Comparative Evaluation of Corrosive Behavior of Four Commercially Available Nickel – Chromuim Alloys in Artificial Saliva by Cylcic Polarisation Test: An Invitro study

One of the most important factors affecting the choice of dental alloys is its biocompatibility and resistance to tarnish and corrosion. Corrosion of an alloy occurs when elements in the alloy ionize .It is a chemical property of an alloy that affects other properties such as esthetics, strength and biocompatibility. The purpose of this study was to evaluate and compare the corrosive behavior of four commercially available nickels – chromium alloy with high noble as the control group. In this study ,forty samples from four nickel –chromium alloys and five samples from high noble alloy were subjected to cyclic polarization test and its corrosive behavior were evaluated. Four parameters such as Corrosion potential [Ecorr], breakdown potential [Eb], repassivation potential [Ep] and corrosion current [Icorr] were analyzed to evaluate the corrosive behavior. The specific elements released from the alloys were determined by inductive coupled plasma –mass spectrometer. Within the limitations of this study, it could be concluded that: 1. High noble alloys are more resistant to corrosion than the base metal alloys. 2. Within the base metal alloys study groups, Group III behaves to be more resistant to corrosion followed by Group II, Group V, Group IV. 3. Both Nickel and Chromium ions were released during the corrosion process, but the percentage of Nickel ions was relatively higher than Chromium ions. Base metal alloys are generally used due to their good mechanical properties and low cost however certain precautions should be taken to ensure biological safety of metal ceramic restoration