前牙全瓷冠粘固后咬合过程的动态三维有限元分析

Three-Dimensional Dynamic Finite Element Analysis of Anterior All-ceramic Crown after Cementation

目的:分析上中切牙全瓷冠粘固后,在模拟前牙动态咬合过程中,基牙与修复体受力状况和粘固效果对其影响,为临床修复体的设计与制作提供理论依据。方法:建立上、下中切牙和上前牙全瓷冠的三维有限元模型,使用动态有限元法在模拟前牙的动态咬合过程中,分析基牙及全瓷冠受力情况,以及粘固面积对修复体受力的影响。结果:全瓷冠切端和唇舌侧肩台处承受的破坏应力(VonMises)较大。咬合过程中,唇舌侧颈缘受力随加载时间增加逐渐增大。前牙覆加深,冠的颈缘肩台处应力逐渐增加而切端逐渐降低。粘结面积与全瓷冠受力呈负相关,粘结面积越大冠的受力越小。结论:基牙切端和唇舌侧肩台处一定要预备出足够的间隙,使全瓷冠能保持一定的厚度和抗折强度。调整前牙咬合关系,避免覆过大或过小而造成冠折裂。冠粘固最好采用树脂进行粘结,保证足够的有效粘结面积。

Objective： To calculate the stresses in the abutment of maxillary central incisor and its all - ceramic crown using three - dimensional dynamic finite element method. Methods： A three - dimensional dynamic finite element model of central incisor and all - ceramic crown constructed during dynamic occluding, and the definition of contact （Tie） between surface of abutment and crown was defined to simulate cementation of the crown. The relation between the area of cementation surface and the stresses on all -ceramic crown was found. Results： Higher stresses（ Von Mises） were observed in the areas of buccal, lingual cervical marginal and incisor ridge of all - ceramic crown. The stresses in the area of cervical marginal increased with increasing of overbite and loading time during dynamic occluding of anterior, but decreased with increasing area of cementation surface. Conclusion： The enough thickness of crown must be kept in the area of buccal, lin- gual cervical marginal and incisor ridge, and the occlusal force should be adjusted properly also, in order to resist the frac- ture of crown. The crown should be cemented properly and with dual - polymerizing resin cement as well, in order to have enough cementing strength.