Release of soluble metal ions from copper based dental alloys mesured by ICP-MS

Describes the release of soluble metal ions from copper based dental alloys mesured by ICP-MS. Presented at the annual congress of the british toxicology society

FORMA MOBILITAS SOSIAL DALAM KAPITALISME PENDIDIKAN

Pendidikan merupakan lembaga kebudayaan di mana manusia belajar memahami diri dan masyarakatnya. Melalui ilmu pengetahuan dan proses pendidikan manusia mencapai taraf kesadaran diri. Saat ini, di era kapitalisme, pendidikan dan ilmu pengetahuan telah memaksa orang untuk hidup dalam perkembangan teknologi dan ilmu penge-tahuan. Kemudian, idea kapitalisme telah mempengaruhi tujuan ideal pendidikan dan ilmu pengetahuan untuk mewujudkan tujuan akhir kapitalisme. Pendidikan adalah sarana mobilitas sosial, vertikal mau-pun horisontal. Dalam hal pendidikan, gerak sosial idealnya meng-arahkan masyarakat dari keadaan ketidaksadaran menuju kesadaran. Namun dalam kapitalisme pendidikan, komitmen tujuan lembaga pendidikan telah bergeser dan jauh menyimpang dari tujuan filosofisnya.ABSTRACTEducation is a cultural institution where human being learns how to understand him or her self. Through science and educational process people reach their self-consciousness. Nowadays, in the age of capitalism, education and science have forced people to live within the technological and science developments. Capitalism has forced education and science to realize their ultimate goal, which is to gain capital accumulation. Education can transform people into different social mobility, whether vertical or horizontal of social mobility. In this case, social mobility initially comes from unconsciousness to be consciousness. But then, it purpose commitment of education as institution have extended its resuscitation to human life becomes far swerve from its philosophical purposes

Surface agents' influence on the flexural strength of bilaminated ceramics

The objective of this study was to evaluate the influence of different surface agents on the flexural strength of a ceramic system. Eighty bar-shaped specimens of zirconia were divided into four groups according to the agent to be used: group Control-to be cleaned with alcohol; group VM9-application of a fluid layer of porcelain; group Effect Bonder-application of a bonding agent; and group Coloring Liquid-application of coloring liquid. All specimens received the porcelain application by the layering technique and were then subjected to thermocycling. The four-point bending test was performed to calculate the strength values (s, MPa) and the failure modes were classified. ANOVA did not detect significant differences among the groups. The Weibull modulus were 5 (Control, VM9 and Effect Bonder) and 6 (Coloring Liquid). The cracking of the porcelain ceramic toward the interface was the predominant failure mode. It was concluded that the surface agents tested had no effect on the flexural strength of the bilaminated ceramic specimens.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Instituto de Ciência e Tecnologia - ICT Univ Estadual Paulista - UNESP, São José dos Campos, SPDepartment of Dental Materials and Prosthodontics Instituto de Ciência e Tecnologia - ICT Univ Estadual Paulista - UNESP, São José dos Campos, SPDepartment of Restorative Dentistry Instituto de Ciência e Tecnologia - ICT Univ Estadual Paulista - UNESP, São José dos Campos, SPInstituto de Ciência e Tecnologia - ICT Univ Estadual Paulista - UNESP, São José dos Campos, SPDepartment of Dental Materials and Prosthodontics Instituto de Ciência e Tecnologia - ICT Univ Estadual Paulista - UNESP, São José dos Campos, SPDepartment of Restorative Dentistry Instituto de Ciência e Tecnologia - ICT Univ Estadual Paulista - UNESP, São José dos Campos, SPFAPESP: 11/13085-

Electrochemical investigation of two dental metals. Unalloyed titanium and copper - aluminium alloy

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.</p

Effects of pH and Fluorides on Titanium

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&gt;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</p

Uedle metaller til dentale kroner og broer : Base metals in dental crowns and bridges

KIBS bestånd av denna tidskrift</p

Effects of pH and fluoride concentration on the corrosion of titanium

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.</p

Static immersion and irritation tests of dental metal-ceramic alloys

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.</p

Corrosion and Irritation Tests of a Dental Aluminum Bronze

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.</p