磨牙根分叉病变对固定义齿应力分布的影响

目的：研究磨牙根分叉病变对固定桥应力大小分布的影响。方法：采取CT平描的方法获得健康年轻人下颌牙及其周围组织的二维数据．通过计算机三维重建技术生成下颌第二前磨牙缺失的双端三单位固定义齿的有限元数学模型，在同等水平向载荷和垂直向载荷下分析了磨牙根分叉病变对固定桥应力大小分布的影响。结果：当磨牙根分叉区牙槽骨无吸收时，固定桥双侧两基牙应力大小分布均匀；当磨牙端根分叉区牙槽骨吸收达30％，前磨牙端牙槽骨无病变时，磨牙端根分叉区表现为应力集中；当前磨牙端和磨牙端根分叉区牙槽骨同时吸收达10％时，固定桥两侧基牙均表现为应力集中。结论：磨牙根分叉病变对固定义齿应力分布的影响较为明显，尤其是与前磨牙端基牙牙槽骨同时吸收时对基牙应力分布的影响最大。

The Effects of Molar Furcation Involvement on The Stress Distribution Around Abutment Teeth of Fixed Bridges

objective： To study the effect of molar furcation involvement on the stress distribution around the abutment teeth of fixed bridges. Methods： Serial layers of two dimensional （2-D） images of mandibular teeth and their periodontal supporting tissue of a healthy young male volunteer were obtained by spiral CT and were used to construct a three-dimensional （3-D） digital image model by reverse en gineering. Then a 3-D finite element model of a three-unit bridge with bilateral abutments to restore a missing mandibular second premo lar was developed and used to evaluate the effects of molar furcation involvement on the stress distribution around the abutment teeth when the same load were applied vertically or horizontally. Results： When the first molar abutment had no furcation defect, the mechani cal load showed even distribution without any significant stress concentration around abutment teeth. However, significant stress concen tration appeared in the furcation region of first molar abutment when the alveolar bone in the furcation region of first molar abutment suf fered from an absorption of equal to, or more than, 30% if there was no bone absorption around first premolar abutment. Furthermore, when the alveolar bone absorption around the first premolar abutment as well as that in the furcation region of first molar abutment both reached 10% and more, stress concentration appeared around both abutments. Conclusions： molar furcation involvement has a significant effect on the stress distribution of fixed bridges around abutment teeth, especially when accompanied by alveolar bone absorption around premolar abutments.