无牙颌种植覆盖义齿三维光弹实验模型的建立

目的：建立无牙颌种植覆盖义齿的三维光弹模型。方法：选取标准下颌无牙颌模型,在双侧尖牙区植入两枚种植体,以硅橡胶为模具翻制环氧树脂模型,表面覆盖厚2mm的硅橡胶牙槽黏膜模拟层,制作全口义齿,分别连接球帽、磁性、杆卡附着体制成各型种植覆盖义齿光弹模型,垂直加载,应力冻结切片,观测应力条纹图样。结果：模型均质透明无初始应力,具有良好的冻结性能,为应力测试提供了清晰的图像。结论：实验建立的无牙颌种植覆盖义齿三维光弹模型可定性分析功能状态下支持组织的应力分布情况。     

不同固位形式可摘局部义齿对支持组织应力分布的研究

目的:探讨附着体义齿与常见可摘局部义齿修复单侧游离端缺失对支持组织应力分布的影响.方法:分别以磁性附着体、RPI卡环组、联合卡环组三种固位形式的可摘局部义齿修复下颌单侧游离端缺失,用三维光弹应力冻结切片技术测试义齿加载后对基牙和缺牙区牙槽骨应力分布,并与基牙不戴义齿时载荷下的应力比较.结果:磁性附着体对54|基牙和缺牙区的牙槽骨应力稍大于RPI,只占54|基牙应力的48%,且对基牙近、远中应力基本相等;联合卡环对基牙牙槽骨应力最小,对缺牙区牙槽骨应力最大.结论:磁性附着体义齿修复单侧游离端缺失能够达到RPI义齿功能效果,特别适合于对美观和舒适要求较高者,不主张使用仅靠单侧固位的联合卡环组义齿.     

无牙下颌种植全口覆盖义齿不同上部结构光弹模型的建立

目的:建立无牙颌光弹模型,为研究不同上部结构的种植全口覆盖义齿种植体周围支持组织的应力分布提供基础模型。方法:以光弹性环氧树脂模拟下颌骨,牙龈硅橡胶模拟牙槽黏膜。采用临床常用种植体、4种上部附着结构,按临床实际操作步骤制得双种植体支持的下颌全口覆盖义齿光弹模型。以正中全牙列加载为例测试光弹应力。结果:制得含种植体的环氧树脂光弹模型呈淡黄色,质地均匀,透明,无初应力,为应力测试提供了良好的实验基础。结论:该模型可用于定性分析种植体周围支持组织内的应力分布情况。     

不同基牙数目附着体义齿对支持组织应力分布的影响

目的探讨铰链式冠外附着体修复末端游离缺损时,不同基牙数目对支持组织应力分布的影响。方法以铰链式附着体为固位体,修复右下第二磨牙游离缺损,分别制作以第一磨牙为基牙的单基牙附着体义齿的三维光弹模型和以第一磨牙及第二前磨牙为基牙的双基牙附着体义齿的三维光弹模型。采用光弹性应力分析法,定性分析不同基牙数目时,该附着体义齿对基牙牙周支持组织应力分布的影响。结果附着体义齿在正中咬合情况下,单基牙时,在该附着体义齿的缺牙区牙槽骨内、基牙的远中根尖和近中根尖处,可见应力集中;双基牙时,得到的结果相似。结论用该附着体修复第二磨牙末端游离缺损时,在正中咬合情况下,基牙数目对支持组织的应力分布无明显影响,提示临床可采用单基牙;在正中咬合情况下,基牙与牙槽嵴黏膜应力分布均匀,提示该附着体适用于基牙条件稍差、而牙槽嵴黏膜条件较好的患者。     

牙颌三维光弹模型的制作法

制作光弹模型是光弹应力分析实验中非常重要的步骤之一。本文介绍了和牙颌形态相似、大小一致的三维光弹模型的制作方法。采用弹性好、变形小的硅橡胶作模具;在牙、颌模具中分别灌注测试牙及牙槽骨的环氧树脂模型;将环氧牙的根部插入相应的牙槽窝中,制成三维光弹模型。这种分层、分部的浇注方法,消除了牙颌光弹模型的初应力。     

不同设计形式RPD对支持组织应力分布影响的光弹分析

目的:探讨分裂式设计与RPI设计制作的钴铬合金铸造支架RPD修复KennedyⅠ类缺损对支持组织应力分布的影响,为优化义齿设计提供实验依据。方法:分别以分裂式设计和RPI设计两种设计形式的钴铬合金铸造支架RPD修复下颌牙双侧游离缺失,用三维光弹应力冻结切片技术测试义齿加载后对基牙和缺牙区牙槽骨的应力分布,并加以分析比较。结果:钴铬合金分裂式设计的铸造支架RPD承受压力沿基牙牙体长轴传导,基牙远中所受扭力较小。结论:对于KennedyⅠ类牙列缺损,钴铬合金分裂式设计的铸造支架RPD使支持组织受力均匀、合理,减小了基牙受到的扭力,达到基牙保护的目的,是一种值得推广的设计。     

改良杆卡式附着体与不同可摘局部义齿对支持组织应力分布的研究

目的探讨改良杆卡式附着体义齿与RPI卡环组、联合卡环组可摘局部义齿修复单侧游离缺失对支持组织的应力分布。方法在下颌47、46单侧游离缺失的环氧树脂模型上分别以改良杆卡式附着体、RPI卡环组、联合卡环组3种固位形式的可摘义齿修复,用三维光弹应力冻结切片技术测试义齿加载后对基牙和缺牙区牙槽骨应力分布。结果对基牙牙槽骨的应力：改良杆卡式附着体义齿〉RPI卡环组〉联合卡环组（P〈0．05）;附着体义齿对基牙的近、远中应力无显著性：差异（P〉0．05）;RPI卡环组义齿有猞支托处的应力大于无拾支托处的应力（P〈0．05）;联合卡环组对远中的应力大于近中（P〈0．05）。对缺牙区牙槽骨应力：改良杆卡式附着体与RPI卡环组均小于联合卡环组（P〈0．05）;附着体义齿、RPI对缺牙区牙从近中到远中的4个切片应力无显著性差异（P〉0．05）,联合卡环组远中大于近中（P〈0．05）。结论改良杆卡式附着体义齿有应力中断作用,各点应力分布较均匀。RPI固位的活动义齿应力主要分布在基牙上,缺牙区应力稍小。联合卡环组义齿对失牙区的应力最大,基牙上应力较小。     

口腔生物力学

弹性模量和初始应力对种植体骨界面应力分布影响的三维有限元分析；通用混合型复合树脂收缩应力的光弹分析；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；利用Matlab和Pro／E软件辅助建立桩核冠的三维有限元模型；纳米（PMMA／蒙托土）义齿基托复合材料力学性能的研究；冷冻／冷冻干燥处理对犬下颌骨生物力学性能的影响。[编者按]     

三种桩材桩核修复上颌中切牙光弹模型的建立

目的:为分析不同弹性模量桩对根管壁应力分布的影响,建立上颌中切牙桩核修复的光弹模型.方法:以环氧树脂模拟上颌中切牙牙根部、牙槽骨;室温硫化硅橡胶模拟牙周膜;复合树脂制作核,建立桩为成品纤维桩、铸造钛合金、铸造镍铬合金的上颌中切牙桩核修复光弹模型.结果:建立了表面光洁、透明度高,几何尺寸接近实际情况,牙根、牙槽骨、牙周膜弹性模量比接近于1.37:1:0.0003的光弹模型.结论:该模型可以用于分析不同弹性模量桩对根管壁应力分布影响的光弹性实验.     

下颌牙列三维光弹模型的设计和制作

目的 探讨下颌牙列三维比弹模型的设计和制作。方法 根据相似性原理，用不同弹性模量的环氧树脂模拟牙体、牙槽骨，用硅橡胶模拟牙周膜制作下颌牙列三维光弹模型，结果 制作了与实体相近的下颌牙列三维光弹模型。牙体、牙槽骨及牙周膜的弹性模量之比为13．2：1：0．0003。结论 该三维光弹模型可用于定性分析牙周支持组织的应力分布情况。     

生物功能性全口义齿牙槽骨的三维光弹应力分析

目的：研究生物功能性全口义齿在各向咬合状态时下颌牙槽骨的应力分布。方法：标准无牙颌模型翻制环氧树脂模型,制作生物功能性全口义齿,分别在正中、前伸、侧向咬合时进行三维光弹应力分析。结果：正中牙槽骨内最大应力出现在第一磨牙区牙槽嵴舌侧;侧向牙槽骨内最大应力值出现在双侧第二磨牙区,工作侧最大应力出现在牙槽嵴唇颊侧,平衡侧最大应力出现在牙槽嵴舌侧;前伸牙槽骨内最大应力出现在第二磨牙区舌侧。结论：生物功能性全口义齿在各向咬合状态时下颌牙槽骨的应力分布基本与平衡理论相一致。     

The effects of increasing the reverse curve of Spee in a lower archwire examined using a dynamic photo-elastic gelatine model.

This paper describes the development and testing of a dynamic in vitro photo-elastic model for evaluating the effects of orthodontic mechanics on an entire arch of teeth. A model of a mandibular arch was made and the teeth were embedded in a gelatine material with a high level of mechanical creep which permitted tooth movement in response to orthodontic forces. The excellent photo-elastic properties of this material also facilitated the analysis of the stress distribution around the roots of the teeth. The model of a mandibular arch was used to investigate the tooth movements and stress distributions produced by increasing the reverse curve of Spee in a 0.018 x 0.025-inch stainless steel archwire. The results revealed that a 1-mm reverse curve of Spee increased the arch length by 1.6 mm, but increasing the reverse curve of Spee to 5 mm did not increase arch length further. Photo-elastic analysis showed an increased stress distribution around the roots of the incisors and molars as the reverse curve of Spee was increased in the archwire.     

磁性附着体下颌种植覆盖义齿牙槽骨的三维光弹应力分析

目的：研究磁性附着体下颌种植覆盖义齿在各种咬合状态时下颌牙槽骨的应力分布。方法：选取标准无牙颌模型,在双侧尖牙区植入种植体,连接磁性附着体,翻制下颌环氧树脂模型,制作生物功能性全口义齿,分别在正中、前伸、侧向咬合时加载应力,冻结切片,观测各牙位应力条纹。结果：磁性附着体下颌种植覆盖义齿在正中、侧向、前伸咬合应力加载时种植体周围牙槽骨应力值最大,余留牙槽嵴后牙区所受应力大于前牙区。正中、前伸磨牙区最大应力值出现于颊侧,切牙区最大应力值出现于舌侧。侧向工作侧最大应力值出现于唇颊侧,平衡侧最大应力值出现于舌侧。结论：磁性附着体种植覆盖义齿各向咬合时,应力既分布到种植体,也分布到剩余牙槽嵴,可以明显降低种植体周围骨组织的受力,有利于种植体的健康。     

不同连接设计种植全口义齿的三维光弹应力分析

目的：研究常规半口义齿、种植杆卡覆盖义齿及种植固定义齿在牙合力作用下其支持组织——牙槽骨及种植体周围的应力分布状况。方法：用三维光弹应力冻结切片法,对在牙合力作用下的应力状况进行应力冻结,并分别在切牙区、尖牙区、前磨牙区、第一磨牙区、第二磨牙区作３ｍｍ厚切片;并在４颗种植体周围作包含种植体的５ｍｍ厚切片,分析其内部的应力分布状况。结果：种植覆盖义齿的种植体周围骨界面,牙槽骨的应力值均比常规义齿及种植固定义齿低,无论是哪种形式的种植义齿,都易发生远中种植体受力过大而松动。结论：种植覆盖义齿具有良好的力学特性;在义齿设计时应采取措施保护远中种植体。     

冲击载荷下下颌种植覆盖总义齿与下颌常规总义齿应力分布特点的比较研究

目的比较分析下颌种植覆盖总义齿及下颌常规总义齿的应力分布特点。方法应用ＣＴ扫描法建立下颌种植覆盖总义齿及下颌常规总义齿的三维有限元模型,并采用更为接近　力性质的冲击载荷,将咀嚼动态过程引入有限元研究,比较分析两种义齿应力分布特点。结果①种植体内部应力最大值出现于侧方种植体内,骨界面及软组织界面应力最大值出现于侧方种植体远中舌侧皮质骨及粘骨膜内;②下颌种植覆盖总义齿种植体的应用降低了剩余牙槽嵴表面压应力峰值;③下颌常规总义齿及种植覆盖总义齿基托应力峰值分别出现于前牙区舌侧基托及侧方种植体顶部基托处。结论①下颌种植覆盖总义齿机械并发症易发生于侧方种植体内及侧方种植体骨界面处;②种植体的应用有利于保护剩余牙槽嵴,减缓骨吸收;③二种义齿基托易折部位不同。     

An analysis of stress around abutment teeth and periodontium in three-unit fixed partial dentures--photoelastic analysis with simulated periodontal ligament

The mechanical characteristics of zirconia, hybrid hard resin and dental metal for crowns and fixed partial dentures (FPD) have been researched for clinical applications. However, for these kinds of restorations, the distribution of mechanical stress around the abutment teeth and periodontium during function has not been sufficiently assessed. The aim of this study was to clarify the influence of these materials upon abutment teeth and periodontium through a two-dimensional photoelastic method. Two-dimensional simulation models of three-unit FPDs were constructed from these materials. By applying a force of 400 N vertically to these FPDs, the stress distribution around the abutment teeth and alveolar bone was analyzed and the fringe orders were recorded with a transmission polariscope. As a result, the fringe order values at the root dentin around the marginal area of the pontic joint were the highest in zirconia, and the smallest in hybrid hard resin. The spread of internal stress around the marginal area was larger in the hybrid hard resin model and dental metal model than in the zirconia model. This study suggested that differences in stress distribution within the abutment teeth and around the alveolar bone were related to differences in elastic coefficients of the materials used in FPDs.     

Three-dimensional photo-elastic stress analysis of maxillary and mandibular complete dentures

Three-dimensional photo-elasticity was used to study the stress distribution in complete dentures in functional positions. A new loading device was developed utilizing a linear motion bearing as its main component and mandibular dentures were evaluated for the first time. The stress concentrations were highest (2.5 fringes) on the working side of the mandibular denture. This was also demonstrated in the maxillary denture; however, the magnitude was less (1.8 fringes). The results indicate that this method could be used to quantitatively evaluate the effect of various occlusal schemes upon the denture bases.     

Effects of cantilever design and material on stress distribution in fixed partial dentures--a finite element analysis

The purpose of this study was to examine the stress distribution in distal cantilevered fixed partial dentures (FPDs) that are designed with different cantilever morphology and made from different restorative materials. The finite element (FE) method was used to create models of two restoration types; metal-ceramic and an all-ceramic FPDs. Both models were designed with distal cantilevers involving the first and second premolars as abutments and cantilever extension involving at the premolar or molar. The width of connector between the cantilever and the primary abutment restoration was 2.25 mm. The load applied during the FE analysis was positioned at the cusp tips of all teeth. The FE analysis of the models revealed that Von Mises stress values with maximum stress concentrations were observed on connectors of distal cantilevers. Stress concentration sites were also observed at the distal cervical area of the second premolar tooth. Models with premolar cantilever extensions restored with all-ceramic induced lower Von Mises stress values than metal-ceramic restorations, however models with molar cantilever extensions restored with all-ceramic restorations induced higher Von Misses stress values than metal-ceramic restorations. If the distal cantilever length and restorative material is appropriately chosen, the failure frequency may be reduced. All ceramic can be used as restorative material, when the cantilevers length is not more than the mesiodistal dimension of a premolar tooth and metal-ceramic restorations can be used in longer situations.     

弹性树脂固位体与PMMA基托联合应用改善传统活动义齿的美观

目的：设计联合义齿改善传统活动义齿易显露金属卡环,影响患者美观问题。方法：用弹性树脂制作固位体,聚甲基内烯酸（ＰＭＭＡ）树脂制作基托与人工牙,在弹性固位体上制作固位形加强两种材料的结合,联合应用弹性树脂与ＰＭＭＡ树脂,设计联合义齿,修复缺牙患者５６例。结果：联合义齿获得了良奸的美观效果,并改善了义齿的固位与应力分布,防止食物嵌塞,易于修理。结论：联合义齿结合了弹性树脂与ＰＭＭＡ树脂的优点,是一种值得推广的活动义齿设计。