天然牙-种植体联合桥上部结构应力分布的三维有限元分析

目的 揭示天然牙—种植体联合桥在咀嚼过程中上部结构应力的分布规律，为临床设计该种类固定桥提供理论参考依据。方法 借助于CT扫描和计算机辅助设计手段，用三维有限元方法对天然牙一种植体联合固定桥在不同载荷下，上部结构的应力分布差异以及位移变化进行生物学分析。结果 种植体基台在斜向载荷下的最大应力值是垂直载荷下的4～6倍，且应力分布不均，有应力集中现象，以压应力为主。桥体He面的应力峰值在集中载荷下是分散载荷下的数倍，He面中1／3出现力点高度集中的压应力区，但载荷方向对其无影响。种植体基台在近远中向的最大位移明显大于天然牙颈部，固定桥整体移动方向是朝着天然牙运动。结论 天然牙—种植体联合桥可通过减少斜向力和集中力或提高基台的结构强度及桥体材料的抗挠曲强度，防止上部结构机械并发症的发生。这种固定桥是可行的。

Three dimensional finite element stress analysis on superstructure of the fixed bridge supported by tooth-implant

OBJECTIVE: To reveal the stress distribution in the superstructure of fixed bridge supported by tooth-implant in the process of mastication for improvement of denture design. METHODS: The stress distribution and displacement of the superstructure were studied and analyzed by means of CT Scan, CAD and three-dimensional finite element when various loads were applied. RESULTS: (1) The stress distribution in abutments under oblique loads at forty-five degrees was uneven and the peak value was 4 - 6 times higher than that under vertical loads. Stress concentration occurred with significant compressive stress. (2) Compressive stress widely distributed in the middle area of occlusal surface of pontic, whose peak value under concentrated loads was significantly higher than that under disperse loads. The loading direction had no effect on the stress concentration. (3) The maximum displacement of implant abutment in medial-distal direction was greater than that of the neck of nature tooth. CONCLUSIONS: The mechanic complications of superstructure could be prevented by reducing oblique loads and concentrated ones. It is certain that the further improvements of curve-resistance of pontics and press-resistance of abutments are available.