目的 :探讨单侧部分后牙缺失对下颌牙根尖应力分布规律的影响。方法 :采用透明环氧树脂复制以相同牙排列而成的正常牙合及右侧第二、三磨牙缺失的下颌模型各 1副 ,2 .0kg垂直加载后 ,投影式光弹仪上观测各牙根尖主应力的大小与方向。并分析其与下颌牙根轴的二维倾角关系。结果 :两种咬合的牙长轴倾斜程度间无显著差异 ,根尖主应力方向在近远中向切面或颊舌向切面上也无显著差别。但缺牙对侧牙根尖主应力值普遍比正常牙合高 ,也显著高于缺失侧 (P <0 .0 5 )。结论 :单纯牙数的改变不会对下颌牙根尖主应力方向产生明显影响 ,但可以影响根尖应力的大小和分布 Objective: To investigate the effect of unilateral posterior teeth loss on apical stress distribution in mandibular teeth. Methods: The transparent epoxy resin was used to duplicate the normal occlusion with the same teeth and the mandibular models with the second and third molars missing on the right. After vertical loading of 2.0 kg, each root was observed The main stress of the size and direction. And analyze its relationship with the mandibular root axis of the two-dimensional inclination. RESULTS: There was no significant difference in the inclination of the long axis of the two occlusal teeth. There was no significant difference in the direction of the main stress between apical and lateral incision or buccolingual tongue. However, the main stress values ​​of the contralateral apices of the edentulous teeth were generally higher than those of the normal occlusion, and also significantly higher than those of the missing one (P <0.05). CONCLUSION: The change of simple tooth number will not have a significant effect on the direction of the main stress in the apical tip of the mandibular tooth, but it may affect the size and distribution of apical stress