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

To analyze the incorporation of cardanol trimethacrylate monomer (CTMA), derived from the cashew nut shell liquid, as a substitute for Bis-GMA in acrylic resins formulations and its effect on experimental resin composites’ physicochemical and mechanical properties.

The intermediary cardanol epoxy was synthesized via cardanol epoxidation, followed by the 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 by 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.

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 the 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.

Incorporating CTMA into composites resulted in similar chemical and mechanical properties compared to Bis-GMA-based material while reducing viscosity, water sorption and solubility.

CTMA could be used as a trimethacrylate monomer replacing Bis-GMA in resin composites, thereby minimizing BPA exposure.