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Influência do tempo de tratamento térmico pós-polimerização na microdureza de resinas bis-acrílicas
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Objetivo: Avaliar a influência do tipo e duração de tratamento térmico pós-polimerização na microdureza de duas resinas bis-acrílicas.
Materiais e métodos: Com auxílio de um molde metálico foram confecionados 210 espécimes para cada resina bis-acrílica testada (Protemp™ 4 e Structur® 3) e distribuídos por 28 grupos (n=15): 24 grupos experimentais tendo em conta o tratamento térmico pós-polimerização (banho de água a 60 ºC, secador de cabelo e micro-ondas) e a duração do tratamento térmico (1, 2, 3 e 4 min.), e 2 grupos de controlo sem tratamento, para cada resina, tendo em conta a duração de envelhecimento desde o início da mistura e o teste de microdureza Knoop (30min. e 24h). Para os grupos experimentais, após o tempo de polimerização cada espécime foi submetido a um dos tratamentos e 30 minutos após o início da mistura foram testados à microdureza Knoop (98,07 mN, 20 seg.). Os dados foram analisados com recurso a testes não paramétricos de Mann-Whitney U e Kruskal-Wallis (α=0,05).
Resultados: Na generalidade, o Protemp™ 4 revelou microdureza estatisticamente (p<0,001) mais elevada que o Structur® 3. Relativamente aos tratamentos térmicos, o banho de água a 60
ºC manifestou microdureza estatisticamente (p<0,001) mais elevada que o micro-ondas e secador de cabelo, que não apresentaram diferenças significativas (p=1,000) entre si. De forma geral, não foi observado algum efeito estatisticamente significativo (p=0,171) da duração do tratamento na microdureza. A maioria dos tratamentos possibilitou um aumento estatisticamente significativo (p<0,05) da microdureza quando comparados com os grupos sem tratamento aos 30 min.. Todos os métodos de tratamento possibilitaram valores de microdureza estatisticamente semelhantes (p>0,05) aos obtidos após 24 h sem tratamento, sendo que alguns deles foram estatisticamente (p<0,05) mais elevados que os deste grupo de controlo.
Conclusão: Os valores de microdureza não foram influenciados pelo tempo de tratamento térmico pós-polimerização.
Objective: Evaluate the influence of the type and time of post-polymerization heat treatment on the microhardness of two bis-acrylic resins. Materials and Methods: Using a metallic mold 210 specimens were made for each bis-acrylic resin tested (Protemp™ 4 and Structur® 3) and allocated to 28 groups (n=15): 24 experimental groups according to the post-polymerization heat treatment (water bath at 60 ºC, conventional hair dryer and microwave) and the duration of the heat treatment (1, 2, 3 or 4 min.), and 2 control groups with no treatment for each resin according to the aging period since the beginning of the mixture and the Knoop microhardness test (30 min. and 24 h). For the experimental groups, after the stipulated polymerization time each specimen was submitted to one of the treatments and 30 minutes after the beginning of the mixture was tested for Knoop microhardness (98.07 mN for 20 sec.). The data were analyzed using non-parametric tests Mann-Whitney U and Kruskal-Wallis tests. A significance level of 5% (α=0.05) was considered. Results: In general, Protemp™ 4 presented statistically higher (p<0.001) microhardness than Structur® 3. Regarding heat treatments, the 60 ºC water bath showed statistically higher (p<0.001) microhardness than the microwave and hair dryer, which didn’t present significant differences (p=1.000) between them. Overall there was no statistically significant effect (p=0.171) of the duration of the treatment on microhardness. Most treatments allowed a statistically significant (p<0.05) increase in microhardness when compared to groups without treatment at 30 min.. All treatment methods provided values of microhardness statistically similar (p> 0.05) to those obtained after 24 h without treatment, some of which were statistically (p<0.05) higher than those of this control group. Conclusion: The microhardness was not influenced by the post-polymerization heat treatment time.
Objective: Evaluate the influence of the type and time of post-polymerization heat treatment on the microhardness of two bis-acrylic resins. Materials and Methods: Using a metallic mold 210 specimens were made for each bis-acrylic resin tested (Protemp™ 4 and Structur® 3) and allocated to 28 groups (n=15): 24 experimental groups according to the post-polymerization heat treatment (water bath at 60 ºC, conventional hair dryer and microwave) and the duration of the heat treatment (1, 2, 3 or 4 min.), and 2 control groups with no treatment for each resin according to the aging period since the beginning of the mixture and the Knoop microhardness test (30 min. and 24 h). For the experimental groups, after the stipulated polymerization time each specimen was submitted to one of the treatments and 30 minutes after the beginning of the mixture was tested for Knoop microhardness (98.07 mN for 20 sec.). The data were analyzed using non-parametric tests Mann-Whitney U and Kruskal-Wallis tests. A significance level of 5% (α=0.05) was considered. Results: In general, Protemp™ 4 presented statistically higher (p<0.001) microhardness than Structur® 3. Regarding heat treatments, the 60 ºC water bath showed statistically higher (p<0.001) microhardness than the microwave and hair dryer, which didn’t present significant differences (p=1.000) between them. Overall there was no statistically significant effect (p=0.171) of the duration of the treatment on microhardness. Most treatments allowed a statistically significant (p<0.05) increase in microhardness when compared to groups without treatment at 30 min.. All treatment methods provided values of microhardness statistically similar (p> 0.05) to those obtained after 24 h without treatment, some of which were statistically (p<0.05) higher than those of this control group. Conclusion: The microhardness was not influenced by the post-polymerization heat treatment time.
Descrição
Tese de mestrado, Medicina Dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2020
Palavras-chave
Saúde Oral Teses de mestrado - 2020