Effect of Fluoride Concentration and pH on Corrosion Behavior of Titanium for Dental Use

Abstract

Titanium is used as a metal for biocompatible materials such as dental implants or restorations because of its excellent chemical stability. However, the corrosion of Ti in the prophylactic fluoride-containing environment can become problematic. To clarify the effects of fluoride concentration and pH on the corrosion behavior of Ti, we conducted anodic polarization and immersion tests in NaF solution of various concentrations and pH values. The concentrations of dissolved Ti in the test solutions were analyzed by inductively coupled plasma mass spectroscopy. There were obvious limits of fluoride concentration and the pH value at which the corrosion behavior of Ti changed. The corrosion of Ti in the solution containing fluoride depended on the concentration of hydrofluoric acid (HF). When the HF concentration in the solution was higher than about 30 ppm, the passivation film of the Ti was destroyed. The results of this study revealed a relation between the fluoride concentrations and pH values at which Ti corrosion occurred and provided data on such corrosion in environments where the fluoride concentration and pH value are known.

Evaluation of the effect of fluoride‐containing acetic acid on NiTi wires

“…However, in a phosphoric-acidadjusted solution, it was only 0 ppm. 17 In the case of a 0.05%/pH 4 solution, the result was similar to that reported by Nakagawa and colleagues. However, as the NaF concentration increased, the HF concentration increased tremendously.…”

“…A similar reaction can occur in the presence of phosphoric acid 17,24 3NaF ϩ H 3 PO 4 3 3HF ϩ Na 3 PO 4 (3)…”

“…10 -12 Furthermore, titanium loses corrosion resistance in solutions containing fluoride. [13][14][15][16][17] Due to a cariostatic effect, the use of fluoride-containing products such as toothpastes, dental gels, and rinses have become common in our daily life. Fluoride inhibits bacterial metabolism after diffusing into the bacteria as hydrogen fluoride molecules when plaque is acidified.…”

Tantalum effect on the corrosion behavior of titanium-tantalum alloys in an environment containing fluoride ions

“…These properties predetermine titanium as a first-choice metallic material in medical applications, yet it is not an ideal material. The main reason is that its Young's modulus is higher approximately by order of magnitude than that of cortical bone (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)). This is why current research in the field of metallic biomaterials focuses on the development of materials with a lower elasticity modulus.…”

“…Their negative effect on the stability of the passive layer of titanium, and in an acidic environment in particular, has been clearly proved [11][12][13][14][15][16][17][18]. However, only a small attention has as yet been devoted to Ti-based alloys with tantalum.…”