Abstract: Objective: To explore the electrophysiological changes of IAN during DO after irradiation. Methods: 12 Chinese dogs were randomly divided into 3 groups-GroupA,B,C.Each group owned 4 dogs individually. GroupA received a unilateral irradiation from 60Co in the mandible with a total dose of 22.8Gy in four 5.7Gy fractions (equivalent to 50Gy/25 fractions) within two weeks. GroupB receieved a unilateral irradiation from ⁶⁰Co in the mandible with a total dose of 24.8Gy in four 6.2Gy fractions (equivalent to 60Gy/30 fractions) within two weeks. GroupC receieved a unilateral irradiation from 60Co in the mandible with a total dose of 27.2Gy in four 6.8Gy fractions (equivalent to 70Gy/35 fractions) within two weeks. Bilateral coticotomy was made 3 months after completion of irradiation. After a 1-week latency period bone distraction was activated at a rate of 0.5mm twice daily for 10 days, followed by a consolidation phase of 8 weeks. During the experiment,8 time-points was chosed to examine,record and analyze the evoked potentials(EP) of IAN:pre-irradiation,post-irradiation, pre-distraction, the sixth day amid distraction, post-distraction, the 2th, 4th, 8th week during consolidation.The neural electricity tester was used to each group to carry out the electrophysiologic analysis. Results: The action potential(AP) of IAN showed corresponding change during the irradiation and distraction process in groupA and B,but groupC did not got integrated AP. Conclusion: Low dose irradiation cannot influence the electrophysiologic change of the IAN during DO while high dose irradiation can severely influence it.

Key words: Distraction osteogenesis(DO), Irradiation , Inferior alveolar nerve(IAN), Action potential(AP)