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.     

逆向工程的计算机辅助设计嵌体的研究

目的:研究口腔修复与计算机辅助设计结合的方法，实现嵌体的计算机辅助设计系统。方法:制作修复牙预备体、邻牙、对咬和牙，通过光学测量获得其表面三维形状，输入计算机在基于逆向工程软件surfacer二次开发的口腔固定修复CAD系统进行修复体设计。结果:本文以嵌体修复体为例，实现了嵌体曲面重构。结论:使用口腔固定修复CAD系统设计嵌体符合口腔修复学和解剖生理学理论，操作简单。     

金属嵌体修复磨牙邻He面洞的疗效

目的 比较金属嵌体与银汞合金充填磨牙邻He面洞的疗效。方法 选取上He第一磨牙因龋损而制备近中邻He面洞者；分别以金属嵌体或银汞合金修复各50颗牙，跟踪观察5年(1997-2002年)，比较结果。结果 用嵌体修复上颌第二磨牙近中邻He面洞成功48颗牙，失败2颗牙，用银汞合金修复成功37颗牙失败13颗牙。结论 用嵌体修复上颌第一磨牙近中邻He面洞的疗效明显优于银汞合金修复者。     

不同大小MO洞型复合树脂嵌体修复应力分布的有限元分析

目的 探讨复合树脂嵌体修复后,近中邻（meiso-occlusal,MO）洞型面深度及宽度变化对牙体抗力的影响。方法采用锥形束CT（cone beam computed tomography,CBCT）扫描,结合Mimics、Geomagic Studio逆向工程等软件,建立不同大小邻（II类）MO洞型树脂嵌体修复的三维有限元模型,用ANSYS Workbench软件网格划分并求解分析各模型内部牙体及嵌体在垂直、舌向45°加载下主应力峰值及Von-mises应力分布情况。结果大小不同的MO洞型以复合树脂嵌体修复时,龈壁对应处是嵌体的主要应力所在,洞底部近髓腔处是牙体的主要应力集中区。随着面洞型深度、宽度增加,牙体、修复体的最大应力峰值及Von-mises应力集中区分布范围加大;牙体Von-mises应力受洞型宽度的影响更大,嵌体的Von-mises应力受洞型深度增加影响更大。侧向加载大大增加了牙体和修复体的应力峰值。结论MO洞型以树脂嵌体修复后,洞深、洞宽度加大及侧向加载增加了牙体与嵌体的应力峰值,改变了应力集中区分布范围。     

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。     

人下颌第一磨牙全瓷修复体预备量与粘接面积的初步研究

目的量化和比较下颌第一磨牙不同瓷修复体预备量(磨切的牙体组织占牙冠硬组织的体积百分比)、粘接面积。方法收集10颗人离体下颌第一磨牙,采用Micro CT对其进行扫描和重建,通过3D打印的方法批量复制为4组(A、B、C、D),每组10个,按照牙体预备标准对3组样本分别进行全瓷冠(A1-A10)、邻牙合全瓷嵌体(B1-B10)和多面全瓷嵌体(MOD)(C1-C10)预备,D组(D1-D10)为空白对照组;最后采用逆向工程软件Mimics和Geomagic Studio对修复体预备量、粘接面积进行测量分析。结果下颌第一磨牙全瓷冠、邻牙合全瓷嵌体和MOD全瓷嵌体的预备量依次为36.21%、5.75%和11.93%;粘接面积测量结果为:全瓷冠169.96 mm2、邻牙合全瓷嵌体40.27 mm2、MOD全瓷嵌体81.94 mm2,不同全瓷修复体的预备量、粘接面积的差异均有统计学意义;邻牙合全瓷嵌体和MOD全瓷嵌体牙釉质粘接面积分别为26.55 mm2、55.13 mm2,牙本质粘接面积分别为12.92 mm2、23.97 mm2,牙釉质粘接面积>牙本质。结论下颌第一磨牙全瓷修复体预备量、粘接面积的大小与修复体类型有关;下颌第一磨牙全瓷嵌体粘接边缘线牙体组织为牙釉质,提示临床应采用牙釉质粘接的方式进行修复体粘接。     

嵌体修复磨牙邻He面洞的疗效

目的：比较嵌体与银汞合金充填修复磨牙He面洞的疗效。方法：选择下颌磨牙因龋病需要制备近中邻He面洞者,分别以嵌体或角汞合金修复,各30牙,跟踪观察2年,比较其效果。结果：用嵌体修复成功28牙（93,33％）,失败2年（6．67％）;用银汞合金修复成功21牙（70．00％）,失败9牙（30．00％）。结论：用嵌体修复下颌磨牙近中邻He面洞的疗效明显主于银汞合金修复者。     

粘接性瓷嵌体边缘适合性及适合度

本文采用离体实验比较CAD/CAM计算机辅助设计/计算机辅助制造制作的瓷嵌体同实验室人工制作的瓷嵌体边缘适合性的差异。 选择24颗形态、大小相似的人下颌第一磨牙为研究对象,随机分为4组,每组6只牙。①实验室人工制作的Dicor玻璃陶瓷嵌体;②CAD/CAM制作的Dicor-MGC玻璃陶瓷嵌体;③实验室人工制作Biodent瓷嵌体;④CAD/CAM制作的CEREC Vita MK Ⅰ瓷嵌体。每组中磨牙标本均按标准备出MOD箱状洞型(无短斜面,(牙合)面近远中长度10mm,宽度5mm,(牙合)面、近中邻面、远中邻面的深度分别是3.2mm,5.4mm,6.5mm)。1,3组(牙合)面箱状轴壁聚合度4°,2,4组邻面箱状     

金属嵌体修复磨牙邻(牙合)面洞的疗效

目的 比较金属嵌体与银汞合金充填磨牙邻(牙合)面洞的疗效。方法 选取上(牙合)第一磨牙因龋损而制备近中邻(牙合)面洞者,分别以金属嵌体或银汞合金修复各50颗牙,跟踪观察5年(1997～2002年),比较结果。结果 用嵌体修复上颌第一磨牙近中邻(牙合)面洞成功48颗牙,失败2颗牙,用银汞合金修复成功37颗牙,失败13颗牙。结论 用嵌体修复上颌第一磨牙近中邻(牙合)面洞的疗效明显优于银汞合金修复者。     

全瓷嵌体洞型预备的生物力学研究进展

全瓷嵌体修复牙体缺损后牙体与嵌体的折裂是临床上比较常见的问题，原因较多，其中嵌体洞型预备是影响牙体和嵌体抗力的重要因素。本文就全瓷嵌体洞型预备生物力学方面的研究进展做一综述。     

In vivo and in vitro evaluation of marginal fit of class II ceromer inlays

The aim of this study was to evaluate the marginal adaptation of class II ceromer (Targis, Vivadent) indirect inlay restorations under both in vivo and in vitro conditions. Twenty Targis inlays were produced for class II inlay cavities (13 mandibular and seven maxillary teeth) in 20 patients. The in vivo adaptation of the inlay to the tooth cavity was evaluated by means of silicone replica technique. For in vitro evaluation, 20 mesio-occluso-distal (MOD) Targis inlays were made in extracted upper molars. Half of the inlays were cemented with Variolink high-viscosity resin cement while the other half was cemented with Variolink Ultra. The replica specimens and in vitro samples were sectioned buccolingually and mesiodistally, and marginal adaptation was evaluated at both proximal and occlusal margins at 200x magnification under a light microscope. The data was analyzed with anova (P < 0.05). The in vivo mean film thickness values for occlusal and proximal locations were recorded as 73 and 132 microm respectively. In vitro mean marginal fit values were observed as 48 and 67 microm for occlusal and proximal margins of inlays luted with Variolink II high viscosity. The marginal fit values recorded under in vivo conditions were higher in magnitude than the measurements obtained under in vitro conditions. The use of a highly filled resin luting agent with an ultrasonic insertion technique did not cause an increase in marginal gap width of the inlay.     

Fully automatic CAD design of the occlusal morphology of partial crowns compared to dental technicians' design

Objectives

The aim of this study was to compare the occlusal morphology of partial crown reconstructions made by dental technicians with reconstructions made by a fully automatic software process (biogeneric tooth model) in relation to the original natural tooth shape.

Material and methods

Stone replicas of natural teeth were measured three-dimensionally before preparing inlay and onlay cavities for ceramic restorations (n?=?5). For each preparation, five reconstructions (in total n?=?25) were made by five dental technicians. Additionally, reconstructions were calculated automatically by a software based on the biogeneric tooth model (Cerec 3D). In order to compare the two different kinds of reconstruction, an objective metrical similarity measure (shape similarity value, SSV) based on calculated volumes between compared datasets was used.

Results

In 22 of 25 cases, the reconstructions made by the CAD software were closer to the original situation than the reconstructions made by the technicians. Mean average SSV of reconstructions made by the technicians (310.2?±?78.8 μm) was significantly higher (p?<?0.05) than mean SSV of CAD reconstructions (biogeneric model) (222.0?±?47.7 μm).

Conclusions

In the design of naturally shaped occlusal inlay/onlay surfaces, a fully automatic CAD system can be at least as good as conventional wax-ups by dental technicians.

Clinical relevance

The adjustment of a dental restoration to fit the morphology of surrounding tooth structures, still presents challenges for the dentist.     

Marginal adaptation of a sintered ceramic inlay system before and after cementation

summary The long term clinical performance of porcelain inlays depends on a number of factors and the marginal adaptation is one of significant interest. The purpose of this in vitro study was to evaluate the marginal integrity of a sintered inlay technique (Ducera®), before and after cementation. MOD cavities without bevels were prepared on 10 human mandibular molar teeth and porcelain inlays were fabricated according to the manufacturer's instructions. Inlays were evaluated microscopically for their adaptation to the occlusal and approximal margins of the tooth by means of a replica technique. Inlays were cemented with a dual-cured bybrid composite luting material (Enforce®). After polishing, each tooth was sectioned in buccal/lingual and mesial/distal directions following the same procedure in the sectioning of replicas. The marginal gap and the thickness of exposed cement were measured at each section. The mean marginal gap of 71.83 ± 8.93 μm recorded for the occlusal margin before cementation was significantly smaller than that of 1056 ± 39.33 μm calculated at the approximal margin. Following the cementation, the adaptation of the inlays at the occlusal margin was also found to be superior to that of the approximal margin. Comparison of mean gap values before and after cementation revealed that the marginal gap increased by 6.94 μm and 23.25 μm at the occlusal and approximal margins, respectively. Although polishing was performed after cementation, excess luting material was still observed, that caused an increase in the width of the exposed luting cement.     

创伤咬合实验动物模型的建立和研究

目的　探讨建立创伤咬合动物模型的有效方法 ,为探讨咬合创伤致口面痛机制的研究提供依据。方法　高出咬合面 1.5mm的镍铬合金嵌体粘固于 15只杂种犬右侧上颌第一、二磨牙咬合面的I类洞形内 ,造成对牙合牙的创伤。粘固嵌体后 2个月内观察嵌体固位情况并在 3、7、14、30、6 0d时拍摄上下颌磨牙根尖X片。结果　观测时间内所有嵌体固位良好 ,无一松动脱落 ;30d及 6 0d组可见受伤牙咬合面磨损 ,根尖X片显示牙颈部牙周膜腔增宽。结论　犬磨牙早接触的创伤咬合模型有效、可信 ,可用于咬合创伤的基础研究     

Marginal Gap,Internal Fit,and Fracture Load of Leucite‐Reinforced Ceramic Inlays Fabricated by CEREC inLab and Hot‐Pressed Techniques

Purpose: This in vitro study was designed to evaluate and compare the marginal gap, internal fit, and fracture load of resin‐bonded, leucite‐reinforced glass ceramic mesio‐occlusal‐distal (MOD) inlays fabricated by computer‐aided design/manufacturing (CAD/CAM) or hot pressing. Materials and Methods: Fifty caries‐free extracted human molars were prepared for standardized MOD inlays. Impressions of each specimen were made and poured using type IV dental stone. Dies were randomly divided into two equal groups. Twenty‐five ceramic inlays were fabricated by the hot‐pressed technique using IPS Empress leucite‐reinforced glass ceramics, and the other 25 ceramic inlays were produced by CAD/CAM technology using ProCAD leucite‐reinforced ceramic blocks and CEREC inLab facilities. Inlays were bonded to the teeth using a dual‐cured resin cement. The specimens were stored in distilled water at 37°C for 24 hours and then thermocycled for 5000 cycles. The marginal gap measurements were taken with a stereomicroscope. Specimens in each group of inlay systems were randomly divided into two subgroups of 10 and 15 specimens each. Ten specimens in each subgroup were sectioned mesiodistally for evaluation of the internal fit. The fracture load of specimens in the second subgroup (n = 15) of the two inlay systems was determined under compressive load in a universal testing machine. Data were analyzed using Student's t‐test at a significance level of p < 0.05. Results: The mean marginal and internal gap size in both IPS Empress and ProCAD inlays were less than 100 μm; however, the marginal gap for the IPS Empress restorations was significantly higher than that of ProCAD restorations (p < 0.05). There was no significant difference in the mean internal fit or the fracture load between the two glass ceramic inlays (p > 0.05). Conclusions: The leucite‐reinforced glass ceramic inlay restorations fabricated by CEREC inLab (CAD/CAM) and the hot‐pressed technique provided clinically acceptable marginal and internal fit with comparable fracture loads after luting.     

国产口腔修复CAD-CAM系统的研究与开发

目的 开发具有我国自主知识产权的口腔修复体的计算机辅助设计与辅助制作系统。方法 利用自行研制的3轴三维激光扫描仪获取全牙列28颗标准牙冠的形态数据。利用Matlab 5.3作为数据处理和程序开发平台，对数据进行处理，同时在牙冠表面定义特征区和特征点并进行各种变换和调整。用Surfacer10.5作为开发平台，进行修复体设计程序的研究与开发。用国产3.5轴的数控加工设备进行修复体加工。结果 建立了国人28颗标准牙冠的三维图形数据库。开发了咬合形态调整和修改程序。初步实现了冠修复体的计算机辅助设计全过程并完成了其计算机辅助制作的全过程。结论 本项实验系统的研制成功表明，我国学者已掌握了口腔修复CAD－CAM的基本理论、数学描述、技术和制造工艺。为进一步的产业化开发奠定了基础。     

数字化口腔修复（12）--CAD／CAM全瓷嵌体修复楔状缺损（附病例报告）

目的：观察计算机辅助设计和制作（CAD／CAM）二矽酸锂全瓷嵌体修复牙颈部缺损的临床疗效。方法：临床病例为1颗牙颈部继发龋坏深达龈下的患牙,采用CAD／CAM全瓷嵌体修复,按照改良的USPHS标准分别进行6个月和1年的临床疗效评价。结果：各个复查阶段：嵌体无脱落,折断、劈裂等不良现象,临床指标均达到A级指标。结论：CAD／CAM嵌体修复牙颈部楔状缺损是一种效果良好的修复方法。     

功能路径技术用于计算机辅助设计全冠(牙合)面解剖形态的探讨

目的 在全冠修复体的计算机辅助设计（CAD）过程中引入功能路径技术（FGP），对修复体（牙合）面进行精确调整，旨在获得符合解剖生理要求的修复体（牙合）面形态。方法 选择1例左下第一磨牙全冠修复患者，牙体预备后常规制取印模并灌制工作模型，对工作模型进行机械法扫描获取其表面数字信息。在患者口内取得牙尖交错位（ICP）和FGP咬合记录，将其放置于工作模型上进行机械法扫描获得表面数字信息。在全冠修复体CAD过程中，将ICP和FGP咬合信息作为约束条件，对修复体（牙合）面的牙尖和窝沟形态进行精确调整，使其符合患者个体的咬合特征，消除（牙合）干扰。结果 利用FGP咬合记录，在CAD过程中调整了全冠修复体的（牙合）面解剖形态，使修复体（牙合）面形态符合个体动态咬合的解剖生理要求。结论 FGP简单实用，可用于全冠修复体CAD，获得符合动态功能的（牙合）面形态。     

A technique for verifying the accuracy of the virtual mounting of digital scans against the actual occlusal contacts

The digital scans of dentate arches can be mounted from a virtual interocclusal record to expedite the fabrication of dental prostheses. However, the virtual mounting may develop an occlusal error when combined with less than ideally scanned data and an algorithm that matches poorly. This article describes a method of verifying the accuracy of virtual mounting against the actual occlusal contacts marked with colored articulating paper.     

Three dimensional shape measurement of teeth (2). CAD to produce crown considering occlusion.

Use of a CAD program to design the shape of a crown, restoration of 6 molar was studied. Stone models of 5 to 7 molars with 6 prepared die for crown and a complete 6 crown which was applied for restoration were measured. The 6 crown data were adapted on the 6 die, and adjusted with 5 and 7 proximal teeth. The coordinates of the data of 6 were then transferred to that of the 6 die. The ends of the adapted crown data were linked with the margin of 6 die. Further the occlusal condition with antagonistic tooth was adjusted by applying the FGP (functionally generated path) technique. FGP was recorded on bite wax and measured. Comparing FGP record and adapted crown, modulation of the occlusal surface was accomplished.