Long-term Shear-bond Strength of Luting Cements to Zirconia Ceramic

Objectives: This study evaluated the long-term shear-bond strength of cements to zirconia ceramic (Lava, 3M ESPE) after two pre-treatment procedures. Methods: One half of the zirconia samples were air-abraded with 100-mircometer alumina at 2.8bar, 10s at 10mm distance (pre-treatment I); the other half was tribochemically silica-coated with the Rocatec-System (3M ESPE) (pre-treatment II). Materials tested: 1a) PermaCem self-cured (SC) (DMG), 1b) PermaCem light-cured (LC), 2a) RelyX ARC SC (3M ESPE), 2b) RelyX ARC LC, 3a) Panavia F SC (Kuraray), 3b) Panavia F LC, 4a) Variolink II SC (IvoclarVivadent), 4b) Variolink II LC, 5a) Nexus2 SC (Kerr), 5b) Nexus2 LC, 6a) Calibra SC (DentsplyDeTrey), 6b) Calibra LC, 7a) RelyX Unicem SC (3M ESPE), and 7b) RelyX Unicem LC. Eight specimens per group were fabricated: Group (A) was aged and tested after 150d 37°C water storage; Group (B) 150d at 37°C water storage, then thermocycled (37.500X, 5-55°C). One-way ANOVA of variance was used to analyze the data (p<0.05). Results: Using pre-treatment I cements 3b, 7a and 7b showed highest shear-bond strengths independent of aging procedure. Using pre-treatment II the highest values were achieved by cements 7b and 1b with 13.4 +/- 1.1 MPa and 12.1 +/- 3.8 MPa in aging group (A). The highest results in aging group (B) were achieved for 4b with value of 11.2 +/- 4.5 MPa. 3b, 7b and 1b followed with results of 9.9 +/- 2.5 MPa, 8.9 +/- 2.1 MPa and 8.2 +/- 2.9 MPa respectively. Conclusions: Bonding to air-abraded zirconia of cements 3b, 7a, and 7b was superior to all other materials independent of aging procedure. Most stable bonding to tribochemically silica-coated zirconia was found with cements 1a, 1b, 3b, 4b, 7a and 7b.