Comportamento biomecânico de compósitos resinosos fluidos e termomodificado: análise laboratorial

Abstract

Objective: To evaluate in vitro the physicomechanical properties of three types of resin composites: conventional nanohybrid, thermally modified nanohybrid, and injectable flowable composite. Method: Thirty specimens were divided into three groups (n=10): GC (control – conventional resin), GT (thermally modified – preheated conventional resin) (69 °C/10 min), and GI (injectable – flowable resin). Samples measuring 5×2 mm were subjected to degree of conversion, Knoop microhardness, surface roughness, and radiopacity tests, while samples measuring 25×2×2 mm were tested for flexural strength and Young’s modulus. Data were analyzed using GraphPad Prism software (version 10.5.0; GraphPad Software, LLC). Normality was assessed using the Shapiro-Wilk test (α = 0.05). For variables with a normal distribution, one-way or two-way ANOVA was used (with Tukey’s post hoc test for multiple comparisons). For non-normally distributed data, the Kruskal-Wallis test was applied. Results: The GI group showed superior performance across several parameters. It exhibited the highest top surface degree of conversion (70.79%) and uniform microhardness between top and bottom surfaces, as well as the lowest surface roughness (<0.2 µm). Flexural strength in the GI group was statistically similar to GC but higher than GT. There were no significant differences in Young’s modulus among the groups. All materials displayed radiopacity above the clinical threshold. Conclusion: The flowable composite G-ænial Universal Flo demonstrated superior performance, especially in depth, suggesting it as a preferred option for restorative techniques using a transparent matrix. Preheating the conventional composite resin (Essentia LE) did not provide additional biomechanical benefits and showed limitations, particularly regarding depth of polymerization