Fractographic Study of the Interface Between Zirconia Y-TZP and Its Veneering Ceramic After Shear Strength Testing.

This study analyzed the shear strength and fracture characteristics of the interface between zirconia samples and their veneering ceramic compared with a metal-ceramic and a lithium disilicate glass-ceramic control group together with an assessment of the possible relationship between the fracture characteristics and the recorded shear strength. The greatest shear strengths corresponded to the lithium disilicate glass-ceramic control group followed by the metal-ceramic control group, with lesser strengths in the zirconia groups. Since the fractographic study showed cohesive-type failure to predominate in the zirconia samples, it is concluded that improvements are needed in the veneering ceramic and liner used in zirconia restorations.