Influence of bleaching treatment on flexural resistance of hybrid materials

ABSTRACT

The aim of this study is to evaluate the flexural resistance of three types of restorative materials compomer (Freedom), resin-modified glass-ionomer (Vitremer) and composite resin (Esthet-X), observing whether the application of bleaching agent can cause alterations of their flexural properties. Sixty samples were made using a 10x1x1 mm brass mold, and divided into three groups G1- Freedom (SDI); G2- Vitremer (3M ESPE); G3- Esthet-X (Dentsply). On half of the samples of each group (10 samples) the bleaching treatment was applied and the other half, used as control, was stored in distilled water at a temperature of 37oC. Whiteness HP Maxx bleaching system was applied on the sample surface following the manufacturer's recommendations, simulating the bleaching treatment at the clinic. After this period, a flexural strength (three-point bending) test was conducted using (EMIC DL 1000) machine until the samples fractured. The data were submitted to ANOVA and Tukey tests. Of the restorative materials studied, G3- (87.24±31.40MPa) presented the highest flexural strength, followed by G1-(61.67±21.32MPa) and G2-(61.67±21.32MPa). There was a statistical difference in flexural strength after the bleaching treatment. It was concluded that the use of a beaching agent can promote significant alteration of the flexural strength of these restorative materials.

RESUMO

O objetivo deste trabalho foi o de avaliar a resistencia flexural de tres tipos de materiais restauradores hibridos; compomero (Freedom), cimento de ionomero de vidro modificado por resina (CIV-RM) (Vitremer) e resina composta (Esthet-X) verificando se a aplicacao do agente clareador promove alteracoes em suas propriedades flexurais. Foram confeccionadas 60 amostras, com auxilio de uma matriz metalica 10x1x1mm, as quais foram divididas em tres grupos G1- Freedom (SDI); G2- Vitremer (3M ESPE); G3- Esthet-X (Dentsply). Em metade das amostras de cada grupo, ou seja, 10 amostras, foi realizado o tratamento clareador permanecendo as demais armazenadas em agua destilada 37°C. Utilizou-se o sistema de clareamento Whiteness HP Maxx sobre a superficie das amostras seguindo as orientacoes do fabricante, simulando assim, o tratamento clareador realizado em consultorio. Decorrido este periodo, foi realizado o ensaio mecanico de resistencia a flexao de 3 pontos na maquina de testes universal (EMIC DL 1000) ate a fratura dos especimes. Os dados foram submetidos aos testes ANOVA-2 fatores e Tukey. Observou-se diferenca estatisticamente significante entre os materiais, sendo que G3-(87,24±31,40MPa) apresentou a maior resistencia flexural seguida pelo G1-(61,67±21,32MPa) e G2- (21,04±8,94MPa), e apos a realizacao do tratamento clareador. Concluiu-se que ha diferenca estatisticamente significante entre a resistencia flexural da resina composta, compomero e o CIVRM, sendo a aplicacao do agente clareador capaz de promover alteracoes na resistencia flexural destes materiais.