Effects of pH and fluoride concentration on the corrosion of titanium

Abstract

The aim of this investigation was to confirm and summarize the corrosion behavior of titanium in saline solution at different pH and fluoride concentration, and to characterize the surface films and the stability of a passive and aged titanium surface using open circuit potential measurements, electrochemical impedance spectroscopy, and anodic polarization curves. The results from the electrochemical measurements were related to titanium released after 2-min brushing with saline solutions with different pH and fluoride concentration, that is, simulating tooth brushing with fluoride containing prophylactic substances. Titanium was analyzed using atomic adsorption spectrophotometry. The pH in the saline solution was varied between 4 and 7 with additions of sodium fluoride up to 1.0 wt %. The presence of fluoride in solution was unfavorable for the stability of titanium and led to corrosion and the release of titanium especially at low pH. The combination of low pH and presence of fluoride ions in solution destroyed a passive film on the titanium surface even after aging for 170 h in neutral saline solution. The results do not necessarily imply the occurrence of biological soft tissue related effects even if a physical contact between titanium and the surrounding milieu is prevalent. To provide a general understanding of electrochemical techniques in biomaterial research, much effort was put in the qualitative description of the results, with the intention to provide a broader understanding of especially the impedance method to other researchers.

Titanium(IV) hydrate based on chitosan template for defluoridation from aqueous solution

“…Sorption experiments showed the following results: Ti-CHI could remove fluoride from aqueous solutions with low fluoride concentrations (4.52 mg/L), making water meeting the permitted drinking water standard (0.55 mg/L, below 1 mg/L); the Ti-CHI had an effective defluoridation capacity in a wide pH range (4)(5)(6)(7)(8)(9) and is a potential adsorbent for natural fluoride-contaminated water with a basic pH; and finally, the presence of anions had a deleterious effect on the adsorption of fluoride, particularly for CO 3 2− , HCO 3 − and PO 4 3− . After combining the defluoridation effect, the pH effect and the analysis of the FTIR and Zeta potential data, we found that the adsorption process was governed by both electrostatic adsorption and chemical bonding: the NH groups and Ti OH groups were the adsorption sites for F − on Ti-CHI.…”

“…The applications of titanium-derived adsorbents in defluoridation are limited when exposed to both a low pH and fluoride ions in solution because these conditions accelerate the titanium release [8]. Chitosan has the highest metal coordinating ability among the natural polymers [9].…”

Effects of acidic sodium fluoride-treated, commercially pure titanium on periodontal pathogens and rat bone marrow cells

“…Recent studies that showed the use of hydrofluoric acid at low concentrations to modify titanium dioxide surfaces revealed increased bone-to-implant contact, enhanced removal-torque, pull-out forces, and differentiation of mesenchymal stem cells [16][17][18] . Acidic fluoride solutions have also been observed to corrode commercially pure titanium and its alloys [19][20][21] . Previous clinical studies have shown the effective use of fluorides in the prevention of dental caries [22][23][24] , whereas more recent studies have demonstrated both the bactericidal activity of fluoride against periodontal pathogens and its efficacy in the reduction of periodontitis 24,25) .…”

Effect of fluoride from glass ionomer on discoloration and corrosion of titanium

“…In previous works using a solution of neutral pH titanium was reported to maintain a smooth metallic appearance [17]. The fluoride ions apparently did not cause significant damage in the form of excessive dissolution or localized corrosion attack.…”