title: Onset of mandible and tibia osteoradionecrosis: a comparative pilot study in the rat.
abstract: OBJECTIVE
  Osteoradionecrosis (ORN) is common in the jaws after radiotherapy. We hypothesized that the mandible is more susceptible to ORN than the tibia, based on site disparity in hypoxic, hypocellular, and hypovascular tissue breakdown.
  
  
  METHODS
  Twelve rats received 50 Gy irradiation to mandible or tibia; 4 of the rats further received minor surgical trauma to the irradiated sites. Structural and cellular skeletal changes were assessed with computerized tomography, histology, and immunostaining.
  
  
  RESULTS
  Mandible developed ORN with 70% mean bone loss 10 weeks after irradiation (P < .05), whereas tibia was structurally and radiologically intact 20 weeks after irradiation. Hypocellularity, hypoxia, and oxidative stress were higher in irradiated mandible (P < .001) than tibia (P < .01) but vascular damage was similar at both skeletal sites. Combined effects of radiation and minor trauma promoted mandibular alveolar bone loss and tibial fracture.
  
  
  CONCLUSIONS
  ORN has a more rapid onset in mandible than in tibia in the rat.
authors.affiliation: Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Monika
authors.initials: M
authors.lastname: Damek-Poprawa
authors.forename: Stefan
authors.initials: S
authors.lastname: Both
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Wright
authors.forename: Amit
authors.initials: A
authors.lastname: Maity
authors.forename: Sunday O
authors.initials: SO
authors.lastname: Akintoye
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D007150:Immunohistochemistry; D008334:Mandible / Q000000981:diagnostic imaging / Q000528:radiation effects*; D010025:Osteoradionecrosis / Q000000981:diagnostic imaging / Q000473:pathology*; D010865:Pilot Projects; D011829:Radiation Dosage; D051381:Rats; D013977:Tibia / Q000000981:diagnostic imaging / Q000528:radiation effects*; D055114:X-Ray Microtomography