可摘局部义齿支架的计算机辅助设计与快速制造

目的 自主开发可摘局部义齿支架三维设计软件及选择性激光熔融制造(selective laser melting,SLM)设备,探讨应用其进行可摘局部义齿支架设计并直接成形金属支架的方法 .方法 使用层析扫描仪获得两个牙列缺损模型的三维点云数据.使用自主开发的可摘局部义齿支架三维设计软件进行模型观测及可摘局部义齿支架(牙合)支托、卡环、舌杆、金属加强网、上颌大连接体等组件的设计.组件设计路线:首先确定组织面轮廓,利用轮廓线内的点云数据生成组织面.根据各个组件的特点,设定抛光面截面形态,结合轮廓线生成抛光面.各组件完成后,用小连接体连成完整支架.将完成的支架数据导入SLM设备中,直接成形金属支架.结果 应用自主开发的可摘局部义齿支架三维设计软件及SLM设备,成功进行了两个可摘局部义齿金属支架的计算机辅助设计及快速制造,在模型上试戴后目测金属支架适合性良好.结论 自主开发的具有完全自主知识产权的可摘局部义齿支架计算机辅助设计与辅助制作系统,可为可摘局部义齿金属支架的制作提供一种新的方法.     

激光选区熔化制作口腔修复体纯钛大跨度支架的精度研究

目的探讨采用激光选区熔化(selective laser melting, SLM)技术制作纯钛及钴铬合金下颌全牙弓种植固定义齿上部结构支架和上颌可摘局部义齿支架的精度, 为SLM纯钛支架的临床应用提供参考。方法选择下颌无牙颌模型1个, 于双侧尖牙和第一磨牙处制作螺丝固位的基台替代体, 作为下颌全牙弓种植修复用牙颌模型;同时选用上颌Kennedy第一类牙列缺损牙颌模型1个;扫描牙颌模型获得数字化模型, 并用扫描仪配套软件设计下颌全牙弓种植固定义齿上部结构金属支架和上颌可摘局部义齿金属支架(设计模型)。通过改良的双激光金属打印机分别制作钴铬合金组和纯钛组下颌支架各12个(每组6个进行热处理, 其余6个不进行热处理), 以及钴铬合金组和纯钛组上颌支架各7个, 扫描获得数字化模型, 借助逆向工程软件Geomagic重叠数字化模型与设计模型。以牙颌模型矢状轴为X轴, 牙颌模型冠状轴为Y轴, 打印粉末堆积方向为Z轴, 分析下颌支架数字化模型基台替代体接口中心点在X、Y、Z轴方向上与设计模型的偏差, 作为下颌支架的正确度, 偏差数据越大, 正确度越差。分析上颌支架整体和7个测量点(腭板中心点和双侧...     

可摘局部义齿支架几何模型的设计

目的:利用国产CAD/CAM软件系统,通过对可摘局部义齿支架的计算机辅助设计,探索开发适用于口腔修复专业义齿设计与数控加工制作的国产软件系统。方法:投影光栅测量法获取下颌KennedyⅡ类2亚类牙列缺损石膏模型的点云数据,在国产CAD/CAM系统中,进行数据精简,并在此点云数据基础上,确立观测线和就位道。按照临床设计原则,分别构建卡环、支托、舌杆、加强网等支架各部件的组织面与磨光面,包括舌杆的半梨形截面、加强网的内外终止线和组织终止点等特征性结构的构建,完成支架的三维几何模型计算机辅助设计。结果:成功建立了可摘局部义齿支架的几何模型。该模型可视性强,便于修改,支架与牙颌模型密合良好。模型的输出数据文件格式为STL,这种通用的传输格式有利于后续的计算机辅助制作。结论:基于国产CAD/CAM软件系统进行可摘局部义齿支架几何模型的设计是可行的。     

选择性激光熔覆(SLM)钛合金可摘局部义齿支架的适合性研究

目的:评价选择性激光熔覆(SLM)技术制作的钛合金可摘局部义齿的适合性.方法:用选择性激光熔覆(SLM)技术制作7 个肯氏Ⅲ类Ti-6Al-4V可摘局部义齿支架,采用光学扫描仪分别扫描通过"印模法"得到的粘附有硅橡胶薄膜的石膏模型,以及去除该薄膜的石膏模型的光学印模,导入Geomagic Qualify软件,通过3D比较功能分析支架大连接体组织面与模型之间的间隙,对其适合性进行评价.结果:钛合金支架与模型之间的总体3D偏差值为(0.221 9±0.07) mm.结论:SLM技术制作的钛合金可摘局部义齿支架的适合性基本满足临床要求.     

下颌牙列缺损患者可摘局部义齿铸造支架的计算机辅助设计

目的对20例临床下颌牙列缺损患者可摘局部义齿支架进行三维计算机辅助设计。方法光栅投影测量法获取20例下颌牙列缺损患者石膏模型的三维数据,按照临床设计原则,利用3DMax、Geomagic和RapidForm等软件分别构建卡环、支托、舌杆、舌板和加强网等可摘局部义齿支架各部件的三维数字化模型,组合完成可摘局部义齿支架的计算机辅助设计,并构建了支架及其部件数据库。结果成功构建了20例临床患者下颌可摘局部义齿的个性化计算机三维支架模型。结论通用三维设计软件可以实现个性化支架的计算机辅助设计。     

激光选区熔化钛合金可摘局部义齿支架的临床应用

目的探讨激光选区熔化(selective laser melting,SLM)钛合金可摘局部义齿支架应用于临床时的效果。方法选取本院就诊的牙列缺损患者共20例,按照制作可摘局部义齿钛合金支架的方法不同而分为2组,SLM组与铸造组。对支架的成功率、就位率、义齿的咀嚼效率以及义齿性口炎发生率分别进行比较。结果数据使用SPSS20.0进行统计分析。结果 SLM组支架的成功率为100.00%,高于铸造组支架的成功率90.00%(P<0.001)。SLM组支架的就位率低于铸造组支架的就位率(P<0.05)。SLM组义齿的咀嚼效率高于铸造组义齿的咀嚼效率(0.783±0.030 vs. 0.699±0.037,P<0.001)。SLM组义齿使用一年的义齿性口炎发生率(10.00%)明显低于铸造组义齿的义齿性口炎发生率(30.00%)(P<0.001)。结论利用SLM制作可摘局部义齿支架在咀嚼效率与降低义齿性口炎发生率优于传统铸造法,可以满足临床使用要求,但跨度大的支架精度有待提高。     

基牙牙周损伤影响可摘局部义齿应力分布的三维有限元分析

目的 探讨三维红外扫描用于可摘局部义齿三维有限元建模的可行性,并分析基牙牙周损伤对可摘局部义齿应力分布的影响,以期为临床提供参考.方法 利用齿科非接触式红外扫描仪和Simpleware软件对下颌肯尼迪分类法Ⅱ类缺损的可摘局部义齿进行三维建模,构建正常牙槽骨组、牙槽骨吸收组和牙槽骨吸收伴牙周膜增宽组三维有限元模型.使用Abaqus有限元分析软件,研究垂直加载和颊侧45°加载条件下3组牙槽骨的应力分布.结果 垂直加载和颊侧45°加载条件下,3组模型均在义齿近中基牙和剩余牙槽嵴远中出现应力集中;牙槽骨吸收伴牙周膜增宽组近中基牙的应力最大(分别为3.57和2.50 MPa),其次为牙槽骨吸收组(分别为3.21和2.41 MPa),正常牙槽骨组最小(分别为2.63和1.79 MPa).颊侧45°加载时3组模型剩余牙槽嵴远中颊侧和远中位点上的应力值均大于垂直加载.结论 基于三维红外扫描的有限元建模方法是可摘局部义齿有限元应力分析有效的建模方式.     

负荷汪颌肯氏Ⅱ类可摘义齿游离端基牙牙槽骨位移的全息干涉测量

目的：比较下颌肯氏Ⅱ类可摘局部义齿的不同卡环对基牙牙槽骨产生作用的差异。方法：在离体人下颌骨上,设计制作5种直接固位体的肯氏Ⅱ类可摘局部义齿,即RPA卡环、RPI卡环、改良RPI卡环、铸造三臂卡环、颊侧锻丝固位臂卡环,用全息干涉测量技术,比较5种固位体使基牙颊舌侧牙槽骨产生位移的情况。结果：近中He支托卡环产生的位移小于过错中He支托卡环,杆型卡环产生颊侧牙槽骨位移分布均匀,圆环形卡环引起的颊侧位移信中在根尖,结论：临床修复此类牙列缺损时应尽量使用近中He支托和杆型卡环。     

改良冷弯卡环与铸造支架联合应用修复牙列缺损的疗效观察

目的观察改良冷弯卡环联合铸造支架可摘局部义齿修复的临床效果。方法使用成品不锈钢圆丝锻制,配合扁丝弯制钳弯制成半圆形卡环臂、圆形卡环肩部及连接体、扁圆过度卡环体的改良冷弯卡环,与钴铬铸造支托、基托联合应用修复牙列缺损。并对90件改良冷弯卡环联合铸造支架可摘局部义齿戴入后追踪观察2年,了解义齿使用情况和基牙健康状况,并将其与钴铬合金支架义齿、传统冷弯卡环塑料基托义齿的修复效果对比。结果 2年后改良冷弯卡环联合铸造支架义齿基牙状况良好,不良症状明显低于其他两组义齿。结论改良冷弯卡环联合铸造支架可摘局部义齿具有良好的功能,可以获得良好的修复效果。     

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。     

激光选区熔化技术制作纯钛可摘义齿支架的可行性研究

目的    探讨激光选区熔化技术制作牙科纯钛义齿支架的可行性,并评价不同打印支撑方向对纯钛支架适合性、力学性能和显微结构的影响。方法    采用激光三维金属打印机按照垂直支撑和横向支撑方向各打印制作15个哑铃状拉伸试件,经真空热处理后,测试其力学性能,并使用激光共聚焦显微镜观察拉伸试件的内部组织结构。用3shape D2000扫描仪对一个上颌无牙颌和一个下颌牙列缺损标准模型进行扫描,建立通用的模型设计文件。采用3shape相应的可摘义齿设计软件包设计义齿支架的数字化模型,按照拉伸试件相同条件,各打印6个纯钛义齿支架,经热处理后在标准模型上检查支架的就位情况,用X线检测纯钛支架内部的气孔。结果   打印支撑方向对拉伸试件的力学性能有显著影响,横向支撑打印试件的弹性模量、屈服强度、极限拉伸强度高于垂直支撑打印试件,但试件的延伸率结果则相反,且各个机械性能数值之间的差异均有统计学意义（均P < 0.05）。纯钛义齿支架在上下颌标准模型上的适合性良好,常规X线检测未发现钛试件内有气孔存在,但2种支撑方向打印的纯钛试件组织致密性都欠佳,内部存在散在气孔。结论   激光选区熔化技术制作的纯钛可摘义齿支架适合性良好,机械性能够满足临床要求,但打印支撑设计显著影响试件的力学性能和显微结构。     

选择性激光熔覆钴铬钼合金可摘局部义齿支架的加工精度分析

目的： 采用选择性激光熔覆（selective laser melting,SLM）技术制作钴铬钼合金可摘局部义齿（removable partial denture,RPD）支架,评估其加工精度。方法： 采用3Shape三维光学扫描仪口外扫描上颌肯氏I类牙列缺损石膏模型,将获取的三维形貌数据重建为数字化模型。利用3shape设计软件在其上进行RPD支架的计算机辅助（computer aided design,CAD）设计。SLM制作5个钴铬钼RPD支架,扫描各支架,获取三维数据,与原CAD数据进行逆向比对,评估其加工精度。结果： SLM钴铬钼支架在石膏模型上就位顺利,组织面与模型贴合,无翘动。与原模型之间的总体3D偏差值为(0.088±0.021) mm。结论： 采用SLM技术打印的钴铬钼合金RPD支架偏差较小,精度较高。     

Stress distribution and abutment tooth mobility of distal-extension removable partial dentures with different retainers: an in vivo study

Three types of retainers (wrought wire clasp, Aker's cast clasp, and conical crown telescopic retainer) designed for distal-extension removable partial dentures (RPDs) were assessed in two Kennedy class I patients' mouths. The assessment, included the ratio of denture base shearing load and mobility of the terminal abutments when loaded on a free-end RPD occlusal surface. The mean values of denture base shearing ratios of wrought wire clasp, Aker's clasp and conical crown telescope were 60, 42 and 20%, respectively. The abutment mobility of the three types of retainers were all within the 'mobile ability area' except the wrought wire clasp for patient A's right side. The greatest tooth mobility was observed with the wrought wire clasps, followed by Aker's clasp and the conical crown telescopic retainer. From the analysis the following was concluded: (i) different retainers do influence the occlusal load distribution; (ii) the occlusal load distributed to the free-end saddle is closely related to the connecting rigidity of the retainer; (iii) mucosal support has an indispensable role in sharing the occlusal load with various retainers, even the rigid telescopic retainer.     

Clasp Retention: The Effects of Five Variables

An attempt was made to determine the relative retention of each of the four most commonly used clasp assemblies. They are the rest, proximal plate, 1 bar (RPI); rest, proximal plate, facial circumferential arm (RPA); modified T; and Akers (facial and lingual circumferential arms). A mandibular bilateral distal extension base removable partial denture design was selected because it is most commonly used. A test model was made by removing all mandibular molars from a Columbia Dentoform and replacing the ivorine second bicuspids with natural teeth. These, in turn, were later replaced with gold crowns that were identical in contour to the natural teeth. Eight removable partial dentures were constructed using preformed plastic lingual bars, minor connectors, denture base retention loops, and clasps. Artificial teeth and the denture bases were processed to each framework as for a clinical patient. Each removable partial denture was placed in the Instron testing machine and pulled from the test model. The investigation examined the effectiveness of each of four types of clasps in resisting displacing forces, in both vertical (occlusal) and mesio-occlusal directions. Each clasp was tested using natural teeth and gold crowns, in dry and wet environments, both with and without indirect retainers. Results indicate that, (1) The RPA clasp was the most retentive of all on natural abutments, against both directions of pull, but only slightly so over the RPI clasp with a vertical pull. (2) The Akers clasp was most retentive against a mesio-occlusal pull on the gold abutments. (3) Natural tooth structure gives slightly more frictional resistance than a gold surface. (4) The presence of artificial saliva caused little change in forces required for dislodgment. (5) The absence of indirect retainers greatly reduced the retentive properties of the RPD frameworks.     

Cross sectional study of removable partial denture design in general practitioners

Many reports have been made on statistical observation on prostheses, among which removable partial denture frequently becomes the subject of investigation from the two sides of cross- and longitudinal- sectional surveys, because its constituent factors are divergent. However, many of such reports used, as subject, the removable partial dentures fitted at clinical practices at the hospitals affiliated to dentistry universities (dentistry departments), and it is hard to say that these reports have grasped the actual circumstances in which removable partial denture is involved since each therapeutic principle as educational hospital constitutes its own specific environment, if the fact that difference occurs in the selecting criteria for each constituent factor according to the operators' designing conception and medical environment is taken into consideration. Then, we have made investigation of edentulous pattern and kinds of denture base material and retainers in 141 cases with removable partial denture fitted at general practitioners, and the following conclusions have been reached. 1. Among the direct retainers of free-end denture, those of clasp with distal rest (Aker's clasp) were the largest in number. 2. By base material, among the direct retainers of free-end denture, many of those of Bar type which has mesial rest (RPI clasp) were observed, in case of metal base, compared with resin base, but difference was observed in the frequency of use of the other retainers. 3. Free-end denture held a majority both in the upper and lower jaws. 4. As base material, resin base was overwhelmingly large in number, compared with metal base.     

可摘局部义齿支架铸型的计算机辅助设计与制作

目的 通过对Kennedy第二类第二亚类牙列缺损模型进行可摘局部义齿支架的计算机辅助设计与制作，探索可行的方案，为该课题的深入研究奠定基础。方法激光扫描获取Kennedy第二类第二亚类牙列缺损石膏模型的三维数据，在重建的牙颌三维数字模型上绘出支架的轮廓图，提取轮廓内的数据作为支架的组织面数据，通过抽壳等操作得到支架的三维模型。将数据导入快速成形设备，加工成形。结果初步实现了可摘局部义齿支架的计算机辅助设计，用快速成形机加工出支架树脂铸型。结论将激光扫描获取数据、计算机辅助设计三维构建至快速成形机制作出产品作为一整套方案，可初步实现可摘局部义齿支架的计算机辅助设计与制作。     

Photoelastic analysis and comparison of force-transmission characteristics of intracoronal attachments with clasp distal-extension removable partial dentures

This investigation photoelastically compared the load-transfer characteristics of various bilateral distal-extension removable partial denture designs embodying intracoronal attachments and clasp assemblies. Six distal-extension designs that included the RPI clasp assembly, cast circumferential clasp, P.D. locking semiprecision, Thompson dowel nonlocking semiprecision, and McCollum and Stern G/L precision attachments were tested. Each prosthesis was subjected to various simulated occlusal loads. Evaluation of the load-transfer characteristics of the various designs was based on comparison of the recorded isochromatic fringe distributions. The RPI clasp assembly generated the most uniform stresses. In general, the four intracoronal retainer frameworks produced higher stresses than did the two clasp frameworks. The highest stresses were developed by the Stern G/L precision attachment.