Aims: The aims of this study were as follows: (I) to design a series of experimental composite materials with incremental increases in the filler ratios (5-40 wt%) of newly synthesized bioactive glass (N-BG), (II) to compare the reactive N-BG filler with conventional bioactive glass (45S5-BG) in the experimental composite materials, and (III) to examine the mechanical and chemical changes of the materials that occur as a result of artificial ageing. Materials and methods: Macromechanical properties (flexural strength and modulus) and micromechanical properties (Vickers microhardness) were measured one day following polymerization and following artificial ageing by immersion in water and thermocycling. The ISO 4049 protocol was used to measure water sorption and solubility, while scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy were used to examine calcium phosphate precipitation. Results: A significant decrease in macromechanical and micromechanical properties was observed in composite materials containing 45S5-BG as the ratio of bioactive glass increased. In contrast, composite materials containing N-BG showed significantly more stable macromechanical properties, with statistically significant improvements in micromechanical properties observed at higher fractions of N-BG (20-40 wt%). Water sorption was significantly greater in composite materials containing 45S5-BG, increasing sevenfold when compared to the control material, whereas for N-BG, the increase in water sorption was only twofold. Solubility increased with increasing levels of bioactive glass, with 45S5-BG fractions of 20-40 wt% showing the greatest rise. Calcium phosphate was precipitated on the surfaces of all composite materials containing 10 wt% or more bioactive glass fractions. Conclusion: Improved properties of N-BG-functionalized composite materials indicate better mechanical, chemical and dimensional stability without compromising the potential for calcium phosphate precipitation. Compared to more conventional bioactive glass 45S5-BG, N-BG offers a number of advantages for use as a functional filler in remineralizing composite materials due to its improved mechanical properties with preserved bioactivity.