No abstract available.
Chromium* ; Micronucleus Tests*

The objective of study is to evaluate effects of natrium hyposulphide for treatment the occupational dermatosis due to chromium. 23 rabbits was ulcerated by kalium bichromate 6%, after that they were treated by Hysox 10% solution and Hynax 5% ointment (main composition was natri hyposulphide) and all rabbits were observed generally symptomatically, macro and micro-scopically, and microbiologically. Results showed that : after 2 weeks, the healing rate on the treated rabbit groups was 2.6 and 2.4 times higher than the control group. Authors recommended the further study and the production of this preparation in order to protect the workers exposed to chromium.
Skin Diseases ; Chromium

No abstract available.
Chromium ; Copper ; Zinc

This study was conducted to evaluate the tensile bond strength by bonding the dental bracket with Super-bond after treating the surface of dental Nickel-Chromium alloy with sandblasting, sandblasting & tin-plating, respectively, and tin-plating. 10 pieces of Nickel-Chromium alloys with brackets bonded with Super-bond without their surface treatment were sampled as a control group, 20 pieces of Nickel-Chromium alloy brackets bonded with Super-bond after treating them with sandblasting as group I, 20 pieces of Nickel-Chromium alloys tin-plated and bonded with Super-bond after sandblasting as group II, and then 20 pieces of alloys with brackets bonded with Super-bond after tin-plating as group III. The result of those examination and comparison is summarized as follows: 1. Group I showed the mean tensile bond strength of 14.41+/-2.24MPa which was highest among 4 groups, followed by group III( 13.59+/-L51MPa ), group II( 12.27+/-1.45MPa ), and control group( 10.50+/-1.57MPa ), respectively. However, it was shown that them was no statistically significant difference between group I and III, group III and II, and group II and control group( P>005 ). 2. The main failure pattern of those brackets showed that 70% of the control group had an adhesive failure at the bracket Superbond interface, and 30% at the Nickel-Chromium alloy-Superbond interface, while other groups did the adhesive failure at the bracket-Superbond interface. 3. When examined under SEM, it was shown that adhesives were mostly attached to the surface of the Nickel-Chromium alloy for all groups while a considerable quantity of adhesives were attached to the bracket base. Then, those samples treated only with sandblasting showed the most even and remarkable roughness of their surface.
Adhesives ; Alloys* ; Chromium Alloys

Aims: Chromium salt possesses unique characteristics that render it useful in numerous applications in several industrial processes, especially tanning of animal hides which act as a major source of hexavalent chromium toxicity in environment. This study aimed to evaluate the efficiency of loofah immobilized Cladosporium cladosporioides CEL14 in remediate tannery wastewater which contains hexavalent chromium. Methodology and results: A total of 18 fungal species were isolated from three different sites of tannery wastewater in Egypt, of which C. cladosporioides CEL14 was the most capable species of chromate remediation with 81% after 7 days of incubation as free cells. The experiments were conducted in minimum salt medium supplemented with 200 ppm chromate in the form of potassium dichromate. Different process parameters studies demonstrated that chromate was completely removed at 30 °C, pH 6, 0.1% malt extract and 0.2% glucose after 7 days of incubation with 20% inoculum size. After that, C. cladosporioides was immobilized on a natural support material (loofah). The removal ability of chromate was enhanced through permanent viable immobilization on loofah pieces, which showing complete removal of chromate within 3 days. The toxicity assessment of treated tannery effluents revealed that 74% of Brassica napus seeds were germinated upon exposure to the treated effluent. Conclusion, significance and impact of study This study revealed that C. cladosporioides CEL14 isolate has high potential as bioremediating agent against toxic hexavalent chromium. The removal ability of toxic chromate was enhanced through permanent viable immobilization on loofah pieces. This technology is simple, cost effective, efficient and environmentally friendly. The loofah immobilized with C. cladosporioides CEL14 has potential to be applied in wastewater treatment of small-scale tanneries after onsite trials.
Luffa ; Cladosporium ; Chromium ; Wastewater

OBJECTIVEThe purpose of the study was to investigate the content of nickel (Ni) ion in patients' saliva after wearing the porcelain-fused-to nickel-chromium (Ni-Cr) crown or the porcelain-fused-to nickel-chromium-titanium(Ni-Cr-Ti) crown.

METHODS50 patients who had one molar or premolar needed repairing were selected and divided into two groups randomly. Patients in one group were fabricated with porcelain-fused-to Ni-Cr crown and the patients in the other group were fabricated with porcelain-fused-to Ni-Cr-Ti crown. Collect the patients' saliva before wearing, 1 week, 3 months, and 6 months after wearing. The content of Ni ion in saliva was detected by inductively coupled plasma mass spectrometry (ICP-MS).

RESULTSThe content of Ni ion in both groups increased at the first week, and go back after 6 months. There were no significant differences before wearing, 1 week, 3 months, and 6 months after wearing. There were no significant differences between the two groups.

CONCLUSIONWearing the porcelain-fused-to Ni-Cr crown or the porcelain-fused-to Ni-Cr-Ti crown has no significant influence on the content of Ni ion in saliva.

OBJECTIVEThe aim of this study was to investigate the korrosionsneigung of three metal specimens for casing removable denture by means of electrochemical method.

METHODSThree kinds of test specimens were prepared, including cobalt-chromium alloy, nickel-chrome alloy with titanium and pure titanium. Then they were analyzed via linear polarization in artificial saliva simulating oral environment. From this electrochemical test the polarization curves of these kinds of specimens were recorded. Then the scanning electron microscope (SEM) and X-ray diffractometer (XRD) were applied to assess the morphology and phase changes before and after electrochemical corrosion.

RESULTSNo typical Tafel curve had been recorded for pure titanium, other than cobalt-chromium alloy and nickel-chrome alloy with titanium. Nickel-chrome alloy with titanium got more negative corrosion potential and higher corrosion current than cobalt-chromium alloy. Via SEM, the obvious changes were observed on the morphology and phase before and after corrosion on cobalt-chromium and nickel-chrome alloy with titanium specimens while pure titanium having no change. The XRD provided us little changes on these all three materials.

CONCLUSIONThe results confirm that the korrosionsneigung of the studied cobalt-chromium alloy in artificial saliva is lower than that nickel-chrome alloy with titanium. Pure titanium is the most stable one of the three materials and is extreme hard to be etched.

PURPOSE: The purposes of this study was to evaluates shear bond strength between zirconia core and veneer-ceramic in order to examine the clinical practice of colored zirconia block fabricated by infiltration method into the metal chloride solution. MATERIAL AND METHODS: CNU block and Everest(R) ZS blank were used. VITA In-Ceram(R)2000 YZ Coloring liquid (LL1) and 3 aqueous metal chloride solutions containing chromium and molybdenum ingredients were used. 40 zirconia specimens were prepared into cuboid shape (5 x 5 x 10 mm). All specimens were divided into 5 groups by infiltrating into the coloring liquids. After that, porcelain was build up into the shape of 5 x 5 x 4 mm3, followed by sintering. The maximum loading and shear bond strength was measured. Failure patterns and failure sites were examined. RESULTS: 1. There were no statistical differences in shear bond strength between zirconia blocks (P > .05). 2. There were no statistically significant differences in shear bond strength between non-colored and colored zirconia blocks, while shear bond strength of non-colored zirconia blocks is higher than that of colored specimen (P > .05). 3. In the comparison with shear bond strength among colored zirconia blocks, there were no statistical differences according to kinds of coloring liquid (P > .05). 4. Mixed failure patterns were mainly observed in the failure between zirconia and veneering ceramic. The veneering ceramic failure of all specimens was observed in either interface of zirconia or veneering ceramic. CONCLUSION: Shear bond strength between colored zirconia and veneering ceramic shows lower tendency than non-colored zirconia, but there was clinically allowable value.
Ceramics ; Chromium ; Dental Porcelain ; Ethylnitrosourea ; Molybdenum ; Zirconium

PURPOSE: This study evaluated the effect of span length on the adaptation of implant-supported cobalt chromium frameworks fabricated by three techniques. MATERIALS AND METHODS: Models with two solid abutment analogs at different inter-abutment distances were digitized using a laboratory scanner. Frameworks of two-, three-, and four-unit fixed prostheses were designed by a computer. Six dots with a diameter of 0.2 mm were preset on the surface of each framework. A total of 54 implant-supported cobalt chromium frameworks were fabricated by milling, selective laser melting (SLM), and cast techniques. The frameworks were scanned and exported as Stereolithography files. Distances between two dots in X, Y, and Z coordinates were measured in both the designed and fabricated frameworks. Marginal gaps between the framework and the abutments were also evaluated by impression replica method. RESULTS: In terms of distance measurement, significant differences were found between three- and four-unit frameworks, as well as between two- and four-unit frameworks prepared by milling technique (P<.05). Significant differences were also noted between two- and three-unit frameworks, as well as between two- and four-unit frameworks prepared by cast technique (P<.05). The milling technique presented smaller differences than the SLM technique, and the SLM technique showed smaller differences than the cast technique at any unit prostheses (P<.05). Evaluation with the impression replica method indicated significant differences among the span lengths for any fabrication method (P<.05), as well as among the fabrication methods at any unit prostheses (P<.05). CONCLUSION: The adaptation of implant-supported cobalt chromium frameworks was affected by the span length and fabrication method.
Chromium* ; Cobalt* ; Freezing ; Methods ; Prostheses and Implants

OBJECTIVETo analyze the final color of Solidex in six thickness interacting with three different backgrounds.

METHODSFive specimens of Solidex in each shade A1, A3, and C2 were fabricated at thickness of 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 mm. The CIE L(*)a(*)b(*) values of specimens were measured using a colorimeter (ShadeEye NCC) to determine the colorimetric difference, when the specimens overlaid on different backgrounds.

RESULTSWhen the thickness was more than 1.8 mm, the color difference (DeltaE(*)ab < 1) was not perceived by human observers. When the thickness was 1.4 mm or less than 1.4 mm, the color difference (DeltaE(*)ab > 2.72) was considered clinically unacceptable between alloy background and two types of composite resin background.

CONCLUSIONSAlloy background had more evident influence on the final color of Solidex than composite resin background. When making metal-free crown restoration using Solidex, it was advisable to make the composite resin more than 1.8 mm thick.