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Estudo comparativo in vitro da microdureza de resinas acrílicas usadas em prótese removível
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 6.87 MB | Adobe PDF |
Authors
Abstract(s)
Introdução: Dependendo do tipo de polimerização, as resinas acrílicas utilizadas em bases de próteses removíveis podem apresentar algumas fragilidades mecânicas que podem resultar na sua fratura e levar ao fracasso da prótese. Visto que a capacidade de resistência à fratura é um fator que determina sua aplicabilidade, é de extrema importância avaliar esse parâmetro, especificamente por meio de testes como os que avaliam a microdureza.
Objetivo: Avaliar in vitro a microdureza de Knoop de duas resinas acrílicas, com diferentes métodos de polimerização (térmica e química), utilizadas em próteses removíveis.
Métodos: Os espécimes de cada tipo de resina foram preparados respeitando as normas do fabricante e de acordo com a norma ISO nº 20795-1:2013. A microdureza de cada espécime foi determinada com recurso ao teste de microdureza de Knoop, por meio de uma ponta indentadora Knoop conectada a uma máquina de testes de Knoop. Em cada espécime foram realizadas cinco indentações aleatórias na sua superfície superior, num total de 25 indentações por cada tipo de resina acrílica.
Resultados: A análise estatística dos resultados revelou existir diferenças estatisticamente significativas em relação à média dos valores de microdureza entre os dois tipos de resinas acrílicas ProBase® Hot e ProBase® Cold (p<0.001). Deste modo, a resina acrílica termopolimerizável (PBH) revelou apresentar valores de microdureza significativamente superiores à autopolimerizável (PBC), o que demonstra que o método
de polimerização pode influenciar a microdureza.
Conclusão: A resina acrílica termopolimerizável apresenta valores de microdureza de Knoop significativamente superiores aos da resina acrílica autopolimerizável. O tipo de polimerização parece ter influência na propriedade mecânica de microdureza das resinas acrílicas. Em casos clínicos mais desafiantes do ponto de vista mecânico, deve ser preferida a utilização de uma resina acrílica termopolimerizável para a confeção da base protética da prótese removível.
Introduction: Depending on the type of polymerization, acrylic resins may present some mechanical weaknesses that may result in its fracture and lead to the failure of the prosthesis. As the ability to resist fracture is a factor that determines its applicability, it is extremely important to evaluate this parameter, specifically through tests such as those that assess microhardness. Objective: Evaluate the in vitro Knoop microhardness of two acrylic resins, with different polymerization methods (thermal and chemical), used in removable dentures. Methods: The specimens of each type of resin were prepared in compliance with the manufacturer's standards and in accordance with ISO standard No. 20795-1:2013. The microhardness of each specimen was determined using the Knoop microhardness test, using a Knoop indenter tip connected to a Knoop testing machine. In each specimen, five random indentations were performed on its upper surface, in a total of 25 indentations for each type of acrylic resin. Results: The statistical analysis of the results revealed that there are statistically significant differences in relation to the mean of microhardness values between the two types of acrylic resins ProBase® Hot and ProBase® Cold (p<0.001). Thus, the thermopolymerizable acrylic resin (PBH) revealed to present microhardness values significantly higher than the self-curing resin (PBC), which demonstrates that the polymerization method may influence the microhardness. Conclusion: The heat-polymerized acrylic resin has Knoop microhardness values significantly higher than the self-cure acrylic resin. The type of polymerization seems to influence the mechanical microhardness property of acrylic resins. In clinical cases that are more challenging from a mechanical point of view, the use of a heat-polymerized acrylic resin should be preferred for making the prosthetic base of the removable prosthesis.
Introduction: Depending on the type of polymerization, acrylic resins may present some mechanical weaknesses that may result in its fracture and lead to the failure of the prosthesis. As the ability to resist fracture is a factor that determines its applicability, it is extremely important to evaluate this parameter, specifically through tests such as those that assess microhardness. Objective: Evaluate the in vitro Knoop microhardness of two acrylic resins, with different polymerization methods (thermal and chemical), used in removable dentures. Methods: The specimens of each type of resin were prepared in compliance with the manufacturer's standards and in accordance with ISO standard No. 20795-1:2013. The microhardness of each specimen was determined using the Knoop microhardness test, using a Knoop indenter tip connected to a Knoop testing machine. In each specimen, five random indentations were performed on its upper surface, in a total of 25 indentations for each type of acrylic resin. Results: The statistical analysis of the results revealed that there are statistically significant differences in relation to the mean of microhardness values between the two types of acrylic resins ProBase® Hot and ProBase® Cold (p<0.001). Thus, the thermopolymerizable acrylic resin (PBH) revealed to present microhardness values significantly higher than the self-curing resin (PBC), which demonstrates that the polymerization method may influence the microhardness. Conclusion: The heat-polymerized acrylic resin has Knoop microhardness values significantly higher than the self-cure acrylic resin. The type of polymerization seems to influence the mechanical microhardness property of acrylic resins. In clinical cases that are more challenging from a mechanical point of view, the use of a heat-polymerized acrylic resin should be preferred for making the prosthetic base of the removable prosthesis.
Description
Dissertação para obtenção do grau de Mestre no Instituto Universitário Egas Moniz
Keywords
Resinas acrílicas Polimerização Microdureza Prótese removível