Beagle犬磨牙压低过程中牙根吸收与压低力值的关系

Relationship between root resorption and intrusive force during maxillary molar intrusion in Beagle dogs

背景:牙根吸收是牙齿压低过程中常见的并发症,压低力值大小的选择和根吸收的发展规律是临床医生比较困惑和关注的问题。目的:探讨不同力值对Beagle犬磨牙压低过程中牙根吸收的影响。方法:以Beagle犬为观察对象,建立实验性牙根吸收动物模型,使用微种植钉压低技术,设计不同的力值压低磨牙。通过形态学、苏木精-伊红染色、免疫组织化学和Western blot生物学方法,观察牙根表面吸收情况及牙周组织中核因子κB受体活化因子配体及骨保护素(RANKL/OPG)的表达变化。结果与结论:①苏木精-伊红染色结果表明,150-200 g的压低力值,根吸收局限在牙槽骨和牙骨质;250 g加力组根尖区周围的牙本质也发生了吸收;②免疫组化结果,对照组和加力150 g组RANKL/OPG比值接近,加力200 g组和加力250 g组RANKL/OPG比值呈增加趋势;组间两两比较,除了对照组和加力150 g组,对照组和加力200 g组,其余差异均有显著性意义(P <0.05);③Western blot结果显示,RANKL/OPG比值在加力3-14 d呈增长趋势,14 d后比值有所下降;组间两两比较,除加力3 d组和7 d组差异无显著性意义外,其余差异均有显著性意义(P <0.05);④表明随着加力力值的增大,根吸收程度加重,过大的压低力,会造成不可逆性的牙根吸收,150 g力值是推荐的磨牙压低力值;RANKL/OPG比值可作为一种生物学指标,用于早期诊断根吸收。

BACKGROUND:Root resorption is a common complication in the process of tooth intrusion.The choice of intrusion force and the development of root resorption are issues that clinicians are more confused and concerned about.OBJECTIVE:To investigate the effect of different force values on root absorption during molar intrusion in Beagle dogs.METHODS:In this study,the Beagle dog was used as the research object to establish the animal model of experimental root resorption.Through morphology,hematoxylin-eosin staining,immunohistochemistry and western blot,the root surface absorption and the expression of osteoprotegerin(OPG)/receptor activator for nuclear factor kappa B ligand(RANKL)in periodontal tissue were observed.RESULTS AND CONCLUSION:Hematoxylin-eosin staining results showed that root absorption was limited to alveolar bone and cementum at a intrusive force of 150-200 g.In the 250 g group,dentin absorption also occurred around the root tip.Immunohistochemical results showed similar RANKL/OPG ratios in the control group and the 150 g group,and the RANKL/OPG ratio in the 200 g group and the 250 g group presented an increasing trend.Pairwise comparison between the two groups showed statistically significant differences except for the control group and the 150 g group as well as the control group and the 200 g group(P<0.05).Western blot results showed that RANKL/OPG ratio showed an increasing trend during 3-14 days,and after 14 days,the ratio went down.Pairwise comparison between groups showed that there were statistically significant differences among all the groups except for the 3 days and 7 days groups(P<0.05).To conclude,with the increase of the additive force,the degree of root absorption will be aggravated.Excessive intrusive force will result in irreversible root absorption.A 150 g force is the recommended intrusive force for molar intrusion.RANKL/OPG ratio can be used as a biological indicator for the early diagnosis of root absorption.