Bond Strength of Veneering Ceramics to a Graded Zirconia Core

Abstract

To evaluate bond strength of veneering ceramics to a graded zirconia core. Two zirconia core ceramics (Y-TZP and graded zirconia) were fabricated and veneered with IPS e.max Ceram. A metal ceramic system (IPS d.SIGN, Ivoclar Vivadent, Liechtenstein) was used as a control group for the two all-ceramic test groups (n=20). Shear bond strength test and microtensile bond strength test were conducted by a universal testing machine. Fracture surfaces were also evaluated to determine the failure modes. Additionally, one-way ANOVA and Tukey's HSD tests were used to analyze the data. The shear bond strength test and microtensile bond strength test showed the familiar results. Graded zirconia exhibited the highest bond strength value (SBS: 31.01±2.01 MPa, MTBS: 40.95±1.95 MPa), significantly higher than that of Y-TZP (SBS: 28.14±2.28 MPa, 37.99±2.83 MPa). No significant differences were found between the metal core group and the two zirconia core groups. All test groups demonstrated cohesive failure within the veneer, as well as adhesive failure between the core and the veneer. Glass infiltration to zirconia may affect bond strength between zirconia core and veneering ceramics. A graded zirconia glass structure exhibits a benign bond to a veneering ceramics which could be similar to that of a metal ceramic system.