Effect of alternative polishing techniques on the roughness of acrylic resins

Em uma primeira etapa deste trabalho, buscou-se desenvolver uma técnica de polimento químico de resinas acrílicas que utilizasse o forno de microondas LG Modelo MB (315m1- 1.000watts) para o aquecimento de líquidos para polimento. A potencia do forno de microondas e o tempo necessários para aquecer os líquidos para polimento ate uma temperatura de 81 ± 5°C — intervalo de temperatura equivalente ao obtido na polidora elétrica- foram 900 watts (90% da potencia máxima) e 90 segundos. A seguir, foram confeccionados 100 corpos-de prova, 50 amostras de resina acrílica quimicamente ativada e 50 de resina acrílica ativada por energia de microondas, os quais foram submetidos a cinco diferentes técnicas de polimento: 1) polimento mecânico- controle, 2) polimento químico com liquido para polimento em polidora elétrica, 3) polimento químico com monômero de resina acrílica em polidora elétrica, 4) polimento químico com liquido para polimento aquecido em forno de microondas, 5) polimento químico com monômero de resina acrílica aquecido em forno de microondas. Eles foram comparados, quanto a eficacia da técnica, usando como parâmetro a rugosidade superficial das resinas acrílicas. Para essa avaliação foi usado um rugosímetro SJ-201 (Mitotoyo - Japan). Os resultados foram submetidos a analise de variância e as medias comparadas pelo teste de Tukey (a = 1%). Os resultados mostraram que todas as técnicas de polimento geraram valores de rugosidade com diferença estatística significativa quando comparados com a técnica de polimento mecânico (controle), a qual apresentou valores de rugosidade superficial abaixo do limiar de Ra, estabelecido como 0,2 um. Não houve diferença estatisticamente significante entre as quatro técnicas de polimento químico.ln the first part of this experiment, a chemical polishing technique for acrylic resins using a LG microwave oven model MB (315ml - 1.000watts) to heat the polishing fluids was sought. The microwave oven potency and the time required to heat the polishing fluids to a temperature of81 ± 5%C - temperature interval obtained in the electric polishing machine - was 900watts (90% of the maximum potency) and 90 seconds. Subsequently, a 100 prototypes were made, 50 samples of acrylic resin chemically activated and 50 samples of acrylic resin activated by microwave oven energy, which were submitted to 5 different polishing techniques: l) mechanical polishing - control group, 2) chemical polishing in electric polishing machine using polishing fluid., 3) chemical polishing in electric polishing machine using resin monomer, 4) chemical polishing in microwave oven using polishing fluid, 5) chemical polishing in microwave oven using resin monomer. They were compared using the effectiveness of the technique as a parameter for the superficial roughness of the acrylic resins. For this evaluation a rugosimeter S]-201 (Mitotoyo - ]apan) was used. The results were submitted to the analysis of variance and the means compared using the Tukey test (0= 1%). The results showed that ali polishing techniques promoted roughness values with statistical significative difference when compared to the mechanical polishing technique, which was below the R.,, threshold of 0,2 m, (a= 1%). There were no significant statistical differences among the four chemical polishing techniques

Efeito de técnicas alternativas de polimento sobre a rugosidade superficial de resinas acrílicas

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Efeito de técnicas alternativas de polimento sobre a rugosidade superficial de resinas acrílicas

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Efeito de técnicas alternativas de polimento sobre a rugosidade superficial de resinas acrílicas

Em uma primeira etapa deste trabalho, buscou-se desenvolver uma tecnica de polimento quimico de resinas acrilicas que utilizasse o forno de microondas LG Modelo MB (315m1 - 1.000watts) para o aquecimento de liquidos para polimento. A potencia do forno de microondas e o tempo necessarios para aquecer os liquidos para polimento ate uma temperatura de 81 ± 5°C — intervalo de temperatura equivalente ao obtido na polidora eletrica- foram 900 watts (90% da potencia maxima) e 90 segundos. A seguir, foram confeccionados 100 corpos-deprova, 50 amostras de resina acrilica quimicamente ativada e 50 de resina acrilica ativada por energia de microondas, os quais foram submetidos a cinco diferentes tecnicas de polimento: 1) polimento mecanico- controle, 2) polimento quimico corn liquido para polimento em polidora eletrica, 3) polimento quimico corn monOmero de resina acrilica em polidora eletrica, 4) polimento quimico com liquido para polimento aquecido em forno de microondas, 5) polimento quimico corn monomero de resina acrffica aquecido em forno de microondas. Eles foram comparados, quanto a eficacia da tecnica, usando como parametro a rugosidade superficial das resinas acrilicas. Para essa avaliacao foi usado urn rugosimetro SJ-201 (Mitotoyo - Japan). Os resultados foram submetidos a analise de variancia e as medias comparadas pelo teste de Tukey (β= 1%). Os resultados mostraram que todas as tecnicas de polimento geraram valores de rugosidade com diferenca estatistica significativa quando comparados com a tecnica de polimento mecanico (controle), a qual apresentou valores de rugosidade superficial abaixo do limiar de Ra, estabelecido como 0,2 urn. Nao houve diferenca estatisticamente significante entre as quatro tecnicas de polimento quimico

Avaliação da microdureza e da variação do peso do gesso tipo III seco em forno de microondas

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Avaliação da microdureza e da variação do peso do gesso tipo III seco em forno de microondas

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Avaliação de conhecimentos sobre saúde e tratamento farmacológico de pacientes ambulatoriais da Faculdade de Odontologia da Universidade Federal do Rio Grande do Sul

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Avaliação de conhecimentos sobre saúde e tratamento farmacológico de pacientes ambulatoriais da Faculdade de Odontologia da Universidade Federal do Rio Grande do Sul

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Health-status outcomes with invasive or conservative care in coronary disease

BACKGROUND In the ISCHEMIA trial, an invasive strategy with angiographic assessment and revascularization did not reduce clinical events among patients with stable ischemic heart disease and moderate or severe ischemia. A secondary objective of the trial was to assess angina-related health status among these patients. METHODS We assessed angina-related symptoms, function, and quality of life with the Seattle Angina Questionnaire (SAQ) at randomization, at months 1.5, 3, and 6, and every 6 months thereafter in participants who had been randomly assigned to an invasive treatment strategy (2295 participants) or a conservative strategy (2322). Mixed-effects cumulative probability models within a Bayesian framework were used to estimate differences between the treatment groups. The primary outcome of this health-status analysis was the SAQ summary score (scores range from 0 to 100, with higher scores indicating better health status). All analyses were performed in the overall population and according to baseline angina frequency. RESULTS At baseline, 35% of patients reported having no angina in the previous month. SAQ summary scores increased in both treatment groups, with increases at 3, 12, and 36 months that were 4.1 points (95% credible interval, 3.2 to 5.0), 4.2 points (95% credible interval, 3.3 to 5.1), and 2.9 points (95% credible interval, 2.2 to 3.7) higher with the invasive strategy than with the conservative strategy. Differences were larger among participants who had more frequent angina at baseline (8.5 vs. 0.1 points at 3 months and 5.3 vs. 1.2 points at 36 months among participants with daily or weekly angina as compared with no angina). CONCLUSIONS In the overall trial population with moderate or severe ischemia, which included 35% of participants without angina at baseline, patients randomly assigned to the invasive strategy had greater improvement in angina-related health status than those assigned to the conservative strategy. The modest mean differences favoring the invasive strategy in the overall group reflected minimal differences among asymptomatic patients and larger differences among patients who had had angina at baseline

Initial invasive or conservative strategy for stable coronary disease

BACKGROUND Among patients with stable coronary disease and moderate or severe ischemia, whether clinical outcomes are better in those who receive an invasive intervention plus medical therapy than in those who receive medical therapy alone is uncertain. METHODS We randomly assigned 5179 patients with moderate or severe ischemia to an initial invasive strategy (angiography and revascularization when feasible) and medical therapy or to an initial conservative strategy of medical therapy alone and angiography if medical therapy failed. The primary outcome was a composite of death from cardiovascular causes, myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. A key secondary outcome was death from cardiovascular causes or myocardial infarction. RESULTS Over a median of 3.2 years, 318 primary outcome events occurred in the invasive-strategy group and 352 occurred in the conservative-strategy group. At 6 months, the cumulative event rate was 5.3% in the invasive-strategy group and 3.4% in the conservative-strategy group (difference, 1.9 percentage points; 95% confidence interval [CI], 0.8 to 3.0); at 5 years, the cumulative event rate was 16.4% and 18.2%, respectively (difference, 121.8 percentage points; 95% CI, 124.7 to 1.0). Results were similar with respect to the key secondary outcome. The incidence of the primary outcome was sensitive to the definition of myocardial infarction; a secondary analysis yielded more procedural myocardial infarctions of uncertain clinical importance. There were 145 deaths in the invasive-strategy group and 144 deaths in the conservative-strategy group (hazard ratio, 1.05; 95% CI, 0.83 to 1.32). CONCLUSIONS Among patients with stable coronary disease and moderate or severe ischemia, we did not find evidence that an initial invasive strategy, as compared with an initial conservative strategy, reduced the risk of ischemic cardiovascular events or death from any cause over a median of 3.2 years. The trial findings were sensitive to the definition of myocardial infarction that was used