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Biomedical subjects

D Brune

Publications and source records attributed to D Brune.

At least 73 records · Page 4Linked to original sources
PubMed1981

Levels of methylmethacrylate, formaldehyde, and asbestos in dental workroom air.

The levels of methylmethacrylate and formaldehyde in workroom air of a dental laboratory following finishing and polishing a pour type denture base resin have been measured. The levels of these compounds did not exceed the respective hygienic threshold limit values in the general workroom air or in breathing air close to workpiece. The content of asbestos fibers in breathing air released during dismantling molds from gold casting was measured. During the dismantling procedure the fiber content in the air could exceed threshold limit values by up to about 12 times. However, about 10 min after terminating this process the fiber content had declined to a level below the establish requirements.

Air Pollutants↗
PubMed1981

Corrosion of amalgams.

The release of copper, mercury, silver, tin or zinc from conventional, dispersed phase and spherical high copper content amalgams immersed in artificial saliva solutions for periods up to 30 d has been measured using nuclear tracer techniques. During initial corrosion, i.e. within a few hours substantial amounts of mercury were found to be present in particulate matter in the three types of amalgams. The release of particulate matter was pronounced for the dispersed phase type of amalgam. After about 30 electrochemical corrosion was found to be the predominant process for release of various corrosion products. Zinc was demonstrated to be the major corrosion product released to the artificial saliva solutions from conventional as well as dispersed phase amalgams. Due to low radioactivity levels silver and tin could not be quantitatively assayed. However, the upper limits of silver and tin in the artificial saliva solutions referring to exposure periods up to 30 d were estimated to 0.1 microgram and 25 microgram respectively. The chemical state of the various corrosion products has been evaluated. The deposition of CuCl2 X 3 Cu(OH)2 on the surfaces of copper rich amalgams was observed according to X-ray diffraction analysis.

Chemical Phenomena↗
PubMed1981

Arsenic and selenium in lung, liver, and kidney tissue from dead smelter workers.

Concentrations of arsenic and selenium in lung, liver, and kidney tissue from dead smelter workers and from a control group have been determined with the aid of neutron activation analysis. A sevenfold increase of arsenic was found in lung tissue from the exposed workers compared with the control group. The median value of arsenic in lung tissue from workers dead from respiratory cancer was not higher than corresponding values from workers dead from other malignancies or from cardiovascular or other diseases. With increasing period of retirement the malignancies or from cardiovascular or other diseases. With increasing period of retirement the arsenic content diminished in liver tissue but not in lung tissue, indicating a long biological half life of arsenic in lung tissue. The workers dead from malignancies had a higher As/Se quotient than workers dead from other diseases, which does not contradict the protective theory of selenium. Accumulation of antimony, cadmium, lead and lanthanum was observed in lung tissue from the exposed workers. Six of the workers died from lung cancer and the highest concentrations of any of the elements were always observed in the lung tissue from these six cases. This observation speaks in favour of a multifactorial cause behind the excess mortality from lung cancer in smelter workers.

Adult↗
PubMed1981

Dust in workroom air of dental laboratories.

The general workroom air of eleven dental laboratories has been surveyed with respect to dust levels arising from cutting, grinding or polishing various dental materials like chromium-cobalt-, nickel- or gold alloys, amalgam and gypsum models, porcelain or denture base material. The materials were processed with cut or lathe wheels and various stones. The levels of the elements aluminium, calcium, cobalt, copper, chromium, gold, iron, lead, magnesium, manganese, nickel, silicon, silver, tin or titanium present in the collected dust samples did not exceed the respective threshold limit values. The dust was collected in workrooms with good general ventilation as well as in rooms with no use of ventilation systems. However, in breathing air close to workpiece, i.e. at distances of about 30 cm, threshold limit values for several elements or compounds could be considerably exceeded. The chemical analysis was accomplished by means of optical emission spectrography.

Air Pollutants↗
PubMed1980

Dust in dental laboratories. Part II: Measurement of particle size distributions.

It has been demonstrated in a previous study that threshold limit values of various elements or compounds could be considerably exceeded in various work operations in the dental laboratories when appropriate ventilation systems were not used. This refers to working with chromium-cobalt alloys, amalgam dies, porcelain, and gypsum. In the present study, size distributions of particles arising from cutting, grinding, or polishing of alloys, gypsum, porcelain, or denture base material in dental laboratories have been measured. The particle size distributions were evaluated by means of light and electron microscopy as well as by coulter-counting techniques. The measurements revealed the occurrence of a high proportion of respirable dust associated with these operations. consequently, the use of efficient ventilation systems is strictly necessary to ensure industrial safety with respect to air pollution in the working environment of dental laboratories.

Air Pollutants↗
PubMed1980

Dust in dental laboratories. Part III: Efficiency of ventilation systems and face masks.

The efficiency of local and electrostatic ventilation systems installed in dental laboratories has been measured. With local exhaust systems, dust amounts could be reduced in breathing air close to the emission source to levels lower than threshold limit values for various elements or compounds in dust produced through cutting, grinding, or polishing various dental materials such as chromium-cobalt, nickel, or gold alloys, porcelain, gypsum models, or denture base material. However, the local exhaust system did not enable a dust reduction from handling amalgam dies consistent with criteria of threshold limit values for mercury and silver. The efficiency of electrostatic filters installed in dental laboratories for general ventilation purposes was found to range from 37% to 73% based on weight reduction. Various ventilation systems with bag filters possessing a high efficiency based on weight reductions allowed small, respirable particles less than 5 micrometers to recirculate within the working environment. The efficiency of face masks for the reduction of inhaled dust revealed efficiencies for two commercial masks ranging from 70% to 95% based on weight reduction. However, such masks only partly retained the respirable dust.

Air Movements↗
PubMed1980

Dust in dental laboratories. Part I: Types and levels in specific operations.

The type and levels of dust in breathing air close to the workpiece produced through cutting, grinding, or polishing of alloys in dental laboratories have been characterized. The dust levels were compared with threshold limit values (TWA or STEL). In laboratories with improper local ventilation systems, dust levels considerably exceeding such values were recorded. Levels in excess of 10 times the threshold limit values were observed for solid mercury and silver present in amalgam dust, for cobalt present in nonprecious alloys, and for gypsum. Silver exceeded the threshold limit value 1,750 times in one case. Moderate excess of threshold limit values, that is less than 10 times, were measured for copper, nickel, tin, and porcelain in cases of insufficient ventilation. With the efficient outlet systems available on the commercial market, the dust levels could be reduced to levels consistent with criteria of threshold limit values except when trimming amalgam dies. Such systems comprise tubes with diameters of 35 mm connected to pumps with suction capacities of about 30 l/sec.

Air Pollutants↗
PubMed1980

Levels of antimony, arsenic, cadmium, copper, lead, mercury, selenium, silver, tin and zinc in bone tissue of industrially exposed workers.

The contents of the elements antimony, arsenic, cadmium, copper, lead, mercury, selenium, silver, tin and zinc in bone tissue from autopsy specimens of the femur of workers who had been exposed to a large number of metals in a smeltery and refinery in Northern Sweden as well as of a control group have been quantitatively assayed. The analytical techniques used were atomic absorption spectrophotometry, neutron activation analysis and particle induced X-ray emission analysis (PIXE) in a proton microprobe. Increased levels of lead in the bone tissue of exposed workers compared to a non-exposed control group were observed. The median level of lead in the group of exposed workers exceeded the corresponding value of the control group about 5 times. Using the proton microprobe in the PIXE-mode, concentration profiles of copper, lead and zinc were examined within the Haversian system of the bone samples.

Aged↗
PubMed1980

Distribution of 23 elements in the kidney, liver and lungs of workers from a smeltery and refinery in North Sweden exposed to a number of elements and of a control group.

The levels of antimony, arsenic, cadmium, caesium, chromium, cobalt, copper, gold, iron, lanthanum, lead, manganese, mercury, molybdenum, phosphorus, rubidium, scandium, selenium, silver, tellurium, tin, tungsten and zinc in the kidney, liver and lungs of autopsy specimens from exposed workers in North Sweden, as well as from a control group, have been assayed quantitatively. The workers had been exposed to several elements and their compounds, e.g. lead, mercury, arsenic and cadmium, for long periods in arsenic, lead or selenium plants and in a lead or copper smelter. The chemical analysis was by neutron activation analysis and atomic absorption spectrophotometry. Median levels of antimony, arsenic, cadmium, chromium cobalt, lanthanum, lead or selenium in kidney, liver or lungs in the exposed worker group were found to be about 2 to 16 times as great as the corresponding levels for the control group. Long biological half-life values were observed for these elements, especially in lung tissue.

Aged↗
PubMed1980

Interaction of pulsed carbon dioxide laser beams with teeth in vitro.

Beams of pulsed carbon dioxide lasers with energy densities of about 10, 100 or 200 J/mm2 have been applied perpendicularly to third molars in vitro for the purpose of preparing cavities or pin holes for retention. A pulsed beam with an energy density of about 10 J/mm2 produced a hole approximately 2 mm deep with a diameter of about 0.2 mm. With a beam of 100 J/mm2 the hole produced penetrated the tooth to a depth of 4 mm. Minor cracks around the hole in both enamel and dentin could be observed. Around the position where the beam entered the enamel matrix a white mineralized layer was observed, while a brown discoloration was formed around the hole in the dentin at the beam exit. With an energy density of 200 J/mm2 the formation of cracks and discoloration was very pronounced. X-ray diffraction of lased tissue revealed an apatite structure. The wall in the lased hole exhibited a Vicker hardness number similar to that of enamel.

Carbon Dioxide↗
PubMed1980

Exposure to mercury and silver during removal of amalgam restorations.

The content of particulate matter and mercury vapor in dentist breathing air during removal of amalgam restorations was assessed. Mercury and silver were quantitatively assayed by nuclear chemical analysis, and the mercury vapor concentration was measured with a sniffer. When the water spray was not used, the short time threshold limit values for exposure to mercury and silver were exceeded about 10 times. With water spray the mercury content was reduced to a level considerably lower than the threshold limit value, whereas the silver concentration slightly exceeded the corresponding limit.

Dental Amalgam↗
PubMed1980

Minor and trace inorganic components of toothpastes.

Elements present in minor or trace quantities in various toothpastes available in Scandinavia have been quantitatively assayed by means of emission spectrography and neutron activation analysis. The elements antimony, arsenic, mercury or selenium were observed at levels less than 2 parts/10(6). Boron, gallium, iron, magnesium, manganese and titanium occurred at levels between 0.001 and 1%. Cadmium, copper, lead, nickel and tin could not be identified. The detection limit for these elements amounted to 10 parts/10(6). The amounts of any of these elements which could be transferred to the body after swallowing toothpaste during brushing, have been compared with daily intake of similar elements through food and drinks, and found to be small compared to the diet intake except in the case of titanium. The intake of titanium from toothpaste could exceed the diet intake five times.

Dentifrices↗
PubMed1980

Pulmonary deposition following inhalation of chromium-cobalt grinding dust in rats and distribution in other tissues.

Twenty rats were exposed to dust particles of chromium-cobalt alloy abrasives produced in dental material handling. The exposure was carried out in chambers for periods up to 107 days at concentrations of particulate matter of about 10-50 mg/m3. The content of chromium and cobalt in autopsy specimens of lung, liver, kidney and trachea was measured with nuclear techniques. The alloy particles were found to be markedly accumulated in lung tissue. Increased levels of chromium and cobalt were also observed in the trachea. In addition, a moderate increase of cobalt in liver and kidney was demonstrated. The lungs of six exposed rats were examined microscopically. The main part of the dust particles was observed within macrophages. Only a minor fraction of particles were seen in the bronchial lumen close to the epithelial surface. The majority of dust-filled macrophages were located in groups within the bronchial wall or in the interstitium close to the terminal broncheoli. No fibrosis, dysplasia or tumor formation occurred. No acute adverse effects in the lungs were observed.

Air Pollutants↗
PubMed1980

Analysis of arsenic in dental cements according to the silverdiethyldithiocarbamate photometric method - ISO 2590.

The reliability of the method for analysis for arsenic in dental cements according to the international standard ISO 2590 has been reinvestigated using nuclear tracer techniques and intercomparison of results obtained for the arsenic content of various cements by means of three different methods, i.e. the silverdiethyldithiocarbamate photometric method, neutron activation analysis and atomic absorption spectrophotometry. By means of the two methods first mentioned, results in rough agreement were obtained while the third method, i.e. atomic absorption spectrophotometry revealed lower contents. The interference of antimony in the analysis of arsenic in dental cements was quantitatively assayed.

Arsenic↗