Effect of surface pre-treatment on durability of resin-based cements bonded to titanium

Objectives: Titanium has in recent years become a material of great opportunities in dentistry and orthopedics. In this study, we searched for a method to effectively pre-treat titanium as part of an adhesive luting and/or resin-veneering procedure. Methods: Ti plates were treated with two different solutions of hydrochloric acid (0.1, 1 N), 37 wt% phosphoric acid or kept untreated (control). The tensile bond strength of the composite cement (Panavia Fluoro Cement, Kuraray) to the untreated and pre-treated Ti plates was determined without and after 20,000 thermo-cycles. XPS was used to chemically analyze the effect of the three Ti pre-treatments, as well as the interaction of 10-methacryloxydecyl dihydrogen phosphate (10-MDP; functional monomer of Panavia Fluoro Cement) with Ti treated with 1 N HCl. Results: Although no significant difference in immediate tensile bond strength was measured, thermo-cycling significantly decreased the bond strength of all experimental groups except for Ti treated with 1 N HCl. No difference in surface roughness was found between untreated and treated Ti. XPS demonstrated that HCl effectively decontaminated Ti in a dose-dependent manner, while H₃PO₄ was strongly adsorbed on the Ti surface. While the latter potentially inhibits adsorption of the phosphoric groups of the functional monomer 10-MDP, Ti pre-treated with 1 N HCl improved the adsorption of 10-MDP as compared to untreated Ti. Significance: It is concluded that 1 N HCl effectively pre-treats Ti in order to make it more receptive to resin, while H₃PO₄ should better not be used.