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

Objectives. The 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. Methods. Four 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 Delta R-a, Delta R-ms, and Delta R-z) with the archwire manufacturer and immersion test environment as the factors. Results. Both the archwire manufacturer and immersion environment had a significant influence on Delta R-a, Delta R-ms, and Delta R-z (manufacturer: P < 0.05; environment: P < 0.0001). Regardless of the archwire manufacturer, no statistically significant difference in Delta R-a (<70 nm), Delta R-ms (<90 nm), and Delta R-z (<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 Delta R-a (around 120-250 nm), Delta R-ms (around 140-320 nm), and Delta R-z (around 770-1410 nm), i.e. increasing the surface roughness, was observed on the tested NiTi archwires. Significance. The 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. (C) 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.