上颌第一前磨牙不同形态Ⅱ类洞形对应力影响的三维有限元分析

目的：分析上颌第一前磨牙不同形态的Ⅱ类洞形设计对不同材料充填体的应力影响。方法：在上颌第一前磨牙上制备3种不同的Ⅱ类洞形，假设分别由银汞合金和复合树脂充填，采用三维有限元法对承受垂直和侧向力所产生的应力计算分析。结果：在所设计的洞形中，以复合树脂充填，鸠尾设计与狭缝设计最大应力相差较小，为1％左右；以银汞合金充填，特别是垂直受力时，狭缝设计最大拉应力、切应力和压应力分别下降41％、29％和27％。结论：在前磨牙充填中，龋齿仅限于邻面，建议以狭缝设计并采用复合树脂充填修复。

Three Dimensional Finite Element Stress Analysis in Various Class Ⅱ Cavity Design on First Maxillary Premolar

OBJECTIVE: To evaluate the stress influence in different contour of class II cavity with different filling materials on first maxillary premolar. METHODS: The stress distribution in two types and all three contours of class II cavity in maxillary premolar were analyzed by three dimensional finite element. The cavity was respectively filled with amalgam and composite resin; and the vertical and lateral stress force was calculated. RESULTS: In the different contours, the stress of composite restoration by slot design was close to that by dovetail design, and the stress of amalgam restoration by slot design, especially in vertical force, descended respectively at 41%,29% and 27%. CONCLUSION: When class II lesions is only limited in proximal region of the premolar, the filling of composite resin with slot design is recommended.