种植体类型对下颌游离端义齿应力分布的影响

目的:观察不同类型种植体-天然牙联合可摘义齿修复Kennedy I类牙列缺损时不同部位的应力和位移.方法:建立16个种植体-天然牙联合可摘义齿修复下颌Kennedy I类牙列缺损的三维有限元模型,在垂直加载条件下比较不同类型(ITI Straumann 和NOBEL ReplaceTMTapered)种植体周围骨组织、...     

缓冲圆锥型套筒冠可摘义齿的支持组织应力研究

为探明缓冲型圆锥型套筒冠可摘义齿对多数牙缺失，少数牙残存牙列缺损修复效果的生物力学原理，作者采用有限元法对义齿受力后牙牙周支持组织与基托下支持组织的应力分布与非缓冲型套筒冠可摘义齿作对比分析，结果提示：采用缓冲型圆锥套筒冠固位体，Ｈｅ力通过义齿得到重新分配，减轻基牙所承受的Ｈｅ力而增中基托下支持组织承受Ｈｅ力，使基牙避免创伤同时有一定的生理性刺激；通过扩大基托范围，又可减轻基托下支持组织承受力，减     

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。     

圆锥型套筒冠义齿修复老年下颌牙列缺损1例

对单颌牙列仅余留3-5颗天然牙的老年牙列缺损病例用黏膜支持式或混合支持式可摘局部义齿修复,常会引起基牙的负荷过大,或黏膜支持式可摘义齿基托下软组织受力时被压缩,出现基托下软硬组织的萎缩和吸收,义齿下沉,基牙形成早接触,增加基牙和余留牙的负担,造成牙周支持组织损伤。用套筒冠义齿修复能将牙合力合理分配到基牙、牙槽骨和黏膜,减轻基牙的负担,减缓牙槽骨的吸收,义齿戴入后稳定性好、美观舒适、咀嚼效率高、修复后的远期疗效好。本文报道1例下颌仅余留3颗天然牙用圆锥型套筒冠义齿修复后随诊观察4年的临床效果。     

三种固位体义齿修复Kennedy第一和第二类牙列缺损疗效观察

目的评价太极扣义齿、精密附着体义齿和卡环固位体义齿修复Kennedy第一类和第二类牙列缺损的临床效果。方法收集Kennedy第一类和第二类牙列缺损修复患者823例,随机选择其中太极扣义齿、精密附着体义齿和卡环固位体义齿修复患者各63例,电话联系随访复查,检查患者基牙牙周状况及义齿组织面下黏膜,通过问卷调查获取患者的主观评价,并将结果进行对比研究。结果患者对太极扣义齿、精密附着体义齿的主观评价高于对卡环固位体义齿的主观评价;在舒适度、美观方面太极扣义齿优于精密附着体义齿。戴用3种义齿患者的口腔检查结果差异无统计学意义。结论太极扣义齿比较适合修复Kennedy第一类和第二类牙列缺损。     

垂直载荷下分割式可摘局部义齿与套筒冠义齿的有限元分析

目的研究并比较分割式可摘局部义齿与缓冲圆锥型套筒冠义齿在垂直载荷下的应力情况。方法选择上颌双侧第二前磨牙、第一磨牙缺失并伴有基牙有Ⅰ度松动的患者1名,通过螺旋CT扫描,利用Materialise Mimics、Pro/Engineer WF 2.0软件和ANSYS Workbench软件建立精确的上颌三维有限元模型,并在其上进行垂直方向加载,分析比较分割式可摘局部义齿与缓冲圆锥型套筒冠义齿缺牙区黏膜及基牙牙周膜应力情况。结果垂直载荷下,分割式可摘局部义齿缺牙区黏膜所受von Mises力值大于缓冲圆锥型套筒冠义齿缺牙区黏膜所受力值;分割式可摘局部义齿基牙牙周膜von Mises力值接近或小于缓冲圆锥型套筒冠义齿基牙牙周膜所受力值。结论在垂直载荷下,通过与缓冲圆锥型套筒冠义齿相比,分割式可摘局部义齿具有减少基牙受力,保护基牙的功能。     

套筒冠义齿用于牙周病修复治疗后的疗效观察

目的：对套筒冠义齿用于牙周病修复治疗后基牙的牙周情况进行追踪观察。方法：对15例牙周病患者行缓冲型套筒冠义齿修复治疗,观察治疗前后牙齿松动度、牙周组织炎症、龈附着水平、牙周袋深度、牙槽骨边缘骨高度、牙周膜宽度和硬骨板的丧失、龋患、基托下组织炎症和颞下颌关节、咀嚼肌适应情况变化。并通过随访问答形式了解患者的主观感觉。结果：对15例牙周病患者进行了缓冲型套筒冠义齿修复治疗,共制作套筒冠义齿17件,基牙共计73颗,追踪观察时间1-3年。患牙经修复治疗后,随着时间的推移,牙周袋逐渐消失,牙齿松动度逐渐变小,有根分叉病变的牙齿有新的附着形成,X线片显示基牙的牙周膜和骨硬板清晰完整,牙槽骨边缘高度未再见降低,骨密度明显增加,除个别牙齿有牙龈缘的轻微炎症和萎缩外,所有修复体均应用良好。随访问答结果显示,患者对套筒冠义齿修复的效果是满意的。结论：套筒冠义齿对牙周病伴牙列缺损的修复治疗疗效显著、肯定。     

套筒冠义齿修复牙列重度磨耗的临床评价体会

目的：探讨套筒冠义齿修复重度磨耗[牙合]的临床效果。方法：对9例牙列重度磨耗的患者，进行套筒冠义齿修复（6例患者有颞下颌关节紊乱病），共制作套筒冠义齿12件，观察时间6—48个月，追踪患者主观感觉、咀嚼效果、义齿固位、稳定度及颞下颌关节紊乱病是否缓解；并通过X线片检查基牙牙周膜情况、基牙牙槽骨高度。结果：套筒冠义齿修复重度磨耗[牙合]后，患者自我感觉满意、能提高咀嚼效能，义齿固位稳定性好，颞下颌关节紊乱病疗效好，基牙牙周膜无明显异常，基牙牙槽骨无吸收。结论：采用套筒冠义齿修复牙列重度磨耗导致垂直距离下降的患者，可行而且有效。     

下颌KennedyⅡ类牙列缺损冠外附着体义齿基牙牙周状况对支持组织应力分布的影响

目的探讨不同基牙牙周状况下,下颌后牙单侧游离缺损冠外附着体义齿支持组织的应力分布情况。方法建立下颌KennedyⅡ类牙列缺损冠外附着体义齿修复时基牙牙周健康和基牙牙周吸收的三维有限元模型,分析垂直载荷下基牙牙周状况不同时,基牙牙周组织及缺牙区牙槽嵴的von Mises应力分布。结果基牙数目相同的条件下,与牙周健康的模型相比,牙周吸收的模型第二前磨牙的最大应力升高了约30%,牙周最大应力升高了约10%,缺牙区牙嵴的最大应力升高了36%和14%。对于牙周吸收的模型,基牙数目从两颗增加到三颗时,义齿支持组织的应力值无明显降低。结论在下颌单侧游离缺损修复中,末端基牙牙周部分吸收1/3即可导致基牙牙周组织及缺牙区牙嵴的应力明显增加,增加基牙数目并不能有效地降低义齿支持组织的最大应力值。     

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摘要：目的 探讨斜向载荷下采用不同基牙数目时下颌后牙双侧游离缺损冠外附着体义齿支持组织的应力分布情况。方法 2005年选取一成年健康男性志愿者的头部CT（取下颌牙槽骨部分）和离体尖牙、第一双尖牙、第二双尖牙、第一磨牙、第二磨牙的CT扫描图片。建立下颌KennedyⅠ类牙列缺损冠外附着体义齿修复的三维有限元模型,分析在斜向载荷作用下采用不同基牙数目时,基牙牙周组织及缺牙区牙槽嵴的Von Mises应力分布。结果 斜向载荷下,末端基牙牙周膜应力集中区主要位于颊舌侧的牙颈部,随着基牙数目的增加,基牙牙周组织及缺牙区牙嵴的最大应力值都呈下降趋势,基牙由1颗增加至2颗时,应力明显下降,当基牙增加至3颗时,应力的下降量明显减少。结论 在下颌游离缺损修复中,斜向载荷下冠外附着体义齿支持组织应力的减少与基牙数目的增加不完全成比例,在临床上应根据具体的情况确定联合基牙的数目。     

种植体支持对Kennedy Ⅰ类可摘局部义齿应力分布的影响

目的：分析增加种植体支持对于KennedyⅠ类缺失可摘局部义齿应力分布影响。方法：应用三维有限元法,在不同加载条件下分析比较有无种植体支持对于双侧后牙游离缺失可摘局部义齿应力分布的影响。结果：增加种植体支持可以显著降低可摘局部义齿基托的位移,减小义齿基牙牙周膜和基托下支持组织的应力。结论：由种植体支持的可摘局部义齿有利于保护义齿基牙及基托下支持组织的健康。     

In vitro study of a mandibular implant overdenture retained with ball,magnet, or bar attachments: comparison of load transfer and denture stability

PURPOSE: When implants are used to support a removable overdenture, the optimal stress distribution to minimize both forces on the implants and denture movement is desirable. This study compared the stress patterns generated around implants and denture movement among three retention systems. MATERIALS AND METHODS: Two root-form implants were anchored in a mandibular model made of resin, and a removable overdenture on which all experiments were performed was fabricated. The surface of the model was covered with a layer of impression material to simulate oral mucosa. Ball/ O-ring, bar/clip, and magnetic attachments were used. A vertical force was applied to the left first molar and gradually increased from 0 to 50 N in 5-N steps. The resultant stress distribution and denture movement were evaluated. RESULTS: The ball/O-ring attachment transferred the least stress to both implants and produced less bending moment than the bar/clip attachment. Vertical force applied to the bar/clip attachment created immediate stress patterns of greater magnitude and concentration on both implants. CONCLUSION: This in vitro study suggested that the use of the ball/O-ring attachment could be advantageous for implant-supported overdentures with regard to optimizing stress and minimizing denture movement.     

不同临床设计的ERA附着体义齿修复下颌牙列游离端缺损的三维有限元分析

目的:研究3种不同临床设计ERA附着体义齿修复下颌远中游离端缺损的应力及位移分布.方法:建立ERA附着体义齿修复下颌远中游离端缺损的三维有限元模型,根据临床设计分为基本组、支托组和跨弓组.应用有限元法研究在垂直及45°斜向2种载荷方向100 N的作用下,基牙及基托下黏膜的应力和位移以及基托的位移情况.结果:2种载荷下3组模型均在远中基牙远中邻面肩台出现应力集中,远中基牙预备体咬合面位移最大,支托组基牙位移最大,分别为14.91 μm和63.09μm,其次为基本组(9.38 μm和50.56μm),跨弓组最小(8.85 μm和47.31μnn).结论:在本研究条件下,为远中游离端牙列缺损设计基本的ERA附着体义齿更趋于合理.     

Influence of length and diameter of implants associated with distal extension removable partial dentures

PURPOSE: The aim of this study was to evaluate the influence of the length and diameter of the implant incorporated under the saddle of a distal-extension removable partial denture, acting as support. MATERIALS AND METHODS: Six hemi-mandibular models were made with the presence of left inferior cuspid and first bicuspid, with the following differences: model A, without removable partial denture; model B, removable partial denture only; model C, removable partial denture and implant of 3.75 x x mm; model D, removable partial denture and implant of 3.75 x x3 mm; model E, removable partial denture and implant of 5 x x mm; and model F, removable partial denture and implant of 5 x x3 mm. These models were designed with the aid of AutoCAD 2000 (Autodesk, Inc., San Rafael, CA) and processed for finite element analysis by ANSYS 5.4 (Swanson Analysis Systems, Houston, PA). The loads applied were 50 N vertical on each cuspid point. RESULTS: It was noted that the presence of the removable partial denture overloaded the supporting tooth and other structures. The introduction of the implant reduced tensions, mainly at the extremities of the edentulous edge. Both the length and diameter tended to reduce tensions as their dimensions increased. CONCLUSIONS: Increasing the length of the implant had a great influence on the decrease of displacement and von Mises tension values. Increasing the diameter of the implant had a great influence on the decrease of von Mises tension values, but did not influence the displacement values. According to the results of this study, it is a good choice to use the greater and larger implant possible in the association between implant and distal extension removable partial denture.     

Pressure distribution of implant-supported removable partial dentures with stress-breaking attachments

PurposeThis in vitro study investigated the pressure distribution of the implant-supported removable partial dentures (RPDs) with the stress-breaking attachments under the occlusal force.MethodsThe experimental model of bilateral missing premolars and molars was modified from a commercial simulation model. Five pressure sensors were embedded near the bilateral first molars, first premolars, and medio-lingual alveolar crest. Two implants were placed near the second molars, and they were connected to the denture base using the following conditions: complete separation between the denture base and implant with cover screws (CRPD), flexible connection with a stress-breaking ball (SBB) attachment, and rigid connection without stress breaking with healing caps (HC). The pressure at five different areas of the soft tissue and the displacement of the RPDs were simultaneously measured, loading up to 50 N. The coefficient of variation (CV) for each connection was calculated from all data of the pressure at five areas to evaluate the pressure distribution.ResultsThe pressure on medio-lingual alveolar crest and molars of the HC was less than SBB and CRPD. In contrast, the pressure on premolars of SBB was greater than for the HC and CRPD. The CV of SBB was less than that of HC and CRPD. Denture displacement of HC and SBB was less than for CRPD.ConclusionsWithin the in vitro limitations, precise denture settlements and pressure distribution under the denture base could be controlled using an SBB attachment. An SBB attachment might be able to protect the implant from harmful force.     

Stress distribution of abutments and base displacement with precision attachment- and telescopic crown-retained removable partial dentures

Five types of removable partial dentures (two attachment dentures, two telescopic dentures and one clasp denture) were designed. The two attachment dentures were retained by the rigid-precision attachments with or without a stabilizing arm, and the two telescope dentures were retained with cone telescope crowns with or without cross-arch stabilization. The stresses acting on abutment teeth and denture bases and the movements of denture bases were investigated, and the influences of denture design were clarified. The stress acting on a terminal abutment tooth retained by a rigid-precision attachment or cone telescopic crown was larger than that acting on a terminal abutment tooth retained by a clasp. The attachment dentures tended to concentrate more stress at the terminal abutment tooth than did the telescopic dentures. The stress of denture base of an attachment denture and a telescopic denture was less than that of a clasp denture. There was no difference between the stresses of attachment and telescopic dentures. The displacement of the denture base tended to be less when the denture was designed with a rigid connection for the retainer and with cross-arch stabilization.     

非游离端可摘义齿与固定义齿牙槽骨承力的变形分析

目的：观察非游离端可摘义齿与固定义齿受载前后基牙牙槽骨的变形。方法：选用新鲜人尸离体上下颌骨，制备左下第一恒磨牙缺失模型，先后用铸造三臂卡环为固位体的可摘义齿及整铸双端固定桥对缺失区进行修复。以垂直向均匀加载和集中加载两种方式，用电子散斑干涉技术比较分析基牙牙槽骨受载前后的变形分布。结果：两种修复体都可以使基牙牙槽骨的离面位移减少，以固定修复后基牙牙槽骨的离面位移减少得较为显著。结论：两种设计都有其合理性，以固定义齿修复对于改善牙槽骨的力学状况优于铸造三臂卡环为固位体的活动义齿     

不同加载条件下RPI卡环固位可摘局部义齿的三维有限元分析

目的:分析RPI卡环固位可摘局部义齿在垂直、水平和斜向加载条件下义齿的基牙及基托下支持组织的应力分布情况。方法:利用CT图像建立RPI可摘局部义齿的三维有限元模型,通过三维有限元分析法计算不同加载条件下RPI可摘局部义齿的应力。结果:垂直加载的应力集中部位和应力峰值与水平、斜向加载的结果不同,水平与斜向加载的应力集中部位近似,斜向加载更易产生应力集中。结论:临床设计RPI卡环固位时应充分考虑水平与斜向力的作用。     

Visualization of stress and strain related to removable partial denture abutments.

The following conclusions are based on the conditions set forth in this investigation and apply to forces acting through a vertical direction of application only: 1. The unilateral removable partial denture produced no more stress than the bilateral removable partial denture. 2. The fully active Dalbo removable partial denture resulted in the greatest stressbreaking action. 3. The rigid Dalbo removable partial denture resulted in the least ridge displacement. 4. The rigid Dalbo removable partial denture resulted in the greatest stress concentrations in the distal abutment. 5. None of the attachments tested resulted in a distribution of the stresses along the edentulous ridge. 6. The use of two abutments (double abutments) resulted in greater stress concentrations in the distal abutment than the use of single abutments. 7. Forces in the single abutment were resisted along the long axis of the root. 8. Forces in the double abutments were resisted along the long axis of the distal abutment.     

Clinical application of stress-breaking ball attachment for implant overdenture

PatientThe patient was a 62-year-old partially edentulous woman with missing bilateral premolars and molars in the mandibular jaw. The patient selected implant supported-removable partial denture rehabilitation. Implants were placed bilaterally at the distal extension of the denture base in order to minimize denture displacement. The stress-breaking ball (SBB) attachment consists of a flat-top ball head male and O-ring rubber female. The female was covered by a silicone housing with three amounts of space to allow three kinds of settlement (0.3 mm, 0.5 mm, and 0.7 mm); they were selected by thickness or pressure displacement of the mucosa and occlusal force. After the healing period, the SBB attachments (0.3 mm) were placed on the implants, and the implant-supported removable partial denture was then conventionally fabricated. The delivered denture had sufficient retention and appropriate stress breaking.DiscussionThe advantages of SBB attachments over conventional attachments are as follows: (1) they prevent the implant from excessive occlusal force, (2) they are ready-made, (3) they show appropriate retention, and (4) they can be easily mounted on the denture base. The disadvantages of these attachments are as follows: (1) they are approximately 1 mm higher than conventional ball attachments and (2) the retentive force cannot be adjusted.ConclusionThe use of a stress-breaking attachment for implant overdenture rehabilitation should be considered so that the occlusal force is equally distributed between the alveolar ridge and the implants.