Zirconia Translucency and Cement Systems as Factors Influencing the Zirconia-Titanium and Zirconia-Zirconia Shear Bond Strength

Purpose: To evaluate the bonding ability of self-adhesive and dual-cure resin cement systems applied to zirconia materials of different translucency in combination with each other and with titanium. Materials and Methods: Computer-aided design/computer-assisted manufacture (CAD/CAM) disks of three different zirconia materials (Zenostar MO 0 [medium opacity), MT 0 [medium translucency), and T 1 [translucent], Wieland Dental) were milled and hard sintered in order to obtain cylindrical samples of either 12 mm high x 12 mm diameter (used as a substrate) or 12 mm high x 8 mm diameter (to be bonded to the substrate). CAD/CAM disks of titanium (Starbond Ti4 Disc, S&S Scheftner) were milled in order to obtain a cylinder shape (12 mm high x 8 mm diameter to be bonded to the zirconia substrate). The bonding surfaces were sandblasted with alumina particles (70 mu m/2 ATM). Two resin cement systems were tested in this study: a self-adhesive resin cement (SpeedCEM Plus, Ivoclar Vivadent) and a dual-cure resin cement (Variolink Esthetic DC, Ivoclar Vivadent) in combination with a primer (Monobond Plus, Ivoclar Vivadent). The smaller cylinders were bonded to the substrate following the manufacturer's instructions. After 24 hours at 37 degrees C storage, each specimen was subjected to shear bond strength testing in a universal testing machine. The substrate was fixed to the machine, and shear force was applied to the small cylinder close to the bonding interface. Shear bond strength data were statistically analyzed by a three-way analysis of variance (ANOVA) followed by the Tukey test for post hoc comparison (P < .05). Results: No significant differences were found between substrates in the shear bond strength test (P = .078). Variolink Esthetic DC showed a statistically significantly higher bond strength compared with the SpeedCEM Plus (P = .001) with the exception of Zenostar MT substrate (P = .014). Conclusion: The resin cement systems showed high shear bond strength values when zirconia was resin bonded to either titanium or the corresponding zirconia substrate. Different zirconia translucencies did not affect the bond strength. The use of MDP primer and a dual-cure cement showed statistically significantly higher strength compared with the self-adhesive resin cement system with the only exception being the bonding of the translucent zirconia Zenostar MT.