title: Frictional and mechanical properties of diamond-like carbon-coated orthodontic brackets.
abstract: 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.
authors.affiliation: Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Muguruma
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iijima
authors.forename: William A
authors.initials: WA
authors.lastname: Brantley
authors.forename: Susumu
authors.initials: S
authors.lastname: Nakagaki
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Endo
authors.forename: Itaru
authors.initials: I
authors.lastname: Mizoguchi
mesh_terms: D002244:Carbon; D003799:Dental Stress Analysis; D018130:Diamond; D004548:Elasticity; D017276:Friction; D006245:Hardness Tests; D006801:Humans; D007700:Kinetics; D008297:Male; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013059:Spectrum Analysis, Raman / Q000379:methods; D013193:Stainless Steel
chemical_list: D013193:Stainless Steel; D002244:Carbon; D018130:Diamond