Journal Article

Frictional and mechanical properties of diamond-like carbon-coated orthodontic brackets

Takeshi Muguruma, Masahiro Iijima, William A. Brantley, Susumu Nakagaki, Kazuhiko Endo and Itaru Mizoguchi

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 35, issue 2, pages 216-222
Published in print April 2013 | ISSN: 0141-5387
Published online September 2011 | e-ISSN: 1460-2210 | DOI:
Frictional and mechanical properties of diamond-like carbon-coated orthodontic brackets

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This study investigated the effects of a diamond-like carbon (DLC) coating on frictional and mechanical properties of orthodontic brackets. DLC films were deposited on stainless steel brackets using the plasma-based ion implantation/deposition (PBIID) method under two different atmospheric conditions. As-received metal brackets served as the control. Two sizes of stainless steel archwires, 0.018 inch diameter and 0.017 × 0.025 inch cross-section dimensions, were used for measuring static and kinetic friction by drawing the archwires through the bracket slots, using a mechanical testing machine (n = 10). The DLC-coated brackets were observed with a scanning electron microscope (SEM). Values of hardness and elastic modulus were obtained by nanoindentation testing (n = 10). Friction forces were compared by one-way analysis of variance and the Scheffé test. The hardness and elastic modulus of the brackets were compared using Kruskal–Wallis and Mann–Whitney U-tests. SEM photomicrographs showed DLC layers on the bracket surfaces with thickness of approximately 5–7 μm. DLC-coated brackets deposited under condition 2 showed significantly less static frictional force for the stainless steel wire with 0.017 × 0.025 inch cross-section dimensions than as-received brackets and DLC-coated brackets deposited under condition 1, although both DLC-coated brackets showed significantly less kinetic frictional force than as-received brackets. The hardness of the DLC layers was much higher than that of the as-received bracket surfaces. In conclusion, the surfaces of metal brackets can be successfully modified by the PBIID method to create a DLC layer, and the DLC-coating process significantly reduces frictional forces.

Journal Article.  3336 words.  Illustrated.

Subjects: Restorative Dentistry and Orthodontics

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