Dental Resin Composites Reinforced by Rough Core-Shell SiO₂ Nanoparticles with a Controllable Mesoporous Structure

A porous structure within filler particles may improve interfacial bonding between the resin matrix and fillers for the preparation of dental resin composites (DRCs). In this study, rough core-shell SiO₂ (rSiO₂) nanoparticles with controllable mesoporous structures were synthesized via an oil-water biphase reaction system and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and N₂ adsorption-desorption measurements. The influence of the mesoporous shell thickness of rSiO₂ and mass ratio between rSiO₂ and smooth SiO₂ (sSiO₂) on the physical and mechanical properties of DRCs was studied. The rSiO₂ with a thin mesoporous shell could form a strong physical interlocking with the resin matrix, which improved the mechanical properties with the exception of flexural modulus. The mechanical properties were further optimized by mixing rSiO₂ and sSiO₂. The flexural strength and compressive strength of the DRC at a mass ratio of 5:5 increased by 24.3% and 16.8%, respectively, compared with the DRC filled with sSiO₂ alone. There is no statistically significant difference in the flexural modulus between these two DRCs (p > 0.05). The DRCs in this study showed excellent biocompatibility on the human dental pulp cells (HDPCs) as demonstrated by the cytotoxicity tests. The use of rSiO₂ provides a promising approach to develop strong, durable, and biocompatible DRCs.