大面积缺损的下颌第一前磨牙桩核冠与高嵌体修复的三维有限元分析

摘要

目的:临床可借助三维有限元应力分析比较选择高嵌体和桩核冠修复大面积缺损患牙的临界范围.方法:建立下颌第一前磨牙3种不同缺损情况的三维有限元模型,分别为:A组,二壁缺损(近中壁+远中壁);B组,三壁缺损(近中壁+颊侧壁+远中壁);C组,四壁缺损(近中壁+颊侧壁+远中壁+舌侧壁).各组根据不同剩余牙体组织量分别分4个亚组,然后再分别模拟桩核冠和高嵌体修复(n=12),并在AN-SYS软件中对其进行载荷,以分析比较两种修复方法最大应力值的大小及分布情况.结果:有限元应力分析结果显示,A、B、C组剩余牙体组织的最大Von-Mises应力区域均出现在高嵌体组,且多发生在牙颈部上1/3处,其应力值A组为81.475 MPa,B组为79.808 MPa,C组为78.658 MPa,各组内两种修复方法的剩余牙体组织最大等效应力相近(P>0.05).结论:下颌第一前磨牙牙体大面积缺损可通过高嵌体或核冠修复;其中二壁缺损和三壁缺损时以高嵌体修复最优,而四壁缺损时则以桩核冠修复最优.%AIM:To determine the critical range of onlay or fiber post-and-core crown in the treatment of mandibular first premolar with large defect using three-dimensional finite element stress analysis. METHODS:Three-dimensional finite element models of mandibular first premolar with different defects(residual dentin is located at 2mm a-bove the gingival margin)were respectively established: crown with 2 axial wall defects(group A); crown with 3 axial wall defects( group B);crown with all axial wall defects( group A) . Simulations of pile fiber post-and-core crown and onlay restorations were respectively performed for each group, then stress intensity and stress distribution were analyzed following loading by using the software ANSYS. RESULTS:The maximum Von-Mises stress for residual dental tissues is displayed in all onlay groups, that in onlay group A, B and C was 81. 475 MPa, 79. 808 MPa and 78. 658 MPa respec-tively, between each 2 groups, P>0. 05, between onlay and fiber post-and-core crown groups, P>0. 05. CONCLU-SION:The 3 kinds of tooth defect can be restored by onlay or fiber post-and-core crown, however, the onlay method is the better way to restore the crown with 2 axial wall defect and the crown with 3 axial wall defect, and the fiber post-and-core crown method is the better way to restore the crown with all axial wall defect.