不同咬合状态下预备体受力分析──力学模型及二维光弹实验研究

Mechanical Study of Preparations in Centricand Eccentric Occlusion──Mechanical Model Test and Two-dimensional Photoelastic Stress Analysis

设计牙力学模型和二维光弹模型实验，对不同咬合状态下几种预备体的受力进行分析对比。完整牙在正中轴向受力时抗力值较高，内部应力分布均匀。非正中加载时无论是完整牙还是预备了洞型的牙，其抗力值均明显下降，洞型越大，抗力值越低。非正中加载使牙颈部应力条纹急剧增加，极易发生牙尖折裂。牙折裂多在非正中咬合牙尖斜面受力不均时发生。应避免使单个牙尖斜面受集中载荷作用而造成局部牙体组织承受过大力。

Mechanical model test and two dimensional photoelastic stress analysis were done to determine the breaking load and the stress distribution in preparations with centric and eccentric occlusions. with loading on the occlusal surface of intact tooth and preparation with centric occlusion,the breaking load is higher and the stress distribution is relatively uniform. It means constant centric occlusion contact is helpful to protect tooth structure from fracture.When loading on the bevel of tooth,whether it is prepared or not,in eccentric occlusion the strength was decreased with increased distribution of stress happened. The strength was decreased with the increase of cavity design of preparation. Tooth fracture often happened as a result of excess eccentric force loading on the bevel of cusps of tooth.