Polymerization Kinetics of Composites With Copper-Doped Mesoporous Bioactive Glass Nanospheres
Objectives: Copper-doped mesoporous bioactive glass nanospheres (CuMBGN) with antibacterial and calcium/phosphate releasing properties were used as fillers in experimental resin composites. The effect of CuMBGN addition on the polymerization kinetics and the short-time degree of conversion (DC) was investigated.
Methods: Seven experimental materials were prepared with increasing non-silanized CuMBGN amount (0, 1, 5, and 10%) and identical photoactive resin composition (60/40 BisGMA/TEGDMA). The total filler load was kept constant at 65wt.%, and the remaining filler share consisted of inert silanized barium-glass fillers or a combination of silanized barium-glass and silanized silica. Control materials were filled with conventional 45S5 bioactive glass (45S5). Specimens (n=5) were light-cured for 20 s with 950 mW/cm2. DC was measured in real-time for 5 min using attenuated total reflectance Fourier transform infrared spectroscopy at the data collection rate of 2 s-1. DC, maximum reaction rate, and time of maximum reaction rate were calculated. The data were statistically compared using ANOVA and Tukey post-hoc test (p<0.05).
Results: The DC values after 5 min varied from 51.1-58.8%. The highest DC (58.8±0.9%) and the maximum reaction rate (9.8±0.2 %/s) achieved the material with 10% CuMBGN and no silica fillers. The material with 15% 45S5 had the lowest DC (51.1±0.7%) and the lowest maximum reaction rate (5±0.1 %/s), similar to 10% 45S5. An increasing amount of CuMBGN in combination with silica fillers caused a mild inhibitory effect. There was no difference in the time to achieve maximum reaction rate between any of the tested materials (3.1-3.4 s).
Conclusions: CuMBGN showed lower restriction on polymerization kinetic parameters than commercial 45S5 or silanized silica.
This work has been fully supported by Croatian Science Foundation under the project IP-2019-04-6183.