Comparison of the Effect of Nd:YAG Laser and Sandblasting on Shear Bond Strength of a Commercial Ni-Cr Alloy to Porcelain

Abstract

Introduction: Failures might occur at metal‒ porcelain interfaces as a problem with metal‒ceramic restorations even with the application of airborneparticle abrasion technique. This study was undertaken to evaluate the effect of Nd:YAG laser treatment on the bond strength of porcelain fused to metal. Methods: Twenty-four cylindrical specimens (4 mm in diameter and 4 mm in height) were made of a commercially available nickel‒chromium alloy by lost-wax technique. Half of the specimens were surface-treated by air-borne particles and the other half was irradiated with Nd:YAG laser beams (wavelength of 1064 nm, energy and frequency of 120 mJ and 10 Hz, respectively, and a power setting of 6 kW). All the specimens (air-abraded and laser-treated) were covered with a 4-mm layer of opaque porcelain in two-stage baking and subjected to shear bond strength test (a 10-kgf at 1 mm/min) until fracture occurred. A fractured specimen from each group was evaluated using scanning electron microscopy. T-test was used for statistical analysis and statistical significance was set at P<0.05. Results: Shear bond strength was higher in the sandblasted group compared to the laser-etched group (P<0.05). Conclusion: It can be concluded that Nd:YAG laser irradiation increases the shear bond strength of Ni-Cr alloy to porcelain, but further studies should be carried out to evaluate the effect of different parameters of Nd:YAG laser treatment on shear bond strength.