Glass microparticle‐ versus microsphere‐filled experimental dental adhesives

This study aimed to formulate antibacterial dental adhesives. Phosphate‐substituted methacrylate adhesives were modified with 0–20 wt % copper‐doped glass microparticles. Two shapes of microparticles were used: regular shaped (microspheres) and irregular shaped (microparticles). The morphology/composition, roughness, monomer conversion (DC%), thermogravimetric analysis, and antibacterial action against S. mutans and P. aeruginosa and ion release were investigated. The results showed that microspheres produced adhesives with a relatively smoother surface than microparticles did. The DC% of adhesives increased with increasing glass filler content. Filled adhesives showed polymer decomposition at ~315 °C and glass melting at 600–1000 °C. The weight loss percent of adhesives decreased with increasing weight percent of fillers. Glass microparticles at 0–20 wt % significantly increased the antibacterial action of adhesives against both bacteria. Glass microspheres at 0–5 wt % significantly increased the antibacterial action of adhesives against both bacteria. Only 20 wt % microparticle‐filled adhesive showed an inhibition zone similar to tobramycin (positive control). Microparticle‐filled adhesives (with >5 wt % filler) significantly reduced S. mutans more than their microsphere counterparts. Microsphere‐filled adhesives (with ≤5 wt % filler) significantly reduced P. aeruginosa more than their microparticle counterparts. Microsphere‐filled adhesives showed higher Cu release than their microparticle counterparts. Accordingly, phosphate‐substituted methacrylate filled with glass could be used as an antibacterial adhesive.