effects of co2, er:yag, and nd:yag laser treatments on shear bond strength of resin cement to zirconia

Objective: this study aimed to evaluate the effect of different lasers at various settings on the shear bond strength (sbs) of resin cement to zirconia. methods: in this in vitro study, 165 zirconia discs were divided into 11 groups (n=15). the groups underwent the following treatments: a control group with no treatment, a sandblasted group with 50 μm al₂o₃, three groups treated with a co₂ laser (4 w, 5 w, 6 w), three groups treated with an er:yag laser (3 w, 4 w, 6 w), and three groups treated with a nd:yag laser (2 w, 2.5 w, 3 w). composite cylinders were bonded to the zirconia using resin cement. after 24 hours, the samples were thermocycled and sbs was measured using a universal testing machine. data were analyzed by the welch test and the games-howell test (α=0.05). results: the sandblasted group exhibited the highest sbs, while the control group showed the lowest. a significant difference in sbs was observed between the groups (p<0.001). pairwise comparisons revealed no significant differences between the sandblasted group and the nd:yag laser groups (2 w, 2.5 w, 3 w), the co₂ laser group (6 w), and the er:yag laser group (6 w) (p > 0.05). conclusions: sandblasting with al₂o₃ particles yielded the highest bond strength of resin cement to zirconia. alternatively, nd:yag at all tested parameters, and er:yag, and co₂ lasers at specific settings could be used to enhance bond strength to zirconia. among lasers, the nd:yag laser at 2.5 w achieved the best performance.