Changes in the surface roughness and friction coefficient of orthodontic bracket slots before and after treatment


  • Contract grant sponsor: Beijing Medical Research & Development Fund; Contract grant number: 2009–3036.

Address for reprints: Jiuxiang Lin, Department of Orthodontics, School and Hospital of Stomatology, Peking University, No. 22 Zhongguancun Nandajie, Haidian District, Beijing 100081, P. R. China E-mail: Address for reprints: Peng Ding, Department of Orthodontics, Peking University School and Hospital of Stomatology, No. 22 Zhongguancun Nandajie, Haidian District, Beijing 100081, P. R. China E-mail:


In this study, we tested the surface roughness of bracket slots and the friction coefficient between the bracket and the stainless steel archwire before and after orthodontic treatment. There were four experimental groups: groups 1 and 2 were 3M new and retrieved brackets, respectively, and groups 3 and 4 were BioQuick new and retrieved brackets, respectively. All retrieved brackets were taken from patients with the first premolar extraction and using sliding mechanics to close the extraction space. The surface roughness of specimens was evaluated using an optical interferometry profilometer, which is faster and nondestructive compared with a stylus profilometer, and provided a larger field, needing no sample preparation, compared with atomic force microscopy. Orthodontic treatment resulted in significant increases in surface roughness and coefficient of friction for both brands of brackets. However, there was no significant difference by brand for new or retrieved brackets. These retrieval analysis results highlight the necessity of reevaluating the properties and clinical behavior of brackets during treatment to make appropriate treatment decisions. SCANNING 35: 265-272, 2013. © 2012 Wiley Periodicals, Inc.