低强度超声预防颌骨放射性骨坏死的实验研究

The prevention of canine osteoradionecrosis of jaws by low-intensity ultrasound

目的 证实低强度超声对颌骨放射性骨坏死（osteoradionecrosis of jaws,ORNJ）的预防作用.方法 25只实验犬按照随机数字表法分为实验组（20只）和空白对照组（5只）.实验组接受X射线照射后,又分为实验A组（10只）和实验B组（10只）;空白对照组不接受射线照射.放疗结束后1个月,拔除所有动物下颌双侧第四前磨牙,实验B组立即予以低强度超声处理20 d,实验A组和空白对照组不做处理.拔牙后2个月,确定ORNJ的形成并比较实验A、B组ORNJ的发生率.通过影像学观察和病理学检测比较实验A、B组间照射区下颌骨骨质变化.结果 实验A、B组所有动物均发生ORNJ.影像学观察尽管实验A组和实验B组照射区骨密度均低于空白对照组,但实验B组骨密度明显好于实验A组.微型CT显示实验B组骨小梁的骨体积分数、骨小梁厚度、骨表面积和骨体积的比值和骨小梁数量分别为（0.187±0.029）％、（0.160±O.039） μm、（12.536±2.558）/mm、（1.227±0.192）/mm,均显著大于实验A组相对应值[分别为（0.103±0.014）％、（0.069±0.013） μm、（5.598±0.731）/mm、（0.522±0.064）/mm]（P＜0.05）.微血管密度检测实验B组大于实验A组.结论 应用低强度超声无法阻止ORNJ的形成,但能明显改善ORNJ的症状.

Objective To investigate the preventive effect of low-intensity ultrasound on osteoradionecrosis of jaws （ORNJ）.Methods Twenty-five canines were randomly divided into experimental group （n=20）and control group （n=5）.The canines in experimental group received radiation exposure,and then were randomly subdivided into group A （n=10）and group B （n=10）.Control group did not undergo radiotherapy.One month after radiotherapy,the fourth mandibular premolars of all animals were extracted.Group B was immediately treated by low-intensity ultrasound for twenty days,group A and control group did not receive any treatment.Two months after tooth extraction,the formation of ORNJ was determined and the occurrence rate of ORNJ was compared between group A and B.The microstructure of the mandible and changes in microvascular density in group A and B were evaluated and compared with those of control group.Results All animals in group B and group A developed ORNJ after prophylactic ultrasound was applied for twenty days.Although the imaging examination of bony density of group A and B were lower than normal animals in control group,bone density in group B was significantly better than group A.Micro-CT showed that the trabecular bone volume fraction,trabecular thickness,bone surface/bone volume and trabecular number in group B were respectively （0.187±0.029）%,（0.160±0.039） μm,（12.536±2.558）/mm,（1.227± 0.192）/mm,which were all greater than group A [（0.103±0.014）%,（0.069±0.013） μm,（5.598±0.731）/mm,（0.522 ± 0.064）/mm）] （P〈0.05）.Conclusions Although the preventive application of low intensity ultrasound can not prevent the formation of ORNJ,but can significantly improve the symptoms of ORNJ.