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Results for “CHROMIUM-COBALT ALLOYS”

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At least 19 recordsLinked to original sources
PubMed1990

A dental technician with pulmonary fibrosis: a case of chromium-cobalt alloy pneumoconiosis?

A 45 yr old male developed pulmonary fibrosis after 29 yrs of employment as a dental technician. He subsequently developed adenocarcinoma of the lung. Diffuse interstitial fibrosis was seen using light microscopy. Neutron activation analysis of non-neoplastic lung tissue demonstrated high levels of chromium and cobalt suggesting the possibility of a chromium-cobalt alloy pneumoconiosis.

Biopsy↗
PubMed1979

Immediate permanent reconstruction of a mandibular continuity defect with use of a prosthesis of chromium-cobalt alloy.

A report of ten-year follow-up examinations of a patient who had a hemimandibulectomy with disarticulation because of fibrous dysplasia and immediate permanent reconstruction of the mandible with a Vitallium custom-cast prosthesis is presented. Careful preoperative planning, operative technique, and postoperative follow-up examinations are essential for successful maintenance of the prosthesis. Autogenic bone grafts are, in general, superior to alloplasts in permanent reconstruction of defects in mandibular continuity after resection. However, there are indications for alloplastic reconstruction when the condyle is disarticulated with the resection.

Aged↗
PubMed1991

[Biocompatibility of a chromium-cobalt alloy studied in vitro].

The authors followed the effect of chromcobalt alloy on human cells cultured in vitro. They found out that corrosion increases the cytotoxicity of this alloy, meanwhile the perfectly laboratory elaboration, especially polishing of substitution decreases the cytotoxicity. We recommend for the complex cytotoxicity review, to test the metals and alloys also after laboratory elaboration, it means in the condition it is passed on to the patient.

Biocompatible Materials↗
PubMed1991

Mineral-associated hepatic injury: a report of seven cases with X-ray microanalysis.

The patterns of hepatic injury associated with various minerals were studied in seven patients. The subjects included one patient who was a sandblaster (silica by inhalation), one patient who was a dental laboratory technician (silica and chromium-cobalt alloy by inhalation), one patient with inhalational talcum powder abuse, and four chronic intravenous (IV) drug abusers (talc by IV injection). In all cases, the liver was examined by light and polarizing microscopy, and by scanning electron microscopy with energy-dispersive x-ray microanalysis. In the two patients with silica exposure, silica-containing sclerohyaline nodules were diffusely present in portal tracts and lobules. Both chromium-cobalt alloy and silica were present in the dental technician. In contrast, in all cases of talc exposure, aggregates of talc-laden macrophages were present in portal and centrilobular areas. Three IV drug abusers and the talcum powder abuser had histologic evidence of chronic hepatitis, most probably of viral etiology. We conclude that mineral type plays an important role in the pathogenesis and fibrogenesis of hepatic lesions. Compared with silica, talc primarily elicits a macrophage response without granuloma formation or fibrosis. Hepatic silicosis is a rare complication in dental laboratory technicians, and chromium-cobalt alloy may contribute to hepatic injury and fibrosis in this setting.

Adult↗
PubMed1989

[Problems concerning material for root inlays and their solution].

The author discusses the reduced mechanical resistance of root inlays made from low-melting Koldan silver alloy combined with wire support. The problem is resolved by the use of a chromium-cobalt alloy without a wire nucleus. As modelling material Spofacryl 0 is used which is administered by injection.

Chromium Alloys↗
PubMed1991

Evaluation of finishing and polishing techniques on surface roughness of chromium-cobalt castings.

The effect of finishing and polishing techniques on surface roughness of a chromium-cobalt alloy was evaluated by means of a stylus profile instrumentation and scanning electron microscopy. Scanning electron micrographs, surface profile tracings, surface roughness recordings, and statistical analysis of data support the finding that the best surface finish is obtained when sandblasting, hard stone, medium abrasive disk, second sandblasting, electropolishing, hard rubber point, hard felt disk with pumice slurry, and felt disk and soft brush with polishing paste are used progressively. The results of this study indicate that the finishing procedure should be carried out in a logical, systematic sequence of steps.

Chromium Alloys↗
PubMed1990

Clinical application of electric resistance welding and soldering methods to removable partial dentures.

The joining procedure for uniting metal structures is very important in the construction of removable partial dentures. However, it has several restricted problems in joining wrought wire clasps to rests or major connectors. For example, the base metal wires made of chromium-cobalt alloy are subject to changes in their mechanical properties caused by heating, and damage to acrylic resin materials (denture base and artificial teeth) occurs in the repair of removable partial dentures by using the torch soldering method. In this paper, in order to resolve these problems, an electric resistance welding machine was applied to attach wrought wire components to a removable partial denture framework. This welding machine was used to attach metal structures temporarily to each other, and to solder the welded joint with hard solder. Consequently, some problems of the conventional torch soldering method were improved by using the electric resistance welding and soldering methods. It was suggested that the clinical application of the electric welding and soldering methods was very useful in the construction of removable partial dentures.

Aged↗
PubMed1990

[Removable partial dentures applied by electric welding and soldering methods].

The joining procedure for uniting metal structures is very important in the dental clinic, and various kinds of metal joining methods have been performed for clinical application. The conventional torch soldering method using a blow torch has been generally adopted. However, it has several clinical problems, especially in the construction of removable partial dentures. The base metal wires made of a chromium-cobalt alloy are subject to changes in their mechanical properties caused by heating, when wrought wire clasps are joined to rests or frameworks. In addition to the flexibility of wrought wire clasps, damage to acrylic resin denture bases and acrylic resin teeth occurs in the repair of removable partial dentures. In this paper, the electric resistance welding and soldering methods were applied to attach wrought wire components to a removable partial denture framework to resolve the problems of the torch soldering method. As a result, it is suggested that these electric resistance welding and soldering methods have the following advantages, as compared with the conventional torch soldering method. 1. When using this electric resistance welding method, it is possible to fix metals temporarily to each other more securely and strongly than the conventional temporary fixation methods using sticky wax or acrylic resin. 2. The electric resistance soldering method does not require any heat insulation or a partition as the torch soldering method does, because the soldered area is only heated partially. 3. In the case of soldering electrically wrought wire clasps to metal structures such as rests and connectors, there is no fear of of overheating a wide area of wires.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromium Alloys↗
PubMed1979

[Removable partial denture. Excerpts from the literature 1977--1979].

In partial denture prosthesis research and advances were made principally on: -- the fundamental biomechanical properties of the demodont and the fibromucosa. In the light of these findings, the justification of stressbreaking as a principle is questioned -- the mechanical properties of chromium-cobalt alloys -- checking of castings by radiography -- simplification of the designs for removable partial denture frameworks -- impression materials and techniques (fluid-wax functional impression and altered cast-procedure) -- the combination of restauration and plaque control for successful dentistry.

Biomechanical Phenomena↗
PubMed1990

[The application of an overdenture with a modified Dolder bar joint].

In this article, a modified Dolder bar attachment application is presented in two cases. The egg-shaped bars are casted in chromium-cobalt metal alloy and the retention loops are made of clasp wire in "omega" shape. The bar attachment has some advantages like being easy to fabricate and having lower cost. The laboratory made modified Dolder bar attachment we used with overdentures provided additional retention for the dentures, minimized the horizontal and vertical movements of the dentures and also strengthened the abutment teeth by splinting. As a conclusion we have tried to show that this attachment can be an alternative to use with overdentures.

Denture Precision Attachment↗
PubMed1978

Influence of axiopulpal line angle and proximal retention on fracture strength of amalgam restorations.

Proximal retentive grooves significantly increase the strength of amalgam restorations in Class II cavities. There were no remarkable differences that could have clinical significance between sharp or rounded axiopulpal line angles and rounded or rounded and sloped pulpal walls. Chromium-cobalt dies are effective for tests of fracture strength of amalgam restorations.

Chromium Alloys↗
PubMedDate not supplied

Adherence of ceramic coatings on chromium-cobalt structures.

A method has been developed for the consistent adherence of flame-sprayed ceramic coatings to Vitallium. The critical step involves etching the metal by the anodic polarization technique. This procedure allows complex geometrics to be corroded evenly, and, by suitable choice of etching solution and conditions, enables any metal to be substituted. The bond is capable of sustaining more severe deflections than are experienced during intraoral function. Despite the number of cracks generated during testing, the ceramic layer remains intact. The ceramic-metal bond is mechanical. The corroded surface provides greater surface area, thus permitting a number of retention sites. Analysis of the ceramic microstructure finds it to be suitable for tissue ingrowth.

Ceramics↗