金属表现处理对金—瓷结合强度的影响

本文对金属烤瓷修复体的金属四种不同的表面处理：粗化，清洗，除气，预氧化进行研究。提示金属烤修复体的金属表面处理完整地包括粗化，清洗，除气，预氧化。缺少任何一个步骤都会使金－瓷结合强度明显降低。     

预氧化对烤瓷冠金-瓷结合强度影响的研究现状

金属烤瓷冠合金上瓷前是否需要预氧化一直是研究的热点,本文对预氧化对贵金属和非贵金属烤瓷冠金瓷结合强度的影响的相关研究作系统回顾,认为应根据各种烤瓷用合金的具体情况来决定是否在烤瓷前需要进行除气、预氧化并摸索出相应的时间。     

烤瓷用镍铬合金经不同预处理的表面氧化膜研究

目的：分析烤瓷用镍铬合金在上瓷前经过阳极钝化，除气预氧化处理后对其表面氧化膜的形貌、厚度的影响。方法：将15个试片随机分成3组，分别经不同的实验条件处理后，每组抽取2片进行扫描电镜观察，其余3片采用XPS和AES进行表面氧化膜分析。结果：1)阳极钝化处理的试片表面发生了轻度的选择性溶解，增加了金属的表面积，所形成的氧化膜厚度是空白对照组的1．72倍。2)除气加预氧化组则形成较厚的氧化膜，为空白对照组的23．32倍，而且氧化膜内氧原子的相对含量远远高于其他实验组。厚的氧化膜的热膨胀系数与金、瓷不同，产生较高的残余应力，不利于烤瓷时金属离子向陶瓷内的扩散，且易形成一些碳化物，影响金瓷界面的化学结合。结论：采用阳极钝化法处理镍铬合金表面，方法简便，形成的氧化膜容易控制，操作可重复性强，是烤瓷前金属表面处理的新方法。     

临床修补金属烤瓷修复体的研究

金属烤瓷修复体的瓷体脱落或部分碎裂脱落后,用离体瓷片或光固化复合树脂在口腔内直接修补缺损的部分。本文通过点式电解蚀刻的方法使烤瓷合金表面形成均匀、有规律分布的超微孔隙,氢氟酸蚀刻瓷表面使之粗化,来提高金属、瓷体与复合树脂的粘接强度。在１８例金属烤瓷修复体口腔内修补后观察８～３０个月的过程中,获得了良好的近期效果。     

高原地区制作金瓷修复体的初步探讨

全自动真空烤瓷炉的工作状态,可能与海拔高度有关,金瓷修复体的烧结效果因烧结条件不同而变化。西宁地区海拔高度平均为2275m,本文制作金瓷修复体的真空度及除气、预氧化温度与平原地区相比有较大改变。1　材料与方法1.1　临床资料门诊患者149例,其中男性89例,女性60例,年龄最小12岁,最大57岁,所修复牙大多数为上前牙,其中1194个,2239个。1.2　材料及设备SunFire45烤瓷炉(美国Ney公司);天津产DGE-高频铸造机和PST-喷砂机;上海产超声波清洗器;日本产烤瓷粉以及拜耳-上海齿科公司产Ni-Cr烤瓷合金。1.3　方法1.3.1　调试烤瓷炉　在烤瓷炉…     

瓷修复技术的临床应用Ⅺ.烤瓷熔附金属修复基底冠材料理化性能的比较

烤瓷熔附金属修复体,也称金属烤瓷修复体,是在真空条件下,借助高温的作用将陶瓷粉熔融并结合到经过特殊处理的金属表面而制作的修复体.烤瓷熔附金属修复体是目前较理想的修复方式,其美观性和生物相容性其他修复体无法取代.     

金属烤瓷修复体色度学研究

目的：研究金属烤瓷修复体色度学特征，为临床金属烤瓷修复的比色、配色提供指导。方法：数码照像计算机色度分析系统分别测定1296件金属烤瓷修复体、792颗活体前牙和Vita比色板色片的色度，分析并比较金属烤瓷修复体、活体前牙和Vita比色板各色片色度值范围，金属烤瓷修复体与Vita比色板匹配情况及色度值差异情况。结果：金属烤瓷修复体、活体前牙和Vita比色板各色片色度值范围不吻合，金属烤瓷修复体的颜色主要分布在Vita比色板的个别色片，金属烤瓷修复体与Vita比色板的色度差为△L＊0．45，△a＊1．14，△b＊0．56，△E＊ab2．58。结论：金属烤瓷修复体的色度与Vita比色板色片相差较大。     

除气和预氧化对金—瓷结合强度的影响

通过应用除气和预氧化的不同参数所组成的多种程序,对烤瓷合金和瓷粉之间的结合性能进行了研究。结果表明:在除气过程中,合金表面的氧化不能忽视,在确定氧化时间的同时,除气时间必须包括在内。在相同的除气时间条件下,金-瓷结合强度随预氧化时间的延长呈递减趋势;在相同的预氧化时间的条件下,金-瓷结合强度随除气时间延长也呈递减趋势。R_(100)T_0,R_(200)T_1R_(200)T_0是该套金-瓷系统中合金热处理的最佳程度。     

148例不良金属烤瓷修复体失败原因浅析

目的：分析金属烤瓷修复体的失败原因。方法：通过对148例失败金属烤瓷修复体的病例进行原因分析，提出设计及修复中应采取的预防处理措施。结果：148例失败病例中，牙龈及牙周炎58例，牙龈变色38例，食物嵌塞21例，疼痛15例，崩瓷或瓷裂10例，修复体脱落6例。结论：金属烤瓷修复体的失败原因与临床设计、牙体制备及技工室制作有密切关系。     

258例烤瓷修复体临床疗效观察

目的 观察金属烤瓷修复体的临床修复效果。方法 采用金属烤瓷修复体治疗258例患者,共284件修复体,并进行4年的随访观察。结果 284件修复体效果良好,成功率为90.8％。结论 金属烤瓷修复体的临床效果良好。     

The effect of gold coating agents on residual stress in alloy-ceramic specimens

The use of gold coating agents has been claimed to reduce residual stress in alloy-ceramic composites. The purpose of this study was to evaluate the efficacy of gold coating agents in preventing cracking of bonded porcelain. Residual stress in alloy-ceramic specimens could be increased by decreasing the coefficient of thermal expansion (alpha) of the porcelain. Vitadur-N porcelain (jacket crown type, low alpha) was mixed in increasing proportions with VMK porcelain (high alpha) to prepare five test blends with decreasing values for alpha. For each test blend, alpha was measured by means of a vitreous silica dilatometer, and varied from 13.6 x 10(-6)/K to 11.0 x 10(-6)/K. The test blends were fused around spherical specimens of a substrate alloy, Option (alpha = 14.0 x 10(-6)/K), both with and without the use of three gold coating agents, Wilkote, Spectra-Seal and Deck-Gold (normal). The composite spheres were examined under 20 x magnification after 24 hours and again after eight weeks for evidence of cracking. There was no significant difference in the failure rate of the alloy-ceramic specimens with or without any of the gold coating agents. In a bonding porcelain, alpha can be lowered in a controlled manner by the addition of varying amounts of jacket crown porcelain. Cracking of the ceramic coating occurred at and above an alpha mismatch of 1.8 x 10(-6)/K. Gold coating agents have an insignificant effect on residual stress in alloy-ceramic specimens.     

Bonding to porcelain and gold

To test the effectiveness of bonding orthodontic attachments to porcelain, edgewise brackets were bonded to 160 lower incisor, porcelain denture teeth by means of two different resin systems and three different porcelain bonding agents. Bonding to porcelain was found to be not only effective, but the use of a porcelain primer before bonding resulted in shear strengths comparable to those achieved with conventional acid-etch enamel bonding when the same resin was used. Roughening the porcelain surface and bonding with a heavily filled resin without a porcelain primer provided shear strengths (30.6 Ibs) comparable to conventional acid-etch enamel bonding with a lightly filled resin (28.8 Ibs). Roughening the porcelain surface before bonding, adding porcelain primers, and using highly filled resins all added significantly to bond strength, but caused a progressively greater risk of porcelain fracture during debonding. One of three methods to polish porcelain completely restored a roughened porcelain surface to its former appearance. The porcelain bonding primers failed to provide a significant increase in bond strength when bonding to gold. However, a roughened gold surface bonded with a heavily filled resin provided shear strengths (27.3 Ibs) comparable to conventional acid-etch enamel bonding by means of a lightly filled resin (28.8 Ibs). The use of a highly filled resin on an intact, glazed porcelain surface without using a porcelain primer may provide sufficient bond strength clinically. If more bond strength is needed, the use of Reliance porcelain primer on an intact glaze is preferable to Ormco porcelain primer or Fusion. Still greater bond strength can be developed by roughening the porcelain surface before application of a primer and use of a highly filled resin. The potential for porcelain fracture in debonding, however, is much increased and it is questionable whether bond strengths of this magnitude are required clinically.     

Wear evaluation of porcelain opposing gold, composite resin, and enamel

STATEMENT OF PROBLEM: When porcelain surfaces oppose gold and composite resin restorations as well as enamel, wear resistance and abrasiveness of the porcelain are clinical concerns to maintain the occlusal relationship. However, there is limited information on comparison of mutual wear rates when these materials oppose in 2-body and 3-body conditions. PURPOSE: The purpose of this study was to evaluate mutual wear rates of dental porcelain and opposing materials, including a gold alloy, a composite resin, and human enamel, using an in vitro wear test. MATERIAL AND METHODS: Mutual wear between high-fusing dental porcelain (Ceramco II) disks (9 x 5-mm thick) with a rough or smooth surface and opposing styli made of gold alloy, composite resin, or human enamel was evaluated in 2-body and 3-body conditions using a wear simulator (n=8). Wear depths (microm) of porcelain disks were determined using a profilometer. Wear depths (microm) of the opposing materials were obtained by converting the worn surface areas into wear depths using image-analysis software. All data were statistically analyzed by 3-way analysis of variance and Bonferroni-Dunn test (alpha=.05). The worn surfaces were observed by scanning electron microscope (SEM). RESULTS: The wear values for porcelain opposing composite resin or enamel in the 2-body condition were significantly greater than those in the 3-body condition, regardless of the surface condition of the porcelain (P<.001). For stylus specimens, all values in the 2-body condition were significantly greater than those in the 3-body condition, regardless of the surface condition of the opposing porcelain (P<.001). These results are supported by SEM observations of worn surfaces. CONCLUSION: The results of this study suggest that mutual wear rates, when porcelain opposes gold, composite resin, and enamel, are influenced by 2-body and 3-body wear conditions.     

前牙金沉积烤瓷冠修复临床效果观察

目的探讨金沉积烤瓷冠的临床应用效果。方法临床选择行前牙烤瓷修复的患者96例(共120颗),随机分为3组:金沉积烤瓷冠组、铸造镍铬合金组、铸造金铂合金烤瓷冠组,每组各制作40例。30个月后临床复查,检查临床边缘密合度、颜色、牙龈炎性反应、烤瓷冠的折裂及崩瓷情况。结果金沉积烤瓷冠与金铂合金烤瓷冠边缘密合度接近,均优于镍铬合金烤瓷冠(P<0.05);金沉积烤瓷冠与金铂合金烤瓷冠的颜色均优于镍铬合金烤瓷冠(P<0.05);三者在崩瓷、折裂方面无差异。结论金沉积烤瓷冠具有良好的美观效果,边缘密合度好,抗折强度高。     

Effect of electrodeposition of gold on porcelain-to-metal bond strength

The effect of electrodeposition of two different thicknesses of gold on porcelain-metal bond strength with three different base metal alloys was determined and compared to a control high gold alloy. The following conclusions can be drawn. Mean porcelain-metal bond strengths of all four alloys were in the same range when conventional porcelain application techniques were used. However, the base metal porcelain-metal bond is clinically suspect because of adhesive failure through the porcelain-metal interface. A thin 180A gold coat increased the porcelain-metal bond strength and generally resulted in cohesive failure through the porcelain. A thicker gold coat (720A) decreased the bond strength and generally resulted in adhesive failure. The mechanism of action of the gold coat on bond strength is likely its effect on the oxide layer on the surface of the base metal alloy.     

Reduced dental plaque accumulation on composite gold alloy margins

Restoration of tooth surfaces with materials that inhibit formation of heavy bacterial plaque accumulations could be important in the treatment of patients with existing oral disease or in reducing the likelihood for periodontal disease. Captek is a dental gold composite material used to produce copings for ceramometal restorations that has been reported to inhibit plaque accumulation. In this study, the oral bacteria of nine periodontally healthy subjects with a total of 42 gold composite copings were sampled. Contralateral teeth with normal tooth surfaces were also sampled as controls. The quantitative presence of forty bacteria was determined in each sample by DNA:DNA hybridization. The results indicated that the porcelain/gold composite alloy coping surfaces had significantly fewer bacteria than the control normal tooth surfaces (71% reduction). The percentage composition, however, did not differ significantly between surfaces.     

Experimental observation of silver and gold penetration into dental ceramic by means of a radiotracer technique

A radiotracer technique was used to study silver and gold diffusion into dental porcelain under experimental conditions close to the real conditions in prosthetic laboratories for porcelain bakes. It was clearly shown that these non-oxidizable elements were able to diffuse into the ceramic as well as oxidizable ones. The penetration depth varied widely according to the element. The ratio DAg/DAu was about 10(3) around 850 degrees C. In contrast to gold, the silver diffusion rate was high enough to allow silver, from the metallic alloy, to be present at the external ceramic surface after diffusion into the ceramic. Hence, the greening of dental porcelains baked on silver-rich alloys could be explained mainly by a solid-state diffusion mechanism.     

The dental application of electroformed pure gold. I. Porcelain jacket crown technique.

The use of gold electroforms provides (1) a porcelain jacket crown and adaptable gold margin; (2) a matrix for porcelain inlays; (3) an adaptable margin for cast ceramic bonded to metal crowns or abutments. Further, by the application of electrodeposited tin to the gold, excellent bonding of porcelain occurs. This system can be used advantageously as a substrate for bonding porcelain to metals.     

A comparison of the abrasiveness of six ceramic surfaces and gold.

A type III gold alloy and six different ceramic surfaces were secured in an abrasion machine opposing extracted teeth to determine their relative abrasiveness and resistance to wear. The rankings of restorative materials from least abrasive to most abrasive were: gold alloy, polished; cast ceramic, polished; porcelain, polished; cast ceramic, polished and shaded; porcelain, polished and glazed; cast ceramic, cerammed skin shaded; and cast ceramic, cerammed skin unshaded. The ranking of materials from most wear-resistant to least wear-resistant was: gold alloy, cast ceramic cerammed, cast ceramic cerammed and shaded, porcelain polished, porcelain glazed, cast ceramic polished and shaded, and cast ceramic polished.     

Characterization of the interface between prefabricated gold copings and cast dental alloy in implant restorations

The objective of this study was to analyse the characteristics of the metal interface between the casting of a dental noble alloy and prefabricated gold copings (OCTA-ITI Implant System) after the fabrication procedures of a prosthetic implant-retained superstructure. The microscopical investigation, performed by optical microscopy (OM) and scanning electron microscopy (SEM), of the region around the cylinder after the casting process and the subsequent porcelain firing procedures showed the presence of an ideal interface, including: i) maintenance of coping and casting alloy microstructures up to the interface, and ii) absence of interfacial reaction products. A low content of porosity (less than 3% by volume in average) was observed in the casting alloy bulk as well as at interface. The investigation by energy-dispersive spectroscopy (EDS) of the alloy composition close to the interface showed the presence of a minimal elemental interdiffusion, suggesting that an adequate compatibility between alloy and coping characterized the materials used. A small decrease of the prefabricated coping hardness was also observed after the casting and porcelain firing procedures.