Variation in surface topography of different NiTi orthodontic archwires in various commercial fluoride-containing environments

ObjectivesThe surface topography can affect the friction behavior between an orthodontic wire and brackets during clinical applications. The purpose of this study was to investigate the influence of a fluoride-containing environment on the surface topography variations of different nickel–titanium (NiTi) orthodontic archwires.MethodsFour different NiTi commercial orthodontic archwires were immersed in fluoride mouthwashes and in artificial saliva with the addition of commercial fluoride toothpastes or prophylactic gels for a 28-day period. Atomic force microscopy (AFM) was used to measure the three-dimensional surface topography of NiTi archwires before and after the immersion tests. Two-way analysis of variance (ANOVA) was used to analyze the surface roughness variance (including ΔRa, ΔRms, and ΔRz) with the archwire manufacturer and immersion test environment as the factors.ResultsBoth the archwire manufacturer and immersion environment had a significant influence on ΔRa, ΔRms, and ΔRz (manufacturer: P < 0.05; environment: P < 0.0001). Regardless of the archwire manufacturer, no statistically significant difference in ΔRa (<70 nm), ΔRms (<90 nm), and ΔRz (<450 nm) was observed on the tested NiTi archwires in lower fluoride-containing (<2500 ppm) environments, including the various fluoride mouthwashes and the artificial saliva added with fluoride toothpastes. In artificial saliva added with high fluoride prophylactic gel (around 17,000 ppm), a significant increase in ΔRa (around 120–250 nm), ΔRms (around 140–320 nm), and ΔRz (around 770–1410 nm), i.e. increasing the surface roughness, was observed on the tested NiTi archwires.SignificanceThe variation in the surface topography of the NiTi orthodontic archwires in the commercial fluoride-containing environments should be taken into consideration when the friction between the archwire and bracket is a clinical concern.