| Abstract |
This study aims to evaluate the corrosion resistance of two non. noble dental alloys, namely, the Wiron (R) 88 (Ni-Cr-Mo) and the Remanium 2000+ (Co-Cr-Mo-W). A noble alloy, the V-Gnathos r Plus (Au. Pt) previously studied was also considered for the purpose of comparison. The study was conducted in artificial saliva, pH 7.1, at 37 degrees C, by cyclic and linear sweep voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The Rp value of the alloy of high contents of Ni, the Wiron (R) 88, was 26.2 +/- 0.2 kO cm(2) and of the one with high contents of Co, the Remanium 2000+, was 22.5 +/- 0.6 kO cm(2). Data from linear polarization resistance and electrochemical impedance spectroscopy lead to the same order for the resistance against corrosion. The order from the less to the more reactive alloy is: Wiron (R) 88 -> Remanium 2000+. The galvanic cell obtained by coupling the two non. noble alloys presents very low cell potential (a few mV, -18 mV), while the galvanic cell between one noble alloy (the V-Gnathos (R) Plus) and the Wiron (R) 88 showed a higher cell potential (-104 mV). Both galvanic couples, under short circuit, have lead to the release of cations, namely, Co2+, in the case of the Wiron r 88| Remanium 2000+ and Ni2+ for the Wiron (R) 88| V-Gnathos (R) Plus, galvanic couples, respectively, with the ionic concentrations reaching values of 12.15 and 7.30 mu g L-1 (7.30 ppb), respectively. SEM micrographs obtained after 25 days immersion in artificial saliva, at 37 degrees C, showed the formation of well-defined pits on the surface of the two non-noble alloys. |
