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Objective:

To evaluate corrosion resistance of different casting alloys using the established static corrosion test method and an in house developed dynamic test method.

Method:

The dental alloys were investigated both static according to ISO 22674:2006 and dynamic causing a deflection of the alloy within the elastic area using a Bose Electroforce 3330 Test Instrument. The static test specimens were cast sheets with dimensions (34 x 13 x 1,5)mm and for the dynamic specimens (32 x 6 x 1)mm. The alloys were one Pd – Ag alloy, Aurolite 2B (Pd: 59,9, Ag: 26,3, Au: 1,7, In: 5, Sn: 5, Zn: 2, Ru: < 1) and two Co – Cr alloys, Wirobond 280 (Co: 60,2, Cr: 25, Mo: 4,8, W: 6,2, Ga: 2,9, Mn: < 1) and d. Sign 30 (Co: 60,2, Cr: 30, Ga: 3,9, Nb: 3,2, Mo, Al, Li: < 1) respectively. In the dynamic test the alloys were exposed to 500 000 cyclings during seven days under otherwise the same conditions as the static tests. The elements released in the corrosion solution were determined by ICP-MS.

Results:

The corrosion tests indicated relatively small amounts of elements released compared to the limits stated in ISO 22674:2006. The results from the dynamic corrosion test showed less total release of elements from Aurolite 2B and Wirobond 280 and only a slightly increase for d. Sign 30 compared to the static tests. The tests also showed that small variations in the composition of Co-Cr alloys, for example by addition of Nb, may lead to changes in the release of elements.

Conclusion:

The corrosive resistance of the alloy was acceptable in both tests with metal release lower than the limits stated in ISO 22674. In this study dynamic load had little or no effect on the amount of element released.

 

Authors and affiliation:
M. SYVERUD, Nordic Institute of Dental Materials (NIOM), Oslo, Norway.
J. T. SAMUELSEN, Nordic Institute of Dental Materials (NIOM), Oslo,Norway;
K. HEGERSTROEM HAUGLI, Department of Life Sciences and Health, Oslo and Akershus University College, Oslo, Norway.