Dental Casting Alloys Research Articles

Evaluation of genotoxicity of recycled Ni-Cr dental casting alloys: an in vitro study.

This study was conducted to evaluate the genotoxicity of nickel-chromium (Ni-Cr) base metal alloys in their reused state at different time intervals. Two commercially available Ni-Cr alloys (Wiron 99, remanium Cse) were evaluated. Three groups of alloy specimens (disks 3 mm x 5 mm) were fabricated from each of these alloys. The first groups were made with 100% new alloy, the second groups with 50 wt% of new alloy and 50 wt% of once used alloy and the third groups with 100% once used alloy. Distilled water conditioned with the alloy specimens for four time intervals of 1, 2, 4 and 8 weeks was used for testing the genotoxicity on Chinese hamster V79-HG04 fibroblasts using the micronucleus assay. Cells were examined for the number of micronuclei in the cytoplasm. More numbers of micronuclei the more the DNA damage. Statistical analysis was carried out using one-way ANOVA to determine whether the group means differed from one another significantly. Post hoc analysis was done using Bonferroni 't' test to compare the differences in mean values between groups. The highest genotoxicity was noticed at 4 weeks. It did not alter significantly when the length of conditioning was increased to 8 weeks. The lowest genotoxicity was observed for the first groups, intermediate results for the second groups and the greatest genotoxicity for the third groups when compared to controls. There were no significant differences between Wiron 99 and remanium CSe. Considering the elevated genotoxicity of Ni-Cr alloys in their reused state, the practice of reusing the alloy just for economic reasons should be discouraged.

Brushing-induced surface roughness of nickel-, palladium-, and gold-based dental casting alloys

Alloys with high nickel content have been increasingly used for dental prostheses. These alloys have excellent hardness, elastic modulus, and strength, yet have high corrosion rates when exposed to chemical or physical forces that are common intraorally. The purpose of the current study was to measure the susceptibility of several types of nickel-based alloys to brushing abrasion relative to gold- and palladium-based alloys. Au-Pt, Au-Pd, Pd-Ag, Ni-Cr, and Ni-Cr-Be dental alloys were brushed with a toothbrush (Oral-B Soft) and toothpaste (Ultrabrite) in a linear brushing machine, then the surface roughness was measured by profilometry (R(a), R(v), R(p)). Specimens (n=4) were brushed for 48 hours in a saline solution (pH 7). The effect of brushing was determined using 2-sided t tests (alpha=.05), and roughness among alloys postbrushing was compared using 1-way ANOVA with Tukey post hoc analyses (alpha=.05). All polished alloy surfaces (before brushing) had roughnesses of <or=0.1 microm (R(a)). The Pd-Ag alloy was the most resistant to brushing. The Ni-Cr-Be alloy abraded the most, with a postbrushing surface roughness of >1 microm (R(a)). Ni-Cr alloys without Be had a postbrushing surface roughness of 0.25 microm (R(a)). Postbrushing roughness of all other alloys ranged from 0.1-0.25 microm (R(a)). R(v) and R(p) values behaved similarly to R(a) values for all alloys. Although they have many excellent mechanical properties, Ni-Cr-Be alloys may be prone to degradation from brushing.

Dental casting alloys behaviour during power toothbrushing with toothpastes with various abrasivities. Part I: wear behavior

The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the surface and mechanical properties of dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr, c.p. Ti) and one ceramic were chosen. Four specimens of each material were immersed in artificial saliva, brushed without or with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Mass loss was determined by difference in weight, microhardness and surface roughness were also measured. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens (478 microg/cm(2)) exhibited the most mass loss, whereas ceramic (282 microg/cm(2)) and Co-Cr (262 microg/cm(2)) exhibited the least. However, ceramic demonstrated the most volume loss (0.239 mm(3)). The abrasivity effect of the toothpaste correlated with the RDA values. Slight variations in microhardness were observed after toothbrushing and depended on the material but not on the toothpaste used. Material surfaces were slightly smoothed by toothbrushing but no significant differences were detected. Dental casting alloys and ceramic are susceptible to abrasion by brushing with an electric toothbrush depending on the RDA value of the toothpaste. Variations in microhardness and surface roughness were not clinically relevant.

Dental casting alloys behaviour during power toothbrushing with toothpastes of various abrasivities. Part II: corrosion and ion release

The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the corrosion behavior and ion release of the different dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr and commercially pure Ti) were studied. Four specimens of each material were immersed, brushed without paste or brushed with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Corrosion behavior was determined by means a potenciostat with high sensitivity and the ion release determined by Inductively Coupled Plasma-Mass Spectrometry. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens exhibited the best corrosion behavior after and before the toothbrushed, being the worst of the three alloys the Cr-Ni. Titanium oxide produced spontaneously on the Ti surface is the main cause of the high corrosion resistance of the material. However, the eutectoid of the CrNi with chemical composition between different phases produces pitting on the phases boundaries with an important decrease of the corrosion resistance. Besides, the CrNi produces high values of the Ni and Cr release. Slight increment in roughness were observed after toothbrushing and depended on the material but not on the toothpaste used. The increase of the microhardness (residual stresses) provokes a decrease of the corrosion resistance and an increase of the ion release.

Thermal expansion of prepared dental base-metal casting alloys

Background: The aim of the study was to evaluate the linear thermal expansion of prepared Ni-Cr and Co-Cr dental base-metal casting alloys which were prepared locally in Iraq and compare with other conventional alloys. Materials and methods: Cylindrical shape wax specimen were prepared of 15mm length and 5mm diameter which were invested in phosphate-bonded investment material and casted by using induction casting machine. The liner thermal expansion was tested by using Iraqi made dialometer in which the furnace was set to reach from room temperature to 950 °C in a rate of 10 °C per minute. Results: The prepared Ni-Cr and Co-Cr alloys showed a higher linear thermal expansion than the conventional alloys, however, statistical analysis revealed non significant differences regarding the Co-Cr alloys and highly significant difference regarding the Ni-Cr alloys. Conclusion: In comparison of locally made and other conventional alloys, Co-Cr alloys statistically revealed no difference while Ni-Cr alloys showed a difference.

The effect of hydrogen peroxide concentration on metal ion release from dental casting alloys

There are concerns that tooth bleaching agents may adversely affect dental materials. The aim of this study was to test the hypothesis that increasing concentrations of hydrogen peroxide (HP) are more effective than water at increasing metal ion release from two typical dental casting alloys during bleaching. Discs (n = 28 for each alloy) were prepared by casting and heat treated to simulate a typical porcelain-firing cycle. Discs (n = 7) of each alloy were immersed in either 0%, 3%, 10% or 30% (w/v) HP solutions for 24 h at 37 degrees C. Samples were taken for metal ion release determination using inductively coupled plasma-mass spectrometry and the data analysed using a two-way anova followed by a one-way anova. The surface roughness of each disc was measured using a Talysurf contact profilometer before and after bleaching and the data analysed using a paired t-test. With the exception of gold, the differences in metal ion concentration after treatment with 0% (control) and each of 3%, 10% and 30% HP (w/v) were statistically significant (P < 0.05). Metal ion release from the two alloys increased with increasing HP concentrations (over 3000% increase in Ni and 1400% increase in Pd ions were recorded when HP concentration increased from 0% to 30%). Surface roughness values of the samples before and after bleaching were not significantly different (P > 0.05) Exposure of the two dental casting alloys to HP solutions increased metal ion release of all the elements except gold.

Metallurgical, surface, and corrosion analysis of Ni–Cr dental casting alloys before and after porcelain firing

Objectives A porcelain veneer is often fired on nickel–chromium casting alloys used in dental restorations for aesthetic purposes. The porcelain-fused-to-metal (PFM) process brings the temperature to over 950 °C and may change the alloy's corrosion properties. In this study, the metallurgical, surface, and corrosion properties of two Ni–Cr alloys were examined, before and after PFM firing. Methods Two types of alloy were tested—a high Cr, Mo alloy without Be and a low Cr, Mo alloy with Be. Before the PFM firing, specimens from both alloys were examined for their microstructures, hardness, electrochemical corrosion properties, surface composition, and metal ion release. After the PFM firing, the same specimens were again examined for the same properties. Results Neither of the alloys showed any differences in their electrochemical corrosion properties after the PFM firing. However, both alloys exhibited new phases in their microstructure and significant changes in hardness after firing. In addition, there was a slight increase in CrO x on the surface of the Be-free alloy and increased Mo–Ni was observed on the surface of both alloys via X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). This might be one of the reasons why both alloys had increased Ni and Mo ion release after firing. Significance The PFM firing process changed the alloys’ hardness, microstructure, and surface composition. No significant changes in the alloys’ corrosion behavior were observed, however, the significant increase in metal ion release over a month may need to be further investigated for its clinical effects.

Phase transformation and microstructural changes during ageing process of an Ag–Pd–Cu–Au alloy

Age-hardening behaviour and the related phase transformation and microstructural changes during isothermal ageing process were studied to elucidate the age-hardening mechanism of an Ag-based dental casting alloy composed of Ag–Pd–Cu–Au–Zn, Ir and In by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and energy dispersive spectroscopic microanalysis (EDS). In the hardness test at 350 and 400 °C, the hardness of the solution-treated specimen began to increase and reached a maximum value with increasing ageing time, and subsequently the hardness decreased gradually. By considering XRD results and SEM observations together, the solution-treated specimen consisted of three phases, the Ag-rich α 1 phase as a matrix, the Cu–Pd α 2 phase and the CuPd β phase with a CsCl-type as particle-like structures. By ageing the solution-treated specimen, the Ag-rich α 1 and Cu–Pd α 2 phases were transformed into the Ag-rich α ′ 1 and Cu 3Pd α ′ 2 phases, respectively. The CuPd β phase with a CsCl-type was not changed apparently during the ageing process. From the results of the hardness test, XRD study, SEM observations and EDS analysis, it could be derived that the hardness increased by the diffusion and precipitation of the Cu-rich phase from the Ag-rich matrix during the early stage of phase transformation of α 1 into α ′ 1 and that the progress of coarsening of the Cu-rich precipitates with an entanglement structure caused the hardness decrease during the later stage of phase transformation of α 1 into α ′ 1 . The particle-like structures composed of the Cu–Pd α 2 and the CuPd β phase with a CsCl-type contributed little to the hardness increase which occurred in the early stage of aging process.

The Release of Elements from Dental Casting Alloy into Cell-Culture Medium and Artificial Saliva

The biocompatibility of dental casting alloys is a critical issue because these alloys are in long-term intimate contact with oral tissues. Since the biocompatibility of alloys is not completely known; the release of elements from the alloys has been studied. The aim of this study was to compare the elemental release from dental casting alloy during exposure to artificial saliva and cell-culture medium. Twenty specimens made from Ni-Cr alloy were provided in the form of 5 mm diameter discs, 2 mm in thickness with a 7 mm stem attached to one face to facilitate handling. Ten of twenty samples were polished separately using a conventional technique. The remaining ten samples were left sandblasted with 50 mum Al(2)0(3). Ten samples (5 polished, 5 sandblasted) were separately placed into cell-culture wells with Dulbecco's Modified Eagle's Medium. The other ten samples were placed separately into cell-culture wells with artificial saliva. The samples were subjected in contact with these medium for 30 days. These medium were collected every 7 days. The cell-culture medium and artificial saliva without alloy samples were subjected to elemental analyses as a control. At the end of the exposure time, Atomic Absorption Spectrometry (AAS) was used to determine the release of elements from the alloys into all collected medium. Statistical analyses were assessed with two-way ANOVA. In general, the elemental release occurred with in all medium. The elemental releases of sandblasted alloys were higher than polished alloys. Artificial saliva was found to cause more release from the samples. In both media, Ni released from polished and sandblasted alloys were higher than Cr and Mo. The results suggest that the release of elements from the alloys might have correlated with the environments and the surface of dental alloy.

Fatigue limits and SEM/TEM observations of fracture characteristics for three Pd—Ag dental casting alloys

The fatigue limits and fracture characteristics for three Pd-Ag dental casting alloys (Super Star, Heraeus Kulzer; Rx 91, Pentron; W-1, Ivoclar Vivadent) were studied. Specimens meeting the dimensions for ADA Specifications No. 5 and 38, and having the as-cast surface condition, were subjected to heat treatment simulating dental porcelain firing cycles and fatigued in air at room temperature under uniaxial tension-compression at 10 Hz. A ratio of compressive stress amplitude to tensile stress amplitude (R-ratio) of -1 was used. Alloy microstructures and fracture surfaces were examined with a scanning electron microscope and a transmission electron microscope. Fatigue limits for the three alloys had low values of approximately 15% of the yield strength for 0.2% permanent tensile strain. Complex fracture surfaces with characteristic striations were observed for all three fatigued alloys. Planar slip of dislocations occurred in the Pd solid solution matrix, along with dislocation-precipitate interactions and dislocation networks in the interfaces between the precipitates and surrounding matrix. Twinning occurred in the Pd solid solution matrix of Rx 91, and within discontinuous precipitates in Super Star and Rx 91. The low fatigue limits for these alloys are attributed to their complex microstructures and perhaps to casting defects.

Phase Transformation and Microstructural Changes during Ageing Process of an Ag-Pd-Cu-Au Alloy

Abstract Age-hardening behaviour and the related phase transformation and microstructural changes during isothermal ageing process were studied to elucidate the age-hardening mechanism of an Ag-based dental casting alloy composed of Ag–Pd–Cu–Au–Zn, Ir and In by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and energy dispersive spectroscopic microanalysis (EDS). In the hardness test at 350 and 400 °C, the hardness of the solution-treated specimen began to increase and reached a maximum value with increasing ageing time, and subsequently the hardness decreased gradually. By considering XRD results and SEM observations together, the solution-treated specimen consisted of three phases, the Ag-rich α1 phase as a matrix, the Cu–Pd α2 phase and the CuPd β phase with a CsCl-type as particle-like structures. By ageing the solution-treated specimen, the Ag-rich α1 and Cu–Pd α2 phases were transformed into the Ag-rich α ′ 1 and Cu3Pd α ′ 2 phases, respectively. The CuPd β phase with a CsCl-type was not changed apparently during the ageing process. From the results of the hardness test, XRD study, SEM observations and EDS analysis, it could be derived that the hardness increased by the diffusion and precipitation of the Cu-rich phase from the Ag-rich matrix during the early stage of phase transformation of α1 into α ′ 1 and that the progress of coarsening of the Cu-rich precipitates with an entanglement structure caused the hardness decrease during the later stage of phase transformation of α1 into α ′ 1 . The particle-like structures composed of the Cu–Pd α2 and the CuPd β phase with a CsCl-type contributed little to the hardness increase which occurred in the early stage of aging process.

Corrosion by galvanic coupling between amalgam and different chromium-based alloys

Objectives In recent years there has been an increase in the use of dental casting alloys in prosthodontic treatment. Many patients have metals or alloys, as well as amalgam fillings, in their mouth, and will have them for many years. The aim of this study was to evaluate and compare, in vitro, the galvanic corrosion behavior of chromium–cobalt alloy (Remanium GM 380) and chromium–nickel alloy (Remanium CS) when bound together or coupled with silver-based amalgam (Amalcap plus). Methods An electrochemical characterization of the alloys was performed by potentiostatic and potentiodynamic methods, i.e. the open circuit potential (OCP), the corrosion potential ( E CORR), corrosion current density ( i CORR) and corrosion resistance ( R P). The electromotive force (EMF) of the bimetallic cells was also tested. Electroanalytical techniques were used to estimate the release of any respective element from the dental alloys under study into the artificial saliva solution. Results It was found that a bimetallic cell consisting of Remanium CS and Remanium GM 380 alloys has a very low EMF (a few mV) and is not a potential source of galvanic currents in the oral cavity. However, galvanic cells prepared from Amalcap plus and Remanium CS or Remanium GM 380 showed a much greater EMF: 104 and 109 mV, respectively. This clearly indicates that in these latter cases it is possible to expect some metal ions in the saliva solution as a result of the work of galvanic currents. It was found, by adsorptive stripping voltammetry analysis, that nickel or cobalt, depending on the alloy used, appeared in the saliva solution and increased in concentration over time. Significance The results indicate that the correct design and use of dental alloys are important when determining the appropriate treatment for a specific patient.

A Pd-free high gold dental alloy for porcelain bonding

Recently, some side effects of Pd, such as allergies, were found, and the risk of using Pd in dental casting alloys was raised. The purpose of the present investigation is to report a Pd-free high gold alloy for porcelain bonding. Emphasis is put on the effect of heat treatment on the mechanical properties of the alloy. The gold alloy was based on the ternary system of Au−Pt−Zn with a nominal composition of 86Au-11Pt-1.5Zn-0.5In-0.7Rh-0.2Fe-0.1Ir (wt.%). Both the hardness and tensile strength of the as-cast alloy can be significantly improved by heat treatment at 980°C for 15 min followed by bench cooling, but can't be raised by conventional solution treatment followed by ageing. The strengthening could be attributed to homogenization of microstructure and alloying elements and precipitation of new fine particles. It is suggested that the cast framework of the present new Pd-free alloy could be heat treated before actual firing, and this will improve the processing properties of the alloy during firing.

Corrosion of nickel-based dental casting alloys

Objectives To study the microstructure, corrosion behaviour and cell culture response of two nickel-based dental casting alloys before and after a heat treatment to simulate porcelain firing. Methods The microstructure was studied using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Corrosion behaviour was evaluated by electrochemical measurements in artificial saliva at different values of pH in the presence of a crevice. 3T3 mouse fibroblasts were exposed indirectly to alloy specimens and the number of viable cells counted after 3 and 6 days compared to a control culture. Results Small changes in microstructure were observed after heat treatment but had a negligible effect on the corrosion properties in the conditions tested. The alloy with a lower bulk level of Cr (12.6 wt.%) showed lower corrosion resistance, indicated by an increased passive current density and this stability was greatly reduced at pH 2.5, where crevice corrosion was observed. Selective dissolution occurred at regions within the microstructure containing lower levels of Cr and Mo. Furthermore, the proliferation of 3T3 mouse fibroblasts was reduced ( p < 0.05) when exposed indirectly to this alloy. The alloy containing a higher level of Cr (25 wt.%) showed superior corrosion resistance, which was associated with a more uniform distribution of Cr in the alloy microstructure. Significance The presence of crevices combined with an inhomogeneous distribution of Cr in the microstructure can lead to accelerated corrosion of Ni-based alloys with lower Cr contents. This effect can be avoided by increasing the Cr content of the alloy.

Surface and elemental alterations of dental alloys induced by electro discharge machining (EDM)

Objectives To evaluate the surface and elemental alterations induced by electro discharge machining (EDM) on the surface of dental cast alloys used for the fabrication of implant retained meso- and super-structures. Methods A completed cast model of an arch that received dental implants was used for the preparation of six wax patterns which were divided into three groups (Au, Co and Ti). The wax patterns of the Au and Co groups were invested with conventional phosphate-bonded silica-based investment material and the Ti group with magnesia-based investment material. The investment rings of the Au and Co groups were cast with an Au–Ag alloy (Stabilor G) and a Co–Cr base alloy (Okta C), respectively, while the investment rings of group Ti were cast with cp Ti (Biotan). One casting of each group was subjected to electro discharge machining (EDM); the other was conventionally ground and polished. The surface morphology and the elemental compositions of conventionally and EDM-finished surfaces were studied by SEM/X-ray EDS analysis. Six spectra were collected from each surface employing the area scan mode and the mean value of each element between conventionally and EDM-finished surfaces was statistically analyzed by t-test ( a = 0.05). Then the specimens of each group were cut perpendicular to their longitudinal axis and after metallographic grinding and polishing the cross-sections studied under the SEM. Results The EDM surfaces showed a significant increase in C due to the decomposition of the dielectric fluid during spark erosion. Moreover, a significant Cu uptake was noted on these surfaces from the decomposition of the Cu electrodes used for EDM. Cross-sectional analysis showed that all alloys developed a superficial zone (recast layer) varying from 2 μm for Au–Ag to 10 μm for Co–Cr alloy. Significance The elemental composition of dental alloy surfaces is significantly altered after EDM treatment.

Increased transglutaminase activity was associated with IL-6 release in cultured human gingival fibroblasts exposed to dental cast alloys

Molecular mechanisms underlying gingival and periodontal inflammation caused by dental alloys are still poorly understood. Recently, it has been demonstrated that tissue transglutaminase can be involved in inflammatory cell response. The aim of this study was to evaluate effects of exposure to orthodontic materials on transglutaminase in cultured human gingival fibroblasts. The incubation with Ni-Ti heat-activated (T3) or Ni-Ti super-elastic (T4), and with Ni-Cr-Co (T2) alloys produced respectively 2.5-fold and 8-fold increases in IL-6 release compared with control cultures. Transglutaminase activity was significantly increased in cells exposed to T3 and T4 alloys (about 170% of control; p < 0.05), where it was mainly localized close to inner part of cell membrane. The exposure to T3 and T4 specimens significantly up-regulated also tTG expression compared with control cultures. These data first show an association between IL-6 release and tissue transglutaminase increases, suggesting that TGase-mediated reactions may play a major role in periodontal inflammation.

Pitting Corrosion of TiN Coated Dental Cast Alloy with Casting Methods

Pitting Corrosion of TiN Coated Dental Cast Alloy with Casting Methods

Influence of metal-ceramic fixed dental restorations on the occurrence of discoloration of gingiva

Adverse effects of dental cast alloys on the health of patients are the problem in clinical practice. The aim of this paper was to describe the case of a patient with discolorated gingivae in the presence of fixed dental restorations and used diagnostic and therapeutic procedures. A 30-year old pacient, presented with the complaints about unsatisfactory esthetic of his fixed dental restorations. He complained about the greyish discoloration of gingivae, inappropriate color of the crowns, and a larger space between the central incisors. Both discolorated and normal gingivae around the fixed dental restorations were taken by excision and the samples of gingivae were examined histopathologically, and by using the Atomic Absorption Spectrophotometry test (AAS). Histopathological examination of the discolorated gingivae showed the presence of non-specific inflammation with a foreign body. AAS revealed the presence of various metals in the samples and the higher metal contents in the samples of discolorated gingivae as compared with the samples of normal gingivae. New metal-ceramic crowns were made for the patient. A main cause of greyish discoloration of gingivae was presence of a metal in gingival tissue. After the excision of discolorated gingivae old metal-ceramic crowns should be replaced with new crowns.

Ion release from dental casting alloys as assessed by a continuous flow system: Nutritional and toxicological implications

Objectives The aims of this study were to quantify the metallic ions released by various dental alloys subjected to a continuous flow of saliva and to estimate the nutritional and toxicological implications of such a release. Methods Four pieces of three nickel-based, one noble, one high-noble and two copper–aluminum alloys were cast and then immersed in a continuous flow of artificial saliva for 15 days. To simulate three meals a day, casts were subjected to thrice-daily episodes, lasting 30 min each and consisting of pH decreases and salinity increases. After 15 days, the metallic ions in the artificial saliva were analyzed. Data were expressed as averaged release rate: μg/cm 2/day of ion released for each alloy. The highest value of 95% Cl of each ion was adapted to a hypothetical worst scenario of a subject with 100 cm 2 of exposed metal surface. The results were compared with the tolerable upper daily intake level of each ion. Results The copper–aluminum alloys released copper, aluminum, nickel, manganese and iron. The nickel-based alloys essentially released nickel and chromium, while the beryllium-containing alloy released beryllium and significantly more nickel. The noble and high-noble alloys were very resistant to corrosion. The amount of ions released remained far below the upper tolerable intake level, with the exception of nickel, released by beryllium-containing nickel-based alloy, whose levels approach 50% of this threshold. Significance The daily amount of ions released seems to be far below the tolerable upper intake levels for each ion.

Corrosion of dental aluminium bronze in neutral saline and saline lactic acid

Objective To compare the corrosion behaviours of two aluminium bronze, dental casting alloys during a standard immersion test and for immersion in neutral saline. Methods Cast specimens of aluminium bronzes with 1.4 wt% Fe (G) and 4 wt% Fe (N) were subject to progressively longer periods (up to in total 7 days) immersed in 0.1 M saline, 0.1 M lactic acid solutions and examined by scanning electron microscopy with EDX analysis. Immersion in 0.1 M neutral saline was for 7 days. Results In the acidic solution, exposed interdendritic volumes in alloy N corroded completely away in 7 days with dissolution of Ni-enriched precipitate species as well as the copper-rich matrix. Alloy G begins to corrode more slowly but by a similar mechanism. The number density of an Fe-enriched species is insufficient to maintain a continuous galvanic potential to the copper matrix, and dissolution becomes imperceptible. In neutral saline solution, galvanic action alone caused pit-etching, without the dissolution of either precipitate species. Significance The upper limit for the total dissolution of metallic ions in the standard immersion test can be set at 200 μg cm −2. Aluminium bronze dental alloys can be expected to release both copper and nickel ions into an acidic oral environment.