Titanium and its alloys are finding increasing use in medical devices and dental implants. The strong selling point titanium is its resistance to the highly corrosive body fluids in which an implant must survive. This corrosion resistance is due
to a tenacious passive oxide or film which exists on the metal’s surface and renders it passive. Potentiodynamic polarization measurement is one of the most commonly used electrochemical methods that have been applied to measure corrosion rates. And the potentiodynamic polarization test supplies detailed information such as open circuit, rupture, and passivation potential. Furthermore, it indicates the passive range and sensitivity to pitting corrosion. This study was designed to compare the corrosion resistance of the commonly used dental implant materials such as CP Ti, Ti-6A1-4v, Co-Cr-Mo alloy, and 316L stainless steel. And the effects of galvanic couples between titanium and the dental alloys
were assessed for their usefulness as materials for superstructure. The working electrode is specimen, the reference electrode is a saturated calomel electrode(SCE), and the counter electrode is made of carbon. In N2-saturated 0.9% NaCI solutions, the potential scanning was performed starting from -800mV(SCE) and the scan rate was 1mV/sec. At least three different polarization measurements were carried out for each material on separate specimen. The galvanic corrosion measurements were conducted in the zero-shunt ammeter with an implant supraconstruction surface ratio of 1:1. The contact current density was recorded over a 24-hour period. @ES The results were as follows: @EN 1. In potontial-time curve, all specimens became increasingly more noble after immersion in the test solution and reached between -70mV and 50mV (SCE) respectively after 12 hours. 2. The Ti and Ti alloy in the saline solution were most resistant to corrosion. They showed the typical passive behavior which was exhibited over entire experimental range. Therefore no breakdown potentials were observed. 3. Comparing the rupture potentials. Ti and ti alloy had the highest value(because their breakdown potentials were not observed in this study potential range) followed by Co-Cr-Mo alloy and stainless steel(316L). So, the corrosion resistance of titanium was cecellent, Co-Cr-Mo alloy slightly inferior and stainless steel (316L) much less. 4. The contact current density sinks faster than any other galvanic couple in the case of Ti/gold alloy. 5. Ag-Pd alloy coupled with Ti yieded high current density in the early stage. Furthermore, Ti became anodic. 6. Ti/NiCr alloy showed as showed a relatively high galvanic current and a tendency to increase.
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