Impact of clay content and type on the kinetic and mechanical properties of dental restorations based on Bis-GMA/TEGDMA resin

The main objective of this work was to investigate the influence of the clay on the kinetic and mechanical properties of methacrylate-clay nanocomposites. This nanocomposites were synthesized using two clays (BNT/ MMT). Bentonite (BNT) was exchanged with different quaternary amines, the presence of alkyl ammonium salts was identified from FTIR patterns, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results illustrated that the exchange processes induce an increase in the interlayer spacing of BNT. On the other hand, the outcomes of the work indicated that the silanisation and the incorporation of methacrylate functions has increased the level of dispersion in the organic matrix. The impact of the clay content on the photo- polymerization kinetics was also discussed. FTIR-ATR spectroscopy was used to study the influence of the filler content, thickness of the composite layer and temperature on the ultimate conversion. The study of the kinetics at different temperatures enabled the determination of reaction orders m and n, as well as the activation energy (Ea). The mechanical testing results demonstrated that the system with 0.2 % BNT and 0.5 % MMT exhibited better dispersion, leading to optimal flexural strength (FS). The flexural modulus (FM) test, meanwhile, showed that composites containing both types of clay experienced an increase in FM with higher clay concentrations. Notable hardness values (VH) were observed across all the composites when compared. These outcomes of the work confirm the suitability of composites containing MMT or BNT for utilization in dental restorative resins. Further research is required to better interpret their potential performance.