Objective: To study the stress distribution of rigid fixed bridge in deletion of first molor in mandibular. Methods: Two-dimensional images of maxillary, mandibular teeth and supporting tissue of healthy people were scanned by CT. With the buccolingual diameter of pontic at 100% 90% 66.7% 50% of normal separately or of both pontic and second right mandibular molar at 90% 66.7% 50% of normal respectively, vertical and oblique stress were exerted on the models. Then the effects of height of abutment alveolar bone and size of pontic on stress distribution of fixed bridge were investigated. Results: The vertical stress on the second premolar were significantly concentrated when the buccolingual diameter of pontic at 66.7% and 50% of normal. The concentrated stress on the second premolar and the second mandibular molar were significant when alveolar bone's height of the second mandibular molar decreased not less than 35%. Conclusion: The maximum stress on the fixed bridge was showed to focus on surface of the connector. It may cause damage to the second premolar when the buccolingual diameter of pontic was less than 66.7% of normal. It may also cause damage to both of the abutments when alveolar bone's height of the second mandibular molar decreased not less than 35%.%目的:研究下颌第一磨牙缺失两基牙双端固定桥修复的应力分布.方法:采用CT扫描获取健康成人上、下颌牙及其支持组织二维图像,通过计算机重建技术获得右下颌第一磨牙缺失后的双端固定桥桥体颊舌径分别为正常时的100％、90％、66.7％和50％与右下颌双端固定桥桥体及右下颌第二磨牙颊舌径均分别为正常时的90％、66.7％和50％的7个三维有限元模型,在相同垂直载荷和斜向载荷下分析了基牙牙槽骨高度及桥体大小对固定桥应力分布的影响.结果:当双端固定桥桥体颊舌径分别为正常大小的66.7％和50％时,固定桥两基牙中的第二前磨牙在垂直向加载时均出现明显应力集中；当下颌第二磨牙牙槽骨吸收程度等于及大于35％时,下颌第二前磨牙在其垂直向加载与斜向加载时均出现明显的应力集中,下颌第二磨牙在其垂直向加载时出现明显的应力集中.结论:固定桥受载的Von Mises最大应力集中于连接体表面.对于下颌567双端固定桥,当桥体变窄,颊舌径小于正常大小的66.7％时,有可能会对基牙中的第二前磨牙造成损害.当下颌第二磨牙牙槽骨吸收程度等于及大于35％时,可能对双基牙都造成损害,并可能促使并加速牙槽骨的进一步破坏吸收.
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