目的：本研究拟采用三维有限元法分析上颌后牙区连续三单位种植固定义齿中种植体数目、长短、直径、位置等多因素对种植体颈部骨皮质最大应力的影响，研究其应力变化规律，以指导临床选择合适的种植修复方案。 方法：应用Abaqus6.14建立上颌骨缺牙的骨块简易模型及Straumman 软组织水平标准颈种植体，分别建立不同直径（4.1mm、4.8mm）、不同长度（8mm、10mm、12mm）、不同位置（567、5X7、56X、X67）的种植体固定桥修复模型。根据纳尔逊定律，将接近最大咀嚼牙合力300N按6:10:9的比例进行垂直加载，计算其应力分布、骨皮质的最大Von Mises力（Max Von Mises, 以下简称MVMS）。结果：①每组内三单位种植体修复的种植体颈部周围MVMS分布较其他组较小，关系为G1G3>G2组，组间比较骨皮质最大应力分布关系由小到大依次为4112-G2<4110-G2<4110-G3<4112-G3<4108-G3,4812-G2<4808-G2<4810-G2<4812-G3<4810-G3；③在种植体为不同直径相同长度时，直径为4.8mm组的MVMS分布较每组相对应的直径为4.1mm组更小。结论：①上颌后牙连续三单位缺失时三颗种植体修复所产生的MVMS最小；②上颌后牙连续三单位缺失时可选用两颗种植体支持的种植连桥修复方案（5X7）替代三颗种植体支持的种植连桥修复方案，可减少手术创伤及降低患者医疗费用；③按照MVMS分布关系的统计提示在两端种植体型号同步变化时骨皮质最大应力分布并不是单纯是随着长度及直径的增加而较小。

Abstract: Objective: This study intends to analyze the influence of the number, length, diameter and location of implants on the maximum stress of implant neck bone cortex in maxillary posterior region with three unit implant fixed denture by three-dimensional finite element method, and to study the stress variation law, so as to guide the clinical selection of appropriate implant restoration scheme. Methods: abaqus6.14 was used to establish a simple model of maxillary edentulous bone block and strauman soft tissue horizontal standard neck implant. The fixed bridge models with different diameters (4.1 mm, 4.8 mm), different lengths (8 mm, 10 mm, 12 mm) and different positions (567, 5x7, 56x, X67) were established respectively. According to Nelson's law, 300 n, which is close to the maximum masticatory force, was loaded vertically at the ratio of 6:10:9. The stress distribution and the maximum von Mises force (MVMs) of bone cortex were calculated. Results: ① the distribution of MVMs around the implant neck of three unit implants in each group was smaller than that in other groups, and the relationship was G1 < G2 < G3 < G4; ② in the two unit implant fixed bridge repair model, the distribution of MVMs within the group was G4 > G3 > G2, and the maximum stress distribution of bone cortex was 4112-g2 < 4110-g2 < 4110-g3 < 4112-g3 < 4108-g3, The results showed that the distribution of MVMs in the 4.8mm diameter group was smaller than that in the 4.1mm diameter group. Conclusion: ① the MVMs of three implants is the smallest when three units of maxillary posterior teeth are lost continuously; ② when three units of maxillary posterior teeth are missing continuously, the two implant supported implant bridge (5x7) can be used to replace the three implant supported implant bridge repair scheme, which can reduce the surgical trauma and reduce the patient's medical expenses; ③ according to the statistical analysis of MVMs distribution, it can reduce the surgical trauma and the patient's medical expenses At the same time, the maximum stress distribution of bone cortex is not only smaller with the increase of length and diameter.

内蒙古自治区卫生计生科研计划项目、201701059、 内蒙古自然科学基金项目、2018MS08100、 内蒙古医科大学青年创新基金项目、YKD2017QNCX017、 内蒙古医科大学第一临床医学院2020年大学生“启蒙计划”项目、FYQMJH2020045