title: Biomechanics of mandibular distractor orientation: an animal model analysis.
abstract: OBJECTIVE
  Previous reports suggest that device orientation may be one of the most important parameters affecting the successful application of osteodistraction. However, only computer models or cadaver mandibles have been used to investigate the biomechanical effects of device orientation during mandibular distraction osteogenesis. Therefore, the purpose of this study was to compare two different device orientations during bilateral mandibular osteodistraction in an animal model.
  
  
  METHODS
  Fifteen skeletally mature beagle dogs underwent 10 mm of bilateral mandibular lengthening by intraoral distraction osteogenesis. The dogs were divided into two groups based on the orientation of the distraction device relative to the mandible when viewed occlusally: either parallel to the body of the mandible (group I) or parallel to the axis of distraction (group II). The effects of device orientation during osteodistraction were then analyzed clinically, radiographically, and by dental cast measurements.
  
  
  RESULTS
  Distractors oriented parallel to the body of the mandible caused an increase in the anterior width of the proximal mandibular segments. This lateral displacement of the proximal segments led to several clinical complications, including screw fixation failure and bone resorption under the fixation plates. These effects were minimized when the device was oriented parallel to the axis of distraction.
  
  
  CONCLUSIONS
  Device orientation plays an important role when applying distraction osteogenesis in a clinical setting. Although other intrinsic and extrinsic factors affect the success of osteodistraction, the devices should be oriented parallel to the axis of distraction to minimize adverse biomechanical effects during bilateral mandibular lengthening.
authors.affiliation: Department of Orthodontics, TAMUS-Baylor College of Dentistry, Dallas, TX 75266-0677, USA. jasoncope@orthodontist.net
authors.forename: J B
authors.initials: JB
authors.lastname: Cope
authors.forename: M L
authors.initials: ML
authors.lastname: Samchukov
authors.forename: A M
authors.initials: AM
authors.lastname: Cherkashin
authors.forename: L M
authors.initials: LM
authors.lastname: Wolford
authors.forename: P
authors.initials: P
authors.lastname: Franco
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001860:Bone Plates; D003766:Dental Occlusion; D004285:Dogs; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging / Q000502:physiology / Q000601:surgery*; D003765:Models, Dental; D019857:Osteogenesis, Distraction / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D011861:Radiography, Dental