Effect of replacing Bis-GMA by a biobased trimethacrylate on the physicochemical and mechanical properties of experimental resin composites

Objectives To analyze the incorporation of cardanol trimethacrylate monomer (CTMA), derived from the cashew nut shell liquid, as a substitute for Bis-GMA on the physicochemical and mechanical properties of experimental resin composites. Materials and Methods The intermediary cardanol epoxy was synthesized via cardanol epoxidation, followed by synthesis of CTMA through methacrylic anhydride solvent-free esterification. Experimental resin composites were formulated with an organic matrix composed of Bis-GMA/TEGDMA (50/50 wt %) (control). CTMA was gradually added to replace different proportions of Bis-GMA: 10 wt % (CTMA-10), 20 wt % (CTMA-20), 40 wt % (CTMA-40), and 50 wt % (CTMA-50). The composites were characterized in terms of degree of conversion, water sorption and solubility, viscosity, thermogravimetric analysis, dynamic mechanical analysis, flexural strength and elastic modulus. Data were analyzed with one-way ANOVA and Tukey's post-hoc test (α = 0.05), except for water sorption data, which were analyzed by Kruskall-Wallis and Dunn’s method. Results CTMA-based and control composites did not show statistically significant differences regarding degree of conversion, flexural strength and elastic modulus. CTMA reduced the viscosity and solubility compared to Bis-GMA-based composite. The CTMA-40 and CTMA-50 exhibited significantly lower water sorption compared to the control. Also, acceptable thermal stability and viscoelastic properties were obtained for safe use in the oral cavity. Conclusions The incorporation of CTMA into composites resulted in similar chemical and mechanical properties when compared to Bis-GMA-based material, while reducing viscosity, water sorption and solubility. Clinical Relevance CTMA could be used as a trimethacrylate monomer replacing Bis-GMA in resin composites, thereby minimizing BPA exposure.