Aqueous Synthesis of Plasmonic Gold-Tin Alloy Nanoparticles.

This protocol describes the synthesis of Au nanoparticle seeds and the subsequent formation of Au-Sn bimetallic nanoparticles. These nanoparticles have potential applications in catalysis, optoelectronics, imaging, and drug delivery. Previously, methods for producing alloy nanoparticles have been time-consuming, require complex reaction conditions, and can have inconsistent results. The outlined protocol first describes the synthesis of approximately 13 nm Au nanoparticle seeds using the Turkevich method. The protocol next describes the reduction of Sn and its incorporation into the Au seeds to generate Au-Sn alloy nanoparticles. The optical and structural characterization of these nanoparticles is described. Optically, prominent localized surface plasmon resonances (LSPRs) are apparent using UV-visible spectroscopy. Structurally, powder X-ray diffraction (XRD) reflects all particles to be less than 20 nm and shows patterns for Au, Sn, and multiple Au-Sn intermetallic phases. Spherical morphology and size distribution are obtained from transmission electron microscopy (TEM) imaging. TEM reveals that after Sn incorporation, the nanoparticles grow to approximately 15 nm in diameter.

Near-Infrared Fluorescent Silica Nanoparticles Based on Gold-Silver Alloy Nanoclusters for Clinical Diagnosis.

In clinical diagnosis, fluorescent particles are applied to detect analytes in biofluids, such as blood and saliva. However, current fluorescence detection methods have not been optimized to account for the overlapping autofluorescence peaks of biological substances. Gold and silver nanoclusters are known to the novel fluorescent materials and their emission wavelengths depend on cluster size. In this study, we developed fluorescent silica nanoparticles using gold-silver alloy nanoclusters and chitosan (CS) (NH2-SiO2@Au@CS@AuAg) by the layer-by-layer method. Under UV-light irradiation at 365 nm, the emission wavelength of NH2-SiO2@Au@CS@AuAg reached 750 nm in the near-IR region. Scanning electron microscopy images revealed that the shape of NH2-SiO2@Au@CS@AuAg was uniform and spherical. The fluorescence spectrum of horse blood obtained in the presence of NH2-SiO2@Au@CS@AuAg contained a specific fluorescence peak attributed to NH2-SiO2@Au@CS@AuAg, which was distinguishable from the autofluorescence peaks. These results showed that NH2-SiO2@Au@CS@AuAg has advantageous fluorescence properties for clinical diagnostic applications.

All that glitters is not gold: X-ray fluorescence analysis of a fixed dental prosthesis from Colecção de Esqueletos Identificados Século XXI, Portugal (CEI/XXI).

Access to better health care anticipates that more medical devices can be found alongside skeletal remains. Those employed in oral rehabilitation, with available brands or batch/series, can prove useful in the identification process. A previous study in the Colecção de Esqueletos Identificados Século XXI described macroscopically the dental prostheses. An unusual case of a dental device with chromatic alterations demonstrated to require a more detailed analysis. The individual, a 53-year-old male, exhibited, at both arches, a fixed tooth-supported rehabilitation, with gold colouring classified initially as a gold-palladium alloy. Simultaneously, a green pigmentation deposit was observable in bone and prosthesis. This investigation aimed to verify the elemental composition of the dental prosthesis alloy. Elemental analysis was performed by X-ray fluorescence in two regions (labial surface of the prosthetic crown and the root surface of the lower right lateral incisor). Both the spectra and the qualitative results found higher levels of copper and aluminium, followed by nickel, iron, zinc, and manganese. No gold or palladium was detected. The most probable assumption is that a copper-aluminium alloy was used, as its elemental concentration corresponds to those measured in similar devices. Dental prostheses of copper-aluminium alloys have been made popular since the 1980s, particularly in the USA, Japan, and Eastern Europe. Apart from the biographical information, it was also known that the individual's place of birth was an Eastern European country, which highlighted the usefulness of this type of information when dealing with missing people cases.

In situ habitat clearance rates and particle size preference of indigenous Olympia oysters (Ostrea lurida) and non-native Pacific oysters (Magallana gigas) in North American Pacific coast estuaries.

The Olympia oyster, Ostrea lurida, is the target of many restoration projects along estuaries on the North American Pacific coast, while the non-native Pacific oyster, Magallana gigas, dominates oyster aquaculture globally. Both species provide filtration functions that were investigated in three California bays using a whole-habitat, in situ approach, a laboratory particle selection experiment, and a regional physiological comparison. Measurements of chlorophyll α, temperature, salinity, and turbidity upstream and downstream, as well as point samples of seston total particulate matter and organic content to estimate habitat clearance rates (HCR, L hr-1 m-2) were collected. From February 2018 to June 2019, twenty-two trials were conducted across four sites. HCRs were highly variable within and among sites, ranging from site averages of -464 to 166 L hr-1 m-2, and not significantly different among sites, indicating field filtration performance of O. lurida habitat and M. gigas aquaculture is similar. Using a random forest regression, site was the most important predictor of HCR, with a variable importance score of 25.7 % (SD = 4.6 %). O. lurida and M. gigas had significantly different particle size selection preferences, likely affecting the quality of their filtration. This study's findings suggest that restoring O. lurida habitat may provide similar filtration benefits as M. gigas aquaculture, but the unique hydrodynamics and food quality of individual bays, as well as regional differences in filter feeder communities, must be considered in managing oyster habitat for filtration functions.

[Effects of metal materials for oral fixation and restoration on magnetic resonance imaging artifacts and the health of tissues around dental implants].

PURPOSE: To investigate the effects of metal materials for oral fixation and restoration on magnetic resonance imaging artifacts and the health of tissues around dental implants. METHODS: A total of 153 patients undergoing fixed oral restoration were selected from May 2018 to June 2020. They were divided according to the random number table method into group A (cobalt-chromium alloy, n=31), group B (nickel-chromium alloy, n=32), group C (titanium alloy, n=28), group D (pure titanium, n=29) and group E (gold alloy, n=33). The largest area of metal crown artifacts and the number of layers of the 5 groups were compared. The probing depth(PD), modified plaque index(mPLI), modified sulcus bleeding index(mSBI) and papilla index(PI) 6 months after restoration were evaluated.The data were statistically analyzed with SPSS 22.0 software package. RESULTS: One-way ANOVA showed that the largest area of metal crown artifacts and the number of layers involved in the 5 groups had significant differences(P＜0.05). Pairwise comparison showed that the largest area of metal crown artifacts, and the number of involved layers in group E were significantly lower than those in groups A, B, C, and D(P＜0.05). One-way ANOVA showed that there was no significant difference in PD, mPLI, mSBI and PI among 5 groups (P＞0.05). Pairwise comparison showed that there was no significant difference in PD, mPLI, mSBI and PI between group A and group B,C,D and E (P＞0.05). CONCLUSIONS: The artifacts produced by metal materials for oral fixation and restoration are closely related to the types of metal materials. Among them, cobalt-chromium alloys produce the largest artifacts, and gold alloys produce the smallest artifacts. The use of metal materials for oral fixation and restoration will not affect the health of tissues around dental implants.

Gold-Silver Alloy Nanoparticle-Incorporated Pitaya-Type Silica Nanohybrids for Sensitive Competitive Lateral Flow Immunoassay.

Although the competitive lateral flow immunoassay (CLFIA) using gold nanoparticles (AuNPs) as labels has been widely adopted for the rapid detection of small molecules, its sensitivity is often constrained by the insufficient colorimetric signal produced by conventional AuNPs labels. Herein, we introduce a new type of intensified colorimetric label, denoted as SAAS, which is engineered by integrating gold-silver alloy nanoparticles (Au-Ag NPs) within a dendritic silica scaffold. These pitaya-type silica nanohybrids combine the advantages of the amplified molar extinction coefficient of alloy units with the signal collective effect of numerous Au-Ag NPs in a singular label. The SAAS-based CLFIA strips not only achieve qualitative screening of aflatoxin B1 (AFB1) at an extraordinarily low concentration of 0.2 ng/mL by the naked eye but also enable precise AFB1 quantification through a smartphone, with a remarkable limit of detection of 0.00314 ng/mL. Moreover, by leveraging SAAS as a quencher, we have delved into transforming the conventional signal-off mode of competitive immunoassay into a signal-on configuration. This innovation led to the development of a fluorescent LFIA that augments interpretative precision and sensitivity. Our study demonstrates the substantial potential of the proposed nanohybrid labels in enhancing the sensitivity of CLFIA for detecting small molecules.

The Origin of the Intracellular Silver in Bacteria: A Comprehensive Study using Targeting Gold-Silver Alloy Nanoparticles.

The bactericidal effects of silver nanoparticles (Ag NPs) against infectious strains of multiresistant bacteria is a well-studied phenomenon, highly relevant for many researchers and clinicians battling bacterial infections. However, little is known about the uptake of the Ag NPs into the bacteria, the related uptake mechanisms, and how they are connected to antimicrobial activity. Even less information is available on AgAu alloy NPs uptake. In this work, the interactions between colloidal silver-gold alloy nanoparticles (AgAu NPs) and Staphylococcus aureus (S. aureus) using advanced electron microscopy methods are studied. The localization of the nanoparticles is monitored on the membrane and inside the bacterial cells and the elemental compositions of intra- and extracellular nanoparticle species. The findings reveal the formation of pure silver nanoparticles with diameters smaller than 10 nm inside the bacteria, even though those particles are not present in the original colloid. This finding is explained by a local RElease PEnetration Reduction (REPER) mechanism of silver cations emitted from the AgAu nanoparticles, emphasized by the localization of the AgAu nanoparticles on the bacterial membrane by aptamer targeting ligands. These findings can deepen the understanding of the antimicrobial effect of nanosilver, where the microbes are defusing the attacking silver ions via their reduction, and aid in the development of suitable therapeutic approaches.

Limitations of reuse for silver-palladium alloys -Evaluating post-recasting heat treatment impact on corrosion resistance.

The aim of this study was to investigate the effect of repeated casting and heat treatment on the corrosion resistance of a commercial Ag-Pd-Cu-Au alloy as evaluated by electrochemical techniques. After repeated casting, the fifth cast of the Ag-Pd-Cu-Au alloy exhibited dramatic degradation of properties, although upon heat treatment, this corrosion resistance did improve. Despite the improvement by heat treatment, after five castings, this alloy may not have satisfactory hardness for clinical use. These results of this study demonstrate that, up to the fourth cast and heat treatment, the Ag-Pd-Cu-Au alloy has acceptable corrosion resistance and hardness.

Hollow silver-gold alloy nanoparticles for enhanced photothermal/photodynamic synergetic therapy against bacterial infection and acceleration of wound healing.

Bacterial infection seriously restricts the wound healing process due to severe inflammation and delayed wound healing. Unfortunately, the overuse or improper use of antibiotics leads to the advent of multidrug-resistant strains and intractable biofilms, severely affecting the therapeutic effect. Therefore, there is an urgent need to develop antibiotic-free strategies to accelerate the healing process of wounds with bacterial infection. Considering that single photothermal therapy (PTT) or photodynamic therapy (PDT) cannot fully meet the requirements of clinical sterilization and accelerating wound healing, herein, hollow silver-gold alloy nanoparticles immobilized with the photosensitizer molecule Ce6 (Ag@Au-Ce6 NPs) integrated with PTT and PDT are proposed for killing bacteria and accelerating wound healing. The photothermal conversion properties of Ag@Au-Ce6 NPs are obtained using an infrared thermal imager, and the generation of singlet oxygen (1O2) is verified with an 1O2 fluorescent probe DCFH-DA. Manipulated by near-infrared laser triggered mild hyperthermia and limited ROS amount, Ag@Au-Ce6 NPs could effectively kill bacteria that are free and colonized on the surface of wounded skin, promoting epithelium migration and vascularization, further accelerating wound healing, which showed great promise for biomedical application.

Effect of multi-purpose primer on bonding of acrylic resin to cast titanium and gold alloy after airborne-particle abrasion.

PURPOSE: To clarify the effect of a multi-purpose primer combining several functional monomers on two prosthodontic materials (cast titanium and a gold alloy) after airborne-particle abrasion. METHODS: Disk-shaped adherends were prepared from cast titanium (CP Titanium JIS2) and a gold alloy (Casting Gold M.C. Type IV). A silane-containing two-liquid primer (M&C primer (MC)) and two silane-free single-liquid primers (Alloy Primer (AP) and V-Primer (VP)) were used as surface-treatment agents. The shear bond strengths were determined before and after thermocycling to evaluate the adhesive durability, and the results were compared using a non-parametric statistical analysis. The effect of airborne-particle abrasion with alumina on the titanium surface was analyzed by X-ray photoelectron spectroscopy (XPS). RESULTS: There was no significant difference in bond strength between the MC and AP before and after thermocycling, whereas VP showed significantly lower values. XPS revealed that the titanium acquired hydrophilic properties after the airborne-particle abrasion. CONCLUSIONS: The novelty of this study is that it shows that the presence/absence of the silane had no effect on the bonding of cast titanium with an acrylic resin. The study also showed that the multi-purpose primer can be used without any problems with both cast titanium and gold alloy, in combination with airborne-particle abrasion with alumina.

Surface Protection of Quaternary Gold Alloys by Thiol Self-Assembled Monolayers.

This work deals with a physical and chemical surface characterization of quaternary 18K, 14K, and 9K gold alloys and pure polycrystalline gold substrates. Surface microstructure and composition are evaluated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray fluorescence spectroscopy. Corrosion resistance of 18K gold alloys is explored by potentiodynamic polarization showing the influence of the manufacturing process on materials fabricated as plates and wires. The research is also in the framework of one of the most common strategies on the modification of metallic surface properties, i.e., the building of self-assembled monolayers (SAM) from organic thiols. The metal affinity of the head group to produce the coating of the substrate by covalent binding is approached by using thiol compounds with different molecular structures and functional group chemistries exposed to an electrolyte solution. Therefore, a comparative study on the surface protection of a quaternary 18K gold alloy and pure gold substrates by SAMs of 6-mercaptopurine (6MP), 1-decanethiol (DT), and 11-mercaptoundecanoic acid (MUA) has been carried out. Surface modification and SAM organization are followed by cyclic voltammetry (CV), and the behavior of the double layer of the electrode-electrolyte interface is evaluated by electrochemical impedance spectroscopy (EIS). The study of these materials allows us to extract fundamental knowledge for its potential application in improving the bioactive properties of different jewelry pieces based on 18K gold alloys.

Detection of carcinoembryonic antigens using a wavy gold-silver alloy nanoplate enhanced surface plasmon resonance imaging biosensor.

Carcinoembryonic antigen (CEA) is regarded as a promising broad spectrum tumor biomarker for clinical diagnosis, progression, and prognosis. Surface plasmon resonance imaging (SPRi) was considered as one of the powerful tools for immunoassay with advantages of label-free, real-time detection with high-throughput. Herein, wavy gold-silver alloy nanoplates functionalized with anti-CEA antibodies providing high protein loading capacity and high mass are used as signal enhancers for CEA detection through SPRi sandwich assay. The present method exhibits a dynamic range for CEA determination from 0.1 to 312.5 ng mL-1 and a detection limit of 0.55 ng mL-1, well below normal physiological levels. This biosensing approach demonstrates the advantages of wavy gold-silver alloy nanoplates compared to conventional gold nanoparticles as a signal amplifier to enhance the SPRi signal, which is expected to become a new prospect for detection of cancer markers in biomedical research and clinical diagnosis.

Platinum-Gold Alloy Catalyzes the Aerobic Oxidation of Formic Acid for Hydrogen Peroxide Synthesis.

On-site hydrogen peroxide production through electrocatalytic and photocatalytic oxygen reduction reactions has recently attracted broad research interest. However, practical applications have thus far been plagued by the low activity and the requirement of complex equipment. Here, inspired by the process of biological hydrogen peroxide synthesis catalyzed by enzymes, we report a Pt-Au alloy to mimic the catalytic function of natural formate oxidase for hydrogen peroxide synthesis through aerobic oxidation of formic acid. The mass activity of the Pt-Au alloy is three times higher than that of formate oxidase. Density functional theory calculations revealed that the efficient dehydrogenation of formic acid and the high selectivity of the subsequent reduction of oxygen to hydrogen peroxide account for the high hydrogen peroxide productivity. In addition, the formic acid aqueous solution provides an acidic environment, which is conducive to the utilization of the in situ generated hydrogen peroxide for oxidation reactions, including C-H bond oxidation and sterilization.

Correlation notice on the electrochemical dealloying and antibacterial properties of gold-silver alloy nanoparticles.

Galvanic replacement reaction was used in the synthesis of bimetallic gold-silver alloy nanoparticles (Au-Ag NPs), where pre-synthesized Ag nanoparticles-polyvinylpyrrolidone (AgNPs-PVP) were used to reduce the aryldiazonium tetrachloroaurate(III) salt in water. TEM images and EDS elemental analysis showed the formation of spherical Au-Ag NPs with sizes of 12.8 ± 4.9 nm and 25.6 ± 14.4 nm for corresponding Au-Ag ratios and termed as Au0.91Ag0.09 and Au0.79Ag0.21, respectively, with different concentrations of the gold precursor. The hydrodynamic sizes measured using dynamic light scattering are 46.4 nm and 74.8 nm with corresponding zeta potentials of - 44.56 and - 25.09 mV in water, for Au0.91Ag0.09 and Au0.79Ag0.21 respectively. Oxidative leachability of Ag ion studies from the starting AgNPs-PVP in 1 M NaCl showed a significant decrease in the plasmon peak after 8 h, indicating the complete dissolution of Ag ions, however, there is enhanced oxidation resistivity of Ag from Au-Ag NPs even after 24 h. Electrochemical studies on glassy carbon electrodes displayed a low oxidation peak in aqueous solutions of 20 mM KCl at 0.16 V and KNO3 at 0.33 V vs. saturated calomel electrode (SCE). We studied the antibacterial activity of Au-Ag alloy nanoparticles against gram-positive Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and gram-negative Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa. Our findings demonstrated superior antibacterial activity of Au-Ag NPs compared with AgNPs-PVP. Moreover, the nanoparticles inhibited the S. epidermidis biofilm formation.

Accelerated Discovery of Ternary Gold Alloy Materials with Low Resistivity via an Interpretable Machine Learning Strategy.

New ternary gold alloys with low resistivities (ρ) were screened out via an interpretable machine learning strategy by using the support vector regression (SVR) model integrated with SHAP analysis. The correlation coefficient (R) and the root mean square error (RMSE) of test set were 0.876 and 0.302, respectively, indicating the strong generalization ability of the model. The average ρ of top 10 candidates was 1.22×10-7 â€…Ω m, which was 41% lower than the known minimum of 2.08×10-7 â€…Ω m. The outputs of SVR model were analyzed with the critical SHAP values including first ionization energy of C-site (584 kJ ⋅ mol-1 ), electronegativity of C-site (1.72) and the second ionization energy of B-site (1135 kJ ⋅ mol-1 ), respectively. Moreover, an online web server was developed to share the model at http://materials-data-mining.com/onlineservers/wxdaualloy.

Deformation of implant retaining screws-Study with stereoscopic microscopy and microCT.

BACKGROUND: The prosthetic screw fixes the prostheses to the implants. Upon osteointegration, the untightening of the prosthetic screw is the most common problem in oral rehabilitation with implants. OBJECTIVE: To study the deformation of the implant retaining hexagonal screw head. METHODS: This investigation used two methods for evaluating the screw head's area of deformation (mm2 ): a stereoscopic microscopy and micro computed tomography (microCT). For stereoscopic microscopy, 16 titanium alloy (T) and 16 titanium gold-plated alloy (G) screws of the Zimmer Biomet™ brand were used, divided into eight groups: group 0 (control group), groups T1 and G1 (screws tightened 10 times to 20 Ncm), the groups T2 and G2 (screws tightened 20 times to 20 Ncm) and the groups T3 and G3 (screws tightened 10 times to 30 Ncm). In the study with microCT, one screw was randomly chosen from each of the groups described above to perform the scanning by microCT. RESULTS: When comparing the type of screw material using stereoscopic microscopy, no statistically significant differences were found (p > 0.05). Contrarily, different number of successive grips and different torque value showed statistically significant differences in the head section of the retaining screws (p < 0.05). The observation by microCT showed the torque applied is crucial to the head deformation in titanium screws. In gold-plated screws the successive tightening appears to be pivotal. CONCLUSION: Titanium and gold screws tend to behave similarly. By increasing the tightening cycles and the torque values of protocols greater levels of deformations can be expected. In general, microCT data showed better results for gold-plated titanium alloy. CLINICAL SIGNIFICANCE: To control severe screw head deformation and the impossibility of untightening the implant's restoration, clinicians should avoid extreme torque values and prevent surpassing 10 tightening cycles.

[Clinical guideline of using gold alloy for the restoration of tooth defect].

Since the Society of Prosthodontics, Chinese Stomatological Association was widely soliciting opinions, a recommended application guideline which based on experimental research, clinical and evidence-based medicine results was formed after several discussions and revisions. This guideline formulates the standardized operation procedures for the restoration of tooth defects with gold alloys, in order to guide and standardize the clinical application of gold alloy restorations, to improve the clinical efficacy and long-term survival rate of gold alloy restorations, and to promote the clinical application of gold alloy technique for restoration of dental defects.

Periapical status transitions in teeth with posts versus without posts: a retrospective longitudinal radiographic study.

OBJECTIVES: The aim of this study was to compare periapical status transitions in teeth after post placement compared with other post-endodontic treatments in root-filled teeth. MATERIAL AND METHODS: This retrospective longitudinal radiographic study included radiographs of 284 patients with root filled and restored teeth with composite fillings (Endo-fill group, n = 100), crown or fixed prosthesis (Endo-crown group, n = 82) or post and core restorations (Endo-post group, n = 102). All post and core restorations were made of gold alloy. The radiographs taken at the end of endodontic treatment, at the end of post-endodontic treatment and at least 8 months after post-endodontic treatment were evaluated. Post-operative periapical status was assessed according to the periapical index (PAI) and all teeth included in the study had no apical periodontitis preoperatively. Multi-state Markov analysis was used to assess periapical status transitions among the treatment groups. RESULTS: Of 284 root-filled teeth without apical periodontitis at baseline, 7.7% developed clear apical pathology within a minimum of 8 months observational period. In the Endo-post group 11 (10.78%) teeth transited from Healthy (PAI 1) to Disease (PAI 2-4) state compared with eight (9.75%) in the Endo-crown group and four (4%) in the Endo-fill group. The transition probabilities from Healthy (PAI 1) to Mild diseased (PAI 2) were 17.5% in the Endo-post group, 13.1% in the Endo-crown group and 5.3% in the Endo-fill group. Multivariate analysis showed that teeth in the Endo-fill group had 60% lower hazard to transit from Healthy (PAI 1) to Mild diseased (PAI 2) state [HR 0.40; 95% CI 0.12, 0.94]. A period exceeding 8 months between the end of the endodontic treatment and prosthetic treatment significantly increased the hazard of disease progression by three times compared with a period of ≤8 months [HR 3.16; 95% CI 1.06, 9.42]. CONCLUSIONS: Teeth without radiographic lesions at baseline and restored with posts had higher hazard to transit from healthy to diseased periapical status compared with teeth restored with composite restorations. Controlled clinical trials with longer follow-up periods are needed to validate these findings.

Bonding performance of a thiohydantoin-methacrylate monomer on noble metal alloys.

This study assessed the effect of a primer containing 10-methacryloyloxydecyl-(2-thiohydantoin-4-yl)propionate (MDTHP) on the bonding of noble metal alloys to an acrylic resin. Three noble metal alloys were selected as adherends, and V-Primer containing 6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithione was used as a comparative control. The disk specimens of each noble metal alloy were wet-ground and divided into three conditions: specimens primed with MDTHP primer or V-Primer, and specimens without priming. An acrylic resin was bonded to each specimen, and the specimens were performed the shear bond test. The MDTHP primer showed higher shear bond strength than the V-Primer for all specimens. X-ray photoelectron spectroscopic analysis showed that MDTHP was adsorbed on the Au-Pt-Pd alloy surface even after acetone cleaning. MDTHP binds not only with Cu but also with Au and Ag, promoting the bond strength of noble metal alloys. The effectiveness of MDTHP on dental noble metal alloys was suggested.

ICP-MS measurements of elemental release from two palladium alloys into a corrosion testing medium for different solution volumes and agitation conditions.

STATEMENT OF PROBLEM: The in vivo release of Pd from palladium alloys into the oral environment and sensitivity reactions by patients has been of concern. However, little information is available about the variation in elemental release from different palladium alloys. PURPOSE: The purpose of this in vitro study was to compare the elemental release into a corrosion-testing medium from a high-palladium alloy (Freedom Plus, 78Pd-8Cu-5Ga-6In-2Au) and a Pd-Ag alloy (Super Star, 60Pd-28Ag-6In-5Sn) under different conditions. MATERIAL AND METHODS: Alloys were cast into Ø12×1-mm-thick disks, subjected to simulated porcelain-firing heat treatment, polished, and ultrasonically cleaned in ethanol. Three specimens of each alloy were immersed for 700 hours in a solution for in vitro corrosion testing (ISO Standard 10271) that was maintained at 37 °C. Two solution volumes (125 mL and 250 mL) were used, and the solutions were subjected to either no agitation or agitation. Elemental compositions of the solutions were analyzed by using inductively coupled plasma-mass spectroscopy (ICP-MS). Concentrations of released elements from each alloy for the 2 solution volumes and agitation conditions were compared by using the restricted maximum likelihood estimation method with a 4-way repeated-measures ANOVA, the Satterwhite degrees of freedom method, a lognormal response distribution, and the covariance structure of compound symmetry. RESULTS: For the 4 combinations of solution volume and agitation conditions, the mean amount of palladium released was 3 orders of magnitude less for the Pd-Ag alloy (0.009 to 0.017 µg/cm2 of alloy surface) compared with the Pd-Cu-Ga alloy (17.9 to 28.7 µg/cm2). Larger mean amounts of Sn, Ga, Ag, and In (0.29 to 0.39, 0.57 to 0.83, 0.71 to 1.08, and 0.91 to 1.25 µg/cm2, respectively) compared with Pd were released from the Pd-Ag alloy. Smaller amounts of Cu, Ga, and In (4.8 to 9.9, 5.9 to 12.8, and 4.2 to 9.5 µg/cm2, respectively) compared with Pd were released from the Pd-Cu-Ga alloy. The Ru released was much lower for the Pd-Ag alloy (0.002 µg/cm2) than the Pd-Cu-Ga alloy (0.032 to 0.053 µg/cm2). Statistically significant differences (P<.001) in elemental release were found for the factors of alloy and element and the alloy×element interaction. Significant differences were found for the solution volume (P=.022), solution volume×element interaction (P=.022), and alloy×solution volume×element interaction (P=.004). No significant effect was found for agitation condition. CONCLUSIONS: The relative amounts of released elements from each alloy were not proportional to the relative amounts in the composition. The amounts of Pd and Ga released from the Pd-Cu-Ga alloy were consistent with the breakdown of a Pd2Ga microstructural phase and perhaps some dissolution of the palladium solid solution matrix. Precipitates, rather than the palladium solid solution matrix, appeared to undergo greater dissolution in the Pd-Ag alloy. The Pd-Ag alloy should have lower risk of adverse biological reactions than the Pd-Cu-Ga alloy.