title: Histomorphometric comparison between continuous and discontinuous distraction osteogenesis.
abstract: BACKGROUND
  Experimental research on optimising the distraction protocol has been performed extensively in the past. However, relatively little research has been done on the rhythm of distraction. Findings in the orthopaedic literature showed that the outcome of distraction osteogenesis (DO) is positively influenced by increasing the rhythm of distraction. The aim of this study is to quantitatively compare continuous with discontinuous rhythms of distraction in rabbits.
  
  
  METHODS
  Tissue blocks of regenerated bone were harvested from thirty-eight young adult female New-Zealand White rabbits. After a latency period of three days, rabbits were subjected for eleven days to either single daily activation of the distractor at a rate of 0.9 mm/d, or triple daily activation at a rate of 0.9 mm/d, or continuous activation at a rate of 0.9 mm/d. After three weeks of consolidation, bone regenerates were analysed using histomorphometry.
  
  
  RESULTS
  The continuous DO group showed significantly (p<.01) more regenerate bone volume in the central part of the regenerate than the discontinuous DO groups. Higher osteoblastic activity was seen, as well as more blood vessels (p<.05). Bone volume and the number of blood vessels correlated significantly in the central part of the regenerate (p<.05). Also, the early mineral apposition rate (MAR) was higher than the late MAR (p<.05).
  
  
  CONCLUSIONS
  Continuous DO significantly accelerates bone formation when compared with discontinuous DO.
authors.affiliation: Department of Oral and Maxillofacial Surgery, The Netherlands.
authors.forename: U M
authors.initials: UM
authors.lastname: Djasim
authors.forename: B J
authors.initials: BJ
authors.lastname: Mathot
authors.forename: E B
authors.initials: EB
authors.lastname: Wolvius
authors.forename: J W
authors.initials: JW
authors.lastname: van Neck
authors.forename: K G H
authors.initials: KG
authors.lastname: van der Wal
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000502:physiology*; D005260:Female; D009295:Nasal Bone / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery*; D010012:Osteogenesis / Q000502:physiology; D019857:Osteogenesis, Distraction / Q000379:methods*; D010027:Osteotomy; D010507:Periodicity; D011817:Rabbits; D011897:Random Allocation; D018709:Statistics, Nonparametric