Objective: To study effect of implant position and number on stress distribution among implant and denture with 3-D finite element analysis.Method: A special denture is made for an edentulous maxilla cast to collect 3-dimensionnl finite element data.Three dimensional finite element mode is constructed by CT scanning technology through modifying position and numbers of implants when rigid attachment is used.Model 1: 4 implants, in bi-side canine and central incisor; Model 2: 4 implants, in bi-side canine and lateral incisor, Model 3: 6 implants, in bi-side canine, central incisor and lateral incisor; The part of attachment which connected to implant bridge is call positive part, the other part which connected to removable denture is called negative part.Results: Among the three models, canine implant exhibit the highest stress which all lies in neck of the implant, which is: model 3＜model 2＜model 1 in turn, Maximum stress in canine of model 1 is about 1.85 times higher than that of model 3, Maximum stress in canine of model 1 is about 10 times higher than central incisor, model 2 is about 5 times higher than lateral incisor.Maximum stress in lateral incisor and central incisor of model 3 is near to that of lateral incisor in model 2 and central incisor of model i respectively.Maximum stress in positive part and negative part of attachment of model 1 is higher than that of model 2 and model 3, especially negative part, is about 4 times higher than of model 2 and model 3.Maximum stress in palate plate is centralized mainly in connection between attachment and palate plate, then the connection part between palate plate and resin base, and then in comer between horizontal part and vertical part.Conclusion: 6 implants in front region seems to be more reasonable.Enough strength should be paid more attention in connection between attachment and alloy frame, palate plate and resin base.%目的:探讨修复无牙上颌,种植桥和附着体义齿硬性连接时,种植体部位与数量对应力分布的影响.方法:在无牙上颌模型上制作一个方便采集有限元数据的特殊义齿,螺旋CT扫描后建立3个三维有限元模型.模型1为4个种植体位于双侧中切牙和尖牙;模型2为4个种植体位于双侧侧切牙和尖牙;模型3为6个种植体,位于双侧中切牙、侧切牙和尖牙.前牙区种植体形成固定桥,与后端活动义齿采用硬性附着体连接.附着体与固定桥连接部分为阳性部件,与活动义齿相连部分为阴性部件.结果:三个模型中尖牙种植体的应力值均较大,且都集中在牙颈部,模型3＜模型2＜模型1,模型1约为模型3的1.85倍;在同一模型中,尖牙区种植体最大应力值在模型1约为中切牙的10倍,模型2约为侧切牙的5倍;模型3约为侧切牙的3.1倍,中切牙的6.4倍,但其侧切牙和中切牙所受最大应力分别与模型2和模型1接近.模型1阳性部件与阴性部件最大应力值均比模型2、模型3明显增大,尤其是阴性部件,约为后者的4倍.义齿腭杆的最大应力主要集中在前部附着体连接处,其次为树脂基托的连接处,腭杆水平部的转角处.结论:当附着体采用硬性连接时,前牙区选择6个种植体似乎更符合生物力学要求;建议注意附着体与金属支架连接处,腭杆与树脂基托连接处的加强.
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