后牙牙周附着与牙齿振动频率和动度的有限元分析

Three-dimensional dynamic finite element analysis of the vibration of posterior tooth related to periodontal attachment

目的分析上颌第一磨牙牙周附着水平与牙齿固有振动频率的关系,为定量描述牙周附着水平和牙齿动度等牙周组织的生理、病理状况提供理论依据。方法采用CT图像和3D-doctor图像成型软件对上颌后牙进行三维重建,在此基础上构建反映牙周附着水平和牙周组织弹性特征的动态三维有限元模型,对牙周附着水平与牙齿固有振动频率和动度的相互关系进行动力学分析。结果上颌第一磨牙振动由多阶振动所构成,前四阶振动为主要的振动形式,振型方向与临床常见的牙齿动度方向基本一致。随着牙槽骨的吸收和牙周附着水平的降低,前四阶振动频率逐渐降低,下降趋势与牙周附着水平相关。结论牙周附着水平与振动频率相关,通过牙齿振动频率可以描述出牙周附着水平的变化,牙周附着水平不同牙齿动度可以通过不同方向的振动频率和振型定量表达。

Objective To investigate the relationship between the level of periodontal attachment and the natural frequency of a maxillary first molar, in order to describe the level of periodontal attachment and assess the condition of periodontium. Methods In this study, 3 - D structure of a maxillary first molar was reconstructed by software 3D - Doctor using CT image. The dynamic finite element models of the tooth at the different level of periodontal attachment based on the elastic characteristic of the periodontal ligament were constructed. The dynamics analyses to these models were made with dynamic finite element method. Results The results demonstrated that the vibration of the maxillary first molar could be described by muhimode frequency oscillations. The first four modes were the dominant, and the shapes of the vibration were consistent with the directions of the tooth mobility. The frequencies of the tooth decreased with the lost alveolar bone and the recession of periodontal attachment. Conclusion It suggested that the vibration frequencies of the tooth changed with the level of periodontal attachment. The level of periodontal attachment and the tooth mobility can be predicted definitely through the frequencies and the shapes of the tooth vibration.