Shear Bond Strength of Resin Cement to Zirconia Ceramic After Aluminum Oxide Sandblasting and Various Laser Treatments

Objective:The aim of this study was to evaluate the effect of different surface treatments; sandblasting, Er:YAG, Nd:YAG, or CO2 laser irradiation on the shear bond strength (SBS) of zirconia ceramic to dentin. Background data:Zirconia is not properly luted with resin cements. Various surface treatment methods have been suggested for zirconia to obtain high bond strength to resin cements. There is no study that compared the effect of different laser types (Er:YAG, Nd:YAG, CO2) with sandblasting on SBS between zirconia and dentin. Methods:One hundred and twenty human maxillary third molar teeth were sectioned 3mm below the occlusal surfaces, embedded in a metal ring with autopolymerizing acrylic resin, and stored in distilled water at 37(0)C. One hundred and twenty disc-shaped zirconia specimens were fabricated (6mm in diameter and 4mm in thickness), and randomly assigned to six groups (n = 20):Group 1, untreated (control); Group 2, sandblasted; Group 3, Er:YAG laser irradiated; Group 4, Nd:YAG laser irradiated with contact; Group 5, Nd:YAG laser irradiated with non-contact; Group 6, CO2 laser irradiated. They were cemented onto the dentin with dual-cured resin cement (Variolink (R)). After they were stored in distilled water at 37(0)C for 24 h, the SBS test was performed at a crosshead speed of 1mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. Results:Results of this study did not show statistically significant differences between Groups 1 and 2, or among Groups 3, 4 and 5. The lowest SBS was recorded in Group 6 (CO2 laser), and the highest SBS was recorded in Group 4 (Nd:YAG laser with contact), followed by Group 3 (Er:YAG laser). The adhesive failure mode was predominantly observed in Groups 2, 3, 5, and 6. Group 1 showed 45% mixed failure and Group 4 showed 50% mixed failure. Conclusions:This study shows that Er:YAG and Nd:YAG laser treatment increased the bond strength of zirconia compared to sandbasting and CO2 laser treatment.