Mesoporous silica nanoparticles for improved mechanical properties and stability in bioactive dental resin composites

The mechanical properties of resin composites (RCs) are often compromised by the incorporation of bioactive fillers. To address this, mesoporous silica nanoparticles (MSNs) with unique structural features and surface silanization were developed to synergistically enhance the mechanical performance of RCs while preserving bioactivity, thereby overcoming the traditional trade-off between these properties.

MSNs were synthesized through a combination of dynamic self-assembly and calcination. Following silanization they were incorporated into resin matrix at various weight ratios (0, 2.5, 5, 7.5 and 10 wt%) alongside three further filler types: magnesium oxide nanoparticles (n-MgO), bioactive glass (BAG) and silanized barium borosilicate glass (BaBSi). The mechanical properties of these potentially bioactive RCs were systematically measured, focusing on both initial performance and long-term stability, which was rigorously evaluated through 10,000 thermal cycles (TC) between 5 °C and 55 °C. Additionally, the degree of conversion, physicochemical properties, and cytotoxicity of the RCs were determined. The antibacterial performance and remineralization capacity of the RCs were also evaluated.

MSNs-filled RCs exhibited significantly reduced water contact angles, decreased water sorption (W_sp) and solubility (W_sl), and excellent biocompatibility and bioactivity. Prior to aging, the MSNs-filled RCs exhibited significant improvements in mechanical properties. After aging, groups exhibited some decline in mechanical properties, but MSNs at 5 wt% improved the stability.

MSNs incorporation significantly enhanced the mechanical strength and stability of dental RCs containing n-MgO, BAG and BaBSi fillers, while preserving their bioactive characteristics. This approach establishes a new paradigm for designing RCs, towards harmonious integration of functional durability and potential bioactivity.