Artificial aging-induced changes in surface properties of experimental bioactive glass-containing composites

To determine how artificial aging affects microhardness (MH), surface roughness (Ra), and surface micromorphology of experimental bioactive glass (BG)-containing resin composites functionalized with either conventional BG 45S5 (C-series) or a low-sodium fluoride-containing BG (F-series).

Seven experimental composites were prepared (Control; 5, 10, 20 wt% BG within each series; total filler load 70 wt%) based on a Bis-GMA/TEGDMA (60:40) resin matrix. Light-cured composite specimens were aged in simulated body fluid (SBF, pH 7.4), lactic acid solution (LA, pH 4.0), ethanol/water solution (75% EtOH), 0.1 M NaOH solution (pH 13.0), or thermocycled 10,000 cycles (5-55°C). MH and Ra were measured at baseline, 1, 3, 7, and 30 days, and specimen surfaces were examined by SEM/EDS. Ultrasonication was used to remove loosely bound surface deposits, after which MH, Ra, and SEM/EDS were re-measured.

MH degradation ranked SBF

Under accelerated aging, F-BG composites maintained MH and clinically acceptable smoothness more reliably than 45S5 formulations, with limited roughening under neutral and mildly acidic conditions.

Composites with low-sodium fluoride-containing BG maintained microhardness comparable to the control composite and post-ultrasonication roughness below 0.2 µm, supporting their potential as ion-releasing restoratives with clinically acceptable surfaces.