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 Abstract: Objectives: This study aimed to investigate the effect of different surface treatment methods of nickel-chromium alloy on the shear bond strength (SBS) of composite resin to metal. Materials and Methods: 45 Nickel–Chromium discs were fabricated. The metal blocks were equally assigned into 3 groups. The first group underwent surface treatment with Al2O3 (50mµ particles, 60psi, 10s); the second group underwent surface treatment with Er:YAG laser (500mj, 10Hz, 5w, 20s); and the third group underwent both surface treatment methods. Following the application of bonding, resin composite disks were bonded on the metal blocks. Upon performance of thermocycling (at 5 and 55 °C for 10,000 cycles), the SBS of the specimens was evaluated using universal testing machine. The specimens were then assessed under a stereomicroscope to determine the mode of failure. The data was analyzed using ANOVA at the significance level of 0.05 by SPSS version 24. Results: the SBS in the three groups was significantly different (P<0/001). So that the average SBS in sandblast and Er-YAG laser group was significantly higher than Er-YAG laser group (P<0/001) and sandblast group (P=0/036). Also, the mean of SBS in the sandblast group was significantly higher than the Er-YAG laser group (P<0/001). No statistically significant difference was observed between the groups in terms of Mode of failure (P=0/999). Conclusion: treatment of metal surface by sandblasting with Al2O3 and Er-YAG laser can be used to produce higher SBS to composite resin in comparison to sandblasting and Er-YAG laser alone.   https://fid.tums.ac.ir/index.php/fid/article/view/4601 https://fid.tums.ac.ir/index.php/fid/article/download/4601/2221