Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 23 0 2026 06 30 4601 4601 Seyedeh Maryam Tavangar Department of Operative Dentistry, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran Yousef Jahandideh Department of Prosthodontics, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran Kazem Saber Private Practice, Rasht, Iran Reza Tayefeh Davalloo Department of Operative Dentistry, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran Farideh Darabi Department of Operative Dentistry, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran Dina Maleki Dental Sciences Research Center, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran Reza Ahmadi Department of Operative Dentistry, School of Dentistry, Kermanshah University of Medical Sciences, Kermanshah, Iran 2022 09 17 2024 03 06 Objectives: This study evaluated the effect of different surface treatments of nickel-chromium (Ni-Cr) alloy on its shear bond strength (SBS) to composite resin. Materials and Methods: In this in vitro study, 45 Ni-Cr discs were fabricated and randomly assigned to three groups (n=15). Group 1 underwent sandblasting with 50µm aluminum oxide (Al₂O₃) particles at 60psi for 10 seconds. Group 2 was treated with Er:YAG laser (500mJ, 10Hz, 5W for 20 seconds). Group 3 received sandblasting followed by Er:YAG laser irradiation. A universal adhesive containing 10-MDP monomer was applied on all specimens, and composite resin cylinders were bonded to the treated metal surfaces. After 10,000 thermal cycles (5°C/55°C), SBS was measured using a universal testing machine. Failure modes were examined under a stereomicroscope at ×40 magnification. Data were analyzed by one-way ANOVA (alpha=0.05). Results: Significant differences in the mean SBS was observed among the groups (P<0.001). Sandblasting + Er:YAG laser exhibited the highest mean SBS (14.32±1.83MPa), which was significantly greater than that of the sandblasting group (12.73±1.62MPa; P=0.036) and the Er:YAG laser group (6.85±1.60MPa; P<0.001). The sandblasting group also showed significantly higher SBS than the Er:YAG laser group (P<0.001). No significant difference was found in the mode of failure among the groups (P=0.999), with mixed failure predominating in all groups. Conclusion: Surface treatment of Ni-Cr alloy by a combination of sandblasting with Al₂O₃ particles and Er:YAG laser irradiation produced significantly higher SBS to composite resin than either sandblasting or Er:YAG laser treatment alone. https://fid.tums.ac.ir/index.php/fid/article/view/4601 https://fid.tums.ac.ir/index.php/fid/article/download/4601/2235