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

Huang, Her-Hsiung

doi:10.1016/j.dental.2005.11.042

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Volume 23, Issue 1 , Pages 24-33, January 2007

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

Faculty of Dentistry, School of Dentistry, National Yang-Ming University, Taipei 112, Taiwan

Received 1 June 2005; received in revised form 19 November 2005; accepted 28 November 2005.

Abstract

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 ΔR_a, ΔR_ms, and ΔR_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 ΔR_a, ΔR_ms, and ΔR_z (manufacturer: P<0.05; environment: P<0.0001). Regardless of the archwire manufacturer, no statistically significant difference in ΔR_a (<70nm), ΔR_ms (<90nm), and ΔR_z (<450nm) was observed on the tested NiTi archwires in lower fluoride-containing (<2500ppm) environments, including the various fluoride mouthwashes and the artificial saliva added with fluoride toothpastes. In artificial saliva added with high fluoride prophylactic gel (around 17,000ppm), a significant increase in ΔR_a (around 120–250nm), ΔR_ms (around 140–320nm), and ΔR_z (around 770–1410nm), 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.

Keywords: NiTi, Orthodontic archwire, Surface topography, Roughness, Fluoride