目的 建立全瓷嵌体修复上颌第一前磨牙近中-牙合面-远中(MOD)洞形的三维有限元模型,通过改变洞形的设计,观察应力分布的改变.方法 建立三维有限元模型,设定两个变量分别为髓壁距龈壁的距离(H),龈壁的宽度(G);在Ansys11.0中依照变量进行模型修改,牙合面加载力大小为200N,记录应力数据并分析应力分布.结果 牙体预备MOD洞能够影响牙体全瓷嵌体修复后的应力分布.在龈壁宽度不变的情况下,牙釉质的Von mises应力值随着髓壁的高度增加而减小.近中牙颈部嵌体边缘线处的牙釉质应力分布较为集中.在髓壁距龈壁的距离保持不变的条件下,随着龈壁宽度的增加,牙本质的Von mises应力值和最大主应力σ1都明显增大.结论 全瓷嵌体修复后增加了牙体的应力值,而牙体MOD洞形预备影响了全瓷嵌体修复的应力分布.髓壁高度的变化是牙釉质应力改变的重要参变量,应力值随髓壁高度的增加而减小;龈壁宽度的变化是牙本质应力改变的重要参变量,应力值随龈壁宽度的增加而增大.牙颈部近中嵌体边缘线处的牙釉质易发生折裂.%Objective To establish a three dimensional finite element model of the mesial occlusal distal (MOD) shape of the maxillary first premolar, by setting the distance from pulpal wall to gingival wall as H, the width of gingival wall as G, and anaylzing the change of stress distribution. Methods The models were modified depended on defined parameters (H and G) in Ansys 11.0 software. Under decentralized vertical loading 200N, the figure and data of stress distribution were got by using finite element analysis method. Results The stress distri-bution of all ceramic inlay restorations was affected by MOD dental preparation. Under the condition of constant gingival wall width, the Von Mises stress value of enamel decreased with the increase of pulp wall height. Under the condition that the distance between the pulp wall and the gingival wall remains unchanged, the Von Mises stress and the maximum principal stress of dentin increased with the increase of gingival wall width. Conclusion The stress of the teeth was increased after the restoration of all ceramic inlays. The change of pulp wall height is an important factor affecting enamel stress, which decreases with the increase of pulp wall height. The change of the width of gingival wall is an important factor affecting the stress of dentin, which increases with the increase of gingival wall width. Enamel at the edge of the inlay is prone to fracture.
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