Effects of Triazine Dithione and Hydrophobic Phosphate Monomers on Bonding to Ag-Pd-Cu-Au Alloy and Titanium with a Methacrylic Resin-based Luting Agent

Purpose: The purpose of the current study was to evaluate the effects of thione and phosphate functional monomers on bond strength and durability of a methacrylic resin luting agent joined to silver-palladium based alloy and titanium. Materials and Methods: Disk specimens of two different sizes (10 mm and 8 mm in diameter by 2.5 mm thickness) were prepared from silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy and titanium. The specimens were ground with abrasive paper, and divided into four groups based on the following conditions: 1) unprimed control; 2) priming with Alloy Primer (thione and phosphate); 3) priming with Estenia Opaque Primer (phosphate); and 4) priming with VPrimer (thione). The disks were bonded with tri-n-butylborane (TBB)-initiated resin, and shear bond strengths were determined both before and after thermocycling. Results: The Alloy Primer and V-Primer agents containing a triazine dithione monomer (VTD) bonded the Ag-Pd-Cu-Au alloy, whereas the Alloy Primer and Estenia Opaque Primer agents containing a hydrophobic phosphate monomer (MDP) bonded titanium. The reduction in bond strength after 20,000 thermocycles was not remarkable for the two groups (Alloy Primer and Ag-Pd-Cu-Au alloy; V-Primer and Ag-Pd-Cu-Au alloy). Conclusion: The thione monomer was effective in bonding the Ag-Pd-Cu-Au alloy, whereas the phosphate monomer was useful for bonding titanium. The thione did not interfere with the bonding of MDP to titanium, and MDP did not negatively affect bonding of VTD to the Ag-Pd-Cu-Au alloy. The combinations of two thione primers and the Ag-Pd-Cu- Au alloy exhibited the best adhesive performance within the limitations of the current experiment. Keywords: Ag-Pd-Cu-Au alloy, phosphate, thiol, thione, titanium