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...     

激光熔覆沉积快速成形纯钛试件的性能研究

目的 通过比较激光熔覆沉积快速成形(laser melted rapidly solidified forming,LMRSF)技术和铸造技术制作的纯钛试件的组织结构和力学性能,为LMRSF技术在口腔修复中的应用提供依据.方法 以纯钛粉末为原料,应用LMRSF技术制作LMRSF纯钛试件6个.制作铸造纯钛试件6个作为对照.测定试件的抗拉强度和显微硬度,扫描电镜观察试件的组织结构和拉伸断口的形貌特征.结果 LMRSF纯钛试件组织均匀细致,呈现针状细小晶粒,抗拉强度和维氏显微硬度分别为(510.0±21.2)MPa和(201.4±14.5)MPa,高于铸造纯钛试件[分别为(425.0±35.1)MPa和(186.5±9.5)MPa],差异均有统计学意义(P<0.01).结论 LMRSF纯钛试件的组织结构和力学性能优于铸造纯钛试件,更适合用于制作活动义齿支架.     

可摘局部义齿计算机辅助设计与辅助制作研究应用进展

计算机辅助设计、数控切削、增材制造等数字化技术越来越广泛地应用于口腔修复临床。这些技术的应用不仅改变了可摘局部义齿的设计和制作流程,提高了义齿生产效率,而且改变了义齿的设计和制作理念。关于可摘局部义齿计算机辅助设计与辅助制作的研究方兴未艾,近年涌现了大量研究报道,包括选区激光熔化金属粉末等新材料的性能研究,义齿固位体、连接体、人工牙等组件的创新性设计,支架、基托和人工牙的高精度成形,应用新材料、具有新结构的可摘局部义齿的精度、适合性和力学性能定量评价,以及对可摘局部义齿的临床评价等诸多方面,本文针对近年可摘局部义齿计算机辅助设计与辅助制作研究应用最新进展进行系统论述。     

不同加工工艺对纯钛支架力学性能的影响

目的 探讨不同加工工艺对纯钛支架力学性能的影响。方法 分别用数控铣削、3D打印和传统铸造工艺制作纯钛试件后用X线探伤仪进行检测。试件进行一般打磨抛光和精细打磨抛光后分别测量试件表面粗糙度;用扫描电子显微镜(SEM)分别对各组试件进行表面观察;用万能试验机测量每组试件抗弯曲强度和剪切强度。结果 X线探伤仪显示部分铸造制作的试件内部含有气孔。一般打磨抛光后数控铣削表面粗糙度最小,3D打印粗糙度最大;精细打磨抛光后数控铣削表面粗糙度变化最小;扫描电镜显示数控铣削制作的试件表面致密纹路清晰。万能试验机测量强度显示:数控铣削制作的试件其抗弯曲强度与剪切强度均为最大。结论 数控铣削加工后的纯钛试件结构最为致密,表面粗糙度最小,力学强度最大。     

纯钛激光立体成形件结构与力学性能研究

目的:观察、测试激光立体成形加工的纯钛试件的金相结构及力学性能,为进一步在口腔领域的应用奠定基础。方法:采用激光立体成形技术加工纯钛试件,通过电镜及表面能谱扫描分析纯钛的结构和表面元素构成;分别制作激光立体成形纯钛和工业TA2纯钛拉伸件,采用万能试验机测试并对比抗拉强度、屈服强度及延伸率。结果:激光立体成形纯钛宏观上呈现规则的外延生长的柱状晶,内部结构主要为网篮状,α板条宽度在3~4μm左右;成形中无明显杂质元素加入;其抗拉强度为(713.6±7.8)MPa,屈服强度为(621.3±6.4)MPa,明显高于TA2纯钛的抗拉强度(390.2±5.6)MPa、屈服强度(271.3±3.4)MPa。结论:激光立体成形制备的纯钛能够改善显微结构从而大大提高力学性能,能够适于口腔修复支架等方面的应用。     

热处理对激光选区熔化成型纯钛钛瓷结合强度的影响

目的 探讨热处理对激光选区熔化(selective laser melting,SLM)成型纯钛钛瓷结合强度的影响.方法 利用SLM技术制作ISO 9693标准要求的纯钛试件96个,分为热处理组(A)和未热处理组(B).A、B组试件根据瓷粉种类分为Super Ti22(a)、Titankeramik(b)、Tricer...     

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。     

纯钛铸造支架可摘局部义齿62例临床疗效观察

目的评估纯钛铸造支架可摘局部义齿的临床应用效果。方法患者62例纯钛铸造支架可摘局部义齿69件,检查初戴就位情况,使用3个月、3年后,统计义齿性口炎发生率及患者对修复效果的评价。结果纯钛铸造支架可摘局部义齿就位顺利,固位好,轻巧舒适,修复3个月后无义齿性口炎发生,修复后3年义齿性口炎发生率低,为2.9%（2/69）。患者比较满意。结论纯钛铸造支架可摘局部义齿有很好的临床修复效果。     

支撑角度对选择性激光熔覆制作下颌双侧游离端牙列缺损可摘局部义齿支架适合性的影响

目的评价选择性激光熔覆(selective laser melting,SLM)技术制作下颌双侧游离端牙列缺损可摘局部义齿支架过程中支撑角度对支架适合性的影响。方法以下颌双侧游离端牙列缺损石膏模型为原始模型,设置对照组排除系统误差后,使用钛合金粉末,SLM制作支撑角度分别为0°(水平组)、45°(45°组)和90°(垂直组)的可摘局部义齿支架(每组6个)。将支架戴入原始模型,通过复模法获得具备支架组织面形态的石膏模型。用三维扫描仪分别扫描原始模型和复模得到的石膏模型,数据导入Geomagic Qualify软件,通过目测法以及分析支架组织面与模型的间隙评价支架的适合性。结果3组可摘局部义齿支架与石膏模型紧密贴合,无明显翘动。水平组支架与模型间的总体偏差[(0.146±0.017)mm]显著小于45°组和垂直组[分别为(0.182±0.015)和(0.185±0.022)mm](P<0.05),45°组与垂直组间差异无统计学意义(P>0.05)。水平组支托处偏差显著小于45°组(P<0.05),垂直组支托处偏差与水平组、45°组间差异均无统计学意义(P>0.05);水平组卡环处偏差显著小于45°组和垂直组(P<0.05),45°组与垂直组卡环处偏差差异无统计学意义(P>0.05);3组支架舌杆处偏差差异均无统计学意义(P>0.05)。结论通过3种支撑角度SLM制作的下颌双侧游离端牙列缺损可摘局部义齿支架的适合性均可满足临床要求,推荐优先选择水平向支撑角度制作义齿支架。     

可摘局部义齿计算机辅助设计与辅助制作研究应用进展

计算机辅助设计、数控切削、增材制造等数字化技术越来越广泛地应用于口腔修复临床。这些技术的应用不仅改变了可摘局部义齿的设计和制作流程,提高了义齿生产效率,而且改变了义齿的设计和制作理念。关于可摘局部义齿计算机辅助设计与辅助制作的研究方兴未艾,近年涌现了大量研究报道,包括选区激光熔化金属粉末等新材料的性能研究,义齿固位体、...     

Investigation of the effect of three sprue designs on the porosity and the completeness of titanium cast removable partial denture frameworks.

STATEMENT OF PROBLEM: Although titanium has been used to cast removable partial denture frameworks, the casting process is arduous and requires specialized equipment. PURPOSE: This study evaluated the ability of 3 sprue designs (tree, ball, and circular) to produce complete, void-free castings of removable partial denture frameworks made from commercially pure titanium. METHODS AND MATERIAL: A cast with a Kennedy class III, modification 1, partially edentulous arch was used. The blocked-out cast was modified to facilitate assessment of the completeness of the casting of the clasp arms. Thirty refractory casts were made, and 10 wax patterns for each sprue design were fabricated and invested with ethyl silicate investment. Castings were made with an arc-type automatic casting machine in an argon atmosphere. Castings were examined with radiographic equipment to detect the presence of voids in the castings, and the completeness to each casting was visually verified. Data on porosities were tabulated and statistically analyzed with 1-way ANOVA followed by Student Newman-Keuls test. Chi-square analysis was used to identify statistically significant differences in casting defects among the 3 sprue designs. RESULTS: No statistically significant differences in the total number of porosities were found between the 3 sprue designs (P =.51). Results of completeness of castings evaluated by using chi-square test revealed a statistically significant deference among the 3 sprue designs (P =.008). CONCLUSION: The ball-sprue design produced the most complete castings for the removable partial denture titanium frameworks.     

模型置换印模技术修复下颌游离端牙列缺损的临床研究

目的：探讨模型置换印模技术对双侧下颌游离端缺牙患者的修复效果。方法：在解剖式印模上常规制作铸造支架,在铸造支架上制作自凝暂时基板,经口内肌功能修整并制取咬合记录后于口内取功能性印模。经模型置换后常规完成义齿。结果：90.2%的患者用模型置换印模技术制作的义齿疗效良好。结论：模型置换印模作为游离端可摘部分义齿的重要功能印模方法,可以有效改善义齿修复质量。     

Present status of titanium removable dentures--a review of the literature

Although porcelain and zirconium oxide might be used for fixed partial dental prostheses instead of conventional dental metals in the near future, removable partial denture (RPD) frameworks will probably continue to be cast with biocompatible metals. Commercially pure (CP) titanium has appropriate mechanical properties, it is lightweight (low density) compared with conventional dental alloys, and has outstanding biocompatibility that prevents metal allergic reactions. This literature review describes the laboratory conditions needed for fabricating titanium frameworks and the present status of titanium removable prostheses. The use of titanium for the production of cast RPD frameworks has gradually increased. There are no reports about metallic allergy apparently caused by CP titanium dentures. The laboratory drawbacks still remain, such as the lengthy burn-out, inferior castability and machinability, reaction layer formed on the cast surface, difficulty of polishing, and high initial costs. However, the clinical problems, such as discoloration of the titanium surfaces, unpleasant metal taste, decrease of clasp retention, tendency for plaque to adhere to the surface, detachment of the denture base resin, and severe wear of titanium teeth, have gradually been resolved. Titanium RPD frameworks have never been reported to fail catastrophically. Thus, titanium is recommended as protection against metal allergy, particularly for large-sized prostheses such as RPDs or complete dentures.     

The effect of clinical experience on dental students' ability to design removable partial denture frameworks

To determine whether clinical experience influenced dental students' ability to correctly design removable partial denture frameworks, four combinations of six casts depicting various partially edentulous situations were used in the study. The authors independently rated the casts as to the degree of difficulty on a three-point scale. Only those casts for which there were 100% agreement were used. All of the casts that were used had a moderate degree of difficulty rating (level 2). The dental student sample consisted of 34 second-year students who had just completed 98 hours of instruction in removable partial dentures. Each student was given six casts on which to design removable partial denture frameworks. The students were evaluated before clinical experience in removable prosthodontics and after 1 year of removable prosthodontic experience. The results indicated that the dental students made significantly fewer errors in framework design after clinical experience. Errors on two of 13 framework design items were increased postclinically. The increase in errors on these two items may have been the result of a lack of attention to detail or a lack of reinforcement in learning certain basic concepts.     

Resilient Attachments as an Alternative to Conventional Cast Clasp Removable Partial Denture: 3-Year Follow-up

The present clinical report describes the prosthodontic management for a patient with uncontrolled bleeding and diabetes mellitus treated with a maxillary complete denture and a mandibular partial fixed dental prosthesis designed to interface with a removable cast framework partial denture retained by 2 ERA attachments. This approach was undertaken to improve both retention and stability of the distal extension Kennedy Class I removable partial denture. The rehabilitation provided better anterior esthetics than if treated with a conventional clasp retained removable partial denture, by employing a simple, practical design and offering a significant biomechanical advantages, restoring both oral health and function. Thus, this treatment modality, involving an ERA system and transfixation in fixed crowns, is an effective treatment and can be indicated as a clinical alternative for edentulous and partially edentulous patients with systemic disorders or for patients in economic situations that might preclude implant-based rehabilitation.

     

Discoloration of a titanium alloy removable partial denture: A clinical report

With recent advances in dental technology, titanium is currently used for fabrication of crowns, fixed partial dentures, implant frameworks, and removable partial denture frameworks. The use of titanium-aluminum-vanadium (Ti-6Al-4V) alloy assumes that it imparts similar anti-corrosion characteristics to the commercially pure titanium. This clinical report describes a patient who experienced discoloration of a Ti-6Al-4V alloy removable partial denture.     

Internal porosity of cast titanium removable partial dentures: Influence of sprue direction on porosity in circumferential clasps of a clinical framework design

STATEMENT OF PROBLEM: Although internal porosity is a potential risk factor for clasp fracture, little is known about its frequency in the clasps of titanium removable partial dentures. PURPOSE: This study investigated the influence of the direction of auxiliary sprues on porosity in the circumferential clasps of a pressure-cast titanium removable partial denture. MATERIAL AND METHODS: Wax patterns of a removable partial denture framework were made on 10 identical refractory casts of a Kennedy class II, modification 1, mandibular partially edentulous arch. For the auxiliary sprues directed to the circumferential clasps, 2 designs were used: straight and curved. Casting was performed in a 1-chamber pressure casting machine. Pore number and size were assessed on radiographs of the castings. The data were analyzed with the 2-tailed Student t test (P <.05). Randomly selected specimens were sectioned for morphologic observation of the internal surface of the pores. RESULTS: The number of pores >or=0.5 mm diameter and the total number of pores were significantly lower in the molar lingual arms of the curved sprue group than in the corresponding clasp arms of the straight sprue group (P =.03 and P =.009, respectively). No significant differences between the 2 groups were found for pores of any size in other locations. The pores had smooth internal surfaces. CONCLUSION: Within the limitations of this study, the curved sprue design produced significantly less porosity in the circumferential clasp arms of a cast titanium removable partial denture than the conventional straight design. The results suggest that internal porosity in titanium castings can be controlled through sprue design.     

激光扫描测量全口义齿钛基托适合性的可行性研究

目的:应用LSH600激光扫描设备,对全口义齿钛基托的适合性进行研究,探讨激光扫描法检测义齿基托适合性的可行性.方法:将制作好的上半口钛基托放置在无牙颌模型上,蜡封闭边缘后,装盒;待石膏凝固后,取出无牙颌模型,再次在型盒内灌制超硬石膏模型.待模型结固后,将两个模型分别置LSH600三维激光扫描仪工作台上的同一位置并固定,利用三维激光扫描模型组织面,获得三维点云数据.利用反求软件Surfacer10.0对获得的数据进行数据预处理,对两组数据间的差异进行自动分析.分析结果以颜色来显示两组数据重合情况.结果:通过激光三维扫描和数据三维拟合,钛基托适合性的最大误差0.352 mm,平均误差0.135 mm.结论:应用新型激光扫描法研究义齿基托适合性具有速度快、可靠性高的优点,可以较全面反映义齿基托的适合性.     

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.