计算机辅助后牙全冠修复的设计

目的 通过计算机辅助设计（CAD）获得待修复的全冠的数据,以备计算机辅助加工（CAM）之用。方法 待作全冠修复的牙预备体、邻牙、对He牙经过光学测量,获得其表面三维形状后,选用拟修复的牙的理想牙冠形态,根据缺牙区的大小及邻牙,对He牙的情况进行修改,使理想牙冠形状适合该缺牙区的情况后,用修改后的理想牙冠形状图像与牙预备体形状图像相减,即获得所需修复的全冠的数据,以备CAM加工之用。结果 获得了待修复的全冠的数据和图像。结论 本研究建立了一套通用性良好的冠修复的CAD系统,为CAM的实现奠定了基础。     

后牙嵌体的教育处机辅助设计

目的 通过计算机辅助设计（CAD）获得待修复的后牙嵌体,以备计算机辅助加工（CAM）之用。方法 拟作修复的牙预备体、邻牙、对He牙经过光学测量。获得其表面三维形状后,选用患牙所对应的理想牙冠的形状,根据缺牙区邻牙和对He牙的情况进行修改,使之适合该牙列的情况,然后用修改好的理想牙冠的形状数据减去牙预备体的形状数据,即获得待修复的嵌体的数据。以备CAM加工之用。结果 获得待修复的嵌体的数据和图像,结论 本研究建立了一套通用性良好的嵌体的CAD系统,为CAM的实现奠定了基础。     

用于贴面修复的CAD/CAM系统的研究

目前,计算机和机器人在工业上有了很大的进展,CAD/CAM(计算机辅助设计/计算机辅助制作)技术也已应用于牙科的一些部门。同时,以切削牙体组织少为特点的贴面修复,作为三种前牙的美容修复已引起了人们的重视。然而,它的制作需要一系列联系紧密的步骤和技术。为此,我们做了利用CAD/CAM技术制作贴面的尝试。先制作一个硬质石膏的上颌骨模型,然后用一种配有激光置换表和计算机控制的扫描装置系统进行测量,所得数据作为基础数据,再在模型上进行贴面修复的制备。并再次测量,把这两组数据进行组合,在荧光屏上就可以得到合理的表面数据。这组数据作为CAD/CAM系统在贴面修复过程中的基础数据是很有意义的。     

两种不同牙体预备方法对前牙瓷贴面粘接效果的临床对比研究

目的：对46例242颗牙瓷贴面的临床观察,比较Er,Cr：YSGG激光和金刚砂车针进行前牙预备及瓷贴面的粘接效果。方法：选择242颗需要美容修复的前牙,使用Er,Cr：YSGG激光或金刚砂车针分别进行牙体预备,进行IPS Empress铸瓷贴面修复,每半年进行复查,对修复体密合性、脱落率和破损率进行评价。结果：经过2年的复查,经Er,Cr：YSGG激光进行牙体预备的贴面,其脱落率绝大多数低于4％;金刚砂车针进行牙体预备的贴面,其脱落率绝大多数高于4％。二者的边缘封闭性和破损率大致相同。结论：在前牙区瓷贴面修复中,Er,Cr：YSGG激光进行牙体预备能够获得较为理想的粘接效果。     

计算机辅助设计与制作贴面修复体的临床应用进展

贴面修复设计磨除牙体组织少、美学效果佳,在前牙美学修复中广泛应用.随着计算机辅助设计(computer aided design,CAD)与计算机辅助制作(computer aided manufacture,CAM)系统的发展,以及可切削瓷材料的不断研发,CAD-CAM工艺制作的瓷贴面在临床应用日益广泛.用于制作贴面...     

双排龈技术在CAD/CAM全瓷修复中的临床应用

目的：评价双排龈技术在CAD/CAM全瓷修复中的临床应用效果。方法：对30例48单位前牙行CAD/CAM全瓷修复,牙体预备后采用双排龈技术进行排龈,检查牙龈及预备体、光学印模以及修复体边缘情况。结果：双排龈技术的满意率分别为97.91%,95.83%,100.0%。结论：双排龈技术在CAD/CAM全瓷修复时具有很好的应用效果。     

基于逆向工程技术的贴面计算机辅助设计

目的 探索符合形态美学要求的贴面计算机辅助设计(computer aided design,CAD)方法,为贴面专用CAD平台的开发提供方法学基础.方法 选择1例右上中切牙变色需贴面修复的患者,取牙体预备前与预备后两副超硬石膏模型,牙体预备成切端对接型,经三维激光扫描仪三维数据采集、三维重建、使用逆向工程软件Surfacer10.5与Geomagic Studio 8.0进行贴面CAD.结果 在逆向工程软件基础上确立了贴面CAD的技术路线,完成后的贴面表面光顺,与对侧同名牙对称协调,符合形态美学仿真修复要求.结论 基于逆向工程技术进行贴面CAD,方法简便可行,为自主知识产权贴面CAD软件的开发提供了必要的方法学基础.     

薄型瓷贴面牙体预备术式的分型探讨

薄型瓷贴面是国外治疗变色前牙、染色前牙和前牙小缺损的常规修复方法,国内的临床报表表明瓷贴面明显优于树脂贴面,瓷贴面牙体预备术式的分型目前尚有争议,国外的六型分类法指标多,难于掌握,作者设计了三种牙体预备术式,并用于７８颗上前牙修复,考查粘贴牙的美学效果,探索薄型瓷贴面牙体预备术式新的分型方法,结果表明三型分类法简明扼要,适应范围明确,容易理解,掌握和应用。     

龈色瓷在前牙烤瓷修复中的应用

前牙牙龈缺损较多的患者 ,用一般金属烤瓷冠桥修复 ,常导致牙冠长度与对侧同名牙及邻牙明显不协调 ,达不到美观逼真的效果。采用龈色瓷可在一定程度上改善这种情况。1　适应证1.1　唇侧牙龈退缩1.2　唇侧牙周袋切除后牙根外露 ,牙齿无松动1.3　牙体缺损至龈下 ,为暴露出缺损面龈切量较多1.4　缺牙区牙槽骨缺损 ,凹陷2　方　法2 .1　基牙预备邻舌面及切缘预备同一般修复体 ,颈缘肩台预备以前 ,以无蜡牙线浸血管收缩剂压在龈沟内 2 min,待游离龈退缩后 ,用肩台钻沿牙颈部均匀磨切。制备唇侧颈缘肩台时 ,为保证冠边缘龈瓷的强度和美观 ,尤其应…     

以部分贴面最小侵入性技术修复上颌中切牙缺损

最小侵入性治疗方式可以保留健康的牙体组织。然而，仅局限于牙体缺损部位的牙体预备技术，将可能导致修复体与天然牙之间的界限更多地暴露于可见区域。在材料方面．复合树脂和瓷均可用于前牙区较小缺损的修复治疗。本病例展示一位患者要求更换治疗其上颌中切牙的变色充填体。牙体预备在其原有充填体范围内进行．并以部分瓷贴面给予修复。虽然水平完成线位于临床牙冠中部，但患者对此仍感到满意。证明这种技术在对前牙诸如外伤所导致的较小缺损进行修复时．可作为以往常规采用的直接复合树脂修复技术的良好替代方式。     

Modified Y-TZP core design improves all-ceramic crown reliability

This study tested the hypothesis that all-ceramic core-veneer system crown reliability is improved by modification of the core design. We modeled a tooth preparation by reducing the height of proximal walls by 1.5 mm and the occlusal surface by 2.0 mm. The CAD-based tooth preparation was replicated and positioned in a dental articulator for core and veneer fabrication. Standard (0.5 mm uniform thickness) and modified (2.5 mm height lingual and proximal cervical areas) core designs were produced, followed by the application of veneer porcelain for a total thickness of 1.5 mm. The crowns were cemented to 30-day-aged composite dies and were either single-load-to-failure or step-stress-accelerated fatigue-tested. Use of level probability plots showed significantly higher reliability for the modified core design group. The fatigue fracture modes were veneer chipping not exposing the core for the standard group, and exposing the veneer core interface for the modified group.     

Effect of adhesive resin cement on design of partial veneer crowns.

STATEMENT OF PROBLEM: Procedures involved in the tooth preparation, impression, and casting of partial veneer three-quarter crowns are considered to be complex. PURPOSE: This study assessed whether a simplified partial veneer crown design, when cemented with a 4-META adhesive resin, had a comparable resistance to displacement forces compared with a conventionally prepared partial veneer crown cemented with a traditional luting agent. MATERIAL AND METHODS: Conventional partial veneer crowns were prepared on 20 natural premolars, and 20 other premolars received modified partial veneer crown tooth preparations without proximal grooves. Artificial crowns were made for these teeth with Students alloy. Half the crowns in each of the 2 groups were luted with 4-META resin; the other half were luted with a zinc phosphate cement. Loads required to displace the partial veneer crowns were recorded after 24 hours and thermocycling, then the mode of separation was recorded for each crown. Average force required to displace partial veneer crowns for the 4 groups were subjected to 2-way analysis of variance and Scheffé test. RESULTS: The 2 groups luted with 4-META resin and the group with proximal grooves luted with zinc phosphate were not significantly different. However, they were all greater than the group without proximal grooves luted with zinc phosphate cement. CONCLUSION: Forces required to displace partial veneer crowns prepared in a traditional manner and those teeth prepared without proximal grooves were similar if the artificial crowns were luted with adhesive resin cement.     

Thermal/mechanical simulation and laboratory fatigue testing of an alternative yttria tetragonal zirconia polycrystal core‐veneer all‐ceramic layered crown design

Bonfante EA, Rafferty B, Zavanelli RA, Silva NRFA, Rekow ED, Thompson VP, Coelho PG. Thermal/mechanical simulation and laboratory fatigue testing of an alternative yttria tetragonal zirconia polycrystal core‐veneer all‐ceramic layered crown design. Eur J Oral Sci 2010; 118: 202–209. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci This study evaluated the stress levels at the core layer and the veneer layer of zirconia crowns (comprising an alternative core design vs. a standard core design) under mechanical/thermal simulation, and subjected simulated models to laboratory mouth‐motion fatigue. The dimensions of a mandibular first molar were imported into computer‐aided design (CAD) software and a tooth preparation was modeled. A crown was designed using the space between the original tooth and the prepared tooth. The alternative core presented an additional lingual shoulder that lowered the veneer bulk of the cusps. Finite element analyses evaluated the residual maximum principal stresses fields at the core and veneer of both designs under loading and when cooled from 900°C to 25°C. Crowns were fabricated and mouth‐motion fatigued, generating master Weibull curves and reliability data. Thermal modeling showed low residual stress fields throughout the bulk of the cusps for both groups. Mechanical simulation depicted a shift in stress levels to the core of the alternative design compared with the standard design. Significantly higher reliability was found for the alternative core. Regardless of the alternative configuration, thermal and mechanical computer simulations showed stress in the alternative core design comparable and higher to that of the standard configuration, respectively. Such a mechanical scenario probably led to the higher reliability of the alternative design under fatigue.     

Minimally invasive lithium disilicate ceramic veneers fabricated using chairside CAD/CAM: a clinical report

This clinical report describes the use of modern CAD/CAM technology combined with a conventional impression technique to treat a malformed tooth with ceramic veneer in a single appointment. A thin veneer (0.4 mm) made of lithium disilicate ceramic was used to correct the shape of the malformed tooth with a minimally invasive preparation using a chairside CAD/CAM system. Thus the treatment can be performed during one appointment. To facilitate the CAD/CAM process and fabrication of the veneer, a scanable model fabricated on a modified gypsum definitive cast was used. The malformed tooth was corrected on the cast by use of a composite resin and an impression was then made. This trimmed impression was used intraorally during the scanning process to facilitate fabrication of the veneer.     

Development of the dental CAD/CAM system

Studies have been undertaken to apply CAD/CAM system to Dentistry and to make prosthetic appliances with this system automatically. Specimens are 4 times large plaster models. For the inside of the crown, the plaster model of prepared tooth is measured with laser displacement meter then the numerical data is obtained. After modification of this data for the concave cutting, the modeling machine works with this numerical data. For the outside of the crown, the typical colonal figure data (= CAD Data Base) is prepared. And this data is modified with computer to fit the prepared tooth margin and proximal or antagonical tooth (= CAD). This CAD Data Base was obtained with 3 dimensional point digitizer (3DPD). Because this measuring method with 3DPD is to be able to select points, the CAD Data Base could be consists of characteristic points. When this data base is really used, it is interpolated with s-spline. Spline interpolation is indispensable to the CAD/CAM system. Further understanding of this system, explanation is divided into three parts which are 3D measurement, CAD and CAM. (3D measurement) Two types of 3D measurement is dealed with this system. One is for the CAD data base and another is for the prepared tooth model. 3D measurement of the prepared tooth model is equivalent of the impression takings in the routine method. For the clear marginal line and for the uniform distribution of measuring points, the prepared tooth model is tilted and rotated on the working table when it is measured with laser. (CAD) The CAD Data Base can be extended, contracted, parallel translated and rotated with the Affine transformation. For putting the individual margin data on the CAD Data Base, the prepared tooth margin is re-digitized with 3DPD. Occlusal data is taken from F.G.P. core. (CAM) The application of the spline interpolation to the tool offset theory, which is effective at the groove especially, makes easy to calculate the tool path. When the prepared tooth model is manufactured, it is tilted and rotated on the table like the measurement with laser-scan.     

牙制备体形态对计算机辅助设计与辅助制作全瓷底层冠适合性的影响

目的　研究牙制备体形态对计算机辅助设计与辅助制作 (computeraideddesign computeraidedmanufacture ,CAD CAM )全瓷底层冠适合性的影响。方法　将牙制备体设计成不同的向聚合度和边缘形态 ,采用MC切削陶瓷经Cerec2CAD CAM系统加工制作成全瓷底层冠 ,粘结于制备体上。采用体视显微镜测试全瓷底层冠边缘、肩台、轴面和面的适合性。结果　当向聚合度为 2 0°时 ,全瓷底层冠的适合性最好 (10 1 7～ 12 7 9) μm ;边缘形态对底层冠边缘和肩台的适合性有影响 (P <0 0 5 ) ,凹面型者适合性较好。当牙制备体设计为 2 0°聚合度、边缘形态为凹面型时 ,全瓷底层冠的边缘适合性为 (40 1± 11 8) μm。 结论　临床制作CAD CAM全瓷底层冠时 ,建议牙制备体设计成 2 0°向聚合度及凹面型边缘形态     

Tooth structure removal associated with various preparation designs for anterior teeth

STATEMENT OF PROBLEM: The conservation of sound tooth structure helps preserve tooth vitality and reduce postoperative sensitivity. Innovative preparation designs, like those for porcelain laminate veneers, are much less invasive than conventional complete-coverage crown preparations. However, no study has quantified the amount of tooth structure removed during these preparations. PURPOSE: The purpose of this study was to quantify and compare the amount of tooth structure removed when various innovative and conventional tooth preparation designs were completed on different teeth. MATERIAL AND METHOD:. A new comprehensive tooth preparation design classification system was introduced. Typodont resin teeth representing the maxillary left central incisor, maxillary left canine, and mandibular left central incisor were prepared with the following designs: partial (V1), traditional (V2), extended (V3), and complete (V4) porcelain laminate veneer preparations; resin-bonded retainer preparation with grooves (A1) and with wing/grooves (A2); all-ceramic crown preparation with 0.8 mm axial reduction and tapering chamfer finish line (F1), all-ceramic crown preparation with 1.0 mm axial reduction and rounded shoulder finish line (F2), and metal-ceramic crown with 1.4 mm axial reduction and facial shoulder finish line (F3). After tooth preparations (10 per group), the crown was separated from the root at the CEJ. The removed coronal tooth structure was measured with gravimetric analysis. Means and standard deviations for tooth structure removal with different preparation designs were calculated and analyzed with analysis of variance at a significance level of P<.05. RESULTS: Significant differences in the amount of tooth structure removal were noted between preparation designs. Ceramic veneers and resin-bonded prosthesis retainers were the least invasive preparation designs, removing approximately 3% to 30% of the coronal tooth structure by weight. Approximately 63% to 72% of the coronal tooth structure was removed when teeth were prepared for all-ceramic and metal-ceramic crowns. For a single crown restoration, the tooth structure removal required for an F3 preparation (metal-ceramic crown) was 4.3 times greater than for a V2 preparation (porcelain laminate veneer, facial surface only) and 2.4 times greater than for a V4 preparation (more extensive porcelain laminate veneer). CONCLUSION: Within the limitations of this study, tooth preparations for porcelain laminate veneers and resin-bonded prostheses required approximately one-quarter to one-half the amount of tooth reduction of conventional complete-coverage crowns.     

全冠预备体评价指标的计算机辅助量化方法

目的基于三维扫描和逆向工程技术,研究全冠预备体临床评价指标的量化方法,并为专用评价软件的研发建立关键技术路线。方法在教学用标准牙列石膏模型上,对左侧上颌第一磨牙进行全瓷冠牙体预备,用牙颌模型三维激光扫描仪获取预备前牙冠、预备体代型、邻牙以及对骀牙三维点云数据,通过对预备体及预备前牙冠数据进行点云间三维差异分析,得到牙体预备量的量化分布情况。基于点云分割及特征点云提取分析的方法,在所得截面下进行全冠预备体轴壁倾斜度及肩台宽度的定量表示的研究。结果通过对点云数据进行处理分析,得到牙体预备量、预备体轴壁倾斜度及肩台宽度的量化指标。结论本研究应用逆向工程软件,初步建立一种全冠预备体关键评价指标的量化表示方法。