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PubMed2006

Surgical treatment of amalgam fillings causing iatrogenic sinusitis.

Iatrogenic maxillary sinusitis is a rare disease entity that can be fatal if not managed. Thirteen patients (five men and eight women) were referred to our clinic because of chronic iatrogenic maxillary sinusitis. Eight patients presented with a left-side maxillary sinusitis, four patients presented with right-side maxillary sinusitis, and one patient presented with right-side pan sinusitis. The sinusitis was caused by the intrusion of amalgam filling during root treatment of teeth. All of the patients were treated surgically with a Caldwell-Luc approach. In 12 patients, the amalgam was removed with the infected and inflamed maxillary mucosa. In one patient, the amalgam could not be removed with the Caldwell-Luc technique because it was in the deeper part of the root of the molar tooth. Histologic examination revealed four cases of aspergillosis; three cases of papillary and polypoid sinusitis; three cases of nonspecific pseudo-polypoid sinusitis; two cases of hyperplasic polypoid sinusitis; and one case of catarrhal sinusitis. All patients were relieved of their complaints that were related to sinusitis. Radiologically, the maxillary sinuses were clean 1 month after Caldwell-Luc intervention. Iatrogenic maxillary sinusitis should be considered a serious infection. A smear should be taken whenever a foreign body is intruded into the sinus. Foreign bodies can get jammed in the posterior wall of the sinus and can provoke chronic sinusitis with a risk intracranial extension. Hence, the disease should be managed surgically without delay. Furthermore, dentists should be cautious with dental amalgam filling.

Adult↗

PubMed1975

Status report on silver amalgam. Council on Dental Materials and Devices.

This report discusses the current status of amalgam. The new alloy systems have been reviewed in relation to their advantages, disadvantages, and clinical use. Values for the physical properties of amalgam have increased tremendously in the past 50 years and relatively recent changes in alloy composition, size, and shape of particles can produce clinically observable improvements in restorations, particularly with respect to marginal integrity. New alloys that are now available or are very close to being introduced on the market should be investigated and observed by practitioners. However, it should be recognized that correct alloy manipulation of currently available alloys probably has more influence on the longevity of restorations than the type of alloy selected.

American Dental Association↗

PubMedDate not supplied

Genotoxicity of mercury used in chromosome aberration tests.

The purpose of this study was to investigate the genotoxic effects of Hg released from dental amalgams. The chromosome aberration test was conducted using original extracts and their diluted solutions of conventional type amalgam and high copper amalgam. The concentrations of Hg, Cu and Ag in the original extract of high copper amalgam were 17.64, 7.97 and 43.90 microM, respectively. Those in the original extract of conventional type amalgam were 20.63, 7.87 and 14.79 microM, respectively. 10 and 30 microM Hg(2+) were also used for comparison. The frequency of chromosome aberrations was below 5% with 0 microM Hg(2+) and with a triple dilution of high copper amalgam extract, containing 5.88 microM Hg, 14.63 microM Cu and 2.65 microM Ag. However, 9.5% of the cells showed chromosome aberrations with a quadruple dilution of conventional type amalgam, containing 5.15 microM Hg, 3.69 microM Cu and 1.96 microM Ag. The amount of Hg in the quadruple dilution of conventional type amalgam was less than that in the triple dilution of high copper amalgam extract and 10 microM Hg(2+). A concentration of 30 microM Hg(2+) caused 34.5% of the cells to show chromosome aberrations while with a two-thirds dilution of high copper amalgam extract, containing 11.76 microM Hg, 29.26 microM Cu and 5.31 microM Ag, 58.5% of the cells showed chromosome aberrations. A two-thirds dilution of high copper amalgam extract induced more chromosome aberrations than 30 microM Hg(2+), although the amount of Hg was less than 30 microM Hg(2+). A triple dilution of conventional type amalgam extract, original extracts of conventional type amalgam and high copper amalgam and 100 microM Hg(2+) were induced few metaphases. It was revealed that the conventional type amalgam induced chromosome aberrations with quadruple dilution where cell viability was about 80% and that the high copper amalgam induced a high level of chromosome aberrations with the two-thirds dilution. The effects of low level Hg on humans are not clear.

Animals↗

PubMed1994

Urinary mercury monitoring of university staff and students occasionally exposed to mercury vapor.

To monitor the exposure to mercury (Hg) vapor among university staff members and students who occasionally handle elemental Hg in laboratory experiments, urine samples were collected at health examinations conducted by the Health Service Center, University of Tokyo, for six years. Geometric mean of urinary Hg concentrations of 343 samples collected from 234 subjects was 1.61 micrograms Hg/g creatinine (Cr), with the range of 0.30 to 9.31 micrograms Hg/g Cr. Elevated urinary Hg levels, i.e. 3 micrograms Hg/g Cr or higher, were found only among the subjects who worked in several laboratories. This urinary Hg level is judged to correspond to 1-2 micrograms/m3 of air Hg concentration in working areas. The contribution of dental amalgam fillings to urinary Hg excretion, though it exists, was concluded to be small from the result of multiple regression analysis.

Dental Amalgam↗

PubMed2004

Gastrointestinal absorption of metallic mercury.

The absorption of mercury from the gastrointestinal systems of 7 subjects, of whom none had any amalgam fillings, was examined in this study. The authors obtained quantitative information about mercury concentration in plasma and duodenal fluid after the gastrointestinal systems of the subjects were exposed to liquid elemental mercury enclosed in rubber balloons (i.e., approximately 20 g of mercury), using a standard procedure followed for the sampling of bile. Plasma samples were collected prior to exposure, as well as up to 10 d following exposure, and duodenal fluid was collected 1 h, 2 h, 4 h, and 6 h during the intubation process. The authors studied the kinetics of dissolution in vitro by leaching elemental liquid mercury and mercuric chloride. The results of this study supported the hypothesis that metallic mercury is oxidized in the gastrointestinal tract. In addition, the authors determined that duodenal intubation, while using liquid metallic mercury in rubber bags, resulted in the diffusion of minor amounts of atomic elemental mercury through the rubber walls. The absorbed amount of mercury that reached the central circulation was comparable to a daily dose of mercury from dental amalgam in the amalgam-bearing population.

Absorption↗

PubMed1999

Exposure or absorption and the crucial question of limits for mercury.

Health Canada recently lowered the recommended maximum daily exposure of mercury from all sources for women of child-bearing age and for children less than 10 years. This new exposure guideline does not seem to be based on any new scientific finding of human toxicity. The average daily intake of methylmercury (mainly from fish) that may cause demonstrable health effects in the most sensitive individual is 300 micrograms/day, or 4.3 micrograms Hg/day/kg body weight. The new, lower Health Canada limit is 95% below the level that may cause health effects. A number of studies have looked at methylmercury in human breast milk (where maternal consumption of fish is high), but no strong evidence of toxicity has been reported. The amount of mercury released from dental amalgam is minimal; a person would have to have 490 amalgam surfaces for there to be enough mercury vapour and ionic mercury given off from amalgam fillings to meet the maximum exposure guidelines. The uptake of food-related organic mercury is six times higher than the uptake of mercury from amalgam; moreover, food-related mercury is significantly more toxic. Many studies of amalgam-related mercury are flawed by confusion between exposure and absorption for the various forms of mercury, a limited selection of data, the ignoring of confounding variables or the misclassification of data.

Absorption↗

PubMed1975

In vitro chloride corrosion behaviour of Dispersalloy.

The in vitro chloride corrosion behaviour of Dispersalloy has been investigated by anodic polarization as a function of time after trituration (ageing) and compared with conventional dental amalgam. Dispersalloy is a commercial alloy containing a mechanical mixture of Ag-3-Sn and Ag-Cu eutectic in the ratio 2:1. From measurement of 1 h corrosion potentials it was observed that over a time period of 1 year Dispersalloy became appreciably more noble (potential shift from minus 500 mV to minus 350 mV Vs. SCE), whereas the corrosion potential of conventional amalgam remains unchanged. Initial anodic polarization profiles for Dispersalloy indicated presence of gamma2 and Cu-6-Sn-5 phases as evidenced by presence of the minus 250 mV peak. However, the current density associated with this peak was about three times less than that of conventional amalgam. As a function of ageing time the polarization profile is shifted in the direction of decreasing current density and after 1 year the minus 250 mV peak is absent. The anodic polarization profile of conventional amalgam is unchanges after 1 year. The improved corrosion resistance of Dispersalloy is attributed to the formation of Cu-3-Sn as a function of time due to solid state reaction between Ag-Cu eutectic and gamma2.

Chlorides↗

PubMed1993

Activity of antioxidative enzymes in erythrocytes and concentration of selenium in plasma related to mercury exposure.

The activity of catalase and glutathione peroxidase (GSH-Px) in erythrocytes and concentration of selenium in plasma and mercury in whole blood, plasma, and urine were analyzed in 36 individuals occupationally exposed to mercury vapor, in 14 individuals with skin hypersensitivity to inorganic mercury, and in 17 individuals with subjective symptoms alleged to result from dental amalgam fillings. The control group consisted of 39 individuals with amalgam fillings, but no occupational exposure to mercury. Selenium in plasma was determined by GFAAS with Zeeman background correction. After exclusion of individuals with reported intake of selenium supplement the median plasma selenium concentration in the group with occupational exposure to mercury was 1.24 mumol/L, in the allergy group 1.22 mumol/L, in the amalgam group 1.25 mumol/L, and in the control group 1.22 mumol/L. The activities of catalase and GSH-Px were similar in all groups. However, in females lower GSH-Px activity was found in the amalgam group compared with females in the control group. GSH-Px activity in smokers was slightly lower than in non-smokers. No correlations were found between concentration of selenium or mercury in plasma and activity of glutathione peroxidase or catalase in erythrocytes.

Adult↗

PubMed1990

[Cytotoxic effects of restorative materials on early passage cultured cells derived from human gingiva (in vitro)].

This study evaluated the cytotoxic effects of three common restorative materials on early passage cultured cells derived from human gingiva (HG cells). Other early passage cultured cells derived from human dental pulp tissues (HP cells) and L cells established obtained from mouse subcutaneous tissues, were also examined. Cytotoxicity was assessed according to the uptake of neutral red and dye exclusion with nigrosin. The cytotoxicity was in the order of glass ionomer cement (highest), light cured composite resin and dental amalgam. HG cells were the least sensitive to the materials tested. Both filtration of extracts and addition of serum into the extract affected the cytotoxicity. Glass ionomer cement increased the acidity of the extract, but the two other materials did not. Dissolution of metal ions, aluminium, tin, copper, mercury and zinc occurred from the materials. The extract of the composite resin had a different absorbance. This study disclosed differences in the cellular reaction to the restorative materials. Thus, utilization of early passage cultured cells is necessary for biological evaluation of the dental materials in vitro.

Animals↗

PubMedDate not supplied

Is there a hazard to health by mercury exposure from amalgam due to MRI?

The local magnetic fields from computer monitors are well known. Recently a hypothesis was published that these magnetic fields may lead to a 400% increase of mercury dissolution from dental amalgam fillings. In MRI the exposure to the magnetic field exceeds by far the exposure from computer monitors. Therefore, this study examined the amalgam-related mercury release for typical MRI conditions, separated for both the static and the variable magnetic fields in a 1.5 T MR-unit. First, 20 dental cavities were filled with a non-gamma-2 amalgam, and the mercury release was measured for 14 days in a non-magnetic environment. Second, one half of the specimens were exposed to a static magnetic field for 24 hours (group A), while the other specimens were exposed to a repetitive gradient echo sequence for 60 minutes (group B). In both experiments there was no significant increase in mercury release due to MRI. This in vitro study demonstrated no evidence of an elevated mercury dissolution from a non-gamma-2 amalgam during magnetic field exposure by MRI; therefore, there is no increased risk to health.

Dental Amalgam↗

PubMed1985

The significance of pH for the inhibiting effect of phosphate buffer on the corrosion processes.

The influence of pH on the protective effect of phosphate buffer on the corrosion processes was studied by measuring the amounts of elements released from a dental amalgam. The analyses were conducted by means of atomic absorption spectrophotometry. The protective effect of phosphate buffer was reduced in solutions with low pH, and mercury could be detected in the solutions. Phosphate buffer maintained its aftereffect in the pH region 6.8-5.5. The flow rate of the solution did not influence the inhibiting effect of phosphate buffer.

Buffers↗

PubMed1997

[Chronic unilateral maxillary sinusitis caused by foreign bodies in the maxillary sinus].

Chronic maxillary sinusitis is a common condition. The disease is most often caused by blockage of the sinus ostia or presence of an oroantral fistula. We report two cases of unilateral chronic maxillary sinusitis associated with foreign bodies in the maxillary sinus. In the first case the foreign body consisted of dental amalgam, in the second case of two silastic sponges left behind from a former operation because of "blowout" fracture. In the case of benign chronic maxillary sinusitis and foreign bodies, functional endoscopic sinus surgery (FESS) preceded by a CT-scan is an excellent approach, by which diagnosis as well as treatment can be achieved with minimal surgical trauma.

Adult↗

PubMedDate not supplied

[Evaluation of sources of mercury absorption through studying urinary mercury levels in the general population].

OBJECTIVES: The number of instances where mercury exposure is possible outside the workplace are numerous, with the main source being amalgam dental fillings and diet. It is also possible to envisage environmental exposure in subjects resident in areas where there is existing environmental contamination. This is probably what happened in Tuscany where past mining activity in the Monte Amiata area may have been the cause. This study estimated the concentration of urinary mercury (HgU) in non-occupationally exposed subjects from southern Tuscany, with the aim of evaluating the sources of mercury absorption in the general population. METHODS: A questionnaire aimed at collecting specific information on factors which might influence the uptake of mercury was used. 164 subjects were studied: 82 subjects (41 males, 41 females) came from the Monte Amiata area and the other 82 (41 males, 41 females) from the Province of Siena. In this way it was possible to evaluate the elements associated with everyday life which may have influenced the presence of the metal in the urine. Since the distribution of the variables cannot be assumed multivariate normal as usual, a recently-proposed method based on a permutation procedure was adopted that allows the analysis of the variables as well as the single marginal analyses, without assuming any model for the distribution of variables. RESULTS AND CONCLUSIONS: The results showed significantly lower levels of HgU in the subjects from the Monte Amiata area. Highly significant differences were demonstrated in the population which was sub-divided according to number and surfaces of amalgam fillings, use of contact lenses and type of water drunk (p < 0.001). Correlations between the levels of HgU and the investigated variables were not observed. It was confirmed that mercury uptake is simultaneously influenced by many factors. Probably the presence of higher levels of mercury in the environment in the Monte Amiata area is a factor of minor importance compared to others, especially the number of amalgam fillings, in determining mercury absorption in the general population.

Absorption↗

PubMed2000

In vitro evaluation of the effect of freshly mixed amalgam and gallium-based alloy on the viability of primary periosteal and osteoblast cell cultures.

The effect of freshly mixed specimens of a gallium-based alloy Galloy and a high copper spherical amalgam Tytin on the viability of primary periosteal and osteoblast cells was investigated. The cells were grown from the parietal bones of 2-3 day old Albino Wistar rats and were seeded in multi-well plates and exposed to the test materials for 1 or 6 days. The number of viable cells in each test group was determined using the Trypan blue dye exclusion test and compared with the controls. The area of cell death around the test specimens was also measured. Statistical analysis (ANOVA, Tukey's pairwise comparisons) showed a significant effect of the test materials on cell viability (P < 0.01). The viability of cultures containing Tytin was significantly lower than cultures with Galloy and the controls (P < 0.05). The viability of cultures containing Galloy was significantly lower (P < 0.05) than controls except for periosteal cells after 1 day. The culture media was analysed using atomic absorption spectrophotometry (AAS) for metal ion content. The results suggested that mercury (Hg) was the main element released from the dental amalgam followed by copper (Cu) and silver (Ag) whilst gallium (Ga) was the main element released from the gallium-based alloy followed by indium (In), Ag and Cu.

Alloys↗

PubMed2006

Reducing metal artifacts in cone-beam CT images by preprocessing projection data.

PURPOSE: Computed tomography (CT) streak artifacts caused by metallic implants remain a challenge for the automatic processing of image data. The impact of metal artifacts in the soft-tissue region is magnified in cone-beam CT (CBCT), because the soft-tissue contrast is usually lower in CBCT images. The goal of this study was to develop an effective offline processing technique to minimize the effect. METHODS AND MATERIALS: The geometry calibration cue of the CBCT system was used to track the position of the metal object in projection views. The three-dimensional (3D) representation of the object can be established from only two user-selected viewing angles. The position of the shadowed region in other views can be tracked by projecting the 3D coordinates of the object. Automatic image segmentation was used followed by a Laplacian diffusion method to replace the pixels inside the metal object with the boundary pixels. The modified projection data were then used to reconstruct a new CBCT image. The procedure was tested in phantoms, prostate cancer patients with implanted gold markers and metal prosthesis, and a head-and-neck patient with dental amalgam in the teeth. RESULTS: Both phantom and patient studies demonstrated that the procedure was able to minimize the metal artifacts. Soft-tissue visibility was improved near or away from the metal object. The processing time was 1-2 s per projection. CONCLUSION: We have implemented an effective metal artifact-suppressing algorithm to improve the quality of CBCT images.

Algorithms↗

PubMed2001

Biological monitoring and exposure to mercury.

Occupational health professionals' interest in controlling mercury (Hg) exposure, and the use of biological monitoring in this context, has been ongoing for a number of years. Evidence from urinary Hg results in a number of UK firms who have undertaken some form of biological monitoring or occupational health surveillance suggest that exposure has decreased over the last 10-15 years. This decrease precedes the establishment in the UK of an advisory biological monitoring guidance value (HGV) for urinary Hg and the production of updated medical guidance from the Health & Safety Executive on Hg exposure (MS12 1996). This latter document recommends a urinary sampling interval for urinary Hg of between 1 and 3 months, which is consistent with the reported toxicokinetics of Hg excretion, but we highlight that urinary Hg represents integrated exposure over many previous months. Mercury is a recognized nephrotoxin and MS12 1996 mentions the use of regular dipstick protein estimations. We review our experience of investigating proteinuria and enzymuria in a large-scale cross-sectional occupational study. The incidence of Hg-induced renal disease is probably very rare at current exposure levels. Therefore acceptance of a high false-positive rate of proteinuria not related to Hg exposure needs to be considered in any urinary protein testing regime of Hg workers. The establishment of an HGV for urinary Hg has raised questions about the uncertainty associated with a urinary Hg result, including factors such as diurnal variation, whether urine correction by creatinine or specific gravity is preferable and the possibility of non-occupational sources of Hg contributing significantly towards breaching the HGV. Correction of urinary Hg results by creatinine or specific gravity and the use of a fixed sampling time, such as the beginning or end of the day, substantially reduce the uncertainty in a urinary Hg measurement. But even with good laboratory precision, an individual with a true urinary Hg excretion of 20 nmol/mmol creatinine could supply urine samples of between 14 and 26 nmol/mmol creatinine. The influence of dietary sources in the UK contributing to urinary Hg values approaching or exceeding the HGV is unlikely. The use of tribal or ethnic cosmetics and remedies needs to be considered if a urinary Hg result looks inappropriately high, as some such preparations have been found to contain Hg and can be absorbed through the skin. The ability of excessive chewers or teeth grinders who have a large number of dental amalgam fillings to breach the urinary HGV in the absence of substantial occupational Hg exposure has been reported in a few Scandanavian studies. We report here a likely case of this phenomenon. Since the establishment of the HGV, our biological monitoring Hg data from a number of industry sectors using inorganic or metallic Hg have suggested that a minority of samples (13%) are still greater than the HGV.

Cross-Sectional Studies↗

PubMed2005

Time trends in burdens of cadmium, lead, and mercury in the population of northern Sweden.

The time trends of exposure to heavy metals are not adequately known. This is a worldwide problem with regard to the basis for preventive actions and evaluation of their effects. This study addresses time trends for the three toxic elements cadmium (Cd), mercury (Hg), and lead (Pb). Concentrations in erythrocytes (Ery) were determined in a subsample of the population-based MONICA surveys from 1990, 1994, and 1999 in a total of 600 men and women aged 25-74 years. The study took place in the two northernmost counties in Sweden. To assess the effect of changes in the environment, adjustments were made for life-style factors that are determinants of exposure. Annual decreases of 5-6% were seen for Ery-Pb levels (adjusted for age and changes in alcohol intake) and Ery-Hg levels (adjusted for age and changes in fish intake). Ery-Cd levels (adjusted for age) showed a similar significant decrease in smoking men. It is concluded that for Pb and maybe also Hg the actions against pollution during recent decades have caused a rapid decrease of exposure; for Hg the decreased use of dental amalgam may also have had an influence. For Cd, the decline in Ery-Cd was seen only in smokers, indicating that Cd exposure from tobacco has decreased, while other environmental sources of Cd have not changed significantly. To further improve the health status in Sweden, it is important to decrease the pollution of Cd, and actions against smoking in the community are important.

Adult↗

PubMedDate not supplied

[Compressive and bend strength of experimental admixed high copper alloys].

Mixed alloys for dental amalgams have been used mainly in the form of admixed alloys, where eutectic spheres are blend with conventional flakes. In the present study the compressive strength, bend strength and microstructure of two high-copper alloys (Tytin, Ana-2000) is compared with three experimental alloys prepared of the two high copper by mixing them in proportions of 3:1, 1:1 and 1:3 by weight. The results revealed that experimental alloys inherited high early and final strength values without any significant change in their microstructure.

Copper↗