Corrosion evaluation of recasting non-precious dental alloys.
ABSTRACT The effect of recasting, up to four times, non precious Ni-Cr and Co-Cr commercial dental alloys on their corrosion behaviour in saliva and saline media was carried out. A potentiokinetic technique was utilised to analyse the electrochemical characteristics of the anodic polarisation curves of these alloys. A considerable anodic polarisation range (about 2.0 V vs SCE) was used to investigate the possibility of developing a passive regime at such high potential range. The most important feature noted was a rapid rise in current density above a certain critical potential called pitting potential, Ep. The experimental data show that the open circuit potential, Eoc does not enable differentiation between the corrosion resistance of the four alloys used in this study. However, Ep and the rupture potential Er does distinguish between them. Increasing the number of the successive recastings of Wirolloy leads to enhancing the pitting potential, thus, the corrosion resistance of Wirolloy (Ni-Cr) improves after remelting and recasting. It has been found that Wirolloy corrodes 26 times faster than Wironit alloy under the same solution. The alloys containing cobalt and molybdenum show higher corrosion resistance than those containing nickel. Additionally, their corrosion resistance was not affected by successive melting and recasting. In chloride solutions Ni-Cr alloys show a high susceptibility to pitting corrosion, while Co-Cr alloys show a noble behaviour. The corrosion resistance of the four non precious alloys were in the following order: Biocast > Wironit > Cobond > Wirolloy.
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ABSTRACT: The effect of recasting, up to two times, Ni-Cr (DUCINOX) prosthetic alloy on its corrosion properties was carried out. The corrosion measurements were done in deoxygenated Fusayama Meyer artificial saliva solution at temperature of 37°C. In the study following electrochemical methods were used: measurement of free corrosion potential E cor in open circuit, measurement of polarization resistance according to Stern-Geary's method and measurement of potentiodynamic characteristic in wide range of anodic polarization. In general, it can be stated that casting number weakly influence on corrosion properties of investigated alloy. At free corrosion potential there is no monotonic dependence of corrosion parameters versus casting number. However, at extreme anodic potentials monotonic changes of corrosion parameters with increasing casting number is observed. Obtained results and drawn conclusions are partially compatible with literature data.Archives of Foundry Engineering. 04/2009; 9(3):67-70.
- Eksploatacja i Niezawodnosc - Maintenance and Reliability 01/2015; 17(1):90-94. · 0.51 Impact Factor
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ABSTRACT: Purpose: This study was to assess the extents of the release of metals from the non-precious alloys used for dental casting by measuring the differences in the extents of the release of metals by types of alloys, pH level and elapsed time. Methods: Uniform-sized specimens(10 each) were prepared according to the Medical Device Standard of the Korea Food and Drug Administration(2010) and International Standard Organization(ISO22674, 2006), using four types of alloys(one type of Ni-Cr and one type of Co-Cr used for fixed prosthesis, and one type of Ni-Cr and one type of Co-Cr used for removable prosthesis). A total of 12 metal-release tests were performed at one-day, three-day, and two-week intervals, for up to 20 weeks. The metal ions were quantified using an Inductively Coupled Plasma-Atomic Emission Spectrometer. Results: The results showed that the extent of corrosion was higher in the ascending order of Jdium-, Bellabond-, Starloy-, and Biosil-. The lower the pH and the longer the elapsed time were, the greater the increase in metal corrosion. At pH 2.4, the release of Ni from Jdium-, a Ni-Cr alloy, was up to 15 times greater than the release of Co from the Co-Cr alloy from two weeks over time, indicating that the Ni-Cr alloy is more susceptible to corrosion than the Co-Cr alloy. Conclusion: It is recommended that Co-Cr alloy, which is highly resistant to corrosion, be used for making dental prosthesis with a non-precious alloy for dental casting, and that non-precious alloy prosthesis be designed in such a way as to minimize the area of its oral exposure. For patients with non-precious alloy prostheses, a test of the presence or absence of periodontal tissue inflammation or allergic reaction around the prosthesis should be performed via regular examination, and education on the good management of the prosthesis is needed.Journal of Korean Acedemy of Dental Technology. 03/2013; 35(1).