Evaluation of bioactive glass primer on dentin bonding durability and interface properties

Objective: This study aimed to evaluate the effects of a novel phosphosilicate bioactive glass (BG)-containing primer on dentin bond strength, nanoinfiltration, and the biomechanical and ultrastructural properties of the dentin-primer interface. Methods: A primer was formulated with 7.5% (w/w) phosphosilicate BG particles (SiO₂·P₂O₅·Na₂O·CaO; particle size 0.2–10 μm) suspended in distilled water. Four groups were tested (n = 5): (1) control groups using an etch-and-rinse (ER) or self-etch (SE) adhesive strategy per manufacturer’s instructions, and (2) experimental groups where the BG-primer was applied before the ER or SE adhesive (designated BG-ER and BG-SE, respectively). Specimens were subjected to micro-tensile bond strength (µTBS) testing immediately and after 12 months of aging in distilled water (37 °C). Nanoleakage was assessed by SEM (n = 3 per group). The chemical profile and ion-release potential of the BG-primer were analyzed using ATR-FTIR spectroscopy under dry conditions, immediately after hydration, and after six hours. Data were analyzed using two-way ANOVA and Tukey’s test (α = 0.05). Results: The incorporation of the BG-primer did not significantly affect immediate µTBS compared to control strategies. However, after 12 months, both BG-ER and BG-SE exhibited significantly higher µTBS values than their respective controls. The BG-ER group maintained its bond strength over time, while the BG-SE showed a significant increase. Nanoleakage analysis revealed comparable silver nitrate in filtration among all groups. SEM identified BG particles localized near the hybrid layer and partial dentinal tubule occlusion in BG-treated specimens. ATR-FTIR confirmed sustained ionic release and time-dependent chemical shifts, evidenced by decreased crystallinity upon aqueous exposure and spectral shifts indicating persistent ionic reactivity. Conclusion: Incorporation of a BG-containing primer improved the long-term stability of resin–dentin bonds without compromising immediate adhesion, supporting its potential to enhance the durability of adhesive interfaces.