【摘要】 采用三维有限元的方法,研究髓腔固位冠修复下颌第一前磨牙时,不同形态髓腔壁缺损对牙体组织和修复体所受应力的影响,为临床优化设计提供参考。通过Mimics、Geomagic、UG、Hypermesh软件建立5种髓腔壁缺损形态(A组为完整髓腔壁;B组为舌侧髓腔壁;C组为颊侧髓腔壁;D组为远中髓腔壁;E组为颊舌髓腔壁)的下颌第一前磨牙髓腔固位冠修复有限元模型。加载位置位于颊尖舌斜面中心区域,载荷大小100N,方向为与牙齿长轴成45°、平行于牙体长轴。采用Abaqus软件计算分析5种髓腔壁缺损形态行髓腔固位冠修复后牙体组织和修复体的应力分布情况、von Mises应力峰值、粘结层内的应力分布情况以及Tresca应力峰值。结果表明:45°加载条件下,修复体颈部、牙体组织以及粘结层内应力水平均远远高于平行牙体长轴加载的情况;45°加载时,C组牙体组织内等效应力峰值最小,B组牙体组织内等效应力峰值最大;髓腔壁缺损使粘结层内应力水平显著提高,尤其对于近/远中侧髓腔壁缺损的情况。颊侧髓腔壁在抵抗来自颚侧的侧向力时发挥重要作用。髓腔壁的缺损使粘结层内应力水平显著提高,在长期交变外力作用下,粘结层存在失效的可能性。更多还原

【Abstract】 Three-dimensional finite element method was adopted to evaluate the effect of different types of cavity wall defect on stress distribution in the mandibular first premolar restored with endocrown.With the use of Mimics,Geomagic,UG and Hypermesh software,five finite element models with different types of cavity wall defect of mandibular first premolar were established(Group A:intact cavity wall;Group B:lingual cavity wall;Group C:buccal cavity wall;Group D:distal cavity wall;Group E:buccal and lingual cavity wall).A load of 100 N was applied at the central area of the inclined plane of buccal cusp,either parallel or with an angle of 45°to the long axis of the tooth.The stress distribution in restoration and dental tissue of the five models was calculated.Results include:1)Compared to axial loading condition,the stress level in cervix of restoration,dental tissue and cement layer is much higher when the 45°load is applied;2)Under 45°loading condition,the equivalent stress peak value in dental tissue of group C is the smallest,by contrary,dental tissue of group B obtains the largest equivalent stress peak value;3)Significant improvement of stress level in cement layer was observed when dentin wall defect existed,especially for distal or mesial dentin wall defect.The buccal cavity wall plays an important role in resisting lateral force from palatal side.Defect of cavity wall makes significant improvement of stress level in cement layer,invalidation may occur under the effect of long term alternating force.更多还原