下颌第一前磨牙不同角度楔状缺损的三维有限元应力分析

Three-dimensional Finite Element Method Stress Analysis of First Mandibular Premolar with Various Degree of Wedge-shaped Defects under Loading

目的探讨不同角度的楔状缺损载荷后应力分布状况。方法建立下颌第一前磨牙颊颈部深度为1mm,夹角分别为30°、60°、90°、120°的楔状缺损有限元模型,以未发生楔缺的完整牙体作为对照,加载100N轴向力后,分析楔状缺损局部、楔缺顶部及楔缺尖端所在横断平面的应力分布状况。结果建立了下颌第一前磨牙不同角度楔状缺损的三维有限元模型;载荷后各楔缺模型颈部缺损区域应力分布趋势均为自牙体外表面向髓腔侧递增;不同角度的楔缺模型在楔缺尖端所在平面上的应力集中于颊侧偏近中区域,接近楔缺顶部直线,完整牙体模型在楔缺尖端所在平面上的应力亦集中于近中颊区域,但应力值明显小于各楔缺模型;在楔状缺损顶部直线,各模型应力的分布规律相类似,最大值均为接近近中边缘的节点,范围分布在20.0～26.4MPa;最小值均为最远中的节点,范围分布在6.4～7.9MPa。所有的缺损模型其应力接近,均明显高于完整牙体的应力分布。结论1 mm深度的缺损情况下,不同角度的模型应力的分布情况接近,均较完整牙体有明显的颈部应力集中,其中最明显的集中点位于缺损内的近中颊侧牙体中。

Objective To determine the stress distribution of different degree of wedge - shaped defects on premolar under loading. Methods The three - dimensional finite element premolar models, with various degree of wedge - shaped defects（30°,60°,90°, 120°） which depth was lmm, were developed. Compared with complete tooth, the stress distribution in defect, the line and the plane which the top end lay were investigated under 100N loading. Results There had no significant difference in the stress distribution of different defects models, and the stress were higher than in complete tooth. On the plane which the top end lay, the stress was concentrated on mesiobucal region, near the defeet. On the line which the top end lay, the node near mesial proximal surface endured the maximum stress （20.0 - 26. 4MPa）, and the distal node endured the minimum stress （6.4 - 7.9MPa）. Conclusion There had no significant difference in the stress distribution of different defects models, and the stress were higher than in complete tooth. In cervical region, the stress was most obviously concentrated on mesiobucal region, near the defect.