The Effect of Porcelain Firing on Electrochemical Behavior of a Dental Alloy in Hydrogen Peroxide

Purpose The aim of this study was to evaluate changes in electrochemical corrosion properties of porcelain firing simulated nickel‐chromium dental casting alloy exposed to a 10% hydrogen peroxide bleaching agent. Materials and Methods The electrochemical corrosion behavior of a Ni‐Cr alloy was evaluated by cyclic polarization test in the aerated electrolyte (pH = 6.5). Test groups were produced in as‐cast (group 1, control group) and simulated porcelain firing (group 2: heat‐treated/mean value; group 3: heat‐treated/cycle) conditions. Scanning electron microscopy (SEM) was also used to examine the alloy surfaces before and after the corrosion test. Results The ranking of the groups with respect to E corr and I corr was as follows: 1, 2, 3 and 3, 1, 2, respectively. Group 3 exhibited the greatest and group 2 displayed the least corrosion tendencies. An increase in corrosion rates was observed after heat treatment/cycle state. Post‐corrosion SEM photographs were also consistent with the test results. Conclusion Within the parameters of this study, a single heat treatment is insufficient to cause upheaval in corrosion behavior of a Ni‐Cr alloy subjected to 10% hydrogen peroxide.