Guo Ying, Tang Liang, Pan Yan-huan
Department of Stomatology, Medical College of Jinan University, Guangzhou 510632, China.
Zhonghua Kou Qiang Yi Xue Za Zhi. 2009 Sep;44(9):553-7.
To analyze the stress distribution in the abutment periodontal ligament of posterior cantilever bridge under transient dynamic loads using a three-dimensional finite element(FE) model.
A cantilever bridge using 5, 6 as abutments to restore missing 7 was designed, and its FE model was established and loaded with dynamic loads. The loads were set as 250 N occlusal forces loaded at different positions on the cantilever, and in different directions to simulate the masticatory cycle. FE analysis was conducted on the ANSYS to analyze stress distributions in abutment periodontal ligament under dynamic loads. Stress-time curves were traced to understand the biomechanical behavior of abutment periodontal ligament.
With loading and unloading time accumulated, the stress value in the abutment periodontal ligament increased gradually. Loads in lateral direction induced peak value stress in a masticatory cycle. There was little residual stress in the end of unloading phase. The maximum stress concentrated in abutment periodontal ligament adjacent to the missing tooth. Without restoration abutment periodontal ligament was mainly under compressive stress. However, when 7 was restored with a cantilever bridge, tensile stress was shown in the mesial cervical area of 5, Three masticatory cycles were simulated, and stress values in abutment periodontal ligaments increased with the number of masticatory cycles. But the differences of the stress between different masticatory cycles were not significant.
In the mastication movement, lateral loads induce maximum stress in abutment periodontal ligament. Cantilever fixed bridge design is more demanding for the periodontal condition of the abutment adjacent to the missing tooth than for the other abutment. When loaded with continuous masticatory force, the stress concentration does not increase significantly. Therefore, cantilever bridge is one of the feasible choices to restore missing lower second molar.
使用三维有限元模型分析后牙悬臂桥在瞬态动态载荷下基牙牙周膜的应力分布。
设计以5、6为基牙修复缺失7的悬臂桥，建立其有限元模型并施加动态载荷。载荷设定为在悬臂梁不同位置施加250 N咬合力，并在不同方向模拟咀嚼循环。在ANSYS上进行有限元分析，以分析动态载荷下基牙牙周膜的应力分布。绘制应力-时间曲线以了解基牙牙周膜的生物力学行为。
随着加载和卸载时间的累积，基牙牙周膜中的应力值逐渐增加。侧向载荷在咀嚼循环中引起峰值应力。卸载阶段结束时几乎没有残余应力。最大应力集中在缺失牙相邻的基牙牙周膜中。未修复时基牙牙周膜主要承受压应力。然而，当用悬臂桥修复7时，5的近中颈部区域出现拉应力。模拟了三个咀嚼循环，基牙牙周膜中的应力值随咀嚼循环次数增加。但不同咀嚼循环之间的应力差异不显著。
在咀嚼运动中，侧向载荷在基牙牙周膜中引起最大应力。悬臂固定桥设计对缺失牙相邻基牙的牙周状况要求比对其他基牙更高。当施加连续咀嚼力时，应力集中不会显著增加。因此，悬臂桥是修复下颌第二磨牙缺失的可行选择之一。
