ABSTRACT
OBJECTIVES: In this study hybrid nanofibers embedded with niobium pentoxide (Nb2O5) were synthesized, incorporated in self-adhesive resin cement, and their influence on physical-properties was evaluated. METHODS: Poly(D,L-lactide), PDLLA cotton-wool-like nanofibers with and without silica-based sol-gel precursors were formulated and spun into submicron fibers via solution blow spinning, a rapid fiber forming technology. The morphology, chemical composition and thermal properties of the spun fibers were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC), respectively. Produced fibers were combined with a self-adhesive resin cement (RelyX U200, 3M ESPE) in four formulations: (1) U200 resin cement (control); (2) U200+1wt.% PDLLA fibers; (3) U200+1wt.% Nb2O5-filled PDLLA composite fibers and (4) U200+1wt.% Nb2O5/SiO2-filled PDLLA inorganic-organic hybrid fibers. Physical properties were assessed in flexure by 3-point bending (n=10), Knoop microhardness (n=5) and degree of conversion (n=3). Data were analyzed with One-way ANOVA and Tukey's HSD (α=5%). RESULTS: Composite fibers formed of PDLLA-Nb2O5 exhibited an average diameter of â¼250nm, and hybrid PDLLA+Nb2O5/SiO2 fibers were slightly larger, â¼300nm in diameter. There were significant differences among formulations for hardness and flexural strength (p<0.05). Degree of conversion of resin cement was not affected for all groups, except for Group 4 (p<0.05). SIGNIFICANCE: Hybrid reinforcement nanofibers are promising as fillers for dental materials. The self-adhesive resin cement with PDLLA+Nb2O5 and PDLLA+Nb2O5/SiO2 presented superior mechanical performance than the control group.
