A novel antibacterial dental resin composite material with quaternary ammonium salt modified mesoporous silica nanoparticles – an in vitro and in vivo animal study

Abstract

Secondary caries remains a leading cause of failure in resin composite restorations. To address the compromised mechanical properties and potential biosafety concerns associated with conventional quaternary ammonium salt (QAS) monomers, we developed quaternary ammonium–grafted mesoporous silica nanoparticles (QA-MSN) as antibacterial fillers for dental resin composites. The resulting QA-MSN-modified resin composites (QM-Resins) demonstrated potent and concentration-dependent antibacterial and antibiofilm activity against Streptococcus mutans. Specifically, the composite containing 10 wt% QA-MSN (10QM-Resin) achieved a 99.7% antibacterial rate and markedly suppressed biofilm formation after 48 h. Moreover, after 7 days of culture, the relative proliferation rates of human gingival fibroblasts and human dental pulp stem cells were 99.8% and 99.5%, respectively, indicating excellent cytocompatibility. Owing to the mechanical interlocking afforded by the mesoporous structure, QA-MSN incorporation increased the elastic modulus of the composites without adversely affecting flexural strength, degree of conversion, water sorption, or solubility. In a rat secondary caries, 10QM-Resin significantly reduced both Keyes’ scores and lesion depth, demonstrating effective inhibition of caries progression. Collectively, these findings indicate that QA-MSNs represent promising antibacterial fillers for developing dental resin composites with enhanced resistance to secondary caries.