放射照射后牵张成骨下牙槽神经电生理变化的实验研究

目的:探讨放射照射后牵张成骨过程中下牙槽神经的电生理变化。方法:12只中国杂种犬随机分为A、B、C三组,A、B、C组为实验组,每组4只,单侧下颌A组接受总剂量22.8 Gy,5.7 Gy/4次/2周(相当于50 Gy/25次/5周),B组接受总剂量24.8 Gy,6.2 Gy/4次/2周(相当于60 Gy/30次/6周),C组接受总剂量27.2 Gy,6.8 Gy/4次/2周(相当于70 Gy/35次/7周)的⁶⁰Co放射照射。放射照射完成后3个月时,各组分别于照射区下颌骨切开,置入牵张器。经五天延迟期,以0.5 mm/次,2次/d的速度牵张下颌骨10 d,然后固定8周。分别于放疗前、放疗结束后、牵张前、牵张第6天、牵张完成即时、固定第2,4,8周8个时间点以神经电生理检诊仪测定神经电生理变化。结果:50 Gy和60 Gy组牵张过程中动作电位呈现适应性变化,70 Gy组不能完整导出动作电位。结论:低剂量放射照射不会单独对牵张过程中神经电生理变化造成影响,高剂量放射照射不能完成电生理检查。

Experimental Study of Distraction Osteogenesis in the Irradiated Dog Mandible: the Electrophysiological Changes of IAN.

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.