Friction and Wear Performances of Stainless Steel Archwires After Corrosion in Oral Care Products

To elucidate the corrosion mechanism of orthodontic archwire in fluoride-containing environments, the friction and wear behavior of archwires following corrosion in fluoride-containing oral care products was investigated. Stainless steel archwires were soaked in solutions of fluoride-free toothpaste, fluoride toothpaste, fluoride-free mouthwash, fluoride mouthwash, and sodium monofluorophosphate, followed by friction testing against brackets. The average friction coefficient of the archwire–bracket tribopair increased gradually from 0.17 to 0.28 with prolonged immersion time in the fluoride-containing solution, accompanied by a progressive increase in the wear scar area on the archwire surface. In the fluoride toothpaste solution, the archwire exhibited a corrosion potential and current density of –301.8 mV and 0.348 μA/cm2, respectively, indicating a higher susceptibility to corrosion. Analysis of wear debris revealed significant enrichment of fluorine and oxygen elements on the archwire surface after exposure to fluoride-containing solutions, consistent with pronounced corrosion damage. Integration of friction results and surface characterization elucidated the corrosion mechanism in fluoride-containing environments. It was proposed that fluoride ions facilitated the formation of micro-batteries, while active fluoride species accelerated the dissolution of nickel from the archwire surface and promoted oxygen accumulation, thus driving sustained electrochemical corrosion. This progressive surface degradation ultimately exacerbated the friction and wear of the archwire–bracket tribopair.