Bond strength of prosthodontic luting materials to titanium after localized cyclic loading

To establish an in vitro analysis system to evaluate the effect of cyclic loading on the bond strengths and durability of luting materials bonded to titanium.

Machine-milled titanium disks were finished with 600 grit silicon-carbide paper and pairs of disks were bonded together using the five different luting materials. A stainless steel stylus was vertically loaded at a center position (Model 1) or at the border (Model 2) of the specimens with a force of 75.6 N at 7500 cycles/hr. When the stylus contacted the specimen surface through the water slurry of poly(methyl methacrylate) beads, it rotated clockwise up to 15 degrees and counter-rotated. Shear bond strengths were determined 1 hr after bonding, after storage in water at room temperature for 24 hr, and after the loading for 100,000 cycles.

The bond strengths of the unfilled adhesive resin and resin-based composite cement (RBC) were significantly higher than those of the glass-ionomer cements. Zinc phosphate cement demonstrated no bonding ability to titanium. After 100,000 cycles, peripheral loading in Model 2 significantly reduced the bond strength of the RBC and glass-ionomer cements, while Model 1 loading did not. The highest and the most durable bonds were obtained with the unfilled adhesive resin in both models.