Bond strength of luting cements to zirconium oxide ceramics

Purpose: This study was conducted to determine the bond strength of some resin luting cements to zirconia ceramic. The hypothesis was that adhesive bonding capacity is influenced by different surface pretreatments designed for milled ceramic inlays. Materials and Methods: Composite cylinders 5 mm x 5 mm were light cured on the ceramic surfaces for a shear test conducted in a test jig. Five surface treatments were studied: as received (from the milling machine), sandblasting with either 250- or 50-mu m alumina sand, hydrofluoric acid treatment, and grinding with diamond burs. The tested luting cements were Panavia 21, Twinlook, and Superbond C&B. Results: All debonding occurred at the interface between ceramic and composite cement. Superbond demonstrated the highest bond strength regardless of the surface treatments. Grinding the surface with diamond burs improved the bonding slightly for Twinlook and Panavia 21 and also showed the roughest texture. Washing with hydrofluoric acid had no significant influence on bond strength. Conclusion: Bond strengths for Twinlook and Pananvia 21 were quite low, and only Superbond showed a bond strength reasonably acceptable for clinical use; however, as no standard for bond strength has been established for inlay therapy, the other cements cannot be rejected as luting cements for inlays.