Synergistic effect of wire bending and salivary pH on surface properties and mechanical properties of orthodontic stainless steel archwires

Hobbelink, Marieke G., He, Yan, Xu, Jia, Xie, Huixu, Stoll, Richard, and Ye, Qingsong (2015) Synergistic effect of wire bending and salivary pH on surface properties and mechanical properties of orthodontic stainless steel archwires. Progress In Orthodontics, 16. 37. pp. 1-7.

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Background: The aim of this study was to investigate the corrosive behaviour of stainless steel archwires in a more clinically relevant way by bending and exposing to various pH.

Methods: One hundred and twenty pieces of rectangular stainless steel wires (0.43 × 0.64 mm) were randomly assigned into four groups. In each group, there were 15 pieces of bent wires and 15 straight ones. Prior to measurements of the wires, as individual experimental groups (group 1, 2, and 3), the wires were exposed to artificial saliva for 4 weeks at pH 5.6, 6.6, and 7.6, respectively. A control group of wires (group 4) remained in air for the same period of time before sent for measurements. Surface roughness (Ra-value) was measured by a profilometer. Young's modulus and maximum force were determined by a four-point flexural test apparatus. Scanning electron microscopy was used to observe the surface morphology of straight wire. Differences between groups were examined using a two-way analysis of variance (ANOVA).

Results: Mean surface roughness values, flexural Young's moduli, and maximum force values of bent wires are significantly different from those of the straight wires, which was the main effect of wire bending, ignoring the influence of pH. A significant effect was found between Ra-values regarding the main effect of pH, ignoring the influence of shape. There was a significant interaction effect of bending and pH on flexural Young's moduli of stainless steel archwires, while pH did not show much impact on the maximum force values of those stainless steel wires. Bigger surface irregularities were seen on SEM images of straight wires immersed in artificial saliva at pH 5.6 compared to artificial saliva at other pH values. Surface depth (Rz) was more sensitive than Ra in revealing surface roughness, both measured from 3D reconstructed SEM images. Ra showed a comparable result of surface roughness to Ra-value measured by the profilometer.

Conclusions: Bending has a significant influence on surface roughness and mechanical properties of rectangular SS archwires. pH plays a synergistic effect on the change of mechanical properties of stainless steel (SS) wires along with wire bending.

Item ID: 41861
Item Type: Article (Research - C1)
ISSN: 2196-1042
Keywords: stainless steel archwire; surface roughness; Young's modulus; maximum force; salivary pH; corrosion
Additional Information:

© 2015 Hobbelink et al. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://​creativecommons.​org/​licenses/​by/​4.​0/​), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Date Deposited: 08 Dec 2015 16:05
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1105 Dentistry > 110501 Dental Materials and Equipment @ 50%
11 MEDICAL AND HEALTH SCIENCES > 1105 Dentistry > 110506 Orthodontics and Dentofacial Orthopaedics @ 50%
SEO Codes: 92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920402 Dental Health @ 100%
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