title: [Evaluation of three dimensional orthodontic force produced by magnet of fix appliance].
abstract: OBJECTIVE
  To analyze the feature and magnitude of three dimensional orthodontic force produced by the magnet of fix appliance.
  
  
  METHODS
  Forces detected by universal fatigue test system included the attractive and repulsive,the inclined and rotated orthodontic forces of two magnets in different air gaps, and the integrated inclined and rotated orthodontic forces of two magnets and NiTi wire.
  
  
  RESULTS
  The attractive and repulsive forces of two magnets were 4.68 to 0.45 N and 3.00 to 0.40 N respectively in the air gaps of 0 to 5 mm. The inclined orthodontic forces were 1.54 to 1.67 N, 0.63 to 0.69 N, 0.47 to 0.54 N when the magnets were vertically inclined 10 degrees to 40 degrees in the air gaps of 0, 1, 2mm. The rotated orthodontic forces were 0.97 to 1.32 N, 0.53 to 0.59 N, 0.39 to 0.48 N when the magnets were horizontally rotated 10 degrees to 40 degrees in the air gaps of 0, 1, 2mm. The integrated orthodontic force of two magnets and 0.014-inch NiTi wire was 0.32 to 0.5 N when the magnets was vertically inclined 10 degrees to 40 degrees in the air gap of 4 mm. The integrated orthodontic force of two magnets and 0.012-inch NiTi wire was 0.32 to 0.39 N when the magnets were horizontally rotated 10 degrees to 40 degrees in the air gap of 3 mm.
  
  
  CONCLUSIONS
  Magnets made into orthodontic brackets to some extent could replace the mechanical orthodontic force produced by orthodontic wires and elastics.
authors.affiliation: Department of Orthodontics, China Medical University, Shenyang 110002, China. coco_7737@sohu.com
authors.forename: Xin
authors.initials: X
authors.lastname: Dai
authors.forename: Zhi-ming
authors.initials: ZM
authors.lastname: Hou
authors.forename: Ge
authors.initials: G
authors.lastname: Yao
authors.forename: Jing-long
authors.initials: JL
authors.lastname: Wen
mesh_terms: D006801:Humans; D059346:Magnets; D016910:Orthodontic Brackets; D009969:Orthodontic Wires