Abstract:Com o objetivo de verificar a efetividade da energia de microondas na polimerização da resina acrílica próxima ao metal, foram confeccionados 36 corpos-de-prova cilíndricos com 30,0 mm de diâmetro x 4,0 mm de espessura, contendo no seu interior uma sela metálica com 28,0 mm x 8,0 mm x 0,5 mm, divididos aleatoriamente em 3 grupos e submetidos aos seguintes processamentos: G1) resina Clássico polimerizada em ciclo curto; G2) resina Acron-MC polimerizada em forno de microondas por 3 minutos a 500 W; G3) resina Cl… Show more
“…Regardless of the type of resin and the polishing technique, release of RM decreased after water storage, which is in accordance with Lamb, Ellis and Priestley (1982), Lamb et al . (1983), Stafford and Brooks (1985), Braun, Del Bel Cury and Cury (1998).…”
The effects of chemical polishing on dental acrylic resin properties are not well clarified. This study evaluated the effect of chemical and mechanical polishing on the residual monomer release (RM), Knoop hardness (KH), transverse strength (TS) and surface texture (ST) of a heat- and self-cured acrylic resin. Four groups were formed: GI-self-cured resin/mechanical polishing; GII-self-cured resin/chemical polishing; GIII-heat-cured resin/mechanical polishing; GIV-heat-cured resin/chemical polishing. Following the polishing procedures, specimens were stored in distilled water at 37 degrees C. The KH and RM measurements were taken after 1, 2, 8 and 32 days of storage, and TS after 2, 8 and 32 days. Surface texture was observed under SEM evaluation. Results were compared statistically at a confidence level of 95%. The following conclusions were drawn: (1) regardless of the acrylic resin and the period of analysis, chemical polishing increased RM levels, reduced KH, and did not affect TS significantly; (2) water storage increased the surface hardness of GII and GIV; (3) GII and GIV showed a smooth and wavy surface under SEM evaluation.
“…Regardless of the type of resin and the polishing technique, release of RM decreased after water storage, which is in accordance with Lamb, Ellis and Priestley (1982), Lamb et al . (1983), Stafford and Brooks (1985), Braun, Del Bel Cury and Cury (1998).…”
The effects of chemical polishing on dental acrylic resin properties are not well clarified. This study evaluated the effect of chemical and mechanical polishing on the residual monomer release (RM), Knoop hardness (KH), transverse strength (TS) and surface texture (ST) of a heat- and self-cured acrylic resin. Four groups were formed: GI-self-cured resin/mechanical polishing; GII-self-cured resin/chemical polishing; GIII-heat-cured resin/mechanical polishing; GIV-heat-cured resin/chemical polishing. Following the polishing procedures, specimens were stored in distilled water at 37 degrees C. The KH and RM measurements were taken after 1, 2, 8 and 32 days of storage, and TS after 2, 8 and 32 days. Surface texture was observed under SEM evaluation. Results were compared statistically at a confidence level of 95%. The following conclusions were drawn: (1) regardless of the acrylic resin and the period of analysis, chemical polishing increased RM levels, reduced KH, and did not affect TS significantly; (2) water storage increased the surface hardness of GII and GIV; (3) GII and GIV showed a smooth and wavy surface under SEM evaluation.
“…Estes achados são semelhantes ao trabalho de BRAUN et al (1998), em que avaliaram e compararam a dureza Knoop superficial, em distâncias pré-determinadas de uma sela metálica, das resinas acrílicas Clássico ® (Clássico) e Acron ® (G. C. Dental Ind.…”
Dedico este trabalho À D e u s , pela dádiva da vida, sabedoria, discernim ento e orientação, presentes em todos os m om entos de m inha cam inhada. "Deus nos concede, a cada dia, um a página de vida nova no livro do tem po. Aquilo que colocarm os nela, corre por nossa conta." Chico Xavier iv Aos m eus pais, Jo an e e Maria Vilm a, que com m uito am or, carinho, incentivo e dedicação não pouparam esforços para m inha form ação, sem pre dando exem plos de honestidade, trabalho, respeito e união.
“…Os corpos de prova foram todos polimerizados no forno de microondas 800 W introdução há mais de 60 anos, houve uma contínua procura para modificar os meios de processamento das resinas para melhorar não somente as propriedades físicas e mecânicas, mas também as propriedades de trabalho para facilitar as técnicas laboratoriais da construção de uma dentadura 18,44,47,84,87,89,96 . O desenvolvimento técnico ultra-sofisticado utilizado em muitas áreas para minimizar problemas ou achar soluções ainda não conseguiu dominar totalmente as alterações dimensionais da resina acrílica em prótese total (GOMEZ et al 43 , 1998 propriedades físicas são comparáveis, bem como a adaptação da dentadura é semelhante ou até mesmo superior 2,3,4,8,9,13,32,38,55,61,63,71,78,79,90,91,92 .…”
Section: Ciclo De Polimerizaçãounclassified
“…Com o objetivo de verificar a efetividade da energia de microondas na polimerização da resina acrílica próxima ao metal, BRAUN, DEL BEL CURY & CURY13 (1998) confeccionaram 36 corpos-de-prova cilíndricos com 30,0 mm de diâmetro x 4,0 mm de espessura, contendo no seu interior uma sela metálica com 28,0 mm x 8,0 mm x 0,5 mm, divididos aleatoriamente em 3 grupos e submetidos aos seguintes processamentos: G1) resina Clássico polimerizada em ciclo curto; G2) resina Acron-MC polimerizada em forno de microondas por 3 minutos a 500 W; G3) resina Clássico polimerizada em forno de microondas por 3 minutos a 500 W. Após a polimerização, cada amostra foi dividida em duas partes aproximadamente iguais, sendo que uma das partes foi utilizada para a avaliação de monômero residual, enquanto a outra foi submetida aos testes de dureza e porosidade. Diante dos resultados obtidos, concluíram que a energia de microondas pode ser utilizada para a polimerização da resina acrílica contendo sela metálica no seu interior e que as resinas acrílicas convencionais, quando polimerizadas através da energia de microondas, apresentaram maior quantidade de poros.ALMEIDA et al 4 .…”
Influence of acrylic resin stages and of the space propitiator technique on vertical dimension of occlusion in total dentures Changes in vertical dimension of occlusion in maxillary complete dentures were evaluated after modifying Onda Cryl acrylic resin insertion stages (sandy or stringy) in specifics flasks or employing or not a space propitiator technique. Forty maxillary wax total dentures were made and randomly assigned in four groups, each one with 10 elements. They were all mounted in a semi-adjustable articulator and the initial vertical dimension measurements were recorded by the means of a gauging device attached to the articulator's guideline. The 4 groups were: Group S (Stringy stage, no use of space propitiator technique), Group SP (Stringy stage associated with the space Propitiator technique), Group Sn (Sandy stage, no use of space propitiator technique) and Group SnP (Sandy stage associated with the space Propitiator technique). All specimens were processed in a domestic microwave oven according to Onda cryl manufacturer's instructions. After the curing cycle, the flask was removed from the oven, remaining on the bench until its full cooling and the remounted standardized dentures were replaced in the articulator were reevaluated. The vertical dimensional alterations values were submitted to statistical analysis. Space propitiator technique was effective on reducing the vertical dimension alterations and changing the resin stage (sandy instead stringy stage) results in minor alterations on vertical dimension, although not statiscally significant.
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