Bond strength of zirconia to different core materials

Abstract

Background: Since bonding to zirconia is still questionable,the aim of this study was to evaluate the bond strength of yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) to different materials used to manufacture dental cores,employing a universal self-etching adhesive system. Materials and methods: Cylinders obtained from blocks of Y-TZP Zirconia were sintered in a high-temperature oven. The surfaces to be bonded were blasted with aluminum oxide,then silica-coated aluminum oxide,and finally cleaned in ultrasonic bath. The specimens were divided into six groups according to the core material tested: Silver alloy (Ag/Sn/Cu,Tecnofix),copper alloy (Cu/Ni/Zn,Goldent LA),core buildup resin (Rebilda DC - VOCO),Y-TZP zirconia (IPS e.max ZirCAD,Ivoclar Vivandent),enamel,and dentin. The zirconia cylinders were bonded to the core substrates using the Futurabond U adhesive system (VOCO) and resinous cement (Bifix QM - VOCO). The specimens were shear tested in a universal testing machine at 1 mm/ min. Data was analyzed using ANOVA and Tukey’s test. Results: Bond strength in MPa (±SD) for the different materials tested were dentin: (12.80 ± 3.18)a; enamel: (15.13 ± 3.09) ab; resin: (17.20 ± 4.67)ab; copper alloy: (18.93 ± 4.66)bc; silver alloy: (22.86 ± 5.47)c; and zirconia: (23.65 ± 3.64)c. Groups followed by the same letters are not significantly different at p < 0.05. Conclusion: The metallic alloys and zirconia core materials showed significantly higher bond strength than those obtained directly on dentin. The core buildup resin bond strength to zirconia is similar to that obtained with enamel and dentin.