Effect of different surface treatments on resin cement-zirconium bond strength

Method: Fifty square-shaped ( 10 x 10 x 2 mm) zirconium (Y-TZP)   samples were produced with a copy-milling machine and then sintered . The samples were embedded in the PVC ring with using auto polymerizing acrylic resin.  Zirconium surfaces -excluding  control group-   were ground finished  with 240-400-600-800 grit silicon carbide abrasive papers for 1 min using a 600 rpm  grinding machine.  The samples was divided into five groups (n=10). Group SB,110 µm  Al₂O₃; Group EY, Er:YAG laser; Group NY, Nd:YAG laser; Group FS, Femtosecond laser; Group C, no treatment (control).The shear bond strength (SBS) of the resin cement to zirconium surface was tested by a universal testing machine at 1 mm/min crosshead speed. The SBS  was analyzed by ANOVA/Tukey tests for among the groups. 

Result: The results showed that the femtosecond laser affects the shear bond strength of resin cement to zirconium ceramic.  The SBS values among the groups were exhibit statistically different (ANOVA, P<0.001) The highest SBS values were achieved with FS group. The shear bond strengths ( mean ± SD; MPa) in the groups were as follows: Group C, 9.3 ± 2.1; Group SB, 9.9 ± 2.4; Group EY, 4.7 ± 1.6; Group NY , 15.5 ± 1.5; Group FS, 17.7 ± 1.6.

Conclusion: Statistically significant differences in the bond strength of resin cement to zirconium surface were observed. The use of femtosecond laser  more  increased  the shear bond strength of resin cement to zirconium surface compare to other methods.