title: Comparison of gene expression of osteogenic factors between continuous and intermittent distraction osteogenesis in rabbit mandibular lengthening.
abstract: OBJECTIVE
  This study aimed to evaluate the effect of distraction frequency on the gene expression of osteogenic mediators in mandibular distraction osteogenesis.
  
  
  METHODS
  Forty adult New Zealand white rabbits were randomly assigned to the continuous and intermittent distraction groups. Unilateral mandibular osteotomy was performed and custom-designed manual-driven or autodriven distractor was bridged over the osteotomy segments. Animals were humanely killed at day 6, day 10, day 14, and day 21 after osteotomy. mRNA expression of the osteogenic mediators in the distraction regenerate was examined by real-time polymerase chain reaction.
  
  
  RESULTS
  The expression of transforming growth factor-beta(1) was significantly higher at day 6, and the expression of the bone morphogenetic protein-2 was significantly higher from day 6 to day 14, in the continuous distraction group.
  
  
  CONCLUSIONS
  High-frequency traction up-regulates the expression of osteogenic mediators contributing to the enhanced bone formation.
authors.affiliation: Discipline of Oral & Maxillofacial Surgery, Faculty of Dentistry, University of Hong Kong, Hong Kong, China. lwzheng@hku.hk
authors.forename: Li Wu
authors.initials: LW
authors.lastname: Zheng
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.forename: Lim Kwong
authors.initials: LK
authors.lastname: Cheung
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000032:analysis*; D004867:Equipment Design; D005786:Gene Expression Regulation / Q000235:genetics; D008334:Mandible / Q000601:surgery*; D010012:Osteogenesis / Q000235:genetics*; D019857:Osteogenesis, Distraction / Q000295:instrumentation / Q000379:methods*; D010027:Osteotomy / Q000379:methods; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000032:analysis*; D015854:Up-Regulation
chemical_list: D055396:Bone Morphogenetic Protein 2; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1