Chemical structures of adhesion promoting monomers for precious metals and their bond strengths to dental metals.

Adhesion promoting monomers for dental metals, 5-(4-vinylbenzyl)-2-thiobarbituric acid (5VS), 6- (4-vinylbenzyl-n-propyl) amino-1,3,5-triazine-2,4-dithione (VBATDT) and 9,10-epithiodecyl methacrylate (EP8MA), were synthesized and surface treatment agents were prepared by dissolving each monomer in ethanol or acetone. Four non-precious and three precious metal adherends treated with each agent were butt-jointed together with MMA-PMMA resins. After 2,000 thermal cyclings in water, tensile bond strengths were measured and the percentage of area of cohesive failure after the tensile test was determined. The bond strengths to precious metal alloys generally increased in the order of 5VS<VBATDT<EP8MA. Bonding durability against water based on overall failure mode analysis was improved in the following order: for precious metal alloys; 5VS<VBATDT< or =EP 8MA, and for non-precious metal alloys; EP8MA, VBATDT<<5VS.