RESUMO
STATEMENT OF PROBLEM: Despite numerous advantages such as high strength, the bond of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) to tooth structure requires improvement. PURPOSE: The purpose of this in vitro study was to evaluate the incorporation of TiO2 nanotubes into zirconia surfaces and the bond strength of resin cement to the modified ceramic. MATERIAL AND METHODS: TiO2 nanotubes were produced by alkaline synthesis, mixed with isopropyl alcohol (50 wt%) and applied on presintered zirconia disks. The ceramics were sintered, and the surfaces were characterized by confocal laser microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis. For bond strength, the following 6 groups (n=16) were evaluated: without TiO2 and Single Bond Universal; with TiO2 nanotubes and Single Bond Universal; without TiO2 nanotubes and Z-prime; with TiO2 nanotubes and Z-prime; without TiO2 and Signum Zirconia Bond; with TiO2 and Signum Zirconia Bond. After sintering, resin cement cylinders, diameter of 1.40 mm and 1 mm in height, were prepared and polymerized for 20 seconds. Specimens were stored in water at 37°C for 30 days and submitted to a shear test. Data were analyzed by 2-way ANOVA and Tukey honest significant difference (α=.05) tests. RESULTS: EDS analysis confirmed that nanoagglomerates were composed of TiO2. The shear bond strength showed statistically significant differences among bonding agents (P<.001). No significant differences were found with the application of nanotubes, regardless of the group analyzed (P=.682). The interaction among the bonding agent factors and addition of nanotubes was significant (P=.025). CONCLUSIONS: Nanotubes can be incorporated into zirconia surfaces. However, this incorporation did not improve bond strength.