A niobophosphate bioactive glass suspension for rewetting dentin: Effect on antibacterial activity, pH and resin-dentin bonding durability

Purpose: The aim of this study was evaluate the effect of rewetting suspensions of niobium phosphate bioactive glass (NbG) on the shear bond strength to dentin (SBS) and antibacterial activity. Materials and methods: The NbG was prepared and characterized by XRD and SEM/EDS. Antibacterial activity (Streptococcus mutans ATCC 159) of suspensions NbG was evaluated (n = 6). The pH of control and of suspensions NbG were monitored in different times. Dentin surface of sixty-five human third molars was etched with 35% phosphoric acid, rinsed with water and air-dried (n = 13). The specimens were assigned into 5 groups of four different concentrations of NbG suspensions in distilled water (5%, 10%, 20%, 40% w/v) and one control group (distilled water). Dentin surface was dried and rewetted according to their respective groups and adhesive system (One Step) was applied. The specimens were assembled for SBS testing (Ultradent Jig) and two cylinders of resin composite (AELITE) were built on the bonded dentin surface. Specimens were tested after 24 h and 3 months storage in PBS at 37 degrees C. The data from each test were analyzed by appropriate statistical methods. Results: Suspensions containing the bioactive glass NbG can neutralize the pH. Significant reductions on SBS were observed after 3 months PBS storage for control and NbG 5% suspension groups. All the suspension groups showed significantly inhibition of S. mutans. Conclusion: Rewetting demineralized dentin with NbG 40% prevented bond strength reduction after 3 months storage and showed antibacterial effect against S. mutans.