title: The effects of distraction osteogenesis on mandibular growth in growing minipigs: a report on three-dimensional morphologic changes.
abstract: BACKGROUND
  The purpose of the study was to investigate the morphologic changes of distraction osteogenesis performed on the mandible in growing minipigs.
  
  
  METHODS
  Eighteen piglets were divided into four groups. In group A (n = 6), animals received unilateral osteotomy and the distractor device was activated for 2 weeks after a 1-week latency period. In group B (n = 6), animals underwent the osteotomy procedure and distractor placement. In group C (n = 3), animals received the distractor, and in group D (n = 3), only four reference pins were placed. After completion of distraction, the head portions were sent for computed tomography scanning. The coordinates of each selected mandibular landmark were recorded on three-dimensional computed tomographic reconstruction images for further mathematical linear and angular measurements to quantify morphologic changes.
  
  
  RESULTS
  The sagittal length related to gonial region was increased in group A but decreased in group B. Although all groups had the tendency of increased ramus width, it was only significant in group B. The distraction also reduced the gonial angle and elevated the ramus inclination to the Frankfort horizontal plane at the operated side. On the contrary, osteotomy alone opened the gonial angle and flattened the ramus inclination.
  
  
  CONCLUSIONS
  Distraction could lengthen the mandibles in growing minipigs by reducing the gonial angle and displacing the mandible posteriorly. This effect, which allows for developing a prominent gonial angle, could be further explored in treating syndromic patients with the deficiency in the gonial region. A greater amount of overcorrection should be considered while treating growing patients because the mandibular osteotomy procedure itself seems to retard the growth.
authors.affiliation: Department of Oral and Maxillofacial Surgery, National Taiwan University Hospital, School of Dentistry, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Hao-Hueng
authors.initials: HH
authors.lastname: Chang
authors.forename: Hui
authors.initials: H
authors.lastname: Tseng
authors.forename: Thomas Mon-Hsian
authors.initials: TM
authors.lastname: Hsieh
authors.forename: Chi-Ying
authors.initials: CY
authors.lastname: Huang
authors.forename: Yuan-Hou
authors.initials: YH
authors.lastname: Chen
authors.forename: Chao-Yu
authors.initials: CY
authors.lastname: Hsu
authors.forename: Wei-Ming
authors.initials: WM
authors.lastname: Cheng
authors.forename: Min-Huey
authors.initials: MH
authors.lastname: Chen
authors.forename: Shu-Ru
authors.initials: SR
authors.lastname: Chen
authors.forename: Chung-Chen Jane
authors.initials: CC
authors.lastname: Yao
mesh_terms: D000818:Animals; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008334:Mandible / Q000254:growth & development / Q000601:surgery*; D023421:Models, Animal; D019857:Osteogenesis, Distraction; D013552:Swine; D013556:Swine, Miniature; D014057:Tomography, X-Ray Computed