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

Abstract

The possibility of the formation of hydrofluoric acid by the reaction of fluoride with acetic acid seems natural in the oral cavity. The effect of an acidic fluoride solution on NiTi wires was investigated by testing microhardness and color changes on wires. For aesthetic reasons, the color change on wires was also evaluated. Wires were immersed in four different test solutions for 1 or 3 days. As-received wires were used as a reference. After immersion for 3 days, the microhardness of the tested wires increased 1.8% to 10.4% compared to that of their as-received state. Wires immersed in a higher NaF concentration, lower pH solution with longer immersion yielded a more corroded surface than those of the counter cases. Wires showed a different color after immersion. However, after 3 days in solutions of pH 4, wires showed an appreciable color change regardless of the products. In test solutions, 3M wires showed the highest volumetric and percentage (0.59 for 0.05%; 1.19 for 0.2% solution) weight loss and G&H wires showed the least volumetric and percentage (0.43 for 0.05%; 1.05 for 0.2% solution) weight loss among tested wires. In pH 6 solutions, wires lost weight and were under the detection limit of the testing machine.

Inhibition of hydrogen embrittlement of Ni–Ti superelastic alloy in acid fluoride solution by hydrogen peroxide addition

“…Ni–Ti superelastic alloy is widely used in dental devices, such as orthodontic wires, because of its superior mechanical properties, good corrosion resistance, and biocompatibility. However, in the presence of fluoride, this alloy undergoes a marked corrosion 1–6. Fluoride, such as NaF, is contained in toothpastes, prophylactic agents, and dental rinses, because fluoride has a cariostatic effect.…”

Effect of Fluoride Released from Fluoride-containing Dental Restoratives on NiTi Orthodontic Wires

“…Otherwise, the surface should show some pores or some visible modification. According to our previous study, wires immersed in HF-formed (greater than 10 ppm) acidic fluoride solution showed enhanced microhardness and pores after immersion 25) .…”

“…Further, HF concentration limit can be changed according to the acid added to adjust the pH value, because each acid has a different acidity. According to our previous study, wires immersed in acidic NaF solutions were full of micropores and the severity depended on the concentration of HF 25) . However, in the present study, no surface modification was found regardless of wire type and contacting resin product.…”

The Corrosion Resistance of Composite Arch Wire Laser-Welded By NiTi Shape Memory Alloy and Stainless Steel Wires with Cu Interlayer in Artificial Saliva with Protein

“…Intraoral structures are exposed to an ever-changing environment including saliva, foods, bacteria and their product. Protein in food and digestive enzymes make the saliva not only a single phosphate buffer, but a complex system containing protein 6,7. Limited studies on corrosion behavior of alloys have been reported in protein-containing solutions.…”