不同大小MO洞型复合树脂嵌体修复应力分布的有限元分析

目的 探讨复合树脂嵌体修复后,近中邻（meiso-occlusal,MO）洞型面深度及宽度变化对牙体抗力的影响。方法采用锥形束CT（cone beam computed tomography,CBCT）扫描,结合Mimics、Geomagic Studio逆向工程等软件,建立不同大小邻（II类）MO洞型树脂嵌体修复的三维有限元模型,用ANSYS Workbench软件网格划分并求解分析各模型内部牙体及嵌体在垂直、舌向45°加载下主应力峰值及Von-mises应力分布情况。结果大小不同的MO洞型以复合树脂嵌体修复时,龈壁对应处是嵌体的主要应力所在,洞底部近髓腔处是牙体的主要应力集中区。随着面洞型深度、宽度增加,牙体、修复体的最大应力峰值及Von-mises应力集中区分布范围加大;牙体Von-mises应力受洞型宽度的影响更大,嵌体的Von-mises应力受洞型深度增加影响更大。侧向加载大大增加了牙体和修复体的应力峰值。结论MO洞型以树脂嵌体修复后,洞深、洞宽度加大及侧向加载增加了牙体与嵌体的应力峰值,改变了应力集中区分布范围。

The finite element analysis of stress distribution in different size of MO cavities restored with composite resin inlays

PURPOSE: To explore the effect of different depth and width of meiso-occlusal (Class Ⅱ) cavity type on the tooth tissue resistance stress after restoration with composite resin inlays. METHODS: The 3-D finite element model of mandibular first molar with meiso-occlusal (ClassⅡ) cavity restored with composite resin inlay was established by using CBCT scanning and reverse engineering software Mimics, Geomagic Studio, and finite element analysis software ANSYS. Comparative analysis of restoration with different depth and width meiso-occlusal (ClassⅡ) cavity under the same load of perpendicular and 45° deviation was explored, and finally the main stress and Von-mises stress changed as well as stress distribution were analyzed. RESULTS: The main stress was located in the gingival wall opposite to the inlay, while the major stress concentration area of the tooth was distributed near the canal at the bottom of the cavity. With the increase of the depth and width, the main stress and Von-mises stress distribution areas of tooth were getting larger. The Von-mises stress of tooth was influenced by the width variation of the cavity, while that depth change of cavity was affected by Von Mises stress of the inlay. CONCLUSIONS: With the increase of the depth and width of the cavity as well as lateral loading force, the peak stress of tooth with inlays increased and the distribution of stress concentration is modified after meiso-occlusal (ClassⅡ) cavity being inlayed with composite resin.