Characterizing Multifunctional Mesoporous Cerium Silicate Nanoparticles for Potential Use in Bioactive Dental Materials: A Proof-of-Concept Study

(1) Background: Cerium silicate (CeSi) nanoparticles (NPs) have potential as a restorative filler particle with multifunctional properties to improve longevity. To increase the biological activity, these nanoparticles can be fabricated with ultrasmall pores (mesoporous) (MPCeSi-NP) that can be loaded with a polyphosphate inhibitor, such as gallein. (2) Methods: MPCeSi-NPs were custom-synthesized with a microemulsion method, using cetyltrimethylammonium bromide (CTAB) as a template for self-assembly. Biocompatibility with oral keratinocytes/fibroblasts was tested, with the addition of examining the biomineralization potential with human bone-marrow-derived mesenchymal stromal cells (BM-MSCs). MPCeSi-NP, loaded with gallein, was tested against Rothia dentocariosa (Rd). MPCeSi-NP was added to a resin matrix of triethylene glycol dimethacrylate (TEGDMA) and Bisphenol A-glycidyl methacrylate (BisGMA) with subsequent mechanical properties evaluation. (3) Results: MPCeSi-NPs had high biocompatibility with oral keratinocytes and fibroblasts, especially at concentrations below 300 µg/mL. MPCeSi-NPs induced the biomineralization of BM-MSCs. Higher cerium levels increased mineralization. MPCeSi-NP had weak antimicrobial activity against Rd. At 1% wt, MPCeSi-NPs did not reduce the polymerization potential and mechanical properties of a TEGDMA:BisGMA polymer material, with controlled release of gallein in a simulated degradation model. (4) Conclusions: MPCeSi-NPs are highly biocompatible and bioinductive and have the potential to improve the biological response of current restorative materials.