Objective:To investigate the effects of the tilting angle and length of terminal implants of 6 implant-supported full dental arch by investigating the stress distribution on different implants,surrounding bone and framework with threedimensional finite element data.Methods:Six implants were employed to support a full-arch fixed prosthesis and five three-dimensional finite element models were established with CT images,based on the length (S and L) and distal tilt angle (0°,30° and 45°) of terminal implants for anedentulous mandible,which named:Tilt0-S,Tilt30-S,Tilt30-L,Tilt45-S and Tilt45-L.An oblique 240N was loaded at second molar.The VonMises Stresses were analyzed.The implants were consecutively named #1 to #6 from the loading point.Results:The stress of different implant sites had various changes.Compared with Tilt0-S group,#1 implant had the greatest stress on the implants,with the other groups exhibiting variable reductions;Tilt45-L demonstrated the greatest reduction in stress.#2 implant showed different degrees of increase.Tilt45-L had the least increase.#3 implant also had variable reductions.Tilt45-L demonstrated the greatest reduction.Tilt0-S had the greatest stress at bone around #1 implant neck,and Tilt45-L exhibited the least stress,which was a 36.3％ reduction compared to Tilt0-S.Compared withTilt0-S group,Tilt45-S and Tilt45-L exhibited the least stress in the framework.When the distal implant tilted 30°,Tilt30-S showed 1.7％ lower stress;Tilt30-L showed 8.5％ lower stress,which the greatest stress in the framework was found on the cantilevers distal to #1 implant.Conclusions:Matching different length and tilting angle of the terminal implants led to variable stress reductions on implants,bone and the superstructure.By optimizing implant configuration,the reduction of stress on implants and surrounding bone could be maximized.Under present conditions,If distal implant tilted 30 degrees,the same length with the front implant was better,If distal implant tilted 45 degrees,the longer implant was preferred configuration.More clinical test are needed.%目的:探讨6个种植体全牙弓固定修复时末端种植体倾斜角度和长度对种植体、周围骨界面及固定桥支架应力分布的影响.方法:用三维有限元方法建立五组下颌无牙颌修复设计模型.每组模型均为6个种植体,分别位于双侧侧切牙,第一前磨牙和第二前磨牙位置,前4个种植体相互平行,末端2个种植体根尖位于第二前磨牙位置,根据末端种植体远中倾斜角度及长度分为五组.将240N的力垂直加载于右侧第二前磨牙中央窝,分析记录每组模型各种植体和种植体周围骨界面的VonMises应力值.从加载侧起将种植体依次命名为1-6#.结果:1#末端种植体应力有不同程度降低,降幅依次为:Tilt45-L＞ Tilt30-S＞ Tilt30-L＞ Tilt45-S;2#种植体应力出现不同程度增加或维持不变;3#种植体应力出现不同程度降低.末端种植体倾斜后种植体周围骨组织应力发生不同程度的降低,降幅依次为Tilt45-L＞ Tilt30-S＞ Tilt45-S＞Tilt30-L.上部固定桥支架的应力,末端种植体倾斜45°时,种植体长度的影响不大;倾斜30°时,Tilt30-S组应力降低1.7％,Tilt30°-L组应力值降低8.5％.结论:从最大限度减小各部位应力角度考虑,末端种植体倾斜比平行更有利;倾斜角度和长度可能存在一个适合的匹配关系.本实验条件下,如果倾斜30°,应选择与前部相同长度的种植体;如果倾斜45°,加长种植体更有利.
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