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A galvanic study of different amalgams. Journal of Oral Rehabilitation.

Due to the difference in open circuit potential (OCP) versus SCE for Aristaloy amalgam (-969 mV) and Dispersalloy amalgam (-549 mV) in Ringer’s solution at 25 degrees C, a galvanic cell was created with Dispersalloy amalgam as cathode and Aristaloy amalgam as anode. The galvanic corrosion current was studied as a function of time for the above cell as well as for a cell of type III dental gold (OCP is +0-5 mV) versus Aristaloy amalgam. The initial corrosion current of the latter cell (105 micronA) is about twice that for the cell of Aristaloy amalgam versus Dispersalloy amalgam (54 micronA), however, their passivating behaviour is quite similar. Also, an interrupted galvanic corrosion test simulating the oral ‘make and break’ situation was performed. A much higher corrosion current than the steady state was found when the two electrodes resumed contact.

By |2018-08-25T02:19:01+00:00January 1st, 1977|Mercury|

Mercury intoxication in a dental surgery following unreported spillage.

An unreported spillage of mercury in a dental surgery resulting in four non-fatal cases of mercury intoxication by inhalation of mercury vapour is described and clinical symptoms in relation to urine mercury levels noted and discussed. The method of detection and decontamination of the mercury vapour source is reported, and suggestions for preventing spillage of mercury and for reducing the risk of intoxication from such accidental spillage are made.  Continued vigilance by all persons handling mercury is stressed.

By |2018-07-26T16:57:32+00:00January 1st, 1976|Mercury|

Recurrent contact dermatitis caused by mercury in amalgam dental fillings.

A metal worker had repeated episodes of contact dermatitis over a period of years. Patch tests with 5% ammoniated mercury were strongly positive but occupational contact could not be proved. Recurrence of the dermatitis one day after amalgam dental fillings had been made and again one year later, this time without new fillings, raised the possibility that it was due to the old amalgam fillings. Removal of all the amalgam fillings resulted in a new outbreak of severe dermatitis; during the 5 years ensuing there has been no recurrence. This case history suggests that contact dermatitis may be caused by not only the mercury in new fillings but also by that in old fillings.

By |2018-07-20T20:51:56+00:00January 1st, 1975|Mercury|

The accumulation of fluoride by marine and intertidal animals.

In this paper we report on a preliminary investigation into the accumulation of fluoride by a number of marine and intertidal animals. The work was prompted by the recent building of an aluminium smelter at Lynemouth in Northumberland which discharges a fluoride-loaded effluent into the sea. However, dilution by seawater renders contamination negligible and it is suggested that tissue fluoride concentrations represent background levels for the animals studied.

In both vertebrates and invertebrates, fluoride is largely accumulated in skeletal structures. There is little or no accumulation in soft, edible tissues, with the exception of fish skin.

Preliminary toxicity tests were carried out on a number of marine invertebrates. Even at unnaturally high ambient fluoride levels, no adverse effects were seen, except possibly in the case of the filter-feeding mollusc Mytilus edulis.

By |2018-08-03T19:06:50+00:00January 1st, 1975|Fluoride|

Environmental pollution by fluorides in Flathead National Forest and Glacier National Park.

Vegetation samples were collected in June and Oct. 1970 at varying distances from the Anaconda Aluminium Co. plant at Columbia Falls, Montana. Determinations were of foliar F concn., injury index II (an estimate of gross amount of visible injury or ‘burn’ for foliage of a given year), insect pest populations, and F concn. in insects collected within 0.5 mile of the Al reduction plant. Vegetation in control areas contained <10 p.p.m. F. II was shown to be a conservative parameter of pollution since many samples with high F concn. did not show injury. F concn. in vegetation samples was used as the basis of pollution mapping, whereby the pollution index in ‘isopols’ is equal to the local F conc. (with 10 as the background value). Visible injury occurred above 30 isopols (on a total area of 69 000 acres) in susceptible species, viz. pines (Pinus albicaulis, P. contorta, P. monticola and P. ponderosa) and Douglas fir (Pseudotsuga menziesii); the herb Smilacina stellata was a particularly sensitive indicator of F pollution. Nearly all vegetation was injured moderately at 100-300 isopols and (except grasses) severely at 300-600 isopols. Characteristics symptoms of F injury in conifers included enlarged cell nuclei and hypertrophy of resin-canal epithelium and vascular parenchyma.

By |2018-07-19T18:42:59+00:00January 1st, 1971|Fluoride|

Printing of mercury distribution on the surface of dental amalgams.

Mercury, an essential element of dental amalgams, is not a stable material but one that vaporizes at ordinary temperatures. By use of a simple technique, printings were obtained from mercury amalgam specimens but were not obtainable from alloy-zinc control specimens. Unburnished and unpolished specimens yielded more intense printings than burnished and polished specimens.

By |2018-08-13T18:42:00+00:00January 1st, 1970|Mercury|

The effect of fluorine on dental caries [editorial].

We do know the use of drinking water containing as little as 1.2 to 3.0 parts per million of fluorine will cause such developmental disturbances in bones as osteosclerosis, spondylosis, and osteopetrosis, as well as goiter, and we cannot afford to run the risk of producing such serious systemic disturbances in applying what is at present a doubtful procedure intended to prevent development of dental disfigurements among children.  […]  Because of our anxiety to find some therapeutic procedure that will promote mass prevention of caries, the seeming potentialities of fluorine appear speculatively attractive, but, in the light of our present knowledge or lack of knowledge of the chemistry of the subject, the potentialities for harm far outweigh those for good.

By |2018-07-23T20:57:43+00:00January 1st, 1944|Fluoride|
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