Effect of zirconia surface treatments on the shear bond strength of veneering ceramic.

ABSTRACT

STATEMENT OF PROBLEM: Various surface treatments of zirconia have been recommended for veneering ceramics. However, it has not been determined which of these treatments produces the highest bond strength. PURPOSE: This study examined the effects of various surface treatments on the shear bond strength of zirconia and veneering ceramic. MATERIAL AND METHODS: Square-shaped (5 × 10 × 10 mm) zirconia (Everest) specimens were divided into 4 groups (n=8) according to surface treatment as follows group C, grinding with #320 diamond disc (control); group A, airborne-particle abrasion with 110 µm Al(2)O(3); group L, application of liner (Cerabien); and group AL, airborne-particle abrasion with 110 µm Al(2)O(3) and application of liner. A cylinder of veneering ceramic (2.4 mm in diameter and 3 mm in height) (Cerabien) was fabricated and fired on the zirconia specimens. The shear bond strength was tested using a universal testing machine. The data were analyzed statistically using a 1-way ANOVA and Tukey's multiple comparisons test (α=.05). The interface and fractured surfaces of the specimens were also evaluated by field emission scanning electron microscopy (FE-SEM). RESULTS: The mean and SD values for the shear bond strength of the groups ranged from 27.87 ± 3.59 MPa (for group L) to 36.63 ± 2.96 MPa (for group A). The 1-way ANOVA revealed a significant difference between groups (P=.001). The airborne-particle abrasion group showed significantly higher bond strength than liner applied groups (L, AL) (P<.05). The SEM revealed that liner-applied groups (L, AL) showed primarily adhesive failure. Complete delamination and microspaces were also observed in the liner-applied groups. CONCLUSIONS: The mean in vitro shear bond strength of veneering ceramic on zirconia treated with airborne-particle abrasion was significantly higher than that subjected to liner-applied treatments.