Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 13 1 2016 08 15 29 39 Fariba Ezoji Assistant Professor, Dental Materials Research Center, Department of Operative Dentistry, Faculty of Dentistry, Babol University of Medical Sciences, Babol, Iran Kasra Tabari Assistant Professor, Department of Operative Dentistry, Faculty of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran Zahra Jaberi Ansari Professor, Department of Operative Dentistry, Faculty of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran Hassan Torabzadeh Associate Professor, Department of Operative Dentistry, Faculty of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mohammad Javad Kharrazi fard Epidemiologist, Dental Research Center, Dentistry Research Institute, Tehran, Iran; Statistical and Methodology Department, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran 2016 06 25 2016 06 25 Objectives: Micromechanical retention of resin cements to alloys is an important factor affecting the longevity of metal base restorations. This study aimed to compare the bond strength and etching pattern of a newly introduced experimental etchant gel namely Nano Met Etch with those of conventional surface treatment techniques for nickel-chrome (Ni-Cr) and high noble alloys.  Materials and Methods: A total of 120 discs (8×10×15 mm) were cast with Ni-Cr (n=20), high noble BegoStar (n=50) and gold coin alloys (n=50). Their Surfaces were ground with abrasive papers. Ni-Cr specimens received sandblasting and etching. High noble alloy specimens (begoStar and gold coin) received sandblasting, sandblasting-alloy primer, etching, etch-alloy primer and alloy primer alone. Cylindrical specimens of Panavia were bonded to surfaces using Tygon tubes. Specimens were subjected to micro-shear bond strength testing after storing at 37°C for 24 hours. Results: In gold coin group, the highest bond strength was achieved after sandblasting (25.82±1.37MPa, P<0.001) and etching+alloy primer (26.60 ± 5.47 MPa, P<0.01). The lowest bond strength belonged to sandblasting+alloy primer (17.79±2.96MPa, P<0.01). In BegoStar group, the highest bond strength was obtained in the sandblasted group (38.40±3.29MPa, P<0.001) while the lowest bond strength was detected in the sandblast+ alloy primer group (15.38±2.92MPa, P<0.001). For the Ni-Cr alloy, bond strength in the etched group (20.79±2.01MPa) was higher than that in the sandblasted group (18.25±1.82MPa) (P<0.01). Conclusions: For the Ni-Cr alloy, etching was more efficient than sandblasting but for the high noble alloys, higher Au content increased the efficacy of etching. https://fid.tums.ac.ir/index.php/fid/article/view/1357 https://fid.tums.ac.ir/index.php/fid/article/download/1357/863