Corrosion Resistance and Cytotoxicity of Copper-Based and Nickel-Chromium Alloys for Cast Post and Core Fabrication

Objectives: This study assessed the corrosion resistance and cytotoxicity of two copper-based alloys and one nickel-chromium (Ni-Cr) alloy used for post and core fabrication. Materials and Methods: In this in vitro study, the corrosion resistance of 9 specimens of dental casting alloys including one Ni-Cr-based (VeraBond) and two copper-based (American Dent-All and Aalbadent NPG) alloys (n=3) was assessed by electrochemical impedance spectroscopy (EIS) in artificial saliva in two different pH levels of 2.5 and 7.1. Their cytotoxicity was evaluated by the methyl thiazolyl tetrazolium (MTT) assay using 15 specimens (n=5). Statistical analysis was performed by one-way ANOVA (alpha=0.05). Results: EIS showed that the Ni-Cr alloy had the highest corrosion resistance. Aalbadent NPG and American Dent-All alloys showed significantly lower corrosion resistance than the Ni-Cr alloy (P<0.05). Aalbadent NPG showed higher corrosion resistance than American Dent-All in early hours, but its corrosion resistance decreased over time and became similar to that of American Dent-All at later time points. Although all groups showed higher corrosion in acidic environment, Ni-Cr showed good corrosion resistance in acidic pH. The cytotoxicity test revealed a significant difference between the copper-based groups (P<0.05). Ni-Cr was the most biocompatible alloy amongst all, followed by Aalbadent NPG. American Dent-All showed a high degree of cytotoxicity. Conclusion: The findings of this study raised some concerns regarding the clinical suitability of copper-based alloys for dental treatments, and the first choice for cast post and core restorations should be Ni-Cr alloys because they are more resistant to corrosion, and are less cytotoxic.