The purpose of the investigation was to create a new gold alloy of yellow for casting the frames of metal ceramic dentures. The yellow color corresponds to the consumer and aesthetic needs of some patients, because it...The purpose of the investigation was to create a new gold alloy of yellow for casting the frames of metal ceramic dentures. The yellow color corresponds to the consumer and aesthetic needs of some patients, because it is a sign of the metal, which is noble and innocuous. The main alloying elements of the majority of gold alloys for metal-ceramics are platinum and palladium, which increase the strength characteristics. Copper, tin, and other precious metals and base metals are also introduced in these alloys. At the same time, it is necessary to ensure the correspondence of the properties of the alloy with those of the ceramics applied onto the metal frame. For this purpose, the thermal expansion coefficient of the alloy (TEC) should be in a range of 13.5~14.5 ×10 6 K 1 when heated from 20 to 600 ℃ . The two-component alloys, alloying of gold with platinum and palladium results in a decrease in the TEC, and the introduction of copper, silver, and tin, increases it. Multidirectional influence of the alloying elements is a factor in achieving compliance of the TEC with the given values of the alloy. In multicomponent systems, however, the mutual influence of individual components on the properties of the alloy is unpredictable. This also applies to the color characteristics of the alloys, which vary in the direction of reducing the yellowness with increasing concentration of platinum and palladium, while other elements may have the opposite effect on the results. Yellowness index (YI), calculated according to the results of spectrophotometric studies, has been chosen as an objective indicator of color. In this study, the requirement for YI was given not less than 25; the color of such alloys can be called light yellow. All the alloys investigated contained 85% (by weight) of gold. Therefore, higher corrosion resistance and biological inertness of a finished dental products were ensured. Among the alloys that met the yellowness/TEC requirements, two alloys have been selected that were 'most yellow' (PLAGODENT-PLUS and PLAGODENT-BIO). Their adhesive properties met the requirements of GOST R 51736-2001 to alloys for metal ceramics.展开更多
The keeper and cast dowel-coping, as a primary component for a magnetic attachment, is easily subjected to corrosion in a wet environment, such as the oral cavity, which contains electrolyte-rich saliva, complex micro...The keeper and cast dowel-coping, as a primary component for a magnetic attachment, is easily subjected to corrosion in a wet environment, such as the oral cavity, which contains electrolyte-rich saliva, complex microflora and chewing behaviour and so on. The objective of this in vitro study was to examine the corrosion resistance of a dowel and coping-keeper complex fabricated by finish keeper and three alloys （cobalt-chromium, CoCr; silver-palladium-gold, PdAu; gold-platinum, AuPt） using a laser- welding process and a casting technique. The surface morphology characteristics and microstructures of the samples were examined by means of metallographic microscope and scanning electron microscope （SEM）. Energy-dispersive spectroscopy （EDS） with SEM provided elements analysis information for the test samples after 10% oxalic acid solution etching test. Tafel polarization curve recordings demonstrated parameter values indicating corrosion of the samples when subjected to electrochemical testing. This study has suggested that massive oxides are attached to the surface of the CoCr-keeper complex but not to the AuPt-keeper complex. Only the keeper area of cast CoCr-keeper complex displayed obvious intergranular corrosion and changes in the Fe and Co elements, Both cast and laser-welded AuPt-keeper complexes had the highest free corrosion potential, followed by the PdAu-keeper complex. We concluded that although the corrosion resistance of the CoCr-keeper complex was worst, the keeper surface passive film was actually preserved to its maximum extent. The laser-welded CoCr- and PdAu-keeper complexes possessed superior corrosion resistance as compared with their cast specimens, but no significant difference was found between the cast and laser-welded AuPt-keeper complexes. The Fe-poor and Cr-rich band, appearing on the edge of the keeper when casting, has been proven to be a corrosion-prone area.展开更多
目的:比较镍铬合金和金铂合金2种烤瓷熔附金属全冠(porcelain fused to metal,PFM)对犬牙龈组织结构的影响,观察PFM修复术的生物学效果,为临床上选择烤瓷熔附金属材料提供参考。方法:将3只健康犬以镍铬合金和金铂合金2种PFM修复犬牙,通...目的:比较镍铬合金和金铂合金2种烤瓷熔附金属全冠(porcelain fused to metal,PFM)对犬牙龈组织结构的影响,观察PFM修复术的生物学效果,为临床上选择烤瓷熔附金属材料提供参考。方法:将3只健康犬以镍铬合金和金铂合金2种PFM修复犬牙,通过光镜和透射电镜观察犬牙龈组织的结构,用TUNEL方法检测细胞凋亡,并进行统计学分析。结果:镍铬合金PFM修复犬的牙龈组织,光镜下可见大量的炎性细胞浸润,局部血管出血;电镜下有大量细胞凋亡,凋亡指数为58.63%±11.12%,有细胞核固缩等反应。金铂合金PFM修复犬的牙龈组织光镜下未见大量的炎性细胞浸润及局部血管出血;电镜下少有细胞凋亡;凋亡指数为(26.90±17.35)%。统计分析显示镍铬合金PFM组和金铂合金PFM组的凋亡数与对照组都具有统计学意义,镍铬合金PFM组和金铂合金PFM组细胞凋亡数量有明显差异(P<0.05),镍铬合金组凋亡指数高。结论:镍铬合金PFM对犬牙龈组织结构的影响大,而金铂合金PFM对犬牙龈组织结构的影响小。临床PFM修复时,尽可能选择金铂合金制作PFM基底冠。展开更多
文摘The purpose of the investigation was to create a new gold alloy of yellow for casting the frames of metal ceramic dentures. The yellow color corresponds to the consumer and aesthetic needs of some patients, because it is a sign of the metal, which is noble and innocuous. The main alloying elements of the majority of gold alloys for metal-ceramics are platinum and palladium, which increase the strength characteristics. Copper, tin, and other precious metals and base metals are also introduced in these alloys. At the same time, it is necessary to ensure the correspondence of the properties of the alloy with those of the ceramics applied onto the metal frame. For this purpose, the thermal expansion coefficient of the alloy (TEC) should be in a range of 13.5~14.5 ×10 6 K 1 when heated from 20 to 600 ℃ . The two-component alloys, alloying of gold with platinum and palladium results in a decrease in the TEC, and the introduction of copper, silver, and tin, increases it. Multidirectional influence of the alloying elements is a factor in achieving compliance of the TEC with the given values of the alloy. In multicomponent systems, however, the mutual influence of individual components on the properties of the alloy is unpredictable. This also applies to the color characteristics of the alloys, which vary in the direction of reducing the yellowness with increasing concentration of platinum and palladium, while other elements may have the opposite effect on the results. Yellowness index (YI), calculated according to the results of spectrophotometric studies, has been chosen as an objective indicator of color. In this study, the requirement for YI was given not less than 25; the color of such alloys can be called light yellow. All the alloys investigated contained 85% (by weight) of gold. Therefore, higher corrosion resistance and biological inertness of a finished dental products were ensured. Among the alloys that met the yellowness/TEC requirements, two alloys have been selected that were 'most yellow' (PLAGODENT-PLUS and PLAGODENT-BIO). Their adhesive properties met the requirements of GOST R 51736-2001 to alloys for metal ceramics.
基金funded by the National Natural Science Foundation of China (Grant No. 81000456)the Science and Technology Department of Sichuan Province (Grant No. 2015JY0146)the Science and Technology Bureau of Chengdu (Grant No. 2014-HM01-00203-SF)
文摘The keeper and cast dowel-coping, as a primary component for a magnetic attachment, is easily subjected to corrosion in a wet environment, such as the oral cavity, which contains electrolyte-rich saliva, complex microflora and chewing behaviour and so on. The objective of this in vitro study was to examine the corrosion resistance of a dowel and coping-keeper complex fabricated by finish keeper and three alloys （cobalt-chromium, CoCr; silver-palladium-gold, PdAu; gold-platinum, AuPt） using a laser- welding process and a casting technique. The surface morphology characteristics and microstructures of the samples were examined by means of metallographic microscope and scanning electron microscope （SEM）. Energy-dispersive spectroscopy （EDS） with SEM provided elements analysis information for the test samples after 10% oxalic acid solution etching test. Tafel polarization curve recordings demonstrated parameter values indicating corrosion of the samples when subjected to electrochemical testing. This study has suggested that massive oxides are attached to the surface of the CoCr-keeper complex but not to the AuPt-keeper complex. Only the keeper area of cast CoCr-keeper complex displayed obvious intergranular corrosion and changes in the Fe and Co elements, Both cast and laser-welded AuPt-keeper complexes had the highest free corrosion potential, followed by the PdAu-keeper complex. We concluded that although the corrosion resistance of the CoCr-keeper complex was worst, the keeper surface passive film was actually preserved to its maximum extent. The laser-welded CoCr- and PdAu-keeper complexes possessed superior corrosion resistance as compared with their cast specimens, but no significant difference was found between the cast and laser-welded AuPt-keeper complexes. The Fe-poor and Cr-rich band, appearing on the edge of the keeper when casting, has been proven to be a corrosion-prone area.
文摘目的:比较镍铬合金和金铂合金2种烤瓷熔附金属全冠(porcelain fused to metal,PFM)对犬牙龈组织结构的影响,观察PFM修复术的生物学效果,为临床上选择烤瓷熔附金属材料提供参考。方法:将3只健康犬以镍铬合金和金铂合金2种PFM修复犬牙,通过光镜和透射电镜观察犬牙龈组织的结构,用TUNEL方法检测细胞凋亡,并进行统计学分析。结果:镍铬合金PFM修复犬的牙龈组织,光镜下可见大量的炎性细胞浸润,局部血管出血;电镜下有大量细胞凋亡,凋亡指数为58.63%±11.12%,有细胞核固缩等反应。金铂合金PFM修复犬的牙龈组织光镜下未见大量的炎性细胞浸润及局部血管出血;电镜下少有细胞凋亡;凋亡指数为(26.90±17.35)%。统计分析显示镍铬合金PFM组和金铂合金PFM组的凋亡数与对照组都具有统计学意义,镍铬合金PFM组和金铂合金PFM组细胞凋亡数量有明显差异(P<0.05),镍铬合金组凋亡指数高。结论:镍铬合金PFM对犬牙龈组织结构的影响大,而金铂合金PFM对犬牙龈组织结构的影响小。临床PFM修复时,尽可能选择金铂合金制作PFM基底冠。
