天然牙与种植体联合支持套简冠固定桥的骨组织应力分析

目的：研究天然牙与种植体联合支持式套筒冠固定桥牙周组织的应力分布情况。方法：选择1例左侧下颌第一磨牙缺失病例，分别设计以左侧下颌第二前磨牙与种植体（位于下颌第二磨牙）联合支持固定桥模型（模型Ⅰ）和套筒冠固定桥模型（模型Ⅱ）。在分散垂直和分散斜向2种载荷情况下，采用三维有限元法分析基牙及种植体周围骨组织的应力分布情况。结果：分散垂直载荷下，模型Ⅰ中的天然牙和种植体周围骨组织最大等效应力值分别为2．58MPa和43．92MPa；模型Ⅱ中，相应的最大等效应力值分别为2．17MPa和20．23MPa。分散斜向载荷下，模型Ⅰ中的天然牙和种植体周围骨组织最大等效应力值分别为2．23MPa和46．37MPa；模型Ⅱ中．相应的最大等效应力值分别为1．91MPa和21.19MPa。结论：套筒冠固位体能缓冲种植体周围骨组织的部分应力，但对垂直应力和侧向应力的缓冲能力差别不大。进行天然牙与种植体联合支持固定桥修复时，可在种植体端设计套筒冠固位体．以缓冲种植体周围骨组织的应力水平，防止或减轻种植体支持组织的损伤。     

种植体上部不同结构对下颌游离端义齿应力分布的影响

目的:观察不同上部结构的种植体支持可摘局部义齿修复下颌KennedyⅠ类牙列缺损时的应力和位移。方法:使用软件GeoStar(COSMOSM 2.85,SRAC,USA)建立4个种植体-天然牙联合可摘义齿修复下颌KennedyⅠ类牙列缺损的三维有限元模型,比较不同上部结构时种植体周围骨组织、基牙牙周膜、基托下黏膜的最大等效应力及基托下黏膜组织的位移变化。结果:有种植体支持时,单冠形式的种植体周围骨组织最大等效应力最大;缓冲型套筒冠的基牙牙周膜最大等效应力、基托下黏膜最大等效应力和位移值最大;微型太极扣种植体周围骨组织最大等效应力、基牙牙周膜最大等效应力和黏膜的最大等效应力及位移值均最小。缓冲型套筒冠种植体周围骨组织最大等效应力小于非缓冲型套筒冠,但基牙牙周膜最大等效应力、基托下黏膜最大等效应力和位移则大于非缓冲型。结论:选用种植体-天然牙联合支持修复远中游离端牙列缺损时,种植体上部结构采用微型太极扣作为附着体联接形式是最佳选择。     

三种支持类型固定义齿负载时基牙周围骨组织应力分析

目的研究三种支持形式固定义齿在载荷情况下基牙周围骨组织应力分布情况。方法选择1位右侧下颌第一磨牙缺失的志愿者,进行固定义齿修复后,建立天然牙支持式固定义齿三维有限元模型(模型Ⅰ),运用建模软件将模型Ⅰ中的天然牙根替换为种植体,分别建立天然牙与种植体联合支持式固定桥模型(模型Ⅱ)和种植体支持式固定义齿模型(模型Ⅲ)。在分散垂直和分散斜向下加载200N,采用三维有限元法分析基牙及种植体周围骨组织的应力分布情况。结果种植体支持式固定义齿种植体周围骨组织应力最高,且明显集中于种植体颈部;天然牙支持式固定义齿基牙周围骨组织应力最小,且分布较为均匀。斜向加载可以提高固定义齿基牙周围骨组织应力,并增加应力分布的集中程度。结论天然牙支持是固定义齿修复理想的支持形式,在进行各种支持形式固定义齿修复时,都应尽量减小侧向力对支持组织的破坏。     

种植体与天然牙联合支持固定桥桥体长度的应力分析

目的 研究种植体与天然牙联合支持固定桥在不同桥体长度下的应力分布情况.方法 利用三维有限元法,建立三种桥体长度的种植体与天然牙联合支持固定桥有限元模型,进行计算分析.结果 种植体与天然牙联合支持固定桥的最大应力值位于种植体、天然牙及其周围骨组织的颈缘部位;分散斜向加载时,种植体颈缘处及其周围骨组织的最大应力值是分散垂直载荷下最大应力值的两倍以上,表现出明显的应力分布不均;无论基牙还是周围骨组织,最大应力值在桥体加长时均有明显增加.结论 种植体与天然牙联合支持固定桥主要支撑力的部位是颈缘处,桥体长度设计以一个单位以内为宜.     

附着体义齿修复近中倾斜30°基牙的牙周组织应力分析

目的研究两种附着体义齿（栓道附着体义齿和套筒冠固定义齿）修复下颌第一磨牙缺失伴下颌第二磨牙近中倾斜30°的基牙的牙周组织应力分布。方法在已经建立的下颌第一磨牙缺失伴下颌第二磨牙近中倾斜30°修复前及两种附着体义齿修复后的三维有限元模型上,将200N垂直负荷和斜向负荷分别模拟加载于下颌第二磨牙,计算分析基牙牙周组织的应力情况。结果在下颌第二磨牙近中倾斜30°时,两种附着体义齿修复后倾斜基牙应力主要集中在其颈部牙槽骨或根分叉区。斜向加载下,栓道附着体义齿修复后倾斜基牙牙周组织应力小于套筒冠义齿修复。斜向加载下,下颌第二前磨牙和第二磨牙牙周组织应力远远大于垂直加载。结论在下颌第二磨牙近中倾斜30°时,栓道附着体义齿修复在改善倾斜基牙牙周组织应力方面更优于套筒冠义齿修复。斜向加载时,下颌第二前磨牙和第二磨牙牙周组织中产生较大的应力集中。     

不同直径种植体与天然牙联合支持固定桥的应力分析

目的:通过三维有限元方法研究种植体直径对天然牙种植体联合固定桥周围骨组织应力的影响。方法:CT扫描获得志愿者DICOM数据,通过Mimics软件、Imageware逆向工程软件及ANSYS软件处理,先建立左侧下颌第二前磨牙和第二磨牙支持的天然牙固定桥三维有限元模型,用不同直径种植体替换下颌第二磨牙得到一系列种植体-天然牙联合支持式固定桥的三维有限元模型。分别在垂直向和斜向45°集中加载下,对比分析天然牙及种植体周围的应力分布情况。结果:相同加载条件下,不同模型的第二前磨牙(天然牙)颈部应力无明显区别。对联合支持式固定桥,当种植体直径由3.5 mm增加为4.3 mm时,种植体颈部和基台的应力明显降低(近1/2);随种植体直径增加,2处应力也继续降低,但降低的幅度明显放缓。结论:随着种植体直径的增大,种植体颈缘处骨组织及基台的von Mises应力逐渐减小,但对天然牙周围的应力影响较小。斜向载荷时,天然牙、种植体周围骨组织及基台受到的von Mises应力显著增大,更易导致固定桥修复的失败。     

不同载荷下天然牙—种植牙联合桥基牙应力分布

目的 :揭示天然牙—种植体联合支持固定桥在不同载荷下基牙的应力反应规律 ,指导临床优化设计。方法 :采用三维有限元方法建模型计算、分析。结果 :斜向载荷下种植体的最大应力值是天然牙的2～2.5倍 ,集中斜向载荷与分散斜向载荷下种植体最大应力值无明显差异 ,是垂直载荷下种值体最大应力值2～2.5倍。集中垂直载荷下天然牙、种植体的最大应力值高于分散垂直载荷下的最大应力值。天然牙集中斜向载荷下最大应力值大于分散斜向载荷下的最大应力值。结论 :天然牙—种植体联合桥承受侧向力的能力弱 ,种值体应具有高强度,天然牙根应粗大 ,减小侧向力 ;集中载荷比分散载荷破坏作用大 ,桥体与基牙的面咬合接触点应分布均匀 ,建立多点咬合接触     

天然牙-游离端叶状种植体联合固定义齿三维有限元研究：Ⅰ．对分散载荷的应力分析

采用3D-FEM分析天然牙-游离端叶状种植体联合支持的固定义齿在分散载荷下的应力和位移规律。结果发现：垂直向加载时，天然基牙最大位移小于种植体最大位移，但二者很接近；天然基牙的应力集中区位于颈部，根是部牙周膜应力值较低；种植体远中桩颈部及相应区域皮质骨界面为高应力区；斜向加载时各结构应力值较垂直加载相比增大显著，应力分布情况也发生改变．两种基牙的最大位移值仍很接近。     

天然牙-游离端种植牙联合支持固定桥的应力分布

目的 :揭示天然牙—种植体联合支持固定桥不同桥长度的设计时应力分布特点 ,为临床优化设计提供实验力学依据。方法 :采用三维有限元的方法研究三种长度桥体的天然牙—游离端种植牙联合支持固定桥的应力分布。结果 :天然牙—种植牙固定桥应力集中于基牙的颈部 ;种植体颈部骨组织的应力大于天然牙颈部骨组织的应力 ;集中垂直载荷时种植体颈部骨的应力分布较均匀 ;集中斜向载荷时种植体的颊舌侧骨组织有明显的应力集中区 ,并且桥体跨度增加 ,种植体周骨的最大应力值增加 ,天然牙周骨的应力值无显著变化。结论 :天然牙—种植体固定桥受集中斜向载荷易导致种植牙周骨损伤 ,尤其桥体长度增加时应减小侧向力并增加基牙数量     

天然牙一种植体联合支持固定桥对种植体周骨组织应力的影响

目的 不同桥体长度结构下天然牙－牙种植体联合支持固定桥中种植体周骨组织的应力反应特点。方法 采用三维有限元方法建立不同桥长的固定桥力学模型计算分析。结果 天然牙－牙种植体联合支持固定桥中种植体颈部周围骨应力最大;长桥体固定桥在集中斜向载荷作用下种植体颈缘骨最大应力是集中垂直载荷下种植体周骨最大就力的3倍,桥体长度增加,应力值增加。结论 桥体长度对种植修复体应力分布有显著影响,桥体长度增加导致牙种植体及其周围骨应力集中程度增大,对其破坏作用增强,因此临床设计桥体不宜过长。     

Analysis of stress on a fixed partial denture with a blade-vent implant abutment.

Using a two-dimensional finite element method, a study was made that compared the behavior of a model mandibular posterior fixed partial denture constructed on the second premolar abutment and a blade-vent implant imbedded at the site of the second molar with the behavior of a fixed partial denture constructed on the second premolar and second molar abutments. The following were the results: 1. Deflections of the implant fixed partial denture were less than those of the natural tooth fixed partial denture in vertical and inclined loads. 2. Stress concentration was markedly found in the pontic and the mesial and distal parts of the premolar retainer in both restorations and the implant neck in the implant fixed partial denture. 3. In the implant fixed partial denture, stresses induced in the surrounding bone became higher around the posterior abutment and became lower around the premolar retainer than the stresses produced with the natural tooth fixed partial denture. 4. Therefore it was suggested that, to relieve stress to the surrounding bone around the implant abutment, occlusal forces loaded to the implant fixed partial denture have to be more concentrated on the premolar abutment than do forces loaded to the natural tooth fixed partial denture.     

天然牙-种植体共同支持式固定义齿的生物力学研究Ⅰ.垂直集中载荷对种植体、天然牙骨界面应力的影响

目的:通过对天然牙-种植体共同支持式固定义齿受垂直集中载荷时,种植体、天然牙骨界面应力分布情况进行测试,为临床能否使用该方式修复牙列缺损提供生物力学的理论依据。方法:应用电阻应变计电测技术的方法。结果:天然牙-种植体共同支持式固定义齿修复时,在垂直集中载荷下,随着载荷的不断加大,天然牙-种植体与骨组织界面处的应力值不断加大,最大应力出现在种植体、天然牙根颈部区,种植体与稳固的天然牙共同支持式固定修复时,天然牙与骨界面应力分布较均匀。结论:从生物力学的角度来看,在优化临床设计的前提下,天然牙-种植体共同支持式固定义齿是临床可采用的特殊固定义齿,尤其适用于末端游离缺牙的患者。     

Peri-implant bone loss as a function of tooth-implant distance

PURPOSE: In a retrospective study, the radiographs of 39 patients with Applegate-Kennedy Class I or II in the posterior mandible who had been treated with screw-anchored fixed partial dentures supported by IMZ implants and natural teeth were examined for the presence of radiologically detectable peri-implant bone loss. Furthermore, the results were correlated with a mathematical model. MATERIALS AND METHODS: The radiographs of the implants were digitized, and the areas of bone atrophy mesial and distal to the implants were determined semi-automatically. The data obtained were correlated with the distance between the implant and the abutment tooth. The connection between the tooth-supported crown and the implant-supported denture was made with a vertical screw-lock precision attachment. In a mathematical analysis it was assumed that the fixed partial prosthesis was a rigid beam with 3 elastically embedded supports. RESULTS: The mean distance between the tooth and the first implant was 11.02 mm (SD: 4.24), and between the tooth and the second implant was 20.25 mm (SD: 5.16). Peri-implant bone loss significantly followed a rational function (mesial implant: P = .03, distal implant: P = .02), meaning that, as the tooth-implant distance increased, the area of atrophy became rapidly larger and then diminished gradually. Distances of 8 to 14 mm between the tooth and the first implant and of 17 to 21 mm between the tooth and the second implant were associated with a more pronounced bone loss. These results were also confirmed mathematically. CONCLUSION: A tooth-implant distance of 8 to 14 mm for the first implant and 17 to 21 mm for the second implant should be avoided for implant placement if prosthetic rehabilitation is planned using a fixed partial denture supported by a premolar and 2 IMZ implants in the mandible. Although this investigation was done on IMZ implants only, the results were confirmed by a mathematical model, which indicated that the observed bone loss may be the same in other types of implants placed in the same positions.     

三种不同连接方式的天然牙—游离端种植体联合支持的 固定义齿集中载荷应力分析

目的 研究三种不同连接方式的天然牙——游离端种植体联合支持的固定义齿在集中载荷下的应力值和应力分布。方法 应用三维有限元应力分析法。结果 ①固定连接式固定义齿的种植体基牙应力峰值高于天然牙;②刚性栓道式固定义齿的种植体基牙应力峰值最高;③缓冲式固定义齿的种植体基牙应力峰值最低。结论 ①固定连接式固定义齿设计可能损伤种植体基牙,需采取适当措施;②刚性栓道式固定义齿设计对种植体基牙损伤最大;③缓冲式固定义齿设计有利于保护种植体基牙。     

种植体长度对天然牙-种植体联合修复体应力影响的研究

目的:建立天然牙-种植体联合支持固定桥的三维有限元模型.探讨不同种植体长度对天然牙-种植体联合支持固定桥的修复体上部结构、天然牙等应力分布的影响.方法:对模型施加200N垂直向集中的力和200N颊舌向集中的力,运用CT扫描、三维有限元分析方法等手段,对比观察不同长度的种植体对天然牙及其修复体上部结构应力分布的影响.结果...     

天然牙-种植体联合桥上部结构应力分布的三维有限元分析

目的 揭示天然牙—种植体联合桥在咀嚼过程中上部结构应力的分布规律，为临床设计该种类固定桥提供理论参考依据。方法 借助于CT扫描和计算机辅助设计手段，用三维有限元方法对天然牙一种植体联合固定桥在不同载荷下，上部结构的应力分布差异以及位移变化进行生物学分析。结果 种植体基台在斜向载荷下的最大应力值是垂直载荷下的4～6倍，且应力分布不均，有应力集中现象，以压应力为主。桥体He面的应力峰值在集中载荷下是分散载荷下的数倍，He面中1／3出现力点高度集中的压应力区，但载荷方向对其无影响。种植体基台在近远中向的最大位移明显大于天然牙颈部，固定桥整体移动方向是朝着天然牙运动。结论 天然牙—种植体联合桥可通过减少斜向力和集中力或提高基台的结构强度及桥体材料的抗挠曲强度，防止上部结构机械并发症的发生。这种固定桥是可行的。     

The three-dimensional finite element analysis of fixed bridge restoration supported by the combination of teeth and osseointegrated implants

This study investigated the designs of osseointegrated prostheses in cases of free-end partial edentulism using comparative stress interpreted with the three-dimensional finite element method. Three free-end fixed osseointegrated prostheses models with various connection designs (i.e., rigidly connected to an abutment tooth and an implant, rigidly connected to an implant and two abutment teeth, and rigidly connected to an implant and three abutment teeth) were studied. The stress values of the three models loaded with vertical, buccolingual, and linguobuccal directions at 30 degrees angled to vertical axis forces were analyzed. When the fixed partial denture was connected to the three natural abutment teeth and an implant, the lowest levels of stress in the bone were noted.     

Photoelastic stress analysis of implant-tooth connected prostheses with segmented and nonsegmented abutments

STATEMENT OF PROBLEM: There is some question about whether implant abutment selection affects the transfer of load between connected implants and natural teeth. PURPOSE: The purpose of this study was to compare stress transfer patterns with either 1 or 2 posterior implants connected to a single anteriorly located simulated natural tooth with either 1 or 2 segmented and nonsegmented implant abutments under relevant functional loads by use of the photoelastic stress analysis technique. MATERIAL AND METHODS: A model of a human left mandible, edentulous posterior to the first premolar, with two 3.75-mm x 13-mm screw-type implants embedded within the edentulous area, was fabricated from photoelastic materials. The implants were in the first and second molar positions. Two fixed partial denture prosthetic restorations were fabricated with either segmented conical abutments or nonsegmented UCLA abutments. Vertical occlusal loads were applied at fixed locations on the restorations. The photoelastic stress fringes that developed in the supporting mandible were monitored visually and recorded photographically. The stress intensity (number of fringes), stress concentrations (closeness of fringes), and their locations were subjectively compared. RESULTS: Loading on the restoration over the simulated tooth generated apical stresses of similar intensity (fringe order) at the tooth and the first molar implant for both abutment types. Low-level stress was transferred to the second molar implant. Loading directed on the implant-supported region of the restoration demonstrated low transfer of stress to the simulated tooth. Nonvertical stress transfer with slightly higher intensity was observed for the nonsegmented abutment. CONCLUSION: Within the limitations of this simulation study, stress distribution and intensity for the 2 implant conditions was similar for segmented and nonsegmented abutment designs. Magnitude of stresses observed for both abutment designs was similar for the single implant condition. Vertical loading produced more nonaxial stresses away from the force applied for the 1 implant condition with the nonsegmented abutment. Direct loading results were similar for both abutment designs. Specific recommendations for selection of implant abutment and application should be based on clinical criteria.