[Studies on the discoloration of dental hard tissues by amalgam filling. On the penetration of amalgam elements into the dental hard tissues].
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Dental Amalgam↗
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Long-term mercury excretion in urine after removal of amalgam fillings.
The long-term urinary mercury excretion was determined in 17 28- to 55-year-old persons before and at varying times (up to 14 months) after removal of all (4-24) dental amalgam fillings. Before removal the urinary mercury excretion correlated with the number of amalgam fillings. In the immediate post-removal phase (up to 6 days after removal) a mean increase of 30% was observed. Within 12 months the geometric mean of the mercury excretion was reduced by a factor of 5 from 1.44 micrograms/g (range: 0.57-4.38 micrograms/g) to 0.36 microgram/g (range: 0.13-0.88 microgram/g). After cessation of exposure to dental amalgam the mean half-life was 95 days. These results show that the release of mercury from dental amalgam contributes predominantly to the mercury exposure of non-occupationally exposed persons. The exposure from amalgam fillings thus exceeds the exposure from food, air and beverages. Within 12 months after removal of all amalgam fillings the participants showed substantially lower urinary mercury levels which were comparable to those found in subjects who have never had dental amalgam fillings. A relationship between the urinary mercury excretion and adverse effects was not found. Differences in the frequency of effects between the pre- and the post-removal phase were not observed.
Adult↗
Phase content of a high copper dental silver amalgam.
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Chemical Fractionation↗
Dental research at the National Bureau of Standards: how it changed the practice of dental health service.
A history of dental research at the National Bureau of Standards since its inception in 1919 is presented. The initial thrust on dental amalgam by the US Army Dental Corps, the assignment of Dr. William Souder to the project, and subsequent developments are traced. Difficulties in obtaining support for the early stages of the program following World War I are described. The involvement of the American Dental Association in 1928, issuance of the first ADA specification on dental amalgam, and the ultimate ramifications on dental (and medical) standards programs throughout the world are described. Benefits to patients, dentists, and taxpayers from support of the dental research program have been calculated as exceeding the combined budgets of the currently supporting institutions--NBS, ADA, and National Institute of Dental Research.
Chemistry, Physical↗
[Comparative studies between various amalgams].
A number of dental amalgam products have been compared in the context of a thesis. Four products, each of them possessing different characteristics, have been selected. Six Eighty Amalgam Alloy is a conventional product; Fluor Alloy contains a quantity of SnF2; Amalcap non gamma2 belongs to the group of the so-called non gamma2-alloys; Indiloy is spherical and contains indium. Each product was subjected to a series of tests and investigations: structure, dimensional changes after condensation, compressive strength, behaviour during a relaxation-test and resistance to corrosion. Indiloy was the product with the most interesting structure and it could be ascertained the mercury especially attacked silver and indium of the original alloy. Thus a sort of matrix is formed. The measuring of the dimensional changes was done by introducing a new method. Fluor Alloy and Indiloy present a behaviour that differs a lot from the expected one: at first a contraction followed by a more important expansion. A relaxation-test is an alternative to the creep-test and the connection between both is demonstrated. Combining the results of the resistances to the compressive forces with those of the relaxation-tests shows Indiloy possesses superior mechanical properties while those of Six Eighty Amalgam Alloy are rather inferior. A final series of tests concerns the resistance to corrosion. Amalcap non gamma2 and Indiloy have a much greater rough resistance to corrosion than the two other ones.
Corrosion↗
[Methods of determination of fluoride in trace amounts. Application to the study of the diffusion of fluoride from an amalgam in dental tissues].
The study of fluoride diffusion in dental tissues has been performed by microprobe analysis. The fluoride supply is carried out in vivo by various fluorides added to conventional amalgams. This method differs then from previous work (topical applications, electrophoresis or fluoride solutions) by the study of fluoride penetration from amalgams either in dentine or in deep enamel, which are more susceptible to caries than superficial enamel. These experiments give evidence of a fast penetration of fluoride into dental tissues, which may be characterized by an apparent diffusion coefficient of about 10(-10) cm2/s.
Dental Amalgam↗
Dental mercury hygiene recommendations.
BACKGROUND: The ADA has long recognized the importance of observing proper mercury hygiene practices for the safety of dental professionals. In 1999, the ADA Council on Scientific Affairs adopted mercury hygiene recommendations to provide guidance to dentists and their staff members for safe handling of mercury and dental amalgam. These mercury hygiene recommendations have been developed to update those previously adopted by the Council. OVERVIEW: In addition to discussing sources of mercury in the dental office, this Council report describes office engineering considerations and hygiene recommendations to be used during preparation and placement of dental amalgam restorations. New information included in this report covers the management of mercury spills. PRACTICE IMPLICATIONS: These recommendations are intended to provide guidance to the dental practitioner in ensuring the safety of personnel who handle dental amalgam and in minimizing the release of mercury into the dental office environment.
Air Pollution, Indoor↗
Copper allergy from dental copper amalgam?
A 65-year-old female was investigated due to a gradually increasing greenish colour change of her plastic dental splint, which she used to prevent teeth grinding when sleeping. Furthermore, she had noted a greenish/bluish colour change on the back of her black gloves, which she used to wipe her tears away while walking outdoors. The investigation revealed that the patient had a contact allergy to copper, which is very rare. She had, however, had no occupational exposure to copper. The contact allergy may be caused by long-term exposure of the oral mucosa to copper from copper-rich amalgam fillings, which were frequently used in childhood dentistry up to the 1960s in Sweden. The deposition of a copper-containing coating on the dental splint may be caused by a raised copper intake from drinking water, increasing the copper excretion in saliva, in combination with release of copper due to electrochemical corrosion of dental amalgam. The greenish colour change of the surface of the splint is probably caused by deposition of a mixture of copper compounds, e.g. copper carbonates. Analysis by the X-ray diffraction technique indicates that the dominant component is copper oxide (Cu2O and CuO). The corresponding greenish/bluish discoloration observed on the back of the patient's gloves may be caused by increased copper excretion in tears.
Copper↗
Application of a latent variable model for a multicenter study on early effects due to mercury exposure.
A latent variable model was applied to the results of an Italian multicenter nation-wide cross-sectional study to assess the earliest health effects due to mercury (Hg) exposure caused by occupation, dental amalgams (DENTAM) and fish eating (FISH). The studied population included subjects recruited from four different geographical areas. A total number of 122 workers from chloroalkali plants and production of thermometers and neon lamps formed the occupationally exposed group, whereas 196 subjects, recruited from the same areas and not occupationally exposed to mercury, formed the control group. Neuropsychological functions were assessed with neurobehavioral testing including vigilance, motor and cognitive function, tremor measurements, and with symptoms concerning neuropsychological and mood assessment. Neuroendocrine function was examined with the measurement of prolactin (PRL) level. Parameters of immunological and renal function were also measured. The target population was characterized by the number and surface of dental amalgams and consumption of fish. In the exposed workers the average urinary mercury (U-Hg) was 10.4+/-6.9 (geometric mean 8.3, range 0.2-35.2) microg/g creatinine, whereas in the control group it was 1.9+/-2.8 (geometric mean 1.2, range 0.1-33.2) microg/g creatinine. The preliminary results indicated that finger tapping (FT) and the Branches alternate movement task (BAMT) coordination test were associated with the occupational exposure (OCCEXP). PRL was significantly decreased among the exposed workers, and inversely related to U-Hg. Among the immunological and renal parameters, cytokine serum interleuchin-8 (sIL8) and beta(2) micro globulin (beta(2)MG) were lower in the exposed group and negatively correlated to U-Hg. Small-size fish consumption was associated to a beneficial effect on symptoms reporting. No effects were observed concerning dental amalgams. After first evaluating the relationship between mercury exposure and each indicator of effect, further assessment was performed to identify the earliest effects related to mercury exposure among those who resulted in being associated in the preliminary elaboration. Two latent variables "exposure" and "effect" were identified, integrating respectively the different forms of exposure (occupational, due to dental amalgams and fish consumption) and the indicators of effects (FT, BAMT, PRL, sIL8, beta(2)MG). Confounding factors (age, alcohol, body mass index (BMI)) were considered in the same model. This further analysis showed that an inverse association of occupational exposure to mercury with PRL and BAMT, with Hg-U mediating the effect on PRL, was predominant with respect to the other form of mercury exposure, the other indicators of effect and the confounders. In conclusion, this study supports the finding of alterations of neuroendocrine secretion and motor coordination at very low occupational exposure levels of inorganic mercury, below the current ACGIH Biological Exposure Index. These changes occur at lower levels than other subtle effects on the renal function and the immunitary system. On the contrary, dental amalgams and small-size fish consumption do not seem to be associated to any adverse health effect at these exposure levels.
Adult↗
Oral changes in divers working with electrical welding/cutting underwater.
Divers performing electrical welding/cutting underwater often complain about a metallic taste in the mouth, strictly related to their work. In a nationwide clinical investigation, professional commercial divers were examined orally. The majority of the divers complained about a metallic taste. An increased surface deterioration of dental amalgam was detected in those divers who had performed electrical welding/cutting during the previous two years. In addition, after clinical and bacteriological examination, divers were found to belong to a caries risk group. In order to study the intraoral electrical activity, several actual dives were performed. When they were welding or cutting, the electrical activity registered intraorally in dental amalgam test samples was too low in magnitude to explain the metallic taste and the clinical appearance of the amalgam. The divers were dressed in a dry-suit and full-face mask. When leakage occurred or when a hot-water heated suit was used higher electrical activity was registered. This activity was still not of a magnitude, which could explain the symptoms theoretically, although a metallic taste and a subjective change in the divers dental amalgam were provoked. No increased levels of Hg and Cu could be detected in saliva, blood or urine. The flux density of the intraoral magnetic field created by a current of 650 ADC was calculated and measured to be 1.15 mT, which is approximately 25 times stronger than that of the earth. When exposing divers in-vivo to a field generated by a 200 ADC current, no symptoms other than magnetophosphenes were reported, such as metallic taste. The divers helmets offered almost no shielding effect towards the magnetic field. In-vitro exposure of dental amalgams to a magnetic field (1.15 mT; 50 Hz) increased the mobility of cupper and especially mercurity in the superficial layers of the amalgam after 24 h exposure, and gave rise to slight morphological changes within the amalgam.
Adult↗
Five-year performance of high-copper content amalgam restorations in a multiclinical trial of a posterior composite.
PURPOSE: This paper reports the 5-year performance of the restorations of the high-copper content dental amalgam alloys included in the worldwide programme of clinical trials of Occlusin, including unique data on wear. METHODS: The methods employed are common to those previously reported for the multiclinical evaluation of Occlusin. Analysis of the data is limited to simple statistical procedures. RESULTS: The findings lend support to existing knowledge concerning the favourable performance of restorations of high-copper content dental amalgam alloys, notably in relation to restorations in moderate- to large-sized Class II preparations in permanent molar teeth. Analysis of the data sheds new light on the influences of variables, including type of tooth restored, size and class of restoration and the presence or absence of occlusal contact(s) on performance. CONCLUSION: Conclusions are drawn regarding ways in which protocols for future evaluations of the type reported should be expanded, and, together with suggestions for further work, it is concluded that this paper is a timely reminder of the value of existing dental amalgam alloys.
Adolescent↗
Amalgam at the new millennium.
Dental amalgam has served as an excellent and versatile restorative material for many years, despite periods of controversy. The authors review its history, summarize the evidence in regard to its performance and offer predictions for the future of this material. For the present, amalgam should remain the material of choice for economical direct restoration of posterior teeth. When esthetic concerns are paramount, tooth-colored materials, placed meticulously, can provide an acceptable alternative.
Biocompatible Materials↗
Mercury in saliva and feces after removal of amalgam fillings.
The toxicological consequences of exposure to mercury (Hg) from dental amalgam fillings is a matter of debate in several countries. The purpose of this study was to obtain data on Hg concentrations in saliva and feces before and after removal of dental amalgam fillings. In addition Hg concentrations in urine, blood, and plasma were determined. Ten subjects had all amalgam fillings removed at one dental session. Before removal, the median Hg concentration in feces was more than 10 times higher than in samples from an amalgam free reference group consisting of 10 individuals (2.7 vs 0.23 mumol Hg/kg dry weight, p < 0.001). A considerable increase of the Hg concentration in feces 2 days after amalgam removal (median 280 mumol Hg/kg dry weight) was followed by a significant decrease. Sixty days after removal the median Hg concentration was still slightly higher than in samples from the reference group. In plasma, the median Hg concentration was 4 nmol/liter at baseline. Two days after removal the median Hg concentration in plasma was increased to 5 nmol/liter and declined subsequently to 1.3 nmol/liter by Day 60. In saliva, there was an exponential decline in the Hg concentration during the first 2 weeks after amalgam removal (t 1/2 = 1.8 days). It was concluded that amalgam fillings are a significant source of Hg in saliva and feces. Hg levels in all media decrease considerably after amalgam removal. The uptake of amalgam mercury in the GI tract in conjunction with removal of amalgam fillings seems to be low.
Adult↗
Oral lichenoid reactions associated with amalgam: improvement after amalgam removal.
BACKGROUND: The pathogenetic relationship between oral lichenoid reactions (OLR) and dental amalgam fillings is still a matter of controversy. OBJECTIVES: To determine the diagnostic value of patch tests with amalgam and inorganic mercury (INM) and the effect of amalgam removal in OLR associated with amalgam fillings. METHODS: In 134 consecutive patients 467 OLR were classified according to clinical criteria. One hundred and fifty-nine biopsies from OLR lesions were histologically diagnosed according to the World Health Organization criteria for oral lichen planus (OLP) and compared with 47 OLP lesions from edentulous patients without amalgam exposure. One hundred and nineteen patients were patch tested with an amalgam series. In 105 patients (357 of 467 lesions) the amalgam fillings were removed regardless of the patch test results and OLR were re-examined within a follow-up period of about 3 years. Twenty-nine patients refused amalgam removal and were taken as a control group. RESULTS: Eleven patients with OLR (8.2%) had skin lesions of lichen planus (LP). Histologically, the lesions in the OLR group could not be distinguished from those seen in the OLP group. Thirty-three patients (27.7%) showed a positive patch test to INM or amalgam. Amalgam removal led to benefit in 102 of 105 patients (97.1%), of whom 31 (29.5%) were cured completely. Of 357 lesions, 213 (59.7%) cleared after removal of amalgam, whereas 65 (18.2%) did not improve. In the control group without amalgam removal (n = 29) only two patients (6.9%) showed an improvement (P < 0.05). Amalgam removal had the strongest impact on lesions of the tongue compared with lesions at other sites (P < 0.05), but had very little impact on intraoral lesions in patients with cutaneous LP compared with patients without cutaneous lesions (P < 0.05). Patients with a positive patch test reaction to amalgam showed complete healing more frequently than the amalgam-negative group (P < 0.05). After an initial cure following amalgam removal, 13 lesions (3.6%) in eight patients (7.6%) recurred after a mean of 14.6 months. CONCLUSIONS: Of all patients with OLR associated with dental amalgam fillings, 97.1% benefited from amalgam removal regardless of patch test results with amalgam or INM. We suggest that the removal of amalgam fillings can be recommended in all patients with symptomatic OLR associated with amalgam fillings if no cutaneous LP is present.
Adult↗
Cadmium, mercury, and lead in kidney cortex of the general Swedish population: a study of biopsies from living kidney donors.
Cadmium, mercury, and lead concentrations were determined in deep-frozen kidney cortex biopsies taken from 36 living, healthy Swedish kidney donors (18 males and 18 females), who were 30-71 (mean 53) years of age. Information about occupation, smoking, the presence of dental amalgam, and fish consumption could be obtained for 27 of the donors. The samples (median dry weight 0.74 mg) were analyzed using inductively coupled plasma mass spectrometry, and the results were transformed to wet-weight concentrations. The median kidney Cd was 17 micrograms/g (95% confidence interval, 14-23 micrograms/g), which was similar in males and females. In 10 active smokers, the median kidney Cd was 24 micrograms/g, and in 12 who never smoked, it was 17 micrograms/g. The median kidney Hg was 0.29 micrograms/g, with higher levels in females (median 0.54 micrograms/g) than in males (median 0.16 micrograms/g). Subjects with amalgam fillings had higher kidney Hg (median 0.47 micrograms/g, n = 20) than those without dental amalgam (median 0.15 micrograms;g/g, n = 6), but kidney Hg was below the detection limit in some samples. Nearly half of the samples had kidney Pb below the detection limit. The median kidney Pb was estimated as 0. 14 micrograms/g. This is the first study of heavy metals in kidney cortex of living, healthy subjects, and the results are relatively similar to those of a few previous autopsy studies, indicating that results from autopsy cases are not seriously biased in relation to kidney metal concentrations in the general population. Cd concentrations in those who never smoked were relatively high, indicating considerable Cd intake from the diet in Sweden. The effect of dental amalgam on kidney Hg was as expected, although the reason for the difference in Hg levels between males and females is unclear.
Adult↗
Copper-tin phases in dental silver amalgam.
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Absorptiometry, Photon↗
Urinary mercury concentrations associated with dental restorations in adult women aged 16-49 years: United States, 1999-2000.
BACKGROUND: Mercury amalgam dental restorations have been used by dentists since the mid 19th century and issues on safety continue to be periodically debated within the scientific and public health communities. Previous studies have reported a positive association between urine mercury levels and the number of dental amalgams, but this relation has never been described in a nationally representative sample in the United States. AIMS AND METHODS: Using household interview, dietary interview, dental examination, and laboratory data from the 1999-2000 National Health and Nutrition Examination Survey (NHANES), the association between mercury concentrations and dental restorations was examined in US women of reproductive age. RESULTS: In women of childbearing age, approximately 13% of all posterior dental surfaces were restored with amalgams and the average urinary mercury level in women was low (1.34 microg/l). It is estimated that an increase of 1.8 microg/l in the log transformed values for mercury in urine would occur for each 10 dental surfaces restored with amalgam. CONCLUSIONS: Although the findings do not address the important issues of adverse health effects at low thresholds of mercury exposure, they do provide important reference data that should contribute significantly to the ongoing scientific and public health policy debate on the use of dental amalgams in the USA.
Adolescent↗
Anodic polarization behavior and microstructure of a gallium-based alloy.
A gallium-based alloy (GA) that was developed as a substitute for dental amalgam was investigated for anodic polarization behavior in deoxygenated Ringers solution, 37 degrees C. The related microstructures were examined and microanalyses were conducted. Four polarization tests were conducted by scanning from -300mV to +1,000 mV (vs. SCE) at 2 mV/s. Polarization of the first sample (GA-1) was stopped after the first anodic dissolution peak (-100 mV, 1.5-2.0 x 10(-3) A/cm2). The fourth sample (GA-4) was interrupted at the secondary peak (+1000 mV, 0.3 A/cm2). It was found that (1) the early stage of the first peak is related to selective dissolution of divalent tin ions, followed by a dissolution of Ga. Transmission electron diffraction (TED) identified the brown corrosion product as Ga2O3; (2) the GA-4 sample was covered with the white corrosion product of mainly Sn+4, identified as SnO2. In addition, the current density of the GA sample when coupled with a high-copper dental amalgam was 0.03 A/cm2 (with +1,000 mV) at the second peak which was about a ten times lower value than for the uncoupled sample; (3) the uncoupled gallium alloy and gallium alloy coupled with a high-copper dental amalgam showed 10(3)-10(4) times higher anodic current density than that of an uncoupled high-copper dental amalgam, suggesting that the gallium alloy is more corrosion prone.
Corrosion↗