West China Journal of Stomatology

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Effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes

Yang Qiuxia1, Yang Ying2, Xu Han1, Wu Di3, Guo Ke1   

  1. 1. Dept. of Prosthodontics, Jiujiang University Affiliated Stomatological Hospital, Jiujiang 332000, China; 2. Dept. of Prosthodontics, Affiliated Stomatological Hospital of Nanchang University, Nanchang 330006, China; 3. Dept. of Oral and Maxillofacial Surgery, The First People's Hospital of Jiujiang, Jiujiang 332000, China
  • Online:2016-02-01 Published:2016-02-01

Abstract:

Objective  This study aims to determine the effect of fluoride concentration on the corrosion behavior of cobaltchromium alloy fabricated by two different technology processes in a simulated oral environment. Methods  A total of 15 specimens were employed with selective laser melting (SLM) and another 15 for traditional casting (Cast) in cobalt-chromium alloy powders and blocks with the same material composition. The corrosion behavior of the specimens was studied by potentiodynamic polarization test under different oral environments with varying solubilities of fluorine (0, 0.05%, and 0.20% for each) in acid artificial saliva (pH=5.0). The specimens were soaked in fluorine for 24 h, and the surface microstructure was observed under a field emission scanning electron microscope after immersing the specimens in the test solution at constant temperature. Results  The corrosion potential (Ecorr) value of the cobalt-chromium alloy cast decreased with increasing fluoride concentration in acidic artificial saliva. The Ecorr, Icorr, and Rp values of the cobalt-chromium alloy fabricated by two different technology processes changed significantly when the fluoride concentration was 0.20% (P<0.05). The Ecorr, Icorr, and Rp values of the cobalt-chromium alloy fabricated by two different technology processes exhibited a statistically significant difference. The Icorr value of the cobalt-chromium alloy cast was higher than that in the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20% (P<0.05). The Ecorr and Rp values of the cobalt-chromium alloy cast were lower than those of the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20% (P<0.05). Conclusion  Fluoride ions adversely affected the corrosion resistance of the cobalt-chromium alloy fabricated by two different technology processes. The corrosion resistance of the cobalt-chromium alloy cast was worse than that of the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20%.

Key words: selective laser melting, casting technique, cobalt-chromium alloy, fluoride ions, corrosion resistance