Effect of different surface treatments of presintered or sintered zirconia on bond strength to dentine

AIM: To compare the effect of different zirconia surface treatments on cement bond strength to dentine. MATERIALS AND METHODS: Stick-shaped pre-sintered zirconia (N = 128) were prepared and divided into eight groups (n = 16). Three surface treatments (sandblasting, neodymium-doped yttrium aluminum garnet [Nd:YAG] or carbon dioxide laser irradiation) were applied, either before (later to be sintered) or after sintering. The last test group was sintered zirconia coated with feldspathic veneering ceramic. Sintered zirconia without surface treatment was tested as the control group. Zirconia samples were cemented to dentine using Panavia F2 cement. The micro-shear bond strength was measured after 24 h (n = 8) or 10,000 thermocycling (n = 8). STATISTICAL ANALYSIS: Data were analyzed using one-way analysis of variances and Student's t-tests. RESULTS: Zirconia coated with feldspathic ceramic revealed the highest bond strength (P < 0.001). Presintered zirconia treated with Nd: YAG laser showed a significantly improved bond strength compared to the control group before and after thermocycling. The bond strength after thermocycling was significantly reduced in presintered zirconia treated with Nd: YAG or sandblasting. Adhesive failure at the zirconia-cement interface was the dominant failure type. CONCLUSIONS: Surface treatment of presintered zirconia by Nd:YAG laser or coating of the sintered specimens with feldspathic veneering ceramic increased the zirconia-cement bond strength.