Effect of Laser Irradiation on Bond Strength of Zirconia Ceramic to Self-Adhesive Resin Cement

  Bonding of zirconia to resin cement is challenging, and the zirconia surface requires surface treatment to yield an acceptable bond strength. This study aimed to evaluate the effect of different surface treatments on the bond strength of zirconia to a resin cement. In this in-vitro experimental study, 60 zirconia discs measuring 12 mm in diameter and 2 mm in thickness were randomly divided in to six groups of 10: (I) No treatment, (II) sandblasting plus neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1 W), (III) sandblasting plus Nd:YAG laser (2 W), (IV) Nd:YAG laser alone (1 W), (V) Nd:YAG laser alone (2 W), and (VI) sandblasting. Using a custom-made punch, a V-shaped bonding area with a 4-mm diameter and 90° angle was created in a Teflon tape. Composite cylinders (Filtek Z250) were then fabricated and bonded to conditioned zirconia ceramic using Clearfil self-adhesive lut-ing cement. Specimens were stored in distilled water at 37°C for 24 hours. Then, the specimens were tested for bond strength using a universal testing machine. Data were analyzed using two-way analysis of variance (ANOVA) followed by t-test. One-way ANOVA and Tukey's HSD (honestly significant difference) test were applied for evaluating the effect of the laser. Sandblasting caused a significantly higher bond strength compared to other methods (P=0.00). Among the laser-irradiated groups, Nd:YAG laser (2 W) yielded a higher bond strength (P<0.05). Sandblasting of high-strength zirconia ceramic can significantly increase its bond strength, but no significant difference in bond strength was noted in the laser-irradiated groups