Microstructural,mechanical, ionic release and tarnish resistance characterization of porcelain fused to metal Co–Cr alloys manufactured via casting and three different CAD/CAM techniques

PurposeTo perform a comparative analysis of the microstructure, porosity, mechanical properties, corrosion, and tarnish resistance of Co–Cr alloys prepared by casting and three different computer aided designed/computer aided manufacturing (CAD/CAM) techniques.MethodsFour groups of metallic specimens were prepared, one each by conventional casting (CST), milling (MIL), selective laser melting (SLM), and milling soft metal (MSM). Ten samples were tested by X-rays, after which their microstructure and elemental composition were tested by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) analysis. Martens hardness (HM) and elastic index (η_IT) were determined by instrumented indentation testing (IIT), while modulus of elasticity (E) was determined by three-point bending. Corrosion measurements were tested according to International Organization for Standardization (ISO) 10271. The electrolytes were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The results were analyzed by one-way ANOVA and Holm–Sidak’s multiple-comparison test (α = 0.05).ResultsThe CST group illustrated internal flaws while all CAD/CAM group samples were found to be free of them. No statistically significant differences were identified among groups in their elemental composition. SLM showed the highest HM, followed by the MIL, CST, and MSM. Elastic index showed significant differences among all groups, with CST showing the lowest and SLM the highest values. SLM showed the highest elastic modulus values, followed by MSM, MIL, and CST. No significant differences were found in ionic release among groups. No surface deterioration after static and cyclic tarnish testing was determined.ConclusionsThe manufacturing procedure significantly affects the microstructure, porosity, and mechanical properties of Co–Cr alloys. In contrast, ionic release and tarnish resistance are independent of the manufacturing technique used.     

Chemical composition,surface roughness,and ceramic bond strength of additively manufactured cobalt-chromium dental alloys

Statement of problemSelective laser melting (SLM) additive manufacturing (AM) technology is a current option to fabricate cobalt-chromium (Co-Cr) metal frameworks for dental prostheses. However, the Co-Cr alloy composition, surface roughness, and ceramic bond strength values that SLM metals can obtain are not well-defined.PurposeThe purpose of this in vitro study was to compare the chemical composition, surface roughness, and ceramic shear bond strength of the milled and SLM Co-Cr dental alloys.Material and methodsA total of 50 disks of 5 mm in diameter and 1 mm in thickness were fabricated by using subtractive (control group) and AM with each of following SLM providers: SLM-1 (EOS), SLM-2 (3D systems), and SLM-3 (Concept Laser). The milled disks were airborne-particle abraded with 100-μm aluminum oxide particles. All the specimens were cleaned before surface roughness (Ra), weight (Wt%), and atomic (At%) percentages were analyzed. Three-dimensional profilometry was used to analyze the topographical properties of the surface parameters Ra (mean surface roughness). The chemical composition of Co-Cr alloy specimens was determined by using energy dispersive X-ray (EDAX) elemental analysis in a scanning electron microscope (SEM). Thereafter, the specimens were bonded to a ceramic (Dentine A3 and Enamel S-59; Creation CC) interface. Specimens were stored for 24 hours at 23 °C. The bond strength of the SLM-ceramic interface was measured by using the macroshear test (SBT) method (n=10). Adhesion tests were performed in a universal testing machine (1 mm/min). The Shapiro-Wilk test revealed that the chemical composition data were not normally distributed. Therefore, the atomic (At%) and weight percentages (Wt%) were analyzed by using the Kruskal-Wallis test, followed by pairwise Mann-Whitney U tests between the control and AM groups (AM-1 to AM-4). However, the Shapiro-Wilk test revealed that the surface roughness (Ra) and ceramic bond strength data were normally distributed. Therefore, data were analyzed by using 1-way ANOVA, followed by the post hoc Sidak test (α=.05).ResultsSignificant differences were obtained in Wt%, At%, and Ra values among the Co-Cr alloys evaluated (P<.05). Furthermore, the control group revealed significantly lower mean ±standard deviation Ra values (0.79 ±0.11 μm), followed by AM-3 (1.57 ±0.15 μm), AM-2 (1.80 ±0.43 μm), AM-1 (2.43 ±0.34 μm), and AM-4 (2.84 ±0.27 μm). However, no significant differences were obtained in the metal-ceramic shear bond strength among the different groups evaluated, ranging from mean ±standard deviation 75.77 ±11.92 MPa to 83.65 ±12.21 MPa.ConclusionsCo-Cr dental alloys demonstrated a significant difference in their chemical compositions. Subtractive and additive manufacturing procedures demonstrated a significant influence on the surface roughness of the Co-Cr alloy specimens. However, the metal-ceramic shear bond strength of Co-Cr alloys was found to be independent of the manufacturing process.     

选择性激光熔覆钴铬合金与瓷的结合性能研究

目的:评价选择性激光熔覆(selective laser melting,SLM)技术制作的钴铬合金与瓷粉的结合强度。方法:根据YY 0621-2008标准采用三点弯曲法测试比较SLM和传统失蜡铸造法的钴铬合金的金瓷结合强度,采用Vita瓷粉和Noritake瓷粉,对金瓷界面进行扫描电镜观察。结果:无论Vita瓷粉或Noritake瓷粉,SLM制作法的钴铬合金的金瓷结合强度均大于传统铸造法的金瓷结合强度(P<0.05)。SEM检测显示SLM钴铬合金的金瓷渗透深度均大于传统铸造钴铬合金的金瓷渗透深度。结论:SLM钴铬合金的金瓷结合强度大于YY0621-2008标准(25 MPa),也大于传统失蜡铸造法所获得的金瓷结合强度。     

Multitechnique characterization of conventional and experimental Ag-based brazing alloys for orthodontic applications

Objectives

To characterize the microstructure, mechanical properties, ionic release and tarnish resistance of conventional and experimental Ag-based soldering alloys for orthodontic applications.

Fracture strength of porcelain fused to metal crowns made of cast,milled or laser-sintered cobalt-chromium

Abstract

Aims. The aim was to compare the fracture strength of porcelain fused to metal crowns with copings fabricated in Co-Cr using different manufacturing techniques (casting, milling and laser-sintering) with crowns manufactured in a high-gold alloy. Methods. A total of 50 identical crowns were fabricated and sub-divided into five groups; cast Co-Cr, milled Co-Cr, two groups of laser-sintered Co-Cr and a control group cast in a high-gold alloy. After thermocycling (5000 cycles, 5–55°C) and pre-load (30–300 N, 10,000 cycles) the crowns were loaded until fracture. Load (N) and fracture mode were recorded. Results. There was a significant difference (p < 0.05) in fracture strength between the control group and one of the laser-sintered groups. The mean values (N) for the groups were as follows: cast Co-Cr, 1560 ± 274; milled Co-Cr, 1643 ± 153; laser-sintered Co-Cr 1, 1448 ± 168; laser-sintered Co-Cr 2, 1562 ± 72; control group, 1725 ± 220. Conclusion. There is no difference in strength between Co-Cr crowns produced using the different production technologies: casting, milling or laser-sintering. Metal ceramic crowns made with copings fabricated in a high-gold alloy present numerically higher fracture strength than crowns made with copings fabricated in Co-Cr alloys. The difference is confirmed when analyzing the fracture surfaces, but the difference in fracture strength value is limited and is only significant with regard to one of the two laser-sintered groups.     

选择性激光熔积技术制作钴铬合金基底冠的边缘密合度研究

目的 研究选择性激光熔积(selective laser melting,SLM)制作的钴铬合金基底冠的边缘密合度.方法 分别采用SLM技术和传统铸造法,各制作20个钴铬合金基底冠,用硅橡胶复制其边缘间隙宽度,在体式显微镜下观察其边缘密合度并加以比较.结果 SLM技术制作的钴铬合金基底冠的边缘间隙宽度平均值为49.6μm,显著小于铸造组的90.8μm (P＜0.05);结论 SLM技术制作的钴铬合金基底冠的边缘密合度优于传统铸造组,具有临床应用前景.     

Effect of Cu and Ti electrodes on surface and electrochemical properties of Electro Discharge Machined (EDMed) structures made of Co-Cr and Ti dental alloys

ObjectivesPrevious studies have shown that the use of Cu electrodes compromises the electrochemical properties of Co-Cr and Ti alloys used for the fabrication of implant retained superstructures by Electro Discharge Machining (EDM). A possible solution is the use of Ti instead of Cu electrodes and thus the aim of this study was to evaluate the effect of Cu and Ti electrodes on surface and electrochemical properties of two types of dental alloys used for fabrication of implant retained superstructures after EDM.MethodsThree full arch frameworks were prepared from a Co–Cr and three from Ti6Al7Nb alloy. One framework from each alloy was used as control, one was subjected to EDM with Cu electrodes and the last one with Ti electrodes. Morphological and elemental characterization was studied by SEM/EDX. The electrochemical properties of the alloys were evaluated by Open Circuit Potential (OCP) and Linear Sweep Voltammetry (LSV) in Ringer’s solution. Electrochemical data were analyzed statistically by one way ANOVA and SNK multiple comparison tests at a = 0.05ResultsAll groups demonstrate the typical surface after EDM treatment with almost circular valleys and an increase in C and O content compared to control groups. Both alloys demonstrated an uptake of C and Cu by Cu electrodes and C and Ti after treatment with Ti electrodes. The use of Cu electrodes had a detrimental effect on corrosion resistance of Ti alloy.SignificanceThe use of Ti electrodes mitigates the degradation of electrochemical properties compared to Cu electrodes and from this standpoint is safer for the EDM of implant retained superstructures made of Co-Cr and Ti alloys.     

牙用烤瓷支架钴铬钼合金的研制及机械性能的测试

目的　研究一种能同时用于烤瓷修复和可摘局部义齿铸造支架的新型钴铬钼合金。方法　设计合金的多元配方,使用真空感应电炉熔炼合金。通过机械性能测试、硬度测试、密度及熔点范围测试、铸造性能测试、显微结构观察及X射线衍射分析进行筛选。结果　①合金的成份为Co 54%~67%、Cr 21%~26%、Mo 5%~8%、W5% ~8%、Si 1%~3%、Mn 0·1%~0·25%、其他微量元素。②合金的屈服强度为584 MPa;抗拉强度为736 MPa;延伸率为15·0%;维氏硬度为322 HV;铸流率为100%。结论　所研制的钴铬钼合金DA9-4的各项机械性能指标接近或达到国外同类产品的性能,能够满足临床要求。     

选择性激光熔积钴铬合金在含氟口腔环境中电化学腐蚀性能的研究

目的 考量采用区域选择性激光熔化(SLM)技术制作的钴铬合金口腔修复材料在含氟口腔环境中的耐腐蚀性能.方法 选取具有相同成分的Co-Cr合金金属粉末和金属块,分别运用SLM技术(SLM组)和传统的铸造工艺(对照组)各制作5个试件(圆柱形,直径10 mm,厚度3 mm),在模拟含氟口腔环境下(pH值6.8,NaF 0.1％),采用电化学交流阻抗谱(EIS)的方法,分析两组试件的耐腐蚀性能.结果 对照组和SLM组的表面氧化层电阻(Rp)值分别为3.28±1.53和6.69±3.30,组间比较差异无统计学意义(P＞0.05).结论 在模拟含氟口腔环境中,SLM技术制作的钴铬合金与传统铸造方式加工的钴铬合金具有相似的耐腐蚀性能,能够满足临床要求.     

Metallurgical and interfacial characterization of PFM Co–Cr dental alloys fabricated via casting,milling or selective laser melting

Objectives

Bulk and interfacial characterization of porcelain fused to metal (PFM) Co–Cr dental alloys fabricated via conventional casting, milling and selective laser melting.

Methods

Three groups of metallic specimens made of PFM Co–Cr dental alloys were prepared using casting (CST), milling (MIL) and selective laser sintering (SLM). The porosity of the groups was evaluated using X-ray scans. The microstructures of the specimens were evaluated via SEM examination, EDX and XRD analysis. Vickers hardness testing was utilized to measure the hardness of the specimens. Interfacial characterization was conducted on the porcelain-covered specimens from each group to test the elemental distribution with and without the application of INmetalbond. The elemental distribution of the probed elements was assessed using EDX line profile analysis. Hardness results were statistically analyzed using one-way ANOVA and Holm–Sidak's method (α = 0.05).

Results

X-ray radiography revealed the presence of porosity only in the CST group. Different microstructures were identified among the groups. Together with the γ phase matrix, a second phase, believed to be the Co₃Mo phase, was also observed by SEM and subsequent XRD analysis. Cr₇C₃ and Cr₂₃C₆ carbides were also identified via XRD analysis in the CST and MIL groups. The hardness values were 320 ± 12 HV, 297 ± 5 HV and 371 ± 10 HV, and statistically significant differences were evident among the groups.

Significance

The microstructure and hardness of PFM Co–Cr dental alloys are dependent on the manufacturing technique employed. Given the differences in microstructural and hardness properties among the tested groups, further differences in their clinical behavior are anticipated.     

Effect of pH on element release from dental casting alloys

Statement of problem. Dental casting alloys are subjected to transient acidity in the oral environment, yet most studies have not investigated the effects of these transient environments on elemental release from alloys. Elemental release is important because it plays a significant role in alloy biocompatibility. Purpose. It was hypothesized that acidic environments would increase elemental release from dental alloys during exposure and after the acidic environment was removed. This hypothesis was based on the known increase in release of nickel from nickel-based alloys in an acidic environment. Material and methods. High-noble, noble, and base metal casting alloys were exposed for 30 minutes to solutions with pH ranging from 1 to 7. Elemental release of representative elements was measured by means of atomic absorption spectrometry during the exposure and in the week after the exposure. This release was compared with elemental release in the week before the exposure. Results. High-noble and noble alloys were resistant to acidic environments. A pH of 4 did not increase elemental release during or after exposure. A pH 1 environment slightly elevated release of Ag, Cu, and Pd in some alloys. However, a Ni-based alloy released large amounts of Ni during the acidic exposure of pH 1 or 4, and more importantly, in the week after the exposure as well. Increased time of exposure to acid did not alter elemental release from noble or high-noble alloys, but markedly increased release from the Ni-based alloy. Conclusions. Transient exposure of casting alloys to an acidic oral environment is likely to significantly increase elemental release from Ni-based alloys, but not from high-noble or noble alloys. (J Prosthet Dent 1998;80:691-8.)     

激光选区熔化成形钴铬合金及钛合金金瓷结合强度的研究

目的　比较激光选区熔化（selective laser melting,SLM）技术与传统方法制作的钴铬合金（Co-Cr）和钛合金（Ti6Al4V）在金瓷结合性能方面的差异。方法　分别采用传统方法（铸造法和锻造法）和SLM技术制作4组直径10 mm、厚1 mm的圆形片状试件,每组各10个,分别记为铸造Co-Cr（CC）组、锻造Ti6Al4V（DT）组、SLM Co-Cr（SC）组、SLM Ti6Al4V（ST）组。流水下打磨抛光试件,氧化铝喷砂剂喷砂后,激光扫描共聚焦显微镜（CLSM）检测试件表面粗糙度。室温下干燥后分别烧结瓷粉,采用剪切强度测试法测定各组的金瓷结合强度,并进行统计学分析。体视显微镜观察瓷层断裂模式。场发射扫描电镜（FE-SEM）对金瓷结合界面形貌进行分析。结果　各组试件表面粗糙度未见明显差异（P > 0.05）。CC组和SC组的剪切强度无明显差异,分别为（25.949 ± 2.708）MPa和（26.707 ± 1.559）MPa,均显著高于DT组［（18.259 ± 1.882）MPa］和ST组［（21.504 ± 3.019）MPa］（P < 0.05）,其中DT组低于ST组（P < 0.05）。各组剪切强度测试后金瓷断裂模式均为混合断裂。FE-SEM下观察显示SC组和CC组金瓷界面结合紧密,DT组和ST组金瓷界面偶见气孔和裂隙。结论　SLM技术制作的Co-Cr金瓷结合强度与传统铸造法相当,SLM技术制作的Ti6Al4V金瓷结合强度明显高于传统锻造法。SLM技术作为一种新型的激光3D打印技术,在口腔修复学领域有极大的应用潜力。     

远缘链球菌g型对铸钛、钴铬合金、镍铬合金修复体腐蚀失泽的研究

目的:研究远缘链球菌g 型对铸钛、Co-Cr 合金、Ni-Cr 合金修复体失泽腐蚀的影响。方法:将Co-Cr 合金、Ni-Cr合金、纯钛分别铸造制备成10 mm×10 mm×1 mm板片,每组30 片。将上述3 组每组随机分空白对照组,培养基对照组、实验组各10 片。需氧环境中,将g 型远缘链球菌接种到蔗糖琼脂培养基后,将试件贴附其表面,每周转换传递一次,共10 周。0105 %戊二醛消灭细菌,清洗,2 周后用MINOLTA CR-100 型色度计观察。结果:经统计学分析可知铸钛、Co-Cr 合金、Ni-Cr 合金修复体的空白对照组与培养基对照组的L*、a*、b*值无显著差异( P > 0105) 。铸钛、Co-Cr 合金、Ni-Cr 合金修复体实验组与空白对照组、培养基对照组的L*、a*、b*值有明显差异( P < 0105) 。结论:按CIE1976 标准检测得出远缘链球菌g 型对Co-Cr 合金、Ni-Cr 合金、铸钛修复体色泽有影响,但未超出黄绿区域。     

钴铬钼合金对L929细胞生物学行为的影响

目的：研究牙科用钴铬钼合金对L929细胞生物学行为的影响。方法：制备医用纯钛、钴铬钼合金、钴铬合金、镍铬合金的浸提液,在浸提液与L929细胞作用24 、48 、72 h后,用倒置相差显微镜观察细胞的生长情况,并通过CCK-8实验评定4种材料的细胞毒性;采用流式细胞仪Annexin V-FITC/PI 双染法评价材料对细胞凋亡的影响;应用吖啶橙染色法检测L929细胞在材料表面的黏附情况;采用SPSS17.0软件包对数据进行统计学分析。结果：倒置相差显微镜下观察,各时间点除镍铬合金组可见少量细胞核固缩,呈现轻微中毒状态外,其余3组细胞生长情况良好;钴铬钼合金组在各时间点的OD值、细胞凋亡率、细胞黏附数量均显著低于医用纯钛组(P<0.05),而高于钴铬合金组 (P<0.05)和镍铬合金组(P<0.05);观察期内,医用纯钛组、钴铬钼合金组、钴铬合金组细胞毒性均为1级,镍铬合金组为2级,表现为轻微毒性。结论：钴铬钼合金对L929细胞的生物学行为无明显不良影响,符合口腔生物材料的临床应用要求,具有良好的生物相容性。     

Influence of alloying elements on cellular response and in-vitro corrosion behavior of titanium-molybdenum-chromium alloys for implant materials

PurposeNot all elements with β-stabilizing properties in titanium alloys are suitable for biomaterial applications, because corrosion and wear processes release the alloying elements to the surrounding tissue. Chromium and molybdenum were selected as the alloying element in this work as to find balance between the strength and modulus of elasticity of β-titanium alloys. This study aimed to investigate the effect of Titanium-10Molybdenum-10Chromium (Ti-10Mo-10Cr), Titanium-10Chromium (Ti-10Cr) and Titanium-10Molybdenum (Ti-10Mo) on the elemental leachability in tissue culture environment and their effect on the viability of human gingival fibroblasts (HGFs).MethodsEach alloy was immersed in growth medium for 0–21 days, and the elution was analyzed to detect the released metals. The elution was further used as the treatment medium and exposed to seeded HGFs overnight. The HGFs were also cultured directly to the titanium alloy for 1, 3 and 7 days. Cell viability was then determined.ResultsSix metal elements were detected in the immersion of titanium alloys. Among these elements, molybdenum released from Ti-10Mo-10Cr had the highest concentration throughout the immersion period. Significant difference in the viability of fibroblast cells treated with growth medium containing metals and with direct exposure technique was not observed. The duration of immersion did not significantly affect cell viability. Nevertheless, cell viability was significantly affected after 1 and 7 days of exposure, when the cells were grown directly onto the alloy surfaces.ConclusionsWithin the limitation of this study, the newly developed β-titanium alloys are non-cytotoxic to human gingival fibroblasts.     

衔铁铸造桩在磁性固位体覆盖义齿中的机械固位力研究

目的：探讨用非贵金属（Co-Cr合金）替代贵金属制作衔铁铸造桩核,提高衔铁铸造桩机械固位力的可行性.方法：选择离体牙下颌尖牙1颗,进行牙体制备.然后,在同一牙根管内,用自凝树脂制作32个树脂桩,随机分为4组,每组8个桩,其中2组分别用Co-Cr合金及金合金（55.6%Au）铸造,另2组用Co-Cr合金制作的衔铁桩核表面分别用金沉积和金粉涂布技术进行表面处理;最后通过离体牙拉伸试验测试,以得到相关数据,用SAS6.2进行单因素方差分析.结果：Co-Cr合金衔铁桩与金合金衔铁桩在牙体的脱位力有显著差异,而Co-Cr合金衔铁桩在分别经过表面金沉积和金粉涂布处理后,与金合金衔铁桩组的脱位力比较,无显著差异.结论：用Co-Cr合金制作的衔铁铸造桩表面通过金沉积和金粉涂布技术处理后,同样能够达到或接近用金合金制作的衔铁铸造桩的临床固位效果,使其机械固位力明显提高.     

Effect of two heat treatments on mechanical properties of selective-laser-melted Co-Cr metal-ceramic alloys for application in thin removable partial dentures

Statement of problem

Heat treatment has been used to reduce the residual stress of alloys fabricated by selective laser melting (SLM) to avoid deformation. Co-Cr metal-ceramic alloys are used to fabricate metal-ceramic restorations and removable partial dentures (RPDs) on the same substrate by SLM. A heat treatment that enables the fabrication of metal-ceramic restorations and RPDs with excellent mechanical properties should be evaluated.

制作方法对钴铬合金金瓷结合性能的影响

目的 比较铸造钴铬合金与选区激光熔化（SLM）钴铬合金金瓷结合强度的差异。方法 用铸造法和SLM技术制作钴铬合金试件各10个,在中间1/3区域熔附瓷粉,采用剪切力试验测试金瓷结合强度并观察断裂类型。采用SPSS 13.0软件中的t检验对结果进行统计学分析。结果铸造组、SLM组剪切力分别为（33.11±4.98）、（30.94±5.98） MPa,二者间差异无统计学意义（P>0.05）。样本的断裂类型为复合断裂。结论 SLM钴铬合金修复体精密度较高,其金瓷结合强度与铸造钴铬合金相近。     

4种义齿基托材料表面润湿性的实验研究

目的 评价临床常用的钴铬合金、钴铬钼合金、纯钛和热凝型义齿基托树脂的润湿性,为临床选择合适的全口义齿基托材料提供理论指导。 方法 分别测定人工唾液在不同处理的钴铬合金、钴铬钼合金、纯钛、热凝型义齿基托树脂上的接触角,通过接触角大小反应4种材料的润湿性。 结果 按临床实际磨光处理组别的接触角均比磨光成镜面状组的小,且差异具有统计学意义。磨光成镜面状组别中热凝型义齿基托树脂接触角最大,其次是纯钛,钴铬合金和钴铬钼合金接触角最小,除钴铬合金和钴铬钼合金外其余材料两两间比较差异均具有统计学意义。按临床实际磨光处理组中接触角最大的是纯钛,其次为热凝型义齿基托树脂,钴铬合金和钴铬钼合金接触角最小,除钴铬合金和钴铬钼合金外其余材料两两间比较差异均具有统计学意义。结论 钴铬合金和钴铬钼合金润湿性优于纯钛和热凝型义齿基托树脂,从润湿性对固位力的影响角度考虑,选择这两种材料制作全口义齿基托对全口义齿的固位更加有利。     

Elements released from dental casting alloys and their cytotoxic effects

PURPOSE: This in vitro study investigated the element release from seven commercially available dental casting alloys and tested their cytotoxic effects. MATERIALS AND METHODS: The casting alloys tested were one high-noble alloy (Bioherador N) and six base-metal alloys, including four Ni-Cr alloys (Remanium CS, Heranium NA, Wiron 99, CB Soft), one Co-Cr alloy (Wirobond C), and one Cu-based alloy (Thermobond). Ten specimens from each alloy were prepared in the form of disks, and each of the seven dental casting alloys (10 disks per group) were conditioned in distilled water at 37 degrees C for either 72 or 168 hours. The conditioning media were analyzed for element release, and the cytotoxic effects were assessed on Balb C fibroblasts using MTT assay. RESULTS: Element release was greater at 168 hours of conditioning than at 72 hours. The extract from the high-noble alloy showed the least amount of element release (only Zn), with no cytotoxic effects. The greatest amount of element release was detected in the Cu-based alloy Thermobond and the Ni-Cr alloy CB Soft; their extracts were significantly more toxic than all the other alloy extracts. The cytotoxic effects of the other Ni-Cr alloy extracts were not statistically significantly different from the high-noble alloy extract. However, the Co-Cr alloy (Wirobond C) extract was significantly more cytotoxic than the high-noble alloy extract. CONCLUSION: Element release from casting alloys is proportional to the conditioning time. The content of Cr and Mo in the alloy protects the alloy from dissolution, while the Cu content makes it more susceptible to corrosion and dissolution, rendering it more cytotoxic.