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Journal of Oral Rehabilitation Sep 1996The release of elements from dental casting alloys is a continuing concern because of the potentially harmful biological effects the elements may have on local tissues.... (Comparative Study)
Comparative Study
The release of elements from dental casting alloys is a continuing concern because of the potentially harmful biological effects the elements may have on local tissues. The surfaces of the alloys appear to be most important in controlling the release of these elements. In the current study, the surfaces of high-, reduced-, and no-gold dental alloys were analysed by X-ray photoelectron spectroscopy before and after they were exposed to a biological medium for up to 96 h. The goal was to relate the release of elements from these alloys to their surface composition, and to determine the depth of the effect of the medium. The depth of the effect of the exposure was determined by argon milling of the alloy surface after exposure to the medium. Elements that were released into the medium were measured by means of atomic absorption spectroscopy. The release of elements from alloys was greater when the atomic ratio of noble to non-noble elements at the surface was less than 1. The depth of the effect of the medium varied with the alloy, but was always less than 100 A. The surface composition was significantly different from layers only 5 A below. It was concluded that the surface concentration of noble elements is important in controlling the release of non-noble elements from these alloys, and the surface composition appeared to be only one or two atomic layers thick. Of the three types of alloys, the high-gold alloy appeared to develop the most stable surface composition which released the lowest levels of elements.
Topics: Dental Alloys; Dental Polishing; Electron Probe Microanalysis; Gold Alloys; Spectrometry, X-Ray Emission; Surface Properties
PubMed: 8890058
DOI: 10.1046/j.1365-2842.1996.d01-204.x -
Odontology May 2016The cytotoxicity of a dental alloy depends on, but is not limited to, the extent of its corrosion behavior. Individual ions may have effects on cell viability that are...
The cytotoxicity of a dental alloy depends on, but is not limited to, the extent of its corrosion behavior. Individual ions may have effects on cell viability that are different from metals interacting within the alloy structure. We aimed to investigate the cytotoxicity of individual metal ions in concentrations similar to those reported to be released from Pd-based dental alloys on mouse fibroblast cells. Metal salts were used to prepare seven solutions (concentration range 100 ppm-1 ppb) of the transition metals, such as Ni(II), Pd(II), Cu(II), and Ag(I), and the metals, such as Ga(III), In(III), and Sn(II). Cytotoxicity on mouse fibroblasts L929 was evaluated using the MTT assay. Ni, Cu, and Ag are cytotoxic at 10 ppm, Pd and Ga at 100 ppm. Sn and In were not able to induce cytotoxicity at the tested concentrations. Transition metals were able to induce cytotoxic effects in concentrations similar to those reported to be released from Pd-based dental alloys. Ni, Cu, and Ag were the most cytotoxic followed by Pd and Ga; Sn and In were not cytotoxic. Cytotoxic reactions might be considered in the etiopathogenesis of clinically observed local adverse reactions.
Topics: Animals; Cells, Cultured; Dental Alloys; Fibroblasts; Ions; Materials Testing; Metals; Mice; Palladium; Toxicity Tests
PubMed: 25549610
DOI: 10.1007/s10266-014-0192-z -
Trends & Techniques in the Contemporary... Nov 1986
Topics: Dental Alloys
PubMed: 3466328
DOI: No ID Found -
Contact Dermatitis Jan 2014Cobalt-chromium alloys are used as casting alloys by dental technicians when producing dental prostheses and implants. Skin exposure and metal release from alloys and...
BACKGROUND
Cobalt-chromium alloys are used as casting alloys by dental technicians when producing dental prostheses and implants. Skin exposure and metal release from alloys and tools used by the dental technicians have not been studied previously.
OBJECTIVES
To study the release of cobalt, nickel and chromium from alloys and tools that come into contact with the skin of dental technicians.
METHODS
Cobalt and nickel release from tools and alloys was tested with the cobalt spot test and the dimethylglyoxime test for nickel. Also, the release of cobalt, nickel and chromium in artificial sweat (EN1811) at different time-points was assessed. Analysis was performed with inductively coupled plasma-mass spectrometry.
RESULTS
Sixty-one tools were spot tested; 20% released nickel and 23% released cobalt. Twenty-one tools and five dental alloys were immersed in artificial sweat. All tools released cobalt, nickel and chromium. The ranges were 0.0047-820, 0.0051-10 and 0.010-160 µg/cm(2) /week for cobalt, nickel and chromium, respectively. All dental alloys released cobalt in artificial sweat, with a range of 0.0010-17 µg/cm(2) /week, and they also released nickel and chromium at low concentrations.
CONCLUSIONS
Sensitizing metals are released from tools and alloys used by dental technicians. This may cause contact allergy and hand eczema.
Topics: Chromium; Cobalt; Dental Alloys; Dental Instruments; Dental Technicians; Humans; Kinetics; Mass Spectrometry; Nickel; Occupational Exposure; Sweat
PubMed: 23844864
DOI: 10.1111/cod.12111 -
Bio-medical Materials and Engineering 2015The stability of the Co-Cr-Mo dental alloy immersed in artificial salivas (pH 6.7) was investigated over 24 h. Three artificial salivas have been studied: saline saliva...
The stability of the Co-Cr-Mo dental alloy immersed in artificial salivas (pH 6.7) was investigated over 24 h. Three artificial salivas have been studied: saline saliva (saliva I); saline saliva buffered with phosphate ions (saliva II) and saliva II plus mucin molecules (saliva III). For all the systems, open circuit potential shift positively over 24 hours of immersion. Data extracted from the steady-state polarization curves demonstrated that the Co-Cr-Mo alloy has higher corrosion potential in saliva III, lower corrosion potential in saliva I and lower initial corrosion resistance in saliva III. After 24 hours of immersion in the artificial salivas, the Co-Cr-Mo alloy presents high corrosion stability, due to the protective action created by the presence of corrosion products. From the analysis of the breakdown potential it was concluded that, the presence of the phosphate ions and mucin promote the oxidation process, inducing the formation of etch pits. Regarding the effect of the mucin concentration in the corrosion behaviour of the Co-Cr-Mo dental alloy, it was observed a negative shift in the corrosion potential, pointing to a cathodic inhibitor role for the mucin molecules. Nevertheless, no correlation between the mucin concentration and corrosion rate was possible to establish.
Topics: Alloys; Cobalt; Dental Alloys; Dentistry; Electrochemistry; Glycoproteins; Humans; Metals; Microscopy, Electron, Scanning; Molybdenum; Mucins; Phosphates; Saliva, Artificial; Surface Properties; Vitallium; X-Ray Diffraction
PubMed: 25585980
DOI: 10.3233/BME-141241 -
The Journal of Prosthetic Dentistry Sep 2009Remelting previously cast metal can produce a critical change in metal-oxide composition at the dental alloy surface. (Comparative Study)
Comparative Study
STATEMENT OF PROBLEM
Remelting previously cast metal can produce a critical change in metal-oxide composition at the dental alloy surface.
PURPOSE
The purpose of this study was to evaluate the effect of multiple castings on bonding of a single selected base metal and a dental ceramic, and to compare results from shear bond and 3-point-bending tests.
MATERIAL AND METHODS
Three groups of dental alloy (Remanium CSe) were prepared by mixing 50% fresh alloy to alloy remnants from previous castings. The specimens in the first casting group used 100% fresh alloy and served as control (C0). The second group consisted of equal amounts of fresh alloy and alloy remnants cast only once (C1). The third and fourth groups contained 50% fresh alloy and alloy cast twice (C2) and 3 times (C3), respectively. The bond load (N) between alloy and dental porcelain (VMK 95 Metal Ceramic) was evaluated, using shear bond and 3-point bending tests. The fracture surfaces of the specimens subjected to testing were analyzed using a stereomicroscope and scanning electron microscope. One-way ANOVA followed by the Tukey multiple comparison test was used for analysis of bond data (alpha=.01).
RESULTS
The mean shear bond load (SD) of C0 (738.0 (77.1) N) was significantly higher than that of C1 (577.8(139.4) N), C2 (494.8 (77.6) N), and C3 (480.5 (60.9) N). Mean peak load for the 3-point-bending test of specimens cast from C0 (39.8 (1.79) N) was significantly higher than for other groups (P<.01). No significant difference was found between C1 (24.4 (5.60) N), C2 (23.2 (4.03) N), and C3 (22.8 (1.79) N) in terms of the shear bond test and the 3-point bending test.
CONCLUSIONS
In general, there was agreement between the 2 bond strength tests to indicate that including re cast base alloy with fresh alloy for metal decreases metal-to-ceramic bond strengths. (J Prosthet Dent 2009;102:165-171)
Topics: Dental Alloys; Dental Bonding; Dental Casting Investment; Dental Casting Technique; Dental Restoration Failure; Dental Restoration, Permanent; Equipment Reuse; Humans; Metal Ceramic Alloys; Shear Strength
PubMed: 19703623
DOI: 10.1016/S0022-3913(09)60139-6 -
Materials Science & Engineering. C,... Feb 2017Biofilm formation on dental biomaterials is implicated in various oral health problems. Thus the challenge is to prevent the formation of this consortium of...
Effect of preconditioning cobalt and nickel based dental alloys with Bacillus sp. extract on their surface physicochemical properties and theoretical prediction of Candida albicans adhesion.
Biofilm formation on dental biomaterials is implicated in various oral health problems. Thus the challenge is to prevent the formation of this consortium of microorganisms using a safe approach such as antimicrobial and anti-adhesive natural products. Indeed, in the present study, the effects of an antifungal extract of Bacillus sp., isolated from plant rhizosphere, on the surface physicochemical properties of cobalt and nickel based dental alloys were studied using the contact angle measurements. Furthermore, in order to predict the adhesion of Candida albicans to the treated and untreated dental alloys, the total free energy of adhesion was calculated based on the extended Derjaguin-Landau-Verwey-Overbeek approach. Results showed hydrophobic and weak electron-donor and electron-acceptor characteristics of both untreated dental alloys. After treatment with the antifungal extract, the surface free energy of both dental alloys was influenced significantly, mostly for cobalt based alloy. In fact, treated cobalt based alloy became hydrophilic and predominantly electron donating. Those effects were time-dependent. Consequently, the total free energy of adhesion of C. albicans to this alloy became unfavorable after treatment with the investigated microbial extract. A linear relationship between the electron-donor property and the total free energy of adhesion has been found for both dental alloys. Also, a linear relationship has been found between this latter and the hydrophobicity for the cobalt based alloy. However, the exposure of nickel based alloy to the antifungal extract failed to produce the same effect.
Topics: Antifungal Agents; Bacillus; Candida albicans; Cobalt; Dental Alloys; Nickel
PubMed: 27987667
DOI: 10.1016/j.msec.2016.09.083 -
Dental Materials Journal Mar 2020The aim of this paper is to study changes in the Ag-Pd-Cu-Au alloy surfaces by alumina air-abrasion process and effect of those changes on the adhesive bonding...
The aim of this paper is to study changes in the Ag-Pd-Cu-Au alloy surfaces by alumina air-abrasion process and effect of those changes on the adhesive bonding characteristic. Surface roughness, surface composition and chemical state of the alumina air-abraded alloys were analyzed by a confocal laser scanning microscope, an energy dispersive X-ray spectroscopy and an X-ray photoelectron spectroscopy. The results showed that the alumina air-abrasion changed the alloy surface by mechanical roughening, alumina remain and copper oxidation. Effect of the changes in the alloy surface on the adhesive bonding characteristic was examined by using a methyl methacrylate/tri-n-butylborane derivative (MMA/TBB) resin cement with the 10-methacryloyloxydecyl dihydrogen phosphate (MDP) contained primer. The shear bond strength test results indicated that the surface oxidation by the abrasion is the main contributor that improved the adhesive bonding rather than other effects such as mechanical roughening or alumina remain.
Topics: Aluminum Oxide; Dental Alloys; Dental Bonding; Dental Cements; Materials Testing; Methacrylates; Resin Cements; Shear Strength; Surface Properties
PubMed: 31723095
DOI: 10.4012/dmj.2019-027 -
Journal of the Mechanical Behavior of... Aug 2012The purpose of this study was to compare the microstructure, hardness, corrosion resistance and metal-porcelain bond strength of a CoCrMo dental alloy obtained by two...
Microstructure, hardness, corrosion resistance and porcelain shear bond strength comparison between cast and hot pressed CoCrMo alloy for metal-ceramic dental restorations.
OBJECTIVES
The purpose of this study was to compare the microstructure, hardness, corrosion resistance and metal-porcelain bond strength of a CoCrMo dental alloy obtained by two routes, cast and hot pressing.
METHODS
CoCrMo alloy substrates were obtained by casting and hot pressing. Substrates' microstructure was examined by the means of Optical Microscopy (OM) and by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). Hardness tests were performed in a microhardness indenter. The electrochemical behavior of substrates was investigated through potentiodynamic tests in a saline solution (8g NaCl/L). Substrates were bonded to dental porcelain and metal-porcelain bond strength was assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Fractured surfaces as well as undestroyed interface specimens were examined with Stereomicroscopy and SEM-EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The t-test (p<0.05) was used to compare shear bond strength results.
RESULTS
Cast specimens exhibited dendritic microstructures whereas hot pressed specimens exhibited a typical globular microstructure with a second phase spread through the matrix. The hardness registered for hot pressed substrates was greater than that of cast specimens, 438±24HV/1 and 324±8HV/1, respectively. Hot pressed substrates showed better corrosion properties than cast ones, i.e. higher OCP; higher corrosion potential (E(corr)) and lower current densities (i(corr)). No significant difference was found (p<0.05) in metal-ceramic bond strength between cast (116.5±6.9 MPa) and hot pressed (114.2±11.9 MPa) substrates. The failure type analysis revealed an adhesive failure for all specimens.
SIGNIFICANCE
Hot pressed products arise as an alternative to cast products in dental prosthetics, as they impart enhanced mechanical and electrochemical properties to prostheses without compromising the metal-ceramic bond strength.
Topics: Alloys; Biomechanical Phenomena; Corrosion; Dental Alloys; Dental Porcelain; Dental Stress Analysis; Electrochemistry; Hardness; Hot Temperature; Materials Testing; Metal Ceramic Alloys; Metals; Microscopy; Shear Strength; Surface Properties; Vitallium
PubMed: 22659369
DOI: 10.1016/j.jmbbm.2012.03.015 -
The Journal of Prosthetic Dentistry Jan 2012Surplus alloy from the initial casting is commonly reused with the addition of new alloy. This recasting procedure could affect the cytotoxicity of dental alloys. (Comparative Study)
Comparative Study
STATEMENT OF PROBLEM
Surplus alloy from the initial casting is commonly reused with the addition of new alloy. This recasting procedure could affect the cytotoxicity of dental alloys.
PURPOSE
The purpose of this in vitro study was to evaluate the effect of repeated casting of high-noble and base metal alloys on gingival fibroblast cytotoxicity.
MATERIAL AND METHODS
Disk-shaped specimens (5 × 2 mm, n=60) of a high-noble (Au-Pt) and 2 base metal (Ni-Cr and Cr-Co, n=20) alloys were prepared with 100% new alloy and 50%, 65%, and 100% once recast alloy. The elemental composition of specimens was analyzed with X-ray energy-dispersive spectroscopy. Five specimens from each group were conditioned in saline with 3% fetal bovine serum albumin. The conditioning media were analyzed for elemental release with atomic absorption spectroscopy. Cytotoxic effects were assessed on human gingival fibroblast with a 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyl tetrazolium bromide (MTT) colorimetric assay. The data were analyzed with 1-way and 2-way ANOVA and Tukey's HSD multiple comparison test (α-=.05).
RESULTS
Elemental compositions of Co-Cr and Au-Pt alloys were significantly different among casting protocols. Elemental release of Co-Cr and Ni-Cr alloys was significantly different between new and recast specimens (P<.001). Nickel release increased with recast alloy addition. The 2-way ANOVA showed a significant effect of the casting procedure (P<.001) alloy group (P<.001) and their interaction for cytotoxicity (P<.001). The Ni-Cr alloy groups with 65% and 100% recast alloy had lower cellular activity than all other specimens (P<.001).
CONCLUSIONS
The results of this study indicated that alloys containing nickel have increased cytotoxic effects and that composition of the alloys affected the cytotoxicity. Furthermore, recasting nickel-containing alloys with 65% surplus metal addition significantly increased the cytotoxic activity.
Topics: Adult; Cell Survival; Cells, Cultured; Chromium; Chromium Alloys; Cobalt; Colorimetry; Coloring Agents; Culture Media, Conditioned; Dental Alloys; Dental Casting Technique; Diffusion; Equipment Reuse; Fibroblasts; Gingiva; Gold; Gold Alloys; Humans; Materials Testing; Microscopy, Electron, Scanning; Nickel; Platinum; Spectrometry, X-Ray Emission; Spectrophotometry, Atomic; Tetrazolium Salts; Thiazoles
PubMed: 22230913
DOI: 10.1016/S0022-3913(12)60013-4