n=20) de 15mm×1mm submetidas a cinco edentações, com carga de 25 gramas e 30 segundos, à temperatura ambiente. Para a avaliação da cor, discos (n=20) de 15mm×1mm foram submetidos ao espectrofotômetro, adotando-se a guia colorimétrica da Comissão internacional de Iluminação (CIE). No ensaio de resistência flexural, os espécimes (n=60) de 12mm×1mm foram armazenados em estufa a 37ºC durante 24 horas para posterior analise na máquina de ensaios universal. Para avaliar a influência da teobromina adicionada ao CIV na formação de biofilme por Streptococcus mutans,, sobre os corpos da prova (n=40) de 12mm×1mm biofilmes foram desenvolvidos. As cepas de S.mutans foram cultivadas em Tryptic Soy Agar (TSA, Difco) a 37°C. Também a dosagem de flúor foi avaliada, em discos de prova (n=10) armazenados em saliva artificial e submersos em solução TISAB para posterior análise com eletrodo de flúor e obtenção da curva da liberação dessa substância. Os dados obtidos nos testes de sorção e solubilidade, microdureza, cor e resistência flexural foram submetidos à análise de variância ANOVA um fator e ao teste de Tukey para comparação entre os grupos, adotando-se 5% de nível de significância (p<0,05). O ensaio da influência da teobromina adicionada ao CIV na quantidade de biofilme de Streptococcus mutans formado e o teste de dosagem de flúor foram submetidos à análise de variância two-way ANOVA e ao teste de Tukey, com nível de significância de 5% para comparação entre os grupos experimentais. O segundo fator avaliado nestes dois ensaios foi o tempo. Os resultados não revelaram alteração da sorção e da solubilidade no CIV que recebeu teobromina (p>0,05). A microdureza aumentou com a adição de teobromina ao CIV (p<0,05). Não houve alteração de cor do CIV que recebeu teobromina (p>0,05). A resistência na flexão biaxial diminuiu quando da adição de teobromina ao CIV (p<0,05). Já a quantidade de biofilme formado foi menor em G2 (p<0,05). Em relação à liberação de flúor, observou-se que a adição de teobromina não altera essa propriedade do CIV (p>0,05). Com base em tais achados, conclui-se que a adição de teobromina a 1% ao cimento do ionômero de vidro convencional não produz alterações significativas nas propriedades desse material, podendo até mesmo otimizar algumas dessas propriedades. Ainda assim, estudos adicionais sobre o assunto devem ser realizados. / The purpose of this experimental in virtro work, was to evaluate if the incorporation of the 1% in weight of an alkaloid: theobromine (Sigma Aldrich Darmstadt, Germany) to the conventional glass ionomer cement (GIC) (GC Gold Fuji 9; GCC Japan Corp) has the capacity to change the properties physicochemical of this material. Whereby, it was proposed two experimental groups: G1 - Conventional GIC and G2 GIC incorporated with theobromine. According to the instructions of the creator, there were created 160 specimens, for which it was used circular matrices. To analyze the mentioned properties, the specimens were analyzed under the International Standard Organization (ISO) for each property. It was used matrices of 15mmx1mm diameter for the sorption (n=5) solubility (n=5) tests. With the help of an analytical balance, desiccators and a stove at 23º and 37° for various weeks; it was made essays of micro firmness using 20 matrices of 15mmx1mm, were submitted to five indentations with a charge of 26 grams and 30 seconds in environmental temperature. For the color evaluation it was used 20 matrices of 15mmx1mm, that were submitted to a spectrophotometer following the colorimetric guide of the International Commission of Illumination (CIE). An essay of biaxial flexural strength was made in 60 matrices of 12mmx1mm that were stored in a stove at 37º for 24 hours, for a later analysis in a universal testing machine. To evaluate the influence of the theobromine incorporated to the glass ionomer cement (GIC) in the creation of biofilm Streptococcus mutans, there were developed 40 matrices of 12mmx1mm of biofilm. The strains of the Streptococcus mutans were cultivated in Tryptic Soy-Agar at 37°. It was also evaluated the fluorine release capacity using 10 test matrices stored in artificial saliva and submerged in TISAB substance for a later analysis with an fluorine electrode, to obtain the release curve of that substance. The obtained information from the test of sorption, solubility, micro strength, color and biaxial flexural strength, were submitted to an analysis of variance ANOVA one factor and Tukey\'s test for a comparison between groups assuming the 5% level of significance (p <0,05). The essay of the influence of the theobromine added to the GIC in the amount of biofilm Streptococcus mutans formed and the test of fluorine release were submitted to the Bidirectional Variance Analysis ANOVA and Tukey\'s test, with a significant level of 5% to the comparison between experimental groups; the second factor evaluated in this two essays was time. The results didn\'t show an alteration in the sorption and solubility in the GIC that received theobromine (p >0,05). The micro strength increased with the addition of the theobromine to the GIC (p< 0,05). There were not any alterations in the color of the GIC that received theobromine (p >0.05). The resistance to the biaxial flexural strength decreased when the theobromine was added to the GIC (p <0.05). The amount of formed biofilm was less in the G2. In relation to the fluorine release it was observed that the addition of theobromine does not change the properties of GIC (p >0.05). Based on these findings, it is concluded that the addition of theobromine in 1% to the conventional glass ionomer cement, does not produce significant changes over this material properties and also, it can optimize some of these properties. However, more studies should be done about this topic.

Magister Scientiae Dentium - MSc(Dent) / Introduction: Micro-leakage and enamel demineralization is still a major challenge in dental practice. It can lead to formation of demineralization lesions around and beneath the adhesive–enamel interface (Mali et al., 2006). Enamel demineralization adjacent to orthodontic brackets is one of the risks associated with orthodontic treatment. The prevention of demineralization during orthodontic treatment is therefore essential for aesthetic reasons and to circumvent the onset of caries. Aim: To assess micro-leakage and enamel demineralization around orthodontic direct attachments (brackets) using three different orthodontic cements. Materials and methods: In this in-vitro study, intact (non carious) extracted human premolars were used to compare the micro-leakage and enamel demineralization of three different cements (Fuji Ortho LC, Rely X luting 2 and Transbond XT). The dye penetration technique was used to evaluate micro-leakage on extracted human premolars. Micro-hardness testing was performed on 21 teeth to determine enamel demineralization. Sixty teeth were randomly divided into 3 groups of twenty teeth each. Direct attachments were cemented on each tooth using 3 different cements; Fuji Ortho LC (GC Fuji II LC GC Corporation Tokyo, Japan), (group 1), Rely X luting 2 cement (3M ESPE dental product, USA), (group 2), Transbond XT Light Cure (3M Unitek, Monrovia, Calif), (group 3). After the orthodontic direct attachments were fitted, they were exposed to 500 thermo-cycles between 5°C and 55°C, with a dwell time of 15 seconds in a buffered (pH 7) 1% methylene blue dye solution (Grobler et al, 2007). The specimens were viewed under a stereomicroscope (Nikon, Japan) at magnification of 40 times. Photographs of each specimen were taken with a Leica camera (Leica DFC 290 micro-systems, Germany) fitted onto a stereomicroscope. The ACDsee photo editing programme was used to transfer the photographs to a computer to measure the dye penetration along the enamel–adhesive and adhesive–bracket interfaces, both on the gingival and occlusal edge at × 40 magnification. For the demineralization sample, 21 teeth were divided into 3 groups of seven teeth each, where direct attachments were cemented using each of the 3 cements, group 1, Fuji Ortho LC (GC Fuji II LC GC Corporation Tokyo, Japan); group 2, Rely X luting 2 cement (3M ESPE dental product, USA) and group 3, Transbond XT Light Cure (3M Unitek, Monrovia, Calif). A digital hardness tester with Vickers diamond indenter (Zwick RoellIndentec (ZHV; Indentec UK) was used to measure surface micro-hardness of enamel before and after attaching the brackets. Ten indentations were made on the enamel surface of each tooth before bonding the brackets with a 300g load applied for 15 seconds to establish the baseline hardness value. After de-bonding the brackets, the hardness was measured again in the same area as mentioned above to determine the degree of enamel demineralization (softening). Result: The result showed statistically significantly lower levels of micro-leakage for Transbond XT (P= <0.001). The amount of micro-leakage on the margins was significantly higher in the gingival portion (P <0.05) as compared with the occlusal margin. Enamel micro-hardness tests before bonding using the three different cements showed that the variances are not significantly different (Chi-squared = 3.051, df = 2, p-value = 0.218). However, the micro-hardness tests done after bonding and thermo-cycling was statistically significantly different (Chi-squared = 13.435, df = 2, p-value = 0.001). Clearly, the Transbond XT group had less hardness, implying greater demineralization than the Fuji Ortho LC and Rely X luting 2 groups. Two sample t-tests show that mean value for the Fuji Ortho and Rely X luting 2 were not significantly different from each other (t = -0.636, df = 12, p-value = 0.537). The mean value for Transbond XT differed significantly from both the other two means: Transbond XT vs Fuji Ortho LC (t = 3.249, df = 6.9, p-value = 0.014). Transbond XT vs Rely X luting 2 (t = 3.493, df = 6.8, p-value = 0.011). Conclusions: This study showed that Fuji Ortho LC and Rely X luting 2 show more micro-leakage than Transbond XT. However Transbond XT had significant lower micro-leakage, less hardness (greater demineralization) than the Fuji Ortho LC and Rely X luting 2. This may have been due to the fluoride release which significantly reduces demineralization. Therefore the Fuji Ortho LC and Rely X luting 2 may be recommended for prevention of demineralization during orthodontic treatment.

Per-Fluoro-Sulphonic-Acid (PFSA) ionomers have been singled out as the preferable ionomers for making the Polymer Electrolyte Membrane Fuel Cells (PEMFC) membranes owing to their extensive intrinsic chemical stability and super sulfonic acid strength which is core to the PEMFC proton conductivity. This thesis presents a deeper analysis into these PFSA ionomer membrane electrode assemblies (MEA), presenting an electrochemical-analytical comparative analysis of the two basic types, which are the Long-Side-Chain (LSC) Nafion® and the ShortSide-Chain (SSC) Aquivion® ionomer MEA with emphasis on performance and durability which are currently not well understood. In particular, electrochemical circuit models and semiempirical models were employed to enable distinguishable comparative analysis. Also, in this thesis, we present a further probe into the effect of ionomer ink making processes, critically investigating the effect of the High Share Dispersion (HSD) process on both the Nafion® and Aquivion® ionomer membrane electrode assembly (MEA). The findings in this research provides a valuable insight into the performance and durability of PFSA ionomer membrane under various application criteria. The effect of operating parameters and accelerated stress testing (AST) on the PFSA ionomers was determined using electrochemical impedance spectroscopy (EIS) and electronic circuit model (ECM) analysis. The result of this study, shows that the ionomer ink making process for Nafion® and Aquivion® MEAs are not transferrable. Analysis of the PEMFC performance upon application of the high shear dispersion (HSD) process showed that Nafion® MEA had a 10.47% increase in voltage while the Aquivion® MEA had a 2.53% decrease in voltage at current density of 1.14A/cm2 . Also, upon accelerated stress testing, the Nafion® showed a 10.49% increase in its voltage while the Aquivion® on the other hand had a 7.16% decrease in voltage at 0.66A/cm2 . Thus indicating the HSD process enhances the performance of the Nafion® MEA and inhibits the performance of the Aquivion® MEA.

Ionomers are polymers that contain ionic groups in relatively low concentrations along the polymer backbone. These ionic groups, in the presence of oppositely charged ions, form aggregates that lead to novel physical properties of the polymer. React-A-Seal® and Surlyn® are poly(ethylene-co-methacrylic acid) (EMAA) ionomer-based materials and Nucrel® is the EMAA acid copolymer neutralized to produce Surlyn®. React-A-Seal® , Surlyn® , and Nucrel® recover into their original shapes following a high impact puncture at velocities ranging from 300 to 1200 ft/s ("self-healing"). This self-healing process may be of great benefit in space applications where structures are exposed to matter impacts. A thermal IR camera indicated a temperature increase to 98°C for Nucrel® 925, Surlyn® 8940, React-A-Seal® , and Surlyn® 8920 after initial penetration. To understand and generalize the observed phenomena, questions concerning the mechanism of the puncture resealing must be answered. One suggestion is that the elastic character of the melt created by the puncture drives the self-healing. This inference is based on the observed temperature rise of ~3°C above the melting temperature of the samples (~95°C) during the impact. With the expectation of gaining additional insight into the self-healing phenomenon, a thermodynamic and viscoelastic investigation was conducted using primarily DSC and DMA. Surlyn® and React-A-Seal® showed the characteristic order-disorder transition at ~52°C that has been reported in literature. Master curves were constructed from the creep isotherms for the four EMAA samples. An aging study was performed to investigate the irreproducibility and ®tailing effect” observed in the creep data. The aging study indicated that, with increased aging time and temperature, changes in the polyethylene matrix lead to complexities in morphology resulting in changes in the magnitude and shape of the creep curves. As a result of the thermodynamic, viscoelastic, and high-speed impact experiments it has been theorized that self-healing can occur in Nucrel® 925, Surlyn® 8940, React-A-Seal® , and Surlyn® 8920 because of two features, ionic aggregation and complex flow behavior. / Master of Science