Effect of Nd: YAG laser and CO₂ laser treatment on the resin bond strength to zirconia ceramic

Objective: This study evaluated the effect of surface treatments (Nd:YAG laser, CO2 laser, Al203 airborne-particle abrasion, and silica-coating) on the zirconia-to-resin shear bond strength (SBS). Method and Materials: Eighty-one Lava (3M ESPE) blocks (13 × 4 × 2 mm) were embedded in acrylic resin, polished, and randomly divided into three groups, which received the following surface treatments: no abrasion, Al2O3 airborneparticle abrasion (50 µm), or silica-coating (Cojet, 3M ESPE). Each group was divided into three subgroups that were treated with Nd:YAG laser, CO₂laser, or no laser irradiation. Following application of a monomer phosphate-containing primer, cylinders of resin cement (Panavia F, Kuraray) (n = 18) were built on the surface. SBS testing was carried out after 24 hours of storage in water. Surface roughness and topography (SEM) after treatments were evaluated. Results: According to ANOVA and Tukey test (α = 0.05), mean SBS after Nd:YAG laser treatment ranged from 14.09 to 16.20 MPa and was statistically higher than CO₂laser (6.24 to 10.51 MPa) and no laser treatment (4.65 to 8.79 MPa). The Nd:YAG laser created more roughness on zirconia when compared to the CO₂ laser and abrasion treatments. Silica-coating increased the SBS of lased and nonlased zirconia. Significant microcracks were found on specimens treated with CO₂. Conclusion: Nd:YAG laser pretreatment, whether associated with abrasion methods or not, created consistent roughness on the zirconia surface and significantly increased zirconia SBS to Panavia F. Silica-coating could potentially increase the SBS of lased and nonlased zirconia. Significant microcracks were found on specimens treated with the CO₂laser.