Influence of silanization on early bond strength to sandblasted densely sintered alumina

Objective: The increased popularity of alumina-based restorations has resulted in an interest in proper adhesive techniques to assure a strong and predictable bond to these restorations. This study investigated the early bond strength of three different resin-cement systems to densely sintered alumina (aluminum-oxide ceramic) with and without the use of their corresponding silane coupling agent (silanization). Method and materials: Ninety samples of densely sintered high-purity aluminum-oxide ceramic were randomly divided into three groups. Composite cylinders were bonded to the ceramic samples with three resin-cement/bonding-agent systems: Noribond DC (NOR), Panavia 21 EX (PAN), and Variolink II (VAR). Each resin-cement/bonding-agent system was used with and without their corresponding silane (SIL) coupling agent (n = 15). After fabrication, the specimens were stored in distilled water for 3 days at room temperature, and shear bond strength was tested. Results: Application of the silane-coupling agent on sandblasted densely sintered alumina did not significantly influence bond strengths with PAN. Silanization significantly improved shear bond strengths with NOR and VAR. NOR-SIL and VAR-SIL revealed the statistically highest values, with NOR-SIL showing the highest mean bond strength of all groups. Conclusions: Silanization of sandblasted densely sintered alumina had mixed effects on the applied resin cements: It had no effect on the performance of the phosphate-modified resin cement PAN, but significantly improved shear bond strength of the Bis-GMA composite resin cements VAR and NOR. NOR-SIL revealed the highest overall mean bond strength.