Objective To study the concentration of stresses at the cervix of teeth with wedge-shaped defects. Methods Using the two-dimensional finite element stress analysis, the stresses at the cervix of mandibular first premolar with wedge-shaped defects induced by the simulation were analyzed. Results There were 3 directions of load resulting in significant concentration of stress in the deepest defect. The effect of the load of 90° inclined to the axis of the tooth applying on the buccal cusp tip formed the maximal tensile stress, which was 6 times the normal, at the cervix of defect. The effect of the load of 0° inclined to the axis of the tooth applying on the buccal cusp tip and 30°inclined to the axis of the tooth applying on the center of the occlusal surface formed the maximal compressive stress, which was 2-4 times the normal, at the cervix of defect. The concentrations of stresses were greatly increased with the severity of defects. Conclusions The concentration of stresses was greatly increased in cervical area of teeth with wedge-shaped defects under loading.%目的 研究楔状缺损患牙牙颈部硬组织的应力分布. 方法在下颌前磨牙颊舌向纵剖面上设计楔状缺损模型,用二维有限元应力分析法对各种模型受5种模拟(牙合)力作用时牙颈部应力进行分析. 结果有3种模拟(牙合)力作用均在楔状缺损的最深处生产应力集中现象.作用于颊尖与牙长轴呈90°方向力引起的最大主应力为拉应力,为正常值的6倍;作用于颊尖与牙长轴方向一致和于胎面中央与牙长轴呈30°方向力引起的最大主应力为压应力,为正常值的2～4倍.缺损最深处的应力集中随缺损程度加蕈而加强,应力值加大. 结论楔状缺损一旦形成,在(牙合)力作用下,楔状缺损最深处的硬组织应力集中程度较正常牙齿明显增加.
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