OBJECTIVE: The objective of this study was to explore the probability of distraction osteogenesis (DO) in the irradiated dog mandible after 60-Gy irradiation. STUDY DESIGN: Fourteen Chinese dogs were randomly divided into 2 groups. Twelve dogs received a preoperative unilateral irradiation from (60)Co (group R) in the mandible with a total dose of 24.8 Gy in four 6.2-Gy fractions (biologically equivalent to 60 Gy/25 fractions). The other 2 dogs without irradiation served as the control (group C). Bilateral corticotomies were made 6 months after completion of irradiation. Bone distraction was activated at a rate of 0.5 mm twice daily for 10 days after a 1-week latency period, followed by a consolidation phase of 8 weeks. The inferior alveolar nerve (IAN) underwent electrophysiologic analysis. Dog mandibles were subsequently subjected to histologic and radiographic analysis. RESULTS: All the animals had successful distractions. After 8 weeks of consolidation, no difference was found between the percentage area of new bone in both groups. New bone was more mature and organized in group C than in group R. The action potential of IAN showed corresponding alternation during the irradiation and distraction process. CONCLUSIONS: Based on this study it seems that DO may be feasible in dog mandible under 60-Gy irradiation. Further research is indicated.
OBJECTIVE: The objective of this study was to explore the probability of distraction osteogenesis (DO) in the irradiated dog mandible after 60-Gy irradiation. STUDY DESIGN: Fourteen Chinese dogs were randomly divided into 2 groups. Twelve dogs received a preoperative unilateral irradiation from (60)Co (group R) in the mandible with a total dose of 24.8 Gy in four 6.2-Gy fractions (biologically equivalent to 60 Gy/25 fractions). The other 2 dogs without irradiation served as the control (group C). Bilateral corticotomies were made 6 months after completion of irradiation. Bone distraction was activated at a rate of 0.5 mm twice daily for 10 days after a 1-week latency period, followed by a consolidation phase of 8 weeks. The inferior alveolar nerve (IAN) underwent electrophysiologic analysis. Dog mandibles were subsequently subjected to histologic and radiographic analysis. RESULTS: All the animals had successful distractions. After 8 weeks of consolidation, no difference was found between the percentage area of new bone in both groups. New bone was more mature and organized in group C than in group R. The action potential of IAN showed corresponding alternation during the irradiation and distraction process. CONCLUSIONS: Based on this study it seems that DO may be feasible in dog mandible under 60-Gy irradiation. Further research is indicated.