Water Sorption and Solubility of Composites Containing Bioactive Glass

Objectives: Experimental composites based on copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) were developed as functional restorative materials serving as a source of antimicrobial and remineralising ions. The aim of this study was to investigate the influence of Cu-MBGN on the mass change of an experimental composite material during 180 days of water storage and to compare it with conventional bioactive glass (BG) and inert fillers.
Methods: The experimental composites contained 35 wt% Bis-GMA/TEGDMA base (60/40), 55 wt% silanised barium-glass fillers and 10 wt% of either Cu-MBGN (10-CuBG), 45S5 bioactive glass (10-BG) or inert silica nanofillers (10-Si). Composite specimens were prepared and polymerised in Teflon moulds (d=5 mm, h=2 mm). Water sorption and solubility were measured by a modified ISO 4049 gravimetric method for up to 180 days. Mass change at each time point during water immersion was expressed as a percentage of the initial mass of the specimen (mean±s.d.). The results were statistically analysed using one-way ANOVA with Tukey post-hoc correction.
Results: Both composites containing bioactive glass demonstrated significantly higher mass change at all measured time points compared to the inert control material 10-Si (p<0.001), in the decreasing order 10-BG>10-CuBG>10-Si. 10-BG showed the peak of mass increase after 30 days (4.02±0.21%), followed by a decrease until the end of the measurement after 180 days. At the same time, after 30 days, the mass of 10-CuBG increased to 1.67±0.10%. 10-Si had a similar trend in mass increase (1.19±0.07% after 30 days). 10-CuBG and 10-Si showed a gradual mass increase until the measurement's end after 180 days.
Conclusions: Composite material containing copper-doped nanospherical particles of bioactive glass had a lower mass increase during water immersion than the composite with the commercial bioactive glass 45S5 but higher values than the inert control.