减阻牵张矫治法正畸牙快速移动牙周组织改建的研究

目的: 研究减阻牵张矫治法对正畸移动牙牙周组织结构的影响,为该方法的临床应用奠定理论基础.方法: 将 8只杂种犬随机分为8,6,3,2 wk四组,拔除两侧第2前磨牙,随机选择一侧为实验侧,另一侧为常规方法对照侧,两侧最长加力时间均为2 wk,随后分别固定保持6,4,1,0 wk时,取材观察移动牙牙周组织的变化.结果: 2 wk实验组移动牙张力侧牙周膜较对照侧明显增宽,新生骨小梁呈指状突起相互连接,并与作用力方向一致;压力侧透明性变组织少,减阻间隔骨吸收活跃;3 wk实验组张力侧新生骨小梁变得粗大,对照侧牙周膜已恢复正常,骨沉积线较明显;两组压力侧透明性变区已局限;8,6 wk组实验侧与同组对照侧相比,移动牙张力侧、压力侧牙周膜的组织结构无明显差异.结论:减阻牵张措施可提高牙齿移动速度;加快牙周组织改建;无不可逆的组织损伤.

Method of educing resistance and distraction in periodontal tissue remodeling of rapidly moved orthodontic teeth

AIM: To study the role of the method of reducing resistance and distraction in periodontal tissue remodeling of rapidly moved orthodontic teeth and to provide the theoretic basis for its clinical application.METHODS: Eight native healthy hybrid canines were randomly divided into four groups: 8,6,3 ,and 2 wk groups respectively.The second premolars on both sides were extracted in each dog and one side was randomly selected as experimental side while the other as control side.The longest time of active force delivery was two weeks on each side,followed respectively by 6,4,2 and 0 wk retention period.The canines were sacrificed at the designated time points and the periodontal tissues of the moved teeth were harvested for HE staining and were observed under light microscope.RESULTS: In the 2 wk group,the periodontal ligament (PDL)on the tension side widened significantly compared with that on the control side.New bone grew in finger-shape protuberances and linked to each other and the direction was the same as the force delivered.On the pressure side,the PDL,hyalinized with interseptal bones,absorbed actively.In the 3 wk group,the striated bone on the tension side became stronger while the PDL on the control side almost recovered to normal with a significant laminar.On the pressure side,PDL hyalinization became more limited.There was no significant PDL histological difference between the experimental side and the control side in the 8 wk and 6 wk groups.CONCLUSION: The tooth movement can be accelerated by the method of reducing resistance and distraction.The new method can improve the periodontium structure remodeling without permanent PDL damage.