ObjectiveThe aim of this study is to explore the reinforcing effect and the antimicrobial activity of the core-mesoporous shell structured ZnO@m-SiO2, which possesses the micromechanical resin matrix/filler interlocking in dental composites, and to investigate the effect of filler compositions on their physical-mechanical properties. MethodsZnO@m-SiO2 was synthesized by a simple self-assembly method and then characterized by electron microscopy, X-ray diffraction (XRD) and N2 adsorption/desorption measurements. Mechanical properties of dental composites reinforced with ZnO@m-SiO2 and nonporous SiO2 particles were measured with a universal mechanical testing machine. Fracture morphologies of these composites were observed by field-emission scanning electron microscopy (FE-SEM), and their antimicrobial activities were evaluated according to the ASTM E 2180-07 (2012) method. Resin composites containing unimodal silanized SiO2 were served as the control group. ResultsThe impregnation of lower loading of ZnO@m-SiO2 (≤7wt%) into dental composites including silanized SiO2 substantially increased their mechanical properties. Among all composites, the optimal composite Z7S63 (ZnO@m-SiO2: silanized SiO2=7:63, wt/wt, total filler loading 70wt%) demonstrated the best flexural strength, flexural modulus and compression strength, which were increased by 121.2, 67.1 and 32.5%, respectively, in comparison with the control composite Z0S70. In addition, this optimal composite also exhibited superior antimicrobial activity (>99.9%) and acceptable degree of conversion, polymerization shrinkage and curing depth. SignificanceThe incorporation of ZnO@m-SiO2 and silanized SiO2 as bimodal fillers led to the design and formulation of dental composites with excellent comprehensive performance, especially the improved mechanical properties and the superior antimicrobial activity.