牙根吸收发生早期指征的动物实验研究

目的:针对动物实验中观察到牙根吸收发生早期出现的尖周稀疏聚集期,研究其在牙根吸收发生进程中的作用。方法:选用成年杂种雄性犬5只,以其中3只犬的全部上颌切牙和2只犬的一侧上颌切牙为实验组(共24个);以2只犬的另一侧上颌切牙和5只犬的全部下颌切牙为对照组(共36个)。以种植钉为支抗,实验组牙齿施加约350 g的持续性压低重力;对照组处于非加力状态。通过X线片观察,研究尖周稀疏区在实验牙出现的情况,以及牙根吸收的发生情况。另选用实验犬3只,以A区切牙为实验组,B区切牙为对照组,按上述方法对实验组牙齿进行过大矫治力压低处理,当观察到实验组牙齿有尖周稀疏区出现时,处死动物,制作石蜡切片,进行HE染色,观察尖周区的组织形态学变化。结果:实验组21个牙齿(占87.5%)有尖周稀疏聚集期出现,出现的时间在持续性压低重力后(2.6±0.54)周;对照组则均无尖周稀疏区出现,与实验组相比有显著性差异(P<0.05),实验组牙齿继续压低处理8周,24个牙中有17个观察到有变短性牙根吸收情况。其中15个有尖周稀疏聚集期,占根尖吸收牙总数的88.2%,2个无尖周稀疏聚集期,占牙根吸收总数的11.2%,两者相比差异有统计学意义(P<0.05)。组织形态学观察可见,在尖周稀疏聚集期根尖未见明显牙根吸收,根尖所对应的牙槽骨区域则出现明显的骨吸收情况,呈空泡、脂肪样变性。结论:尖周稀疏聚集期的出现为持续性压低重力作用的结果,可能为牙根吸收发生过程的早期阶段。在这一阶段采取适当措施,可能阻断牙根吸收的发生。

Preliminary experimental study of the role of periapical radiolucent areas in root resorption process

AIM: To investigate the effect of peripical radiolucent area occurrence on the root resorption process in an animal model.METHODS: Five male dogs were used in this study.24 teeth(all maxillary incisors in 3 dogs and one side of maxillary insicors in 2 dogs) were assigned to experimental group,while 36 teeth were assigned to control group(one side of maxillary insicors in 2 dogs and all mandibular incisors in 5 dogs).Heavy intrusive force of 350 g was imposed to the experimental teeth with mini-implant as anchorage.The control teeth were not enforced.Then the peripical radiolucency and development of the resorption were observed by X-ray periapical films.Another 3 dogs were used to investigate the morphologic change of the teeth in periapical radiolucency period.RESULTS: In experimental group,the periapical radiolucent area was detected in 21 teeth(87.5%).It was found(2.6±0.54)w after force engagement.No periapical radiolucency was observed in all the control teeth,which was significantly different from the experimental teeth(P<0.05).When the heavy intrusive force was maintained for 8 weeks,root resorption was detected in 17 teeth in experimental group.By histomorphology study,it was shown that no significant resorption appeared in the peripical radiolucent area,while the apical region of alveolar bone showed apparent resorption,vacuolization and fatty degeneration.CONCLUSION: The periapical radiolucency occurrence was due to the continuous heavy intrusive force,and was possibly the initial period of root resorption process.Taking appropriate measures at this stage might block the occurrence of root resorption.