title: Effect of tooth displacement and vibration on frictional force and stick-slip phenomenon in conventional brackets: a preliminary in vitro mechanical analysis.
abstract: OBJECTIVE
  To evaluate the effects of tooth displacement and vibration on frictional force and stick-slip phenomenon (SSP) when conventional brackets were used with a levelling/alignment wire.
  
  
  METHODS
  The samples consisted of six groups (n = 10 per group) with combinations of tooth displacement (2mm lingual displacement [LD], 2mm gingival displacement [GD], and no displacement [control]) and vibration conditions (absence and presence at 30 Hz and 0.25 N). A stereolithographically made typodont system was used with conventional brackets and elastomeric ligatures. After application of artificial saliva, static/kinetic frictional forces (SFF/KFF) and frequency/amplitude of SSP were measured while drawing a 0.018-inch copper nickel-titanium (Cu-NiTi) archwire at a speed of 0.5mm/min for 5 minutes at 36.5 degree celsius. Two-way analysis of variance and independent t-test were performed.
  
  
  RESULTS
  Tooth displacement increased SFF and KFF (control < LD < GD, all P < 0.001) and reduced SSP frequency (control > [LD, GD], P < 0.01). Vibration reduced SFF, KFF, and SSP amplitude in the control group (P < 0.05, P < 0.05, and P < 0.001, respectively), but not in the LD and GD groups. SSP frequency was increased by vibration in the control, LD, and GD groups (all P < 0.001), and it was lower in the LD and GD groups than in the control group (P < 0.01).
  
  
  CONCLUSIONS
  When conventional brackets and a 0.018-inch Cu-NiTi archwire were used in the tooth displacement conditions (LD and GD), vibration did not significantly reduce SFF, KFF, or SSP amplitude.
authors.affiliation: *Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, **Department of Orthodontics, School of Dentistry, Kyung Hee University and.
authors.forename: Yu-Jin
authors.initials: YJ
authors.lastname: Seo
authors.affiliation: ***Department of Dental Biomaterials Science, School of Dentistry, Seoul National University, Seoul, South Korea.
authors.forename: Bum-Soon
authors.initials: BS
authors.lastname: Lim
authors.affiliation: *Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University.
authors.forename: Young Guk
authors.initials: YG
authors.lastname: Park
authors.affiliation: *Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University.
authors.forename: Il-Hyung
authors.initials: IH
authors.lastname: Yang
authors.affiliation: *Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University.
authors.forename: Seok-Joon
authors.initials: SJ
authors.lastname: Ahn
authors.affiliation: *Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University.
authors.forename: Tae-Woo
authors.initials: TW
authors.lastname: Kim
authors.affiliation: *Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, drwhite@unitel.co.kr.
authors.forename: Seung-Hak
authors.initials: SH
authors.lastname: Baek
mesh_terms: D003300:Copper; D003722:Dental Alloys; D003799:Dental Stress Analysis / Q000379:methods; D017276:Friction; D006801:Humans; D066298:In Vitro Techniques; D008310:Malocclusion / Q000628:therapy*; D008422:Materials Testing / Q000379:methods; D009532:Nickel; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D012464:Saliva, Artificial; D013193:Stainless Steel; D014025:Titanium; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D014732:Vibration
chemical_list: D003722:Dental Alloys; D012464:Saliva, Artificial; C040654:titanium nickelide; D013193:Stainless Steel; D003300:Copper; D009532:Nickel; D014025:Titanium