Bone regeneration after radiotherapy in an animal model.
OBJECTIVE
The study aimed to evaluate dosage-dependent effects of irradiation on bone regeneration and established a radiation-compromised rabbit model of mandibular distraction osteogenesis.


METHODS
Twenty-three rabbits were divided randomly into 7 groups. Group A served as the control group, whereas experimental groups B, C, D, E, F, and G received preoperative irradiation at doses of 6.5, 7.0, 7.5, 8.0, 8.5, and 9.0 Gy, respectively, for 5 fractions. After 1 month, all rabbits underwent osteotomy and distraction osteogenesis with 7 days of latency, 11 days of active distraction at a rate of 0.9 mm/d, and 4 weeks of consolidation; rabbit mandibles were subsequently subjected to histologic, radiographic, and micro-computed tomography analysis.


RESULTS
With increasing doses of irradiation, bone regeneration was markedly hampered. Radiographically, the high-dose groups (8.5 and 9.0 Gy) presented obscure cortical lines. Histologically, in the 8.5- and 9.0-Gy groups, cortical bones were not completely formed, and in the medullary cavity, there existed a large amount of fibrous tissue.


CONCLUSIONS
Radiotherapy compromises bone regeneration during distraction osteogenesis, and the adverse effect is dose dependent.
Zhang
Wen Biao
WB
Department of Oral & Maxillofacial Surgery, Faculty of Dentistry, The University of Hong Kong, Hong Kong, People's Republic of China.
Zheng
Li Wu
LW
Chua
Denial
D
Cheung
Lim Kwong
LK
D000818:Animals; D015519:Bone Density / Q000528:radiation effects; D001853:Bone Marrow / Q000473:pathology / Q000528:radiation effects; D001861:Bone Regeneration / Q000528:radiation effects*; D016723:Bone Remodeling / Q000528:radiation effects; D002113:Calcification, Physiologic / Q000528:radiation effects; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D008334:Mandible / Q000473:pathology / Q000528:radiation effects / Q000601:surgery*; D023421:Models, Animal; D010012:Osteogenesis / Q000528:radiation effects; D019857:Osteogenesis, Distraction; D010027:Osteotomy; D011300:Preoperative Care; D011817:Rabbits; D011879:Radiotherapy Dosage; D011897:Random Allocation; D013997:Time Factors; D055114:X-Ray Microtomography