Sodium montmorillonite concentration effect on Bis-GMA/TEGDMA resin to prepare clay polymer nanocomposites for dental applications

The aim of this work was to evaluate the effect of the addition of sodium montmorillonite (Na+Mt) on the flexural strength, flexural modulus, degree of conversion, steady state shear viscosity and complex viscosity of the Bis-GMA (2,2-bis-[4-(methacryloxypropoxy)-phenyl] propane)/TEGDMA (ethane-1,2-diylbis(oxy)) bis (ethane-2,1-diyl) bis(2-methylacrylate) resin. Two types of clay polymer nanocomposites (CPN) were prepared, the first one by using sodium montmorillonite as received (Na+Mt) and the second one by adding sodium montmorillonite previously dispersed in water (Na+Mt/H2O). Sodium montmorillonite was added at different contents: 0.1, 0.2, 0.3, 0.4 parts per hundred of resin (phr) to Bis-GMA/TEGDMA resin for each type of CPN. A Bis-GMA/TEGDMA resin, without sodium montmorillonite, was used as control. Two-way ANOVA and Tukey's test were applied for statistical analysis. Comparisons were performed using a significance level of α = 0.05. Statistical analysis revealed that the addition of sodium montmorillonite as received or dispersed in water, had no effect on flexural strength (p = .886), flexural modulus (p = .809) and degree of conversion of resin (p = .742). Nevertheless, the content of sodium montmorillonite significantly influenced the flexural strength (p = .004) and flexural modulus (p