Experimental bond containing 45S5 bioactive glass microparticles: adhesive properties, bioactivity and cell viability

The limited durability of resin–dentin adhesion remains a major challenge in adhesive dentistry. This study evaluated the bond strength, nanoleakage, bioactivity, and cell viability of an experimental adhesive incorporating 10 wt% of 45S5 bioactive glass microparticles. Twenty sound third molars were randomly divided into two groups (n = 10): a control group using a commercial self-etch adhesive system (Clearfil SE Bond, CF) and an experimental group using CF Primer combined with an experimental bond (EB). No significant differences in bond strength were observed between groups after 24 h. However, after 1 year, the experimental adhesive showed significantly lower bond strength (p = 0.007). Nanoleakage was significantly lower in the experimental group at both time points (p < 0.001). Bioactivity was observed only in the experimental adhesive, with formation of calcium- and phosphorus-rich precipitates (after 28 days). Both materials showed similar cell viability, with no significant differences. The incorporation of 45S5 bioactive glass microparticles promoted bioactivity and reduced nanoleakage without affecting cell viability. However, these benefits were associated with reduced long-term bond strength after aging, highlighting the need to balance biological performance and adhesive durability.