Brachytherapy-Mediated Bone Damage in a Rat Model Investigating Maxillary Osteoradionecrosis

• Published in: Archives of otolaryngology--head & neck surgery Vol. 138; no. 2; pp. 167 - 171
• Main Authors: Armin, Bob B, Hokugo, Akishige, Nishimura, Ichiro, Tamplen, Matthew, Beumer, John, Steinberg, Michael L, Abemayor, Elliot, Nabili, Vishad
• Format: Journal Article
• Language: English
• Published: Chicago, IL American Medical Association 01.02.2012
• Subjects: Animal models; Animals; Benign; Biological and medical sciences; Bone diseases; Bones; Brachytherapy; Brachytherapy - methods; Computed tomography; Disease Models, Animal; Diseases of the osteoarticular system; Fractures; Head and neck; Imaging, Three-Dimensional; Injuries; Male; Mandible; Maxilla; Maxilla - diagnostic imaging; Maxilla - radiation effects; Medical sciences; Microenvironments; Molars; Mucosa; Osteoradionecrosis; Osteoradionecrosis - diagnostic imaging; Osteoradionecrosis - prevention & control; Otorhinolaryngology. Stomatology; Prospective Studies; Radiation; Radiation Injuries, Experimental; Radiation therapy; Radiotherapy; Rats; Rats, Sprague-Dawley; Rodents; Teeth; Tooth Extraction; Tooth Socket - diagnostic imaging; Tooth Socket - radiation effects; Vascular bone diseases; X-Ray Microtomography; Rat; Diseases of the osteoarticular system; Rodentia; Maxillary; Osteonecrosis; Radiotherapy; Vertebrata; Mammalia; Treatment; Animal; Lesion; Bone; Curietherapy
• ISSN: 0886-4470; 2168-6181; 1538-361X; 1538-361X; 2168-619X
• DOI: 10.1001/archoto.2011.1176

OBJECTIVES To assess clinical and radiologic findings from targeted radiotherapy to the rat maxilla and to compare findings with a recently developed rat model of mandibular osteoradionecrosis (ORN). DESIGN A prospective, controlled animal study. SUBJECTS Ten male Sprague-Dawley rats were divided into an experimental group receiving catheter-assisted high-dose-rate brachytherapy (n = 6) and a control group with catheter-assisted sham therapy (n = 4). INTERVENTIONS The second left maxillary molar was extracted 1 week after radiation, and the maxilla was harvested 3 weeks after dental extraction. MAIN OUTCOME MEASURE We used a standardized method with micro–computed tomography to determine the ratio of bone volume to total volume of the dental extraction socket. RESULTS On the gross clinical examination, all rats had mucosal coverage of the dental extraction site, whereas only the brachytherapy group demonstrated scarring of the mucosa. The median bone volume to total volume was 0.21 for the brachytherapy group and 0.49 for the control group (P = .01). CONCLUSIONS Similar to the mandible, the maxilla is susceptible to radiogenic bone injury as demonstrated by the significant decrease in bone volume of the radiated dental extraction socket. Despite radiologic similarities to mandibular ORN in the rat model, the maxilla demonstrated a more benign clinical course with a complete absence of bone exposure. Differences in the maxillary bone and microenvironment of the maxilla compared with the mandible may explain the subclinical response to radiation and lower incidence of maxillary ORN seen in patients. This maxillary model can be combined with our high-dose-rate mandibular ORN model to investigate these differences and better understand ORN.