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

    CHEN Xi1,2,LIN Zhu1,ZHANG Xiaoª² Dong1

    1Department of Orthodontics,Qindu College of Stomatology,Fourth Military Medical University,Xi¬ðan 710033,China,2Department of Stomatology,First Affiliated Hospital,Xi¬ðan Jiaotong University,Xi¬ðan 710061,China

    ¡¾Abstract¡¿AIM£º 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£º Eight native healthy hybrid canines were randomly divided into four groups£º 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£º 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 fingerª²shape 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£º 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. ......