Corrosion of dental alloys in the oral cavity can affect the mechanical, esthetic properties and efficiency of metallic restorations, and has great influence upon the local and systemic health of patients. The purpose of this study was to clarify
the
corrosion behavior of various dental alloys, and to measure the galvanic currents between dissimilar alloys.
Fifty-eight kinds of dental casting alloys such as twenty-nine high gold alloys, ten low gold alloys, fourteen silver-palladium alloys, five base metal alloys, and twenty kinds of ceramic alloys such as seventeen noble metal alloys, three base
metal
alloys, were used as the experimental alloys.
Modified Fusayama's artificial saliva titrated to pH 6.7 with phosphoric acid was used as an electrolyte. Thespecimens were immersed in the modified artificial saliva of 37℃. The rest potentials. Anodic polarization curves, corrosion potentials,
and
galvanic currents were measured by using the potentiostant / galvanostat and zero shunt ammeter.
@ES From the experiment, the following results were obtained
@EN 1) The gold based alloys showed the high rest potentials and the low current densities within experimental potential range.
2) The rest potentials and the current densities of the palladium-based alloys were influenced by the content of platinum, palladium, and silver.
3) In the nickel-chromium base alloys, the formations of passivation film were influenced by chromium content. The copper-aluminum alloy showed very high current density which was more than 150 mV SCE.
4) The corrosion potentials of ceramic alloys wre lower than those of dental casting alloys, but the trend of anodic polarizations were generally similar to the other alloys.
5) The amount of galvanic current and the polarity in the bimetallic galvanic cell could not be predicted considering only the alloy composition. The galvanic current decreased while the measuring time passed, but flew continuously.
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