Microtensile bond strength of three different veneering porcelain systems to a zirconia core for all ceramic restorations

Purpose: This study investigated the microtensile bond strength of three different ceramic veneering systems to one type of zirconia substrate. 

Methods: Bilayered zirconia veneer discs were fabricated of a LAVA zirconia core and three different veneering ceramics (VITA VM9, Lava Ceram, Creation ZI) using a conventional layering technique. Discs were cut into microbars of 6 mm × 1 mm × 1 mm. Microtensile bond strength between veneer and core was measured. Surfaces of fractured specimens were examined with scanning electron microscopy (SEM). 

Results: The mean microtensile bond strengths were respectively VITA VM9 23.52 MPa (8.33), Creation ZI 18.35 MPa (6.40), and Lava Ceram 14.76 MPa (4.00). The differences were statistically significant. Failures were mainly interfacial in all tested groups.