Material Reliability of Experimental Composites With Zinc-Doped Bioactive Glass

Objectives: To evaluate material reliability using the Weibull modulus (WM) for experimental composites containing mesoporous zinc-doped bioactive glass.
Methods: Experimental zinc-doped mesoporous bioactive glasses nanospheres were synthesized by a micro-emulsion-assisted sol-gel process. Experimental composites were prepared with a light-curable bis-GMA/TEGDMA resin matrix and mesoporous bioactive glasses nanospheres doped with 1% zinc (1ZnBG) or 5% zinc (5ZnBG). The bioactive glass (MBG) was added to the experimental composites in 1, 3, 5, and 7 wt%. Reinforcing fillers were added up to a total filler load of 65 wt%. As reference materials, composites with mesoporous bioactive glass 45S5 (1, 3, 5, and 7 wt%) and silica (10 wt) were used. The bar-shaped composite specimens (2x2x16 mm, n=10 per experimental group) were light-cured and tested in a universal testing machine to record force-displacement diagrams. From flexural strength values, WM was calculated using linear fitting.
Results: For the composites with MBG, lower filler levels (1% and 3%) led to an improved WM after thermocycling, while for (5% and 7%) there was a decrease with thermocycling. For the composites with 1ZnBG, thermocycling mostly improved WM except for the material with 5 wt% of bioactive glass. For 5ZnBG, WM decreased after thermocycling for all filler amounts of bioactive glass. The reference material (10-Si) also showed a decrease in WM after thermocycling. Small amounts of Zn doping (1ZnBG) improved WM after thermocycling, whereas higher Zn doping (5ZnBG) consistently showed a decline in WM.
Conclusions: The lower amount of zinc doping (1ZnBG) and lower filler loads (1 and 3 wt%) generally improved the reliability of experimental composites after thermocycling, while higher zinc doping (5ZnBG) and higher filler loads (5 and 7 wt%) tended to reduce WM after thermocycling.

This work was supported by the Croatian Science Foundation under the project number HRZZ-IP-2024-05-2884.