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.