Evaluation of Surface Roughness of a Ni-Cr Alloy Treated With the Nd/YAG Laser and the Sandblast Technique.

ABSTRACT

Introduction: This study was to assess the effect of various output parameters of laser treatment on roughening the surface of a commercial nickel-chromium (Ni-Cr) alloy as compared to the sandblasting technique. Materials and Methods: Ninety-six disk-shaped (5 mm diameter and 2 mm thickness) specimens in total were made of a nickel-chromium alloy by using the lost-wax technique. Air-abrasion surface treatment was used for sixteen specimens. Specimens were divided into six groups; one of them was sandblasted and the rest were irradiated by different NdYAG laser output parameters as follows Group A energy 122 mJ, frequency 20 Hz, irradiation duration 20 seconds, spot size 1.5 mm; Group B energy 122 mJ, frequency 20 Hz, irradiation duration 20 seconds, spot size 3.5 mm; Group C energy 122 mJ, frequency 10 Hz, irradiation duration 20 seconds, spot size 3.5 mm; Group D energy 102 mJ, frequency 10 Hz, irradiation duration 20 seconds, spot size 3 mm; Group E energy 102 mJ, frequency 20 Hz, irradiation duration 20 seconds, spot size 3 mm. The surface roughness of all surface-treated specimens was evaluated by using a profilometer, and their average roughness (Ra) was calculated. The average value of each group was analyzed by t test and one-way ANOVA (SPSS 17). Results: Significant differences (P<0.05) were observed between the study groups. The highest Ra was achieved for the sandblasted group. The Ra value in group C was the highest value among the laser-etched groups. Conclusion: Based on the results, NdYAG laser irradiation increases surface roughness, but it is not as efficient as the sandblasting method as a gold standard.