Efeito de agentes clareadores na microrrugosidade e microdureza de uma resina composta nanohíbrida: um estudo in vitro

Abstract

The objective of this study was to evaluate the microroughness and microhardness of a nanohybrid resin composite (Filtek Z350XT – A2 enamel; 3M) after exposure to different types of bleaching agents. Materials and methods: Three types of bleaching agents were used (Whiteness Hp Maxx 35% -FGM Produtos Odontológico LTDA; Whiteness HP Blue 35% -FGM Produtos Odontológico LTDA; Opalescence Boost 40% - Ultradent Products Inc.) with different pH. The specimens were identified and stored in distilled water at room temperature and distributed into 6 test groups (n=10), where microroughness and microhardness were analyzed at four times: T0 - 24h after making the bodies; T1 – 7 days after the first gel application; T2 – 7 days after the second application of the gel; T3 - 7 days after the third application of the gel, using a rugosimeter (RugometerSV-400, MITUTOYO, Japan) for microroughness analysis and the Microdurometer ( FISCHERSCOPE®, ISO 14577-1. Microhardness Measurement System, Sindelfingen -Germany ) with a tip Vickers diamond (50g/5s weight) for microhardness analysis. Two-way analysis of variance (ANOVA) for repeated measures was used to assess the influence of the immersion solution (factor 1, 3 levels) and time (factor 2, at 3 levels) for both surface microroughness and microhardness. The Kruskal Wallis test was used to compare mean values between study groups. A statistical software (JAMOVI project (2021), Version 1.6 - Computer Software.) was used at a significance level of 5% (α=0.05). Results: For microroughness, the different bleaching agents did not show any statistical difference among themselves regarding the amount of applications or between the different pH values. For microhardness the pairwise test (Pairwise comparisons) showed a statistically significant difference between the Control and OPB groups at time 2 (p=0.038), and between HPB and OPB after the second and third application of the gels (p=0.07 and p= 0.01), respectively. In addition, a significant difference was also observed between the HPM and OPB groups at time 3 (p=0.002).Conclusion: Hydrogen peroxide bleaching agents with high concentrations are not able to significantly modify the microroughness of the tested nanohybrid composite resin, and this does not depend on the pH value of the bleaching agent. However, regarding the microhardness, the gel with the highest concentration (40%) OPB, significantly reduced the microhardness, which can be worrying for the longevity of the restoration. However, it is noteworthy that these results are from an in vitro study, requiring further investigations to prove these results clinically.