Evaluation of Cardanol Monomer Replacing for TEGDMA in Composites

Objectives: To analyze the effect of replacing TEGDMA with cardanol trimethacrylate monomer (CTMA), a derivative of cashew nutshell liquid, on the physicochemical and mechanical properties of experimental composite resins.
Methods: CTMA was synthesized and characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Nuclear Magnetic Resonance (NMR), and thermogravimetric analysis (TGA). Experimental composite resins were prepared with an organic matrix composed of Bis-GMA/TEGDMA (50/50% by weight) as the control. CTMA was gradually incorporated, replacing TEGDMA at various weight percentages: 10% (CTMA-10), 20% (CTMA-20), 40% (CTMA-40), and 50% (CTMA-50). The composite resins were evaluated for degree of conversion (DC) via FT-IR, water sorption (WS), solubility (SL), flexural strength (FS), elastic modulus (E), and polymerization shrinkage stress (PSS). Statistical analysis was conducted using one-way ANOVA and Tukey's post hoc test (α=0.05), except for solubility data, which were analyzed with the Kruskal-Wallis test.
Results: All composite resins exhibited acceptable thermal stability for safe use in the oral cavity. The CTMA-10 and CTMA-20 groups showed no statistically significant differences compared to the control in terms of DC, FS, and E. The incorporation of CTMA did not influence WS, reduced SL in the CTMA-10 and CTMA-40 groups, and significantly decreased PSS in Class I configurations.
Conclusions: Within the limitations of this in vitro study, the renewable monomer CTMA demonstrated favorable performance when incorporated at 20% as a replacement for TEGDMA in composite resins. It maintained similar physicochemical and mechanical properties to the control while significantly reducing PSS.