Electrochemical corrosion behavior of cast and SLM Co-Cr dental alloys in artificial saliva with variable pH.

This study compares the corrosion resistance of two cobalt-chromium (Co-Cr) dental alloys manufactured by casting (Wirobond SG) and Selective Laser Melting (Mediloy S-Co). Standardized disc specimens were analyzed morphologically (SEM), elementally (EDS), and electrochemically (OCP and Tafel plots). Tests were performed in Carter-Brugirard artificial saliva (pH 4.9 and 6.8) at 37 ± 1°C. Electrochemical parameters (Eoc, Ecor, icor, βa, βc, Rp) were used to evaluate corrosion behavior. The cast alloy showed the highest Rp (1346.29 kΩ•cm2) and lowest icor (30.96 nA/cm2) at pH 6.8, indicating better corrosion resistance. SEM showed process-related surface characteristics, including porosities in SLM samples and carbide precipitates in cast samples. These are components of the material itself that make it harder and more resistant to wear. Corrosion resistance is influenced by both manufacturing method and pH. Cast Co-Cr performed better in near-neutral saliva, while the SLM alloy showed a more electropositive open-circuit potential (E_oc = 67.9 mV) at pH 4.9, indicating higher corrosion resistance from an electrochemical point of view under acidic challenge. Both materials are suitable for dental applications.