Abstract
The objective of this study was to evaluate the change in color and glossiness of four types of titanium alloy immersed in an alkaline denture cleanser containing peroxide, and to clarify the surface properties. After immersion in the denture cleanser, commercially pure titanium discolored with prolonged immersion, and this reduced the glossiness. The Ti-6Al-4V and Ti-6Al-7Nb alloys showed more marked discoloration than pure titanium. The Ti-20Cr alloy showed slight discoloration. After the immersion of titanium alloys, the dissolution of the elements from the tested alloys was confirmed. According to surface analysis, the surface of the markedly discolored Ti-6Al-4V and Ti-6Al-7Nb alloys consisted of a four-fold thicker titanium oxide film than that of pure titanium, and the slightly discolored Ti-20Cr alloys had an oxide film with only a one-third thickness. These results suggest that titanium alloys in an alkaline denture cleanser containing peroxide are oxidized by the oxidation reaction of peroxide, and Ti-20Cr alloy has less of an influence regarding oxidation by peroxide on the alloys.
