| 1. |
- Ardlin, Berit, et al.
(författare)
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Corrosion and Irritation Tests of a Dental Aluminum Bronze
- 2006
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Ingår i: International Association for Dental Research, 84th General Session & Exhibition, Brisbane, Australia.
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Konferensbidrag (refereegranskat)abstract
- Corrosion and irritation tests of a dental aluminium bronze. B.I. ARDLIN*1,2, B. LINDHOLM-SETHSON1 and J.E. DAHL2, 1Umeå University, Sweden, 2NIOM – Nordic Institute of Dental Materials, Haslum, Norway Objectives: The aims of this investigation were to study the corrosion of a copper-aluminium-nickel alloy for fixed prostheses, and to evaluate possible irritant effects of the corrosion products. Methods: The alloy NPG+2 with the nominal composition Cu:77.3; Al:7.8; Ni:4.3; Fe:3.0; Zn:2.7; Au:2.0; Mn:1.7, was characterized. Static immersion in saline lactic acid solution was selected to quantify metallic elements released in a milieu simulating the condition of plaque build-up in interproximal areas. Corrosion and surface reactions in artificial saliva and saline solutions were studied by electrochemical techniques including registration of polarization curves and impedance spectra. Irritative effect of the corrosion products was assed by the Hen’s egg test-chorio-allantoic membrane, HET-CAM. Results: Immersion test. The following metal elements were found in the saline lactic acid solutions after immersion of two specimens for 7 days (specimen 1 / specimen 2 in g cm-2): Cu (769/494); Al (249/172); Ni (164/124), Fe (134/109); Zn (59/37); and Mn (61/43). Electrochemical tests. Higher corrosion rates were found in the saline solution, pH 4 or pH 7, than in the aerated or de-aerated artificial saliva solution. No high-quality passive film was formed on the studied alloy as extensive corrosion was observed on test specimens in both solutions. HET CAM. The saline lactic acid extracts induced coagulation of the blood vessels of the chorio-allantoic membrane after an average time of 1 min and the alloy was rated as a moderate irritant. Conclusions: The copper-aluminium-nickel alloy investigated in this study showed high corrosion caused by an inability to create a stable passivating surface layer. High levels of the elements Cu, Al, Ni, Fe, Zn and Mn were found by static immersion testing, and the corrosion products had an irritant effect. The project was supported by grants from the European Union Structure Foundation Objective One.
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| 2. |
- Ardlin, Berit, et al.
(författare)
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Effects of pH and Fluorides on Titanium
- 2005
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Ingår i: Society for Biomaterials, 30th Annual Meeting & Exposition, Memphis,TN, USA.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Titanium is used in dentistry both for crowns, fixed and removable partial dentures, suprastructures and for implants. In such applications, titanium may come in contact with fluorides. Prophylactic agents such as toothpastes and gels have effects on titanium that are dependent on their acidity and fluoride concentration. In order to obtain rapid bone growth and a strong bond between the implant and the bone, fluorides are used to modify the surfaces of titanium implants1. The aim of this investigation was to study the release of ions and the effects of fluorides on surfaces of titanium cp-II in saline solutions of different pF and pH using a) a brush test and b) electrochemical techniques including impedance spectroscopy2. Materials and Methods: Brush test. An electric toothbrush was used to brush the titanium electrodes for 2 min in aqua solutions of 0.9 % NaCl with 0, 0.3, 0.6 and 1 % NaF. The pH of the solutions was adjusted by adding ultra pure HNO3 and 1 M NaOH. In order to avoid interference with the chemical analyses, the solutions were not buffered. The solutions were divided into two all-embracing groups, pH 4.5 and pH>5.3, with respect to their acidity. An atomic absorption spectrophotometer equipped with a graphite atomizer with Zeeman effect background correction was used to detect titanium in the NaCl solutions. Electrochemical tests. Planar titanium electrodes with surface area of 0.28 cm2 served as working electrodes and were wet-ground with SiC paper through 1200 grit using standard metallographic procedures prior to exposure to the various electrolyte solutions. The solutions employed were similar to those used in the previous experiments, i.e. phosphate-buffered 0.9 % NaCl solutions with a pH between 4 and 7, containing 0, 0.3, 0.6 and 1 % NaF. An ordinary three-electrode setup was used with Ag/AgCl, sat KCl as a reference electrode and a platinum sheet as a counter electrode. The open circuit potential was recorded for 18–20 hours, and the electrode was then polarized to –0.18 V vs. ref. for five minutes. After this an impedance spectrum was recorded at –0.18 V vs. ref in the frequency range 100 000 Hz to 5 mHz and an amplitude of 10 mV peak to peak. Finally a linear anodic polarization curve was recorded from –0.5 V to 1 V vs ref at a sweep rate of 2 mV/sec. Results: The result of the brush tests is shown in Table 1. The highest amount of titanium was detected in the NaCl solutions with 0.6 or 1.0 % NaF at pH 4.5. Titanium remains passive in neutral solutions irrespective of the addition of fluoride and also at pH 4 without addition of fluoride. This is indicated in all three electrochemical experiments: the final electrode potential at open circuit is around -0.1 V vs ref after 18 hours, the impedance spectrum shows an almost pure capacitive behavior and the current at anodic polarization is very small. At low pH with addition of fluoride, titanium becomes active, as evidenced by a negative final electrode potential at open circuit of around -1.0 V vs ref after 18 hours, an impedance spectrum indicating a non-blocking electrode and a high current at anodic polarization. At medium pH and with an addition of fluoride the electrochemical experiments indicate the formation of a porous non-passivating surface film. In the latter case the final open circuit potential is around -0,5 V vs ref, the impedance spectra show a non-blocking electrode with a large charge-storing capacity and the current at anodic polarization is close to the values obtained for the active electrode at pH 4. The results of the electrochemical tests are summarized in Table 2
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| 3. |
- Ardlin, Berit I., et al.
(författare)
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Corrosion of dental nickel-aluminum bronze with a minor gold content-mechanism and biological impact
- 2009
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - Malden : Wiley-Blackwell. - 1552-4973 .- 1552-4981. ; 88B:2, s. 465-473
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To study corrosion and to evaluate biological effects in vitro of corrosion products of a copper-aluminum-nickel alloy with 2% gold. Methods: The alloy NPGTM+2 with the nominal composition Cu:77.3; Al:7.8; Ni:4.3; Fe:3.0; Zn:2.7; Au:2.0; and Mn:1.7 was characterized. Static immersion in acidic saline, pH 2.2-2.4, was used to determine release of metallic elements in a milieu simulating the condition of plaque build-up in interproximal areas of the tooth. Corrosion and surface reactions in saline and artificial saliva were studied by electrochemical techniques including registration of open-circuit-potentials, polarization curves and impedance spectra. Extracts were made in cell culture media and acidic saline and used for MTT test for cytotoxicity and HET-CAM method for irritation. Results: The mean amount of elements released in the acidic saline were in g cm-2 : Cu:632; Al:210; Ni:144; Fe:122; Zn:48; Mn:52. No protective film was formed on the surface of the alloy, as extensive corrosion was observed in both saline and artificial saliva. The corrosion rate was higher in saline than in artificial saliva. Acidic extracts of the alloy diluted up to 64 times reduced cell viability with 80% or more. The extract induced coagulation of the blood vessels of the CAM and was rated as moderate irritant solution. Significance: The nickel-aluminum bronze showed high corrosion rate caused by an inability to create a protective surface layer. High levels of toxic elements were found after static immersion testing, and the corrosion products had a distinct adverse effect on the biological activity.
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| 4. |
- Ardlin, Berit, et al.
(författare)
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Static immersion and irritation tests of dental metal-ceramic alloys
- 2005
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Ingår i: European Journal of Oral Sciences. - 0909-8836. ; 113:1, s. 83-9
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Tidskriftsartikel (refereegranskat)abstract
- The expansion of the European Union is bringing new types of metal-ceramic alloys to the market, i.e. alloys probably unknown in Western-European dentistry. The aim of this study was to investigate recent developments and "classic" alloy compositions (one iron and two cobalt alloys, unalloyed titanium and an experimental titanium-zirconium alloy, and one gold alloy containing copper and zinc). The alloys and titanium were subject to static immersion in a 0.1 mol l(-1) solution of saline lactic acid before and after oxidation, hence simulating the temperature cycles for the application of ceramic to metal. The greatest amounts of released metal ions were found in the electrolytes of the oxidized gold alloy and of a cobalt alloy not exposed to high-temperature oxidation. Corrosion of the titanium and alloy surfaces was related to the condition of the specimen. The irritation potentials of some metal ions found in the electrolyte were investigated by performing the hen's egg test-chorio-allantoic membrane (HET-CAM) procedure with 1 mmol l(-1) solutions of Ce(3+), Co(2+), Cu(2+), Zn(2+), Fe(2+), and Ti(4+) ions. The irritation potential of the electrolyte of the oxidized gold alloy with a high concentration of metal elements was also investigated. Of these solutions, only the 1 mmol l(-1) Cu(2+) solution was graded as slightly irritating.
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| 5. |
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| 6. |
- Dijken, Jan W.V. van, 1947-, et al.
(författare)
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Samarbete breddar forskning : Oral Biomaterialgruppen, Umeå
- 2008
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Ingår i: Tandläkartidningen. - : Sveriges Tandläkarförbund. ; 100:5, s. 74-79
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Vid institutionen för odontologi vid Umeå Universitet finns en lång tradition av biomaterialforskning. För drygt två år sedan samlades större delen av den forskningen i ett vetenskapligt nätverk. Här beskrivs ett axplock av det breda forskningsarbetet.
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| 7. |
- Lindholm-Sethson, Britta, et al.
(författare)
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Effects of pH and fluoride concentration on the corrosion of titanium
- 2008
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Ingår i: Journal of Biomedical Materials Research Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 86A:1, s. 149-159
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to confirm and summarize the corrosion behavior of titanium in saline solution at different pH and fluoride concentration, and to characterize the surface films and the stability of a passive and aged titanium surface using open circuit potential measurements, electrochemical impedance spectroscopy, and anodic polarization curves. The results from the electrochemical measurements were related to titanium released after 2-min brushing with saline solutions with different pH and fluoride concentration, that is, simulating tooth brushing with fluoride containing prophylactic substances. Titanium was analyzed using atomic adsorption spectrophotometry. The pH in the saline solution was varied between 4 and 7 with additions of sodium fluoride up to 1.0 wt %. The presence of fluoride in solution was unfavorable for the stability of titanium and led to corrosion and the release of titanium especially at low pH. The combination of low pH and presence of fluoride ions in solution destroyed a passive film on the titanium surface even after aging for 170 h in neutral saline solution. The results do not necessarily imply the occurrence of biological soft tissue related effects even if a physical contact between titanium and the surrounding milieu is prevalent. To provide a general understanding of electrochemical techniques in biomaterial research, much effort was put in the qualitative description of the results, with the intention to provide a broader understanding of especially the impedance method to other researchers. (c) 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007.
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| 8. |
- Lindholm-Sethson, Britta, et al.
(författare)
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Electrochemical investigation of two dental metals. Unalloyed titanium and copper - aluminium alloy
- 2006
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Ingår i: The European Society for Electroanalytical Chemistry.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Titanium is used in dentistry in many applications: crowns, fixed and removable partial dentures, suprastructures and implants. In these functions, titanium may get in contact with prophylactic agents such as toothpastes and gels that contain fluorides.Dental copper-based alloys have become popular for crowns and fix prostheses in some countries, mostly because they have a gold-like appearance and are much less expensive than gold alloys. The accessibility of copper-based alloys is increasing and they are now available in Western Europe and US, but the discussion of their biocompatibility continues. It has been advocated that the alloys should not be generally used in dentistry.The aim of this investigation was to:• study the effects of fluorides on surfaces of titanium cp-II in saline solutions with different pF and pH using electrochemical techniques• study various aspects of corrosion of a copper-aluminium alloy in saline and artificial saliva using electrochemical techniques.The electrochemical techniques used were recording of open circuit potential, anodic polarisation and electrochemical impedance. Inductively coupled plasma spectroscopy of lactic acid saline extracts was also used.The results clearly show that titanium does not maintain its passivating properties in an acidic environment containing fluorides and that the copper-based alloy is an active corrosion state in the chloride containing electrolyte solutions; either saline or artificial saliva.
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| 9. |
- Tibballs, John E, et al.
(författare)
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Oädla metaller till kronor och broar
- 2006
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Ingår i: Tandläkartidningen. ; 98:12, s. 96-99
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 10. |
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