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PubMed2004

The beneficial effect of amalgam replacement on health in patients with autoimmunity.

BACKGROUND: Patients with certain autoimmune and allergic diseases, such as systemic lupus, multiple sclerosis, autoimmune thyroiditis or atopic eczema, often show increased lymphocyte stimulation by low doses of inorganic mercury in vitro. The patients often report clinical metal hypersensitivity, especially to nickel. OBJECTIVE AND METHODS: In this study we examined the health impact of amalgam replacement in mercury-allergic patients with autoimmunity. The suitability of MELISA, an optimized lymphocyte stimulation test, for the selection of susceptible patients and monitoring of sensitization was also examined. Amalgam fillings were replaced with composites and ceramic materials. Follow-up health status and lymphocyte reactivity were assessed and evaluated half a year or later following amalgam removal. RESULTS: Results of lymphocyte reactivity measured with MELISA indicate that in vitro reactivity after the replacement of dental amalgam decreased significantly to inorganic mercury, silver, organic mercury and lead. Out of 35 patients, 25 patients (71%) showed improvement of health. The remaining patients exhibited either unchanged health (6 patients, 17%) or worsening of symptoms (4 patients, 11%). The highest rate of improvement was observed in patients with multiple sclerosis, the lowest rate was noted in patients with eczema. The initial mercury-specific lymphocyte reactivity was significantly higher in the responder group, than in the non-responders, whose health was not improved by amalgam removal. All patients with health improvement after amalgam replacement showed reduced proliferation to inorganic mercury in follow-up MELISA. In vitro responses to phenylmercury and nickel did not differ between the groups. CONCLUSIONS: Mercury-containing amalgam may be an important risk factor for patients with autoimmune diseases. MELISA is a valuable tool for selection of patients for amalgam replacement and also for monitoring of metal allergies.

Adult↗
PubMed2005

Amalgam exposure and neurological function.

Concerns regarding the safety of silver-mercury amalgam fillings continue to be raised in the absence of any direct evidence of harm. The widespread population exposure to amalgam mandated that a thorough investigation be conducted of its potential effects on the nervous system. The National Institute of Dental and Craniofacial Research and U.S. Air Force investigators collaborated in the ongoing Air Force Health Study (AFHS) of Vietnam era veterans. The primary study question involved adverse health effects associated with exposure to herbicides or dioxin. An assessment of exposure to dental amalgam fillings was added to the 1997-1998 health examination to investigate possible associations between amalgam exposure and neurological abnormalities. Our study population consisted of 1663 dentate AFHS participants, comprised of 986 AFHS controls and 677 Ranch Hand veterans who were exposed to dioxin in Vietnam. Two hundred and fifty-two of the participants had confirmed diabetes mellitus. Study outcomes included clinical neurological signs, vibrotactile thresholds, and summary variables for different levels of peripheral neuropathy. A limitation of our study is that our database did not include more sensitive continuous measures such as nerve conduction studies. No significant associations were found between amalgam exposure and clinical neurological signs of abnormal tremor, coordination, station or gait, strength, sensation, or muscle stretch reflexes or for any level of peripheral neuropathy among our study participants. A statistically significant association was detected between amalgam exposure and the continuous vibrotactile sensation response for the combined non-diabetic participants and separately for non-diabetic AFHS controls. No significant association in this measure was detectable for non-diabetic Ranch Hand veterans or among the combined diabetic participants. The association is a sub-clinical finding that was not associated with symptoms, clinically evident signs of neuropathy, or any functional impairment. Overall, we found no association between amalgam exposure and neurological signs or clinically evident peripheral neuropathy. Our findings do not support the hypothesis that exposure to amalgam produces adverse, clinically evident neurological effects.

Dental Amalgam↗
PubMed2005

Disinfectants' effect on mercury release from amalgam.

BACKGROUND: Mercury environmental discharge is under increased scrutiny by the U.S. Environmental Protection Agency (EPA). Dental amalgam should be processed properly to prevent an additional environmental burden. Some processing agencies require that submitted amalgam be noninfectious. Investigations have demonstrated that oxidizing disinfectants mobilize mercury from amalgam into solution and add mercury to the environmental burden if it is disposed of improperly. The authors conducted a study to evaluate the effect of representative disinfectants on amalgam mercury release. METHODS: The authors sized a high-copper spherical amalgam alloy to match that typically found in dental unit suction traps. They exposed 20 grams of the alloy to several disinfectant solutions and evaluated the filtered supernatant solution for mercury content. RESULTS: Chlorine disinfectant materials discharged the most mercury ions, followed by bromide, iodophor, peroxide/peracetic acid and phenolic disinfectants. The quaternary ammonium compound did not discharge mercury ions above the detection limit (0.2 parts per billion) into solution. CONCLUSIONS: A quaternary ammonium compound did not mobilize mercury ions into solution when used as a disinfectant agent for amalgam. Chlorine disinfectants mobilized mercury ions the most, followed by bromide, iodophor, peroxide/peracetic acid and phenolic disinfectants. CLINICAL IMPLICATIONS: Dentists are obligated to be good environmental stewards and should follow practices that reduce environmental mercury release. Dental personnel should be aware that oxidizing disinfectants mobilize mercury ions into solution, which will be added to the environment if they are processed improperly. If required by processing, dental personnel should consider the different oxidizing effects of commonly used disinfectants.

Anti-Infective Agents, Local↗
PubMed1993

An in vitro and in vivo study of the release of mercury vapor from different types of amalgam alloys.

The aim of the in vitro part of the study was to measure the rate of release of mercury vapor from different types of dental amalgam in air, and in air during cyclic dipping into isotonic saline solution or Fusayama solution. The measurements were carried out by means of the Mercollector/Mercometer system, based on atomic absorption spectrophotometry. Both new (age approximately 2 months) and old (age approximately 1.5 years) amalgam specimens were studied. The variations in the rate of release of mercury vapor in air during cyclic dipping into aqueous media were most pronounced during the first day of the 10-day period studied. In air during cyclic dipping into the aqueous media, the conventional amalgam specimens released mercury vapor at lower rates over the whole period than did the dispersed and single-composition types studied. The aim of the in vivo part of the study was to determine the daily release of mercury vapor from amalgam restorations made of alloys of the same types and batches as those used in the in vitro part of the study. A series of measurements was carried out on each of eight subjects before and after amalgam therapy. None of the subjects was occupationally exposed to mercury. The subjects had to follow a standardized schedule for 24 h, where they ate, drank, and brushed their teeth at predetermined times (Berglund, 1990). The amount of mercury vapor released per time unit was measured at intervals of 30-45 min. Samples of urine and saliva were analyzed formercury.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1998

Mobilization of mercury and arsenic in humans by sodium 2,3-dimercapto-1-propane sulfonate (DMPS).

Sodium 2,3-dimercapto-1-propane sulfonate (DMPS, Dimaval) is a water-soluble chelating agent that can be given by mouth or systemically and has been used to treat metal intoxication since the 1960s in the former Soviet Union and since 1978 in Germany. To better approximate the body burdens of Hg and As in humans, DMPS-Hg andDMPS-As challenge tests have been developed. The tests involve collecting an overnight urine, administering 300 mg DMPS at zero time, collecting the urine from 0 to 6 hr, and determining the urinary Hg before and after DMPS is given. The challenge test, when applied to normal college student volunteers with and without amalgam restorations in their mouths, indicated that two-thirds of the Hg excreted in the urine after DMPS administration originated in their dental amalgams. In addition, there was a positive linear correlation between the amalgam score (a measure of amalgam surface) and urinary Hg after the challenge test. When the DMPS-Hg challenge test was used to study dental personnel occupationally exposed to Hg, the urinary excretion of Hg was 88, 49, and 35 times greater after DMPS administration than before administration in 10 dental technicians, 5 dentists, and 13 nondental personnel, respectively. DMPS also was used to measure the body burden of humans with a history of drinking water containing 600 microgram As/liter. DMPS administration resulted in a tripling of the monomethylarsonic acid percentage and a halving of the dimethylarsinic acid percentage as related to total urinary As. Because South American animals studied were deficient in arsenite methyltransferase, a hypothesis is presented that arsenite and arsenite methyltransferase may have had a role in the evolution of some South American animals.

Adult↗
PubMed1997

[The effect of pH on anti-corrosion nature of amalgams].

Corrosion behavior of alloys are affected not only by themselves but also by environment, such as a change of pH. In this study, the corrosion behavior of four dental amalgams (L, C, DA, GK) in Fusayama saliva with different pH 6.65 and 4.00 are evaluated by electrochemical techniques. It seems that changes in pH may exert different effects on the four amalgams. In the acid environment DA exhibits best anti-corrosion nature and followed by GK, C, and L, which conforms to clinical observations. This may be resulted either from amalgams themselves or from conditions of corrosion products of amalgams' surface. Thus, consideration must be given to the changing oral environment when screening anti-corrosion alloys.

Corrosion↗
PubMed1992

Integrated currents between amalgams and a gold alloy in saline solutions and natural saliva with different chloride content.

The effect of different sodium chloride concentrations on the integrated currents (charge transfers) between dental amalgams and a gold alloy was studied in a bimetallic cell containing saliva or saline solutions. The integrated currents were only to a minor degree affected by increasing chloride concentrations for the high copper amalgams both in saliva and saline solutions. The integrated currents in the experiments involving conventional amalgam were several times higher than those for high copper amalgams. In saline solutions a charge transfer maximum was found at 0.2 M chloride. In saliva an increase of the charge transfer was found with increasing chloride content.

Chlorides↗
PubMed1990

Oral mucosal lesions related to silver amalgam restorations.

A total of 49 consecutive patients with lesions of the oral mucosa that were in contact with corroding dental amalgam restorations were subdivided into two groups. In group 1 the lesions were restricted to the contact area opposing the dental restoration, whereas the extent of the lesions in group 2 exceeded that of the contact area. Epicutaneous test for mercury allergy showed that a significantly greater proportion of the patients in group 1 had positive reactions to mercury than in group 2 (p = 0.019). The amalgam restorations were replaced by composite resin or porcelain fused to gold crowns, or contact between amalgam fillings and oral mucosa was prevented by an acrylic splint. After this treatment regression of lesions was far more pronounced in group 1 than in group 2 (p less than 0.001). On the basis of these findings, contact allergy to mercury is suggested as a possible etiologic factor of the mucosal changes in group 1, and the designation contact lesion is proposed for such lesions. The lesions of patients in group 2 seem unrelated to a contact allergy to mercury, and other causes such as lichen planus should be considered.

Acrylic Resins↗
PubMed1990

Effect of Pd on the clinical performance of amalgam.

The purpose of this study was to determine the effect of a small amount of Pd on the clinical performance of a high-copper spherical-particle dental amalgam. Two identical alloys, with and without 0.5% Pd, were investigated. The marginal fracture, surface texture, and surface luster of 193 clinical restorations were evaluated at one year, those of 182 at two years, and those of 144 at three years of service. In vitro corrosion tests of anodic polarization and constant potential coulometry were also conducted. Over the three-year period, the results showed no differences in marginal fracture or surface texture between the two alloys. However, the alloy with Pd showed a significant superiority in surface luster over this time period. Both corrosion tests showed less electrochemical activity on the part of the alloy containing Pd.

Adolescent↗
PubMed1992

Effectiveness of oxide films in reducing mercury release from amalgams.

The release of mercury from four freshly-triturated amalgams into air, argon, and moist air environments was quantitated at three different temperatures. Although a measurable amount of mercury was released from dental amalgam, the evaporation rate was immediately reduced by several phenomena, the most important being the formation of an oxide film on the surface. This hypothesis was supported by the fact that release rates were elevated in an inert argon environment, but declined dramatically once air was introduced and oxidation could occur. The further amalgamation of "free" mercury, as well as the presence of water vapor, also contributed to the reduced release rates observed during aging. Mercury release was reduced to a negligible level within three to four hours after trituration. Only one of the amalgams, Tytin, demonstrated a thermal dependence for mercury release in air. The results of this study suggest that the exposure to mercury vapor from a freshly placed amalgam restoration would be negligible in consideration of the normal estimated daily intake from all other sources.

Air↗
PubMed2002

Clinical performance of a compomer and amalgam for the interproximal restoration of primary molars: a 24-month evaluation.

OBJECTIVES: To evaluate the clinical performance of a compomer material (Dyract) in comparison with dental amalgam (Contour) for management of proximal caries in primary molars in young children. SETTING: General dental practice, and a dental hospital paediatric clinic. METHOD: This was a prospective study. A split mouth design was used with identical pairs of minimal Class II cavities, of matched tooth type in the same dental arch, usually diagnosed with the use of bitewing radiographs. Seventy-eight pairs of restorations were completed of which 60 pairs were available for evaluation after 24 months. RESULTS: Comparable retention rates were observed for both Dyract and amalgam. The retention rates were high for both materials, with only four amalgam and two Dyract restorations failing over 24 months. Significantly better marginal integrity (P < 0.05) was observed for Dyract compared with amalgam with no significant differences between the two materials for recurrent caries, wear or surface texture. CONCLUSIONS: Dyract seemed to be a suitable alternative to amalgam for proximal restorations in primary molars of young children for use in general dental practice.

Child↗
PubMedDate not supplied

Lichenoid reaction associated to amalgam restoration.

Hypersensitivity to mercury associated with amalgam restorations may occur and present in one of two different ways. Most commonly it presents as an oral lichenoid reaction affecting oral mucosa in direct contact with an amalgam restoration and represents a delayed, type IV, cell mediated immune response to mercury or one of the other constituents of the dental amalgam. We report a case of oral lichenoid reaction associated to amalgam restoration. A 38 year-old woman presented a caries lesion of tooth #37. A Blacks class I preparation was performed and filled with amalgam. After 19 months, intra-oral examination revealed atrophic lesion, lightly erythematous, affecting the left buccal mucous. The lesion contacted directly with the amalgam restoration in the lower first molar. The right buccal mucosa was normal. His medical history was unremarkable, he was taking no medication and had no known allergies. However, the patient had felt certain rare sensation in that zone when eating sharp meals. Biopsy showed histological changes compatible with oral lichen planus. The patient decided not to change again the restoration, because she did not have important annoyances and she did not wish to be treated again. Other restorations were performed with composite resins, and no reaction was evidenced in the mucosa.

Adult↗
PubMed1995

Amalgams made from liquid Hg-In.

The addition of indium to amalgam appears to reduce the mercury vapour above fillings during setting. In the present work the structure and the physical properties of amalgams with In additions to the mercury up to 30 vol.% have been investigated. No new phase or undissolved in could be detected by X-ray diffraction and scanning electron microscopy studies. Energy dispersive spectroscopy measured 4 at.% In in the gamma 1-phase of an amalgam with 20 vol.% In added to the mercury. At the same time, the Ag/Hg ratio was substantially increased compared with amalgam having no In addition. The compression strength decreased with increasing In content, and for amalgam with as much as 30 vol.% In added to the mercury, it fell below the minimum requirement of ISO 1559 (Alloys for dental amalgam, International Organization for Standardization, Geneva, 1986). An abrupt drop of the load at the onset of failure and cracks running through the gamma 1-phase, as well as the eta-phase, indicates embrittlement of these phases with increasing In content.

Alloys↗
PubMed2003

The relationship between amalgam restorations and mercury levels in male dentists and nondental health professionals.

OBJECTIVES: The objectives of this study were: (1) to compare the mercury levels in general dentists with the mercury levels in other health professionals using toenail clippings as a biomarker, (2) to identify risk factors associated with high mercury levels, and (3) to compare practice characteristics of dentists with high and low mercury levels. METHODS: A sample of 579 men was randomly selected from the 33,737 men participating in the Health Professionals Follow-up Study who had provided toenail samples in 1987. A questionnaire was sent to these male subjects in 1991 to obtain information on fish consumption, toothbrushing frequency, number of teeth, number of amalgam restorations, general practice or specialty status, number of amalgam restorations placed and removed per week, mercury storage and handling procedures, and mercury spillage incidents. A measure of long-term mercury exposure was obtained from toenail samples using neutron activation analysis for the 410 respondents (71% response rate). The 90th percentile mercury level in toenails (0.88 ppm) was selected as the threshold for elevated toenail mercury level. RESULTS: No relationship was found between the number of dental amalgams and toenail mercury levels among general dentists, dental specialists, and nondental health professionals. General dentists were found to have more than twice the level of mercury in toenails than nondental health professionals (mean level = 0.94 vs 0.45) and 60 percent higher than dental specialists (mean = 0.59). The combined use of disposable capsules and water storage of scrap amalgam appeared to reduce the risk of elevated mercury levels. Regardless of professional status, consumption of tuna and saltwater fish were the primary exposure factors that were positively associated with toenail mercury levels. CONCLUSIONS: As shown by the associations with dental profession and fish consumption, the mercury content of toenails is a stable biomarker of cumulative long-term mercury exposure. The lack of association between nail mercury levels and number of amalgam restorations suggests that avoidance of mercury amalgam restorative materials cannot be justified by the presence of mercury released from dental amalgams.

Animals↗
PubMed1996

[Amalgam--"etiology" of psychiatric disorders?].

In a liability lawsuit an expertise had to answer the question whether a mania in the course of an affective psychosis could have been caused by chronic mercury intoxication resulting from dental amalgam fillings. On the basis of current psychiatric and toxicological knowledge, such an association can be disproved. Mercury intake from amalgam fillings does not lead to toxic concentrations in organs or body fluids. Therefore physicians and dentists should avoid alarming patients and thus causing iatrogenic harm.

Adult↗
PubMed1988

Restorative dental materials: scanning electron microscopy and x-ray microanalysis.

Restorative dental materials include the materials used to repair damaged teeth and/or replace missing teeth. The definition could be extended to include a much broader group of dental materials, but this paper concentrates only on those materials used to restore the crown portion of damaged teeth. Auxiliary materials, materials for removable denture prostheses, and root canal materials are excluded. Progress and recent research utilizing SEM (Scanning Electron Microscopy), EDS (Energy Dispersive Spectroscopy), and some related methods are presented for the following dental materials: dental amalgam, enamel and dentin bonding agents, dental composites, dental cements, casting alloys for crowns and bridges, and ceramic-metal and ceramic restorative materials. In addition to the basic characterization of these materials by SEM/EDS techniques, examples of replication methods for SEM study of restorative materials in situ are discussed. Some examples are also presented in the direct use of SEM/EDS for characterization of changes and degradation of restorative materials which occur during clinical use.

Dental Materials↗