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Influência do tempo pós-polimerização na resistência à flexão das resinas bis acrílicas
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Objetivos: O presente estudo teve como objetivo estudar a influência do tempo pós- polimerização na resistência à flexão, de duas marcas comerciais de resinas bis-acrílicas.
Materiais e Métodos: Com auxílio de um molde metálico, foram realizados 120 espécimes de cada resina bis-acrílica estudada, e divididos em 6 grupos de 20 espécimes de acordo com o tempo pós-polimerização considerado (5 min, 30 min, 6 h, 24 h, 48 h, 96 h). Desta forma, foram criados 12 grupos experimentais de acordo com as diversas combinações possíveis entre resina bis-acrílica e tempo pós-polimerização (n=20). Após o respetivo tempo pós-polimerização, os espécimes foram submetidos a um teste de resistência à flexão de três pontos. Os dados foram analisados recorrendo a testes de Mann-Whitney e Kruskal-Wallis. O nível de significância foi estabelecido em α=0,05.
Resultados: Não foram observadas diferenças estatisticamente significativas (p=0,735) entre as resinas bis-acrílicas estudadas. No entanto, o tempo pós-polimerização influenciou os resultados de uma forma estatisticamente significativa (p<0,001). Não se observaram diferenças estatisticamente significativas entre os 5 e os 30 minutos (p=0,221). A resistência à flexão aumentou do grupo dos 30 minutos para o das 24 horas (p<0,001). Não se verificaram diferenças entre os grupos das 24, 48 e 96 horas (p>0,05).
Conclusão: Não existem diferenças entre a resistência à flexão das resinas bis-acrílicas testadas. A resistência à flexão aumenta dos 30 minutos às 24 horas, não sofrendo alteração a partir das 24 horas.
Objectives: The present study aimed to evaluate the influence of post-polymerization time on flexural strength of two brands of bis-acrylic resins. Materials and Methods: Using a metal mold, 120 specimens of each bis-acrylic resin were prepared and divided into 6 groups of 20 specimens according to the post- polymerization time (5 min, 30 min, 6 h, 24 h, 48 h, 96h). In this way, 12 experimental groups were created according to the various possible combinations between bis-acrylic resin and post-polymerization time (n=20). After the respective post-polymerization time, the specimens were subjected to a three-point flexural strength test. Data were analyzed using Mann-Whitney and Kruskal-Wallis tests. The level of significance was set at α=0.05. Results: No statistically significant differences (p=0.735) were observed between the bis- acrylic resins studied. However, post-polymerization time influenced the results in a statistically significant way (p<0.001). No statistically significant differences were observed between 5 and 30 minutes (p=0.221). Flexural strength increased from 30 minutes to 24 hours (p<0.001). There were no differences between groups of 24, 48 and 96 hours (p>0.05). Conclusion: There are no differences between the flexural strength of the bis-acrylic resins tested. The flexural strength increases from 30 minutes to 24 hours and does not change after 24 hours.
Objectives: The present study aimed to evaluate the influence of post-polymerization time on flexural strength of two brands of bis-acrylic resins. Materials and Methods: Using a metal mold, 120 specimens of each bis-acrylic resin were prepared and divided into 6 groups of 20 specimens according to the post- polymerization time (5 min, 30 min, 6 h, 24 h, 48 h, 96h). In this way, 12 experimental groups were created according to the various possible combinations between bis-acrylic resin and post-polymerization time (n=20). After the respective post-polymerization time, the specimens were subjected to a three-point flexural strength test. Data were analyzed using Mann-Whitney and Kruskal-Wallis tests. The level of significance was set at α=0.05. Results: No statistically significant differences (p=0.735) were observed between the bis- acrylic resins studied. However, post-polymerization time influenced the results in a statistically significant way (p<0.001). No statistically significant differences were observed between 5 and 30 minutes (p=0.221). Flexural strength increased from 30 minutes to 24 hours (p<0.001). There were no differences between groups of 24, 48 and 96 hours (p>0.05). Conclusion: There are no differences between the flexural strength of the bis-acrylic resins tested. The flexural strength increases from 30 minutes to 24 hours and does not change after 24 hours.
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Saúde oral Teses de mestrado - 2019