Addition of nanoparticles for development of radiopaque dental adhesives

This study evaluate the effect of nanoparticles (Bi2O3 - bismuth oxide; YbF3 - ytterbium trifluoride; SiO2 - silicon dioxide) on radiopacity (R), translucency parameter (TP), degree of conversion (DC), bond strength to dentin (µTBS), and quality of the adhesive interface of experimental two-step, etch-and-rinse adhesive systems. The R was evaluated using an x-ray equipment. TP was verified in five replications and DC was performed in triplicate. The µTBS was evaluated in specimens stored in distilled water after 24 h, 6, 12 and 24 months. The bonded interfaces were qualitatively examined by scanning electron microscopy (SEM), and using x-ray energy dispersive spectroscopy (EDS) for elemental analysis. Data were statistically analyzed at α = 0.05. YbF3 resulted in statistically greater R when compared with all the other groups (p = 0.024), which did not differ from each other. Bi2O3 was the adhesive with lowest TP. For DC, the YbF3 and C showed similar results (p = 0.627). Similar µTBS was obtained between groups. The addition of nanoparticles affected the chemical-mechanical properties. The incorporation of YbF3 could be considered a promising approach for the development of radiopaque dental adhesives.