Evaluation of effect of galvanic corrosion between nickel-chromium metal and titanium on ion release and cell toxicity

PURPOSE: The purpose of this study was to evaluate cell toxicity due to ion release caused by galvanic corrosion as a result of contact between base metal and titanium. MATERIALS AND METHODS: It was hypothesized that Nickel (Ni)-Chromium (Cr) alloys with different compositions possess different corrosion resistances when contacted with titanium abutment, and therefore in this study, specimens (10 x 10 x 1.5 mm) were fabricated using commercial pure titanium and 3 different types of Ni-Cr alloys (T3, Tilite, Bella bond plus) commonly used for metal ceramic restorations. The specimens were divided into 6 groups according to the composition of Ni-Cr alloy and contact with titanium. The experimental groups were in direct contact with titanium and the control groups were not. After the samples were immersed in the culture medium - Dulbecco's modified Eagle's medium[DMEM] for 48 hours, the released metal ions were detected using inductively coupled plasma mass spectrometer (ICP-MS) and analyzed by the Kruskal-Wallis and Mann-Whitney test (P<.05). Mouse L-929 fibroblast cells were used for cell toxicity evaluation. The cell toxicity of specimens was measured by the 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyltetrazolium bromide (MTT) test. Results of MTT assay were statistically analyzed by the two-way ANOVA test (P<.05). Post-hoc multiple comparisons were conducted using Tukey's tests. RESULTS: The amount of metal ions released by galvanic corrosion due to contact between the base metal alloy and titanium was increased in all of the specimens. In the cytotoxicity test, the two-way ANOVA showed a significant effect of the alloy type and galvanic corrosion for cytotoxicity (P<.001). The relative cell growth rate (RGR) was decreased further on the groups in contact with titanium (P<.05). CONCLUSION: The release of metal ions was increased by galvanic corrosion due to contact between base metal and titanium, and it can cause adverse effects on the tissue around the implant by inducing cytotoxicity.

Evaluation of effect of galvanic corrosion between nickel-chromium metal and titanium on ion release and cell toxicity

PURPOSE: The purpose of this study was to evaluate cell toxicity due to ion release caused by galvanic corrosion as a result of contact between base metal and titanium. MATERIALS AND METHODS: It was hypothesized that Nickel (Ni)-Chromium (Cr) alloys with different compositions possess different corrosion resistances when contacted with titanium abutment, and therefore in this study, specimens (10 x 10 x 1.5 mm) were fabricated using commercial pure titanium and 3 different types of Ni-Cr alloys (T3, Tilite, Bella bond plus) commonly used for metal ceramic restorations. The specimens were divided into 6 groups according to the composition of Ni-Cr alloy and contact with titanium. The experimental groups were in direct contact with titanium and the control groups were not. After the samples were immersed in the culture medium - Dulbecco's modified Eagle's medium[DMEM] for 48 hours, the released metal ions were detected using inductively coupled plasma mass spectrometer (ICP-MS) and analyzed by the Kruskal-Wallis and Mann-Whitney test (P<.05). Mouse L-929 fibroblast cells were used for cell toxicity evaluation. The cell toxicity of specimens was measured by the 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyltetrazolium bromide (MTT) test. Results of MTT assay were statistically analyzed by the two-way ANOVA test (P<.05). Post-hoc multiple comparisons were conducted using Tukey's tests. RESULTS: The amount of metal ions released by galvanic corrosion due to contact between the base metal alloy and titanium was increased in all of the specimens. In the cytotoxicity test, the two-way ANOVA showed a significant effect of the alloy type and galvanic corrosion for cytotoxicity (P<.001). The relative cell growth rate (RGR) was decreased further on the groups in contact with titanium (P<.05). CONCLUSION: The release of metal ions was increased by galvanic corrosion due to contact between base metal and titanium, and it can cause adverse effects on the tissue around the implant by inducing cytotoxicity.

Evaluation of flexural bond strength of porcelain to used nickel-chromium alloy in various percentages.

Aim: The aim of this in vitro study was to evaluate the flexural bond strength of porcelain to combinations of used and new nickel-chromium alloy in various proportions. Materials and Methods: Used and new nickel-chromium bonding alloys were combined in various proportions (groups I to V; 10 samples per group) and their flexural bond strengths with porcelain were compared. A three-point loading system was used for the application of load. Load was applied at a constant speed of 0.5 mm/minute and the load required to fracture the porcelain was recorded for each specimen. Statistical Analysis Used: (a) Analysis of variance (ANOVA) and (b) Duncan's multiple range tests. Results: The best bond strength values were seen when 100% new alloy was used. According to the findings of this study, there was no adverse effects noted with up to 75% recast metal, but serious changes were found in the bond strength values when 100% old metal was used. Conclusions: The following conclusions were drawn from the study Fresh nickel-chromium alloy shows the greatest porcelain adherence. There is no significant change in bond strength of ceramic to alloy with up to 75% of used nickel-chromium alloy. At least 25%- of new alloy should be added when recycled nickel-chromium alloy is being used for metal ceramic restorations.

Effect of denture cleansers on metal ion release and surface roughness of denture base materials

Chemical disinfectants are usually associated with mechanical methods to remove stains and reduce biofilm formation. This study evaluated the effect of disinfectants on release of metal ions and surface roughness of commercially pure titanium, metal alloys, and heat-polymerized acrylic resin, simulating 180 immersion trials. Disk-shaped specimens were fabricated with commercially pure titanium (Tritan), nickel-chromium-molybdenum-titanium (Vi-Star), nickel-chromium (Fit Cast-SB Plus), and nickel-chromium-beryllium (Fit Cast-V) alloys. Each cast disk was invested in the flasks, incorporating the metal disk to the heat-polymerized acrylic resin. The specimens (n=5) were immersed in these solutions: sodium hypochlorite 0.05%, Periogard, Cepacol, Corega Tabs, Medical Interporous, and Polident. Deionized water was used as a control. The quantitative analysis of metal ion release was performed using inductively coupled plasma mass spectrometry (ELAN DRC II). A surface analyzer (Surftest SJ-201P) was used to measure the surface roughness (µm). Data were recorded before and after the immersions and evaluated by two-way ANOVA and Tukey's test (α=0.05). The nickel release proved most significant with the Vi-Star and Fit Cast-V alloys after immersion in Medical Interporous. There was a significant difference in surface roughness of the resin (p=0.011) after immersion. Cepacol caused significantly higher resin roughness. The immersion products had no influence on metal roughness (p=0.388). It could be concluded that the tested alloys can be considered safe for removable denture fabrication, but disinfectant solutions as Cepacol and Medical Interporous tablet for daily denture immersion should be used with caution because it caused greater resin surface roughness and greater ion release, respectively.

Desinfetantes químicos são normalmente associados a métodos mecânicos para remover manchas e reduzir a formação do biofilme. Este estudo avaliou o efeito de desinfetantes na liberação de íons metálicos e na rugosidade superficial do titânio comercialmente puro, ligas metálicas e resina acrílica termopolimerizável, simulando 180 ensaios de imersões. Espécimes em formato de discos foram confeccionados com titânio comercialmente puro (Tritan), liga de níquel-cromo-molibdênio-titânio (Vi-Star), liga de níquel-cromo (Fit Cast-SB Plus) e liga de níquel-cromo-berílio (Fit Cast-V). Os espécimes (n=5) foram imersos nestas soluções: hipoclorito de sódio a 0,05%, Periogard, Cepacol, Corega Tabs, Medical Interporous e Polident. Como controle, foi utilizada a água deionizada. A análise quantitativa de liberação de íons metálicos foi realizada por meio de espectrometria de massa com plasma indutivamente acoplado (ELAN DRC II). O rugosímetro (Surftest SJ-201P) foi utilizado para medir a rugosidade superficial (µm). Os dados foram registrados antes e depois das imersões e avaliados por ANOVA com dois fatores e teste de Tukey (α=0,05). A liberação de níquel provou ser mais expressiva nas ligas Vi-Star e Fit Cast-V após a imersão em Medical Interporous. Houve diferença significante na rugosidade superficial da resina (p=0,011) após a imersão. O Cepacol causou maior rugosidade superficial de forma significativa. Os produtos de imersão não influenciaram nos resultados da rugosidade do metal (p=0,388). Pode-se concluir que as ligas metálicas testadas podem ser consideradas seguras para a fabricação de próteses removíveis, mas as soluções desinfetantes como o Cepacol e a pastilha Medical Interporous para a imersão diária da prótese devem ser utilizados com cautela, pois causaram maior rugosidade superficial da resina e maior liberação de íons, respectivamente.

Clinical effects of two kinds of porcelain fused to metal crown / 中国基层医药

Objective To compare advantages and disadvantages of ceramic crown and porcelain fused to metal(PFM),provide better rehabilitation ways for patients.Methods 258 porcelains were,divided into two groups:ceramic crown group 98 and metal ceramic crowns group 160,for preparation of abutment,modulus,colorimetric,feed production.Results Follow-up observation for 2 years,the 15 crowns of all appeared the gingival edge coloring with different degree,are PFM,10 patients were not satisfied with the color of restorations.8 repair body porcelain.Conclusion Inner crown metal of PFM is thin and light,with high hardness and compressive strength.It rarely occur deformation since repeated the barbecue at high temperatures,so suitable for large span bridge restoration.Ceramic crown because of no metal structure,good light transmission and light reflecting function,can reproduce the natural teeth translucent depth and color depth,strong sense of hierarchy,suitable for the repair of anterior teeth.

Surface roughness changes caused by the galvanic corrosion between a titanium abutment and base metal alloy / 대한치과보철학회지

PURPOSE: The purpose of this study was to evaluate the level of electro-chemical corrosion and surface roughness change for the cases of Ti abutment connected to restoration made of base metal alloys. MATERIALS AND METHODS: It was hypothesized that Ni-Cr alloys in different compositions possess different corrosion resistances, and thus the specimens (13x13x1.5 mm) in this study were fabricated with 3 different types of metal alloys, commonly used for metal ceramic restorations. The electrochemical characteristics were evaluated with potentiostat (Parstat 2273A) and the level of surface roughness change was observed with surface roughness tester. Paired t-test was used to compare mean average surface roughness (Ra) changes of each specimen group. RESULTS: All specimens made of nickel-chromium based alloys, average surface roughness was increased significantly (P < .05). Among them, the Ni-Cr-Be alloy (0.016 +/- 0.007 microm) had the largest change of roughness followed by Ni-Cr (0.012 +/- 0.003 microm) and Ni-Cr-Ti (0.012 +/- 0.002 microm) alloy. There was no significant changes in surface roughness between each metal alloys after corrosion. CONCLUSION: In the case of galvanic couples of Ti in contact with all specimens made of nickel-chromium based alloys, average surface roughness was increased.

Avaliação comparativa de propriedades geradas pelos processos de soldagem TIG e brasagem em uma liga odontológica à base de Ni-Cr / Comparative assessment of properties generated by the process of TIG welding and brazing in a Ni-Cr dental alloy

O objetivo deste trabalho foi comparar, por meio de teste de microdureza e técnicas de caracterização metalúrgica, que inclui a metalografia, microscopia óptica, microscopia eletrônica de varredura (MEV) e espectroscopia por dispersão de energia (energy dispersive spectroscopy – EDS), propriedades mecânicas e metalúrgicas de juntas soldadas pelos métodos TIG e brasagem em uma liga odontológica à base de Ni-Cr (FIT-CAST SB). As regiões estudadas em cada amostra foram o metal de base (MB), a zona termicamente afetada (ZTA) e a zona de fusão (ZF). Foram confeccionados 40 corpos-de-prova cilíndricos, em forma de bastão, com 2,5mm de diâmetro e 18,0mm de comprimento, obtidos apartir de fundição odontológica por centrifugação (técnica da cera perdida). Foram separados vinte cilindros para cada técnica, que após a soldagem formaram grupos de dez amostras para cada procedimento. A microestrutura do MB apresentou-se como uma matriz de uma solução sólida à base de Ni-Cr contendo um típico arranjo dendrítico de estrutura eutética. A liga apresentou precipitados metálicos na região interdendrítica da estrutura eutética. A análise química semi-quantitativa obtida através da técnica de EDS apresentou resultados compatíveis com a composição química quantitativa fornecida pelo fabricante da liga. Na brasagem, o MB e a ZF apresentaram microestruturas distintas. A ZF apresentou uma morfologia dendrítica grosseira com a presença de precipitados e porosidades. A análise química semi quantitativa por EDS da ZF mostrou-se bastante semelhante aos resultados obtidos para o MB...

The purpose of this study was to compare, by means of microhardness testing and metallurgical characterization techniques as metallography, optical microscopy, scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS), mechanical and metallurgical properties of welded joints by TIG and brazing methods in a dental alloy based on Ni-Cr (FIT-CAST SB). The studied regions in each sample were the base metal (MB), the heat affected zone (ZTA) and the fusion zone (ZF). Forty cylindrical bodies-of-proof, stick-shaped, with 2.5mm diameter and 18.0mm in length were made from dental casting by centrifugation (lost wax technique). Twenty cylinders were used for each technique, which formed, after the welding, groups of ten samples for each procedure. The microstructure of the MB is presented as a matrix of a solid solution based on Ni-Cr with a typical dendritic arrangement of eutectic structure. The alloy presented metallic precipitates in the interdendritic region of the eutectic structure. The semiquantitative chemical analysis obtained by EDS technique showed results consistent with the quantitative chemical composition provided by the alloy manufacturer. In the brazing method, the MB and ZF showed different microstructures. The ZF showed a rough dendritic morphology with the presence of precipitates and porosities. The semiquantitative chemical analysis by EDS of the ZF had very similar results to those obtained for the MB...

Influence of nickel-chromium alloy and gold-platinum alloy PFM on canine gingival tissues / 实用口腔医学杂志

Objective: To compare the influence of nickel-chromium alloy and gold-platinum alloy porcelain-fused-to-metal ( PFM ) on ultramicrostructure of canine gingival tissues, to survey the biological effects after PFM full crown restoration, and to provide data for selection of PFM materials. Methods; The nickel-chromium alloy and gold-platinum alloy PFM full crowns were used to repair canines in 3 healthy dogs. The microstructure of canine gingival tissue was observed through light microscope and transmission electron microscope. Apoptosis of canine gingival cells was detected by TUNEL method. Results; Under light microscope, inflammatory cell infiltration and partial bleeding were seen in the nickel-chromium alloy PFM full crown repaired canine gingival tissues. Under transmission electron microscope, large amount of cell apoptosis and neuclear condensation were observed in these tissues,and apoptotic index was 58.63% ±11. 12%. While under light microscope, inflammatory cell infiltration and partial bleeding were not seen in the gold-platinum metal PFM full crown repaired canine gingival tissues. Under transmission electron microscope, only small amount of cell apoptosis was detected in these tissues,and apoptotic index was 26. 90% ± 17. 35%. Statistical significance was found in both nickel-chromium alloy group and gold-platinum metal group compared to control group. There was also statistical significance between nickel-chromium alloy group and gold-platinum metal group in cell apoptosis numbers (P <0. 05). Cell apoptosis number in nickel-chromium alloy group was much higher than that in gold-platinum metal group. Conclusion; The negtive effects on ultramicrostructure of gingival tissue using nickel-chromium alloy PFM are more evident than using gold-platinum metal. When select PFM to repair defect teeth, it is better to select the inactive gold-platinum metal PFM as base crown.

Basic study of fabricating dental prosthesis with laser engineered net shaping (LENS) method——The microstructure of LENS components made from Rene95 alloy / 实用口腔医学杂志

objective: To study the effects of laser engineered net shaping(LENS) in the manufacture of dental prosthesis. Methods: An experiment LENS system, including a 5 kW continuous wave CO 2 laser, a four-axes numerical control working table and powder feeding system, was built up, by which, a rectangular LENS component was made from Rene95 alloy powder. The microstructure of the component was observed with scanning electron microscope and ESA analysis. Results: The size of the component was 120 mm?15 mm?15 mm , and the wall of the component was perpendicular to the base. The microstructure of the component was made up of fine columnar dendrite with the length of 10～20 ?m, 10 times less than that of the cast made from the same material. The main elements of the powder distributed homogeneously,the negative effect of segregation could be limited and the properties of the component could be improved.Conclusion: The microstructure of components made by LENS is much better than that of those made by casting from the same material.

The effects of surface treatment of dental nickel-chromium alloy on tensile bond strength / 대한치과교정학회지

This study was conducted to evaluate the tensile bond strength by bonding the dental bracket with Super-bond after treating the surface of dental Nickel-Chromium alloy with sandblasting, sandblasting & tin-plating, respectively, and tin-plating. 10 pieces of Nickel-Chromium alloys with brackets bonded with Super-bond without their surface treatment were sampled as a control group, 20 pieces of Nickel-Chromium alloy brackets bonded with Super-bond after treating them with sandblasting as group I, 20 pieces of Nickel-Chromium alloys tin-plated and bonded with Super-bond after sandblasting as group II, and then 20 pieces of alloys with brackets bonded with Super-bond after tin-plating as group III. The result of those examination and comparison is summarized as follows: 1. Group I showed the mean tensile bond strength of 14.41+/-2.24MPa which was highest among 4 groups, followed by group III( 13.59+/-L51MPa ), group II( 12.27+/-1.45MPa ), and control group( 10.50+/-1.57MPa ), respectively. However, it was shown that them was no statistically significant difference between group I and III, group III and II, and group II and control group( P>005 ). 2. The main failure pattern of those brackets showed that 70% of the control group had an adhesive failure at the bracket Superbond interface, and 30% at the Nickel-Chromium alloy-Superbond interface, while other groups did the adhesive failure at the bracket-Superbond interface. 3. When examined under SEM, it was shown that adhesives were mostly attached to the surface of the Nickel-Chromium alloy for all groups while a considerable quantity of adhesives were attached to the bracket base. Then, those samples treated only with sandblasting showed the most even and remarkable roughness of their surface.