title: Distraction-like phenomena in maxillary bone due to application of orthodontic forces in ovariectomized rats.
abstract: BACKGROUND
  Orthodontic forces may not only influence the dentoalveolar system, but also the adjacent and surrounding cortical bone.
  
  
  OBJECTIVE
  Since there is very limited information on this issue, we aimed to study the possible changes in maxillary cortical bone following the application of heavy orthodontic forces in mature normal and osteoporotic rats.
  
  
  METHODS
  Twenty-four 6-month-old female rats were selected and divided into an ovariectomized group and a normal group. In both groups, the rats were subjected to a 60 grFNx01 orthodontic force on the upper right first molar for 14 days.
  
  
  RESULTS
  In both groups, histological sections showed that the application of this force caused hypertrophy and fatigue failure of the cortical maxillary bone. The osteogenic reaction to distraction is expressed by the formation of subperiosteal callus on the outer bony side, resembling that seen in distracted bones.
  
  
  CONCLUSIONS
  From this study we concluded that heavy experimental orthodontic forces in rats affect the maxillary cortical bone. The osteogenic reaction to these forces, expressed histologically by subperiosteal callus formation, is similar to that seen in distraction osteogenesis models.
authors.affiliation: Department of Orthodontics, School of Dentistry, University of Athens, Greece.
authors.forename: Apostolos I
authors.initials: AI
authors.lastname: Tsolakis
authors.forename: Lubna
authors.initials: L
authors.lastname: Khaldi
authors.forename: Ilias
authors.initials: I
authors.lastname: Bitsanis
authors.forename: Margarita
authors.initials: M
authors.lastname: Makou
authors.forename: Ismene A
authors.initials: IA
authors.lastname: Dontas
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002146:Bony Callus / Q000473:pathology; D005260:Female; D015576:Hyperostosis / Q000473:pathology; D008437:Maxilla / Q000473:pathology*; D008963:Molar / Q000473:pathology; D009969:Orthodontic Wires; D010012:Osteogenesis / Q000502:physiology*; D019857:Osteogenesis, Distraction; D010024:Osteoporosis / Q000503:physiopathology; D010052:Ovariectomy; D010521:Periosteum / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000295:instrumentation*