Effect of zirconia etching solution on the shear bond strength between zirconia and resin cement

Statement of problem. The bond between resin cement and zirconia is essential to the long-term retention of a zirconia crown. However, it is unclear if the existing methods provide a long-term bond between resin cement and zirconia. Purpose. The purpose of this in vitro study was to evaluate the effects of a zirconia etching solution on the shear bond strength between zirconia and resin cement. Material and methods. Sixty yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) disks ((sic)8x5 mm) were divided into 4 groups (n=15). Each group was then treated with 1 of the following methods: airborne-particle abraded with 50-mu m Al2O3 (AA); etched with zirconia etching solution (ZES); airborne-particle abraded with 50-mu m Al2O3 and then etched with ZES (AA-ZES); etched with ZES and then airborne-particle abraded with 50-mu m Al2O3 (ZES-AA). Sixty composite resin cylinders ((sic)2.3x2.4 mm) were luted to the zirconia disks with a self-adhesive resin cement under constant load and then light-polymerized for 40 seconds. Specimens were stored in a 37 degrees C incubator in distilled water for 24 hours and then thermocycled for 1000 cycles between 5 degrees C and 55 degrees C. A universal testing machine with a crosshead speed of 0.5 mm/min was used to measure the shear force (N). The shear bond strength (MPa) was then calculated. One-way ANOVA was used to compare the mean shear bond strength among the groups (alpha=.05). The failure mode was evaluated by using light microscopy at x90 magnification and categorized as an adhesive, cohesive, or mixed failure. Results. Mean +/- standard deviation shear bond strength for AA, ZES, AA-ZES, and ZES-AA groups were 9.9 +/- 2.6, 8.9 +/- 2.9, 9.6 +/- 3.9, and 11.0 +/- 2.3 MPa, respectively. There was no significant difference among the treatment groups (P>.05). Conclusions. A zirconia etching solution did not significantly improve the shear bond strength between zirconia and resin cement compared with airborne-particle abrasion with Al2O3.

Automated summary

The study aimed to evaluate the effects of a zirconia etching solution on the shear bond strength between zirconia and resin cement, and the results showed that the zirconia etching solution did not significantly improve the bond strength compared to airborne-particle abrasion with Al2O3.