【摘要】 目的:探讨磨牙隐裂的生物力学机制。方法:建立上颌第一磨牙的三维有限元模型,根据隐裂与非隐裂上颌第一磨牙的牙尖斜度,确定模型的牙尖斜度。在600N垂直分散载荷和200N轴向、斜向、水平向载荷下,观察不同牙尖斜度时模型的应力变化。结果:隐裂模型的最大拉应力、最大压应力和最大Von Mises应力均高于非隐裂对照模型。随着载荷方向与牙长轴交角的增大,拉应力和Von Mises应力不断增大,水平向加载时拉应力最大。近中舌尖、近远中窝沟和腭侧牙颈部是主要的拉应力集中区。结论:同等加载条件下,牙尖斜度越大,应力峰值越高,磨牙隐裂的可能性越大,而水平向力是其主要因素。更多还原

【Abstract】 Objective:To evaluate the bio-mechanics of the cracked molars. Methods: A three dimensional finite element(3D-FEM) model of an upper first molar was constructed by Ansys 8.0 software. The model’s cuspal inclination was shaped according to the mean value of the cuspal inclination in the cracked maxillary first molars and the intact ones respectively. The influence of cuspal inclination on the stress distribution was evaluated under different loads:Load of 600 N vertically applied to the occlusal surface of the model, or load of 200 N applied from three directions (vertically, at a 45°angle, horizontally). Results:For the model with the cuspal inclination of the cracked maxillary first molars, its maximum tensile stress, compressive stress and Von Mises stress were higher than those of the control models. The tensile stress and Von Mises stress increased with the increase of force direction and became to the highest under horizontal loads. The tensile stress was mainly distributed at the mediolingual cusp, centre groove and the palatal side of the cervical region. Conclusions: Under equivalent loads, the molar with bigger cuspal inclination suffers more unfavorable stress, which will magnify the occurrence of cracked tooth syndrome (CTS), and horizontal bite force may be a critical factor.更多还原