Damek-Poprawa, MonikaBooth, StefanWright, Alexander C.Maity, AmitAkintoye, Sunday O2023-05-222023-05-222013-02-012018-06-28https://repository.upenn.edu/handle/20.500.14332/9389Abstract Objectives Osteoradionecrosis (ORN) is common in the jaws following radiotherapy. We hypothesized that mandible is more susceptible to ORN than tibia based on site-disparity in hypoxic-hypocellular-hypovascular tissue breakdown. Study Design Twelve rats received 50 Gy irradiation to mandible or tibia; 4 of 12 rats further received minor surgical trauma to the irradiated sites. Structural and cellular skeletal changes were assessed with computer tomography, histology and immunostaining. Results Mandible developed ORN with 70% mean bone loss 10 weeks post-irradiation (p < 0.05) while tibia was structurally and radiological intact for 20 weeks post-irradiation. Hypocellularity, hypoxia and oxidative stress were higher in irradiated mandible (p < 0.001) than tibia (p < 0.01) but vascular damage was similar at both skeletal sites. Combined effects of radiation and minor trauma promoted mandibular alveolar bone loss and tibial fracture Conclusion ORN has a more rapid onset in mandible relative to tibia in the ratThis manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/OsteoradionecrosisHypovascularHypocellularRadiotherapyOxidative stressAnimal modelDentistryArticle