不同材料修复下颌第一前磨牙楔状缺损的三维有限元分析

Three-Dimensional Finite Element Analysis of Wedge-Shaped Defects of Mandibular First Premolars Restored with Different Materials

目的采用三维有限元模型,观察不同材料修复下颌第一前磨牙楔状缺损后的应力情况。方法将锥形束CT(CBCT)获取的数据建立下颌第一前磨牙楔状缺损的三维有限元模型,分别采用Vita Enamic树脂(A组)、Lava Ultimate树脂(B组)、IPS e.max CAD树脂(C组)、Z350树脂(D组)修复,同时将未做任何修复治疗的楔状缺损模型作为对照组。对各组模型进行垂直和侧向45°负荷,分析各组修复体的应力分布情况。结果与对照组相比,无论是V形或U形楔状缺损,A、B、C、D组模型在承受垂直和侧向45°负荷时Von Mises应力峰值均明显降低,其中B组最小、降幅最大,C组最大、降幅最小;且各组模型承受侧向45°负荷时的Von Mises应力峰值均明显高于垂直负荷。结论楔状缺损患牙侧向负荷应力大于垂直负荷应力。Vita Enamic树脂、Lava Ultimate树脂均属于树脂基陶瓷,其弹性模量与牙本质相似,能够较好地分散楔状缺损患牙的应力。

Objective To observe the stress of different materials after repairing the wedge-shaped defects of mandibular first premolars using a three-dimensional finite element model.Methods The three-dimensional finite element model of wedge-shaped defects of mandibular first premolars was established using the data obtained by CBCT scan.The defects were restored with Vita Enamic(group A),Lava Ultimate(group B),IPS e.max CAD(group C)and Z350(group D),respectively.The wedge-shaped defects without any repairment were used as the control group.Vertical and lateral load of 45°was applied to analyze the stress distribution of the restorations.Results Compared with the control group,the Von Mises stress peak values in groups A,B,C and D were significantly decreased under vertical and lateral load of 45°when the defects were V-shaped or U-shaped.Group B had the smallest and largest decrease,and group C had the largest and smallest decrease.In addition,the Von Mises stress peak value under 45°lateral force was higher than that under vertical load.Conclusion The lateral stress is greater than vertical stress in teeth with wedge-shaped defects.Both Vita Enamic and Lava Ultimate belong to resin-based ceramics with similar elastic modulus to dentin,which can disperse the stress of teeth with wedge-shaped defects.