Influence of the incorporation of titanium dioxide nanofibers net on bond strength and morphology of a total etching adhesive system.

Background: The aim of this study was to evaluate the nanoleakage and microtensile bond strength (µTBS) of an ethanol based-adhesive containing Titanium dioxide (TiO2) nanofibers to dentin. Material and Methods: TiO2 nanofiber was produced by electrospinning and it was inserted in an ethanol-based adhesive in 0.5, 1.5 and 2.5% by weight. The original adhesive did not receive nanofiber. The middle dentin was exposed by diamond saw under water-cooling and dentin was polished with wet 600-grit SiC abrasive paper. Resin composite build-ups were applied incrementally to the dentin after adhesive application. After storage in distilled water (24 hours/37°C) the teeth were sectioned perpendicularly to the bonded interface and sticks were obtained. Twenty-five sticks per group were tested by µTBS with a crosshead speed of 0.5mm/minute. The average values (MPa) obtained in each substrate were subjected to one-way ANOVA (α=0,05) with the tooth being considered the experimental unit. The nanoleakage pattern was observed in ten sticks per group and analyzed by Chi-square test (α=0,05). Results: There was no difference in µTBS among the experimental groups. However, there was a statistically significant difference among 2.5 % nanofiber adhesive, 0.5 % nanofibers and control groups, (p=0,028) in relation to nanoleakage. Conclusions: TiO2 nanofibers in 2.5% of weight inserted in dental adhesive reduced the nanoleakage, but did not improve the µTBS to dentin. Key words:Dentin-bonding agents, nanoleakage, tensile bond strength.