Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 21 0 2024 08 04 1 8 Behnaz Ebadian Department of Prosthodontics, Dental Implants Research Center, Dental Research Institute, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran Alireza Moazami Department of Prosthodontics, School of Dentistry, Zahedan University of Medical Sciences, Zahedan, Iran Mohammad Jowkar Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran 2021 04 25 2022 09 21 Objectives: Porcelain chipping and delamination are among the shortcomings of all-ceramic restorations. This study aimed to assess the effect of laser irradiation and sandblasting on shear bond strength (SBS) of zirconia to veneering porcelain. Materials and Methods: In this in vitro, experimental study, 60 zirconia blocks were randomly divided into three groups (n=20) for surface treatment with Er:YAG laser, sandblasting, and no surface treatment (control). Each group was randomly divided into two subgroups (n=10) for porcelain application by the layering or the pressing technique. The surface roughness, SBS, and failure mode were determined and analyzed using two-way ANOVA, Tukey’s HSD test, Chi-square test, and Pearson’s correlation test (alpha=0.05). Results: The mean SBS was 8.16±3.66 MPa, 9.32±2.7 MPa, and 11.85±3.06 MPa in the control, laser, and sandblasting groups, respectively. The SBS was significantly different among the three groups (P=0.002). The failure mode of the three groups was not significantly different (P>0.05). The sandblasted group showed significantly higher surface roughness than the control and laser groups (P<0.001). Conclusion: Sandblasting yielded higher SBS particularly when the porcelain was applied by the layering technique. Although laser irradiation increased the SBS, the difference with the control group was not statistically significant. https://fid.tums.ac.ir/index.php/fid/article/view/4039 https://fid.tums.ac.ir/index.php/fid/article/download/4039/2058