Effect of Albumin on Corrosion Resistance of Titanium in Fluoride-solution

Objectives: Fluoride in prophylactic agents is well known to corrode titanium. However, correlation between the corrosion process of titanium and protein in saliva are not clarified. This study attempted to discuss the effect of albumin on the corrosion resistance of titanium in fluoride-containing solution. Methods: Two kinds of titanium specimens were prepared; One was a commercially pure titanium plate by polishing with SiC paper, the other was that the plate soaked in 0.1% albumin containing saline solution for 4-h after polishing for the sake of making albumin adsorb (denoted as cpTI and ALB-TI, respectively). Static immersion test was performed in a 0.2% NaF saline solution (pH 5.0) for up to 168-h. Surface characterization on the cpTI and ALB-TI before and after immersion in a NaF saline solution was examined using X-ray photoelectron spectroscopy (XPS). The titanium concentration in the solutions were measured using inductively coupled plasma emission spectroscopy (n=3). Results: The C1s spectra on the ALB-TI indicated that the peak and shoulder close to 288.0 and 286.3 eV were larger than the cpTI. These peak and shoulder were assigned to amide or calboxyl groups of albumin, indicating that albumin adsorbed on specimens. The N1s and O1s XPS spectra on the ALB-TI suggested the adsorption of albumin as well as C1s spectra. These peaks originating from albumin decreased with immersion in a fluoride solution after 3-h immersion. The ALB-TI had less amount of dissolved titanium in a fluoride-solution than cpTI with in 6-h immersion (p<0.05, ANOVA and Scheffe's test). On the other hand, the amount of dissolved titanium from the ALB-TI was similar to that from the cpTI after 24-h. Conclusion: We demonstrated that the adsorbed-albumin on the plate played a role of protection for dissolution at initial stage within 6-h.