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Currently there is no "standard" finishing and polishing procedure for dental amalgam restorations. This investigation evaluated the effect of four different finishing techniques on the durability of dental amalgam restorations as determined by the marginal breakdown. Burnishing immediately before carving or as part of the condensation process seems to improve the carving characteristics of the amalgam.
This study was undertaken to assess the effect of mixing speed on the setting rate of high-copper dental amalgam. The surface hardness during setting of two representative brands of dental amalgam was related to working and carving times determined by clinicians. From this information, a means of evaluating setting rate of amalgam based on surface hardness was developed.
As part of the European Mercury Emissions from Chlor Alkali Plants (EMECAP) project, we tested the hypothesis that contamination of ambient air with mercury around chlor alkali plants using mercury cells would increase the internal dose of mercury in people living close to the plants. Mercury in urine (U-Hg) was determined in 225 individuals living near a Swedish or an Italian chlor alkali plant, and in 256 age- and sex-matched individuals from two reference areas. Other factors possibly affecting mercury exposure were examined. Emissions and concentrations of total gaseous mercury (TGM) around the plants were measured and modeled. No increase in U-Hg could be demonstrated in the populations living close to the plants. This was the case also when the comparison was restricted to subjects with no dental amalgam and low fish consumption. The emissions of mercury to air doubled the background level, but contributed only about 2 ng/m(3) to long-term averages in the residential areas. The median U-Hg levels in subjects with dental amalgam were 1.2 microg/g creatinine (micro/gC) in Italy and 0.6 microg/gC in Sweden. In individuals without dental amalgam, the medians were 0.9 microg/gC and 0.2 microg/gC, respectively. The number of amalgam fillings, as well as chewing, fish consumption, and female sex were associated with higher U-Hg. The difference between the countries is probably due to higher fish consumption in Italy, demethylated methyl mercury (MeHg) being partly excreted in urine. Post hoc power calculations showed that if the background mercury exposure is low it may be possible to demonstrate an increase in U-Hg of as little as about 10 ng/m(3) as a contribution to ambient mercury from a point source.
The debate about mercury and dental amalgam has been one of the longest running in dentistry, and shows no signs of abating. This study aimed to investigate perceptions about mercury in dental fillings among a representative sample of the Australian public. A random sub-sample of participants in a national dental telephone interview survey completed a follow-up postal questionnaire which included four items on dental mercury. The postal survey response rate was 85.2%. Concern about mercury in dental fillings was expressed by 37.5%, while 16.2% reported having requested fillings that do not contain mercury. Avoidance of dental care because of concern about mercury in fillings was reported by 5.8%, but only 4.7% reported having had fillings replaced because they contained mercury. The data indicate that there is a substantial degree of concern about mercury and dental amalgam among the Australian public, but that the dental behavioural and treatment-pattern consequences of that concern are infrequent.
441 consecutive patients (294 female, 147 male) with suspected contact dermatitis were patch tested to the European standard series, mercury metal (1% pet), ammoniated mercury (1% pet.), and mercuric chloride (0.1% aq.). 14 patients (3.2%), 12 of whom were female, showed a positive response to 1 or more mercury compounds; none reacted to mercuric chloride alone. Primary sensitization was most likely due to either inoculation with vaccines containing merthiolate preservatives or amalgam dental restorations. Mercury allergy was of historical clinical relevance in only 2 patients, both women who developed gingivostomatitis following insertion of amalgam dental fillings. 1 of these women subsequently developed allergic contact dermatitis from contact lens solutions, shampoos and cosmetics which contained mercury preservatives. On the basis of these findings, we recommend patch testing with both metallic mercury and ammoniated mercury in patients with suspected mercury allergy.
The cytotoxicity of one conventional and four non-gamma 2-amalgams was studied in a cell culture system, using the Millipore filter method. Before testing set amalgam specimens were kept in distilled water or in artificial saliva at pH 4, 5, or 7 for up to 28 wk to produce a corrosion layer on the test surface. Non-corroded set amalgam specimens was also tested. None of the noncorroded, set amalgams showed any sign of surface accumulation of cytotoxic products whereas the corroded amalgams showed varying degrees of cytotoxicity. Generally, the non-gamma 2-amalgams gave a more pronounced cytotoxic effect than the conventional amalgam. When the corrosion procedure was carried out at pH 7, the various non-gamma 2-amalgams showed different degrees of cytotoxicity. It appears that the difference in cytotoxic effect between the non-gamma 2-amalgams and the conventional amalgam as well as the differences among the various non-gamma 2-amalgams could be related to variation in the retention of corrosion products deposited on the amalgam surface.
The chelating agent 2,3 dimercaptopropane-1-sulfonate (DMPS) has been used in a mercury mobilization test for diagnoses in illnesses allegedly associated with the presence of amalgam restorations. DMPS is an accepted antidote to heavy metal poisoning. The aim of the present study was to evaluate the diagnostic value of DMPS in patients with symptoms self-related to their amalgam fillings. The subjects consisted of four groups: 19 healthy controls without amalgam experience; 21 healthy controls with amalgam fillings; 20 patients who claimed symptoms of "mercury poisoning" from dental amalgam; and 20 patients who had amalgam fillings removed because of such symptoms. DMPS (2 mg/kg body weight) was injected intravenously, and urine was collected prior to the injection, 30 and 120 min after the injection, and throughout the next 22 hrs. The samples were analyzed for total mercury by cold vapor atomic absorption spectrophotometry. The total median amounts of mercury excreted over 24 hrs for those with complaints allegedly associated with amalgam and for the healthy controls with amalgam fillings were similar. Persons with amalgam fillings excreted about three times more mercury than those without. The controls, who had never had amalgam fillings, and the subjects who had had their fillings removed excreted median amounts of 8.5 microg and 7.2 microg mercury, respectively. The present DMPS challenge test did not differentiate between patients with or those without complaints self-related to their amalgam fillings but did confirm the higher mercury values in patients with dental amalgam.
OBJECTIVE: This study investigated the wear resistance of a mercury-free silver direct-filling material and a dental amalgam. METHOD AND MATERIALS: A precipitated silver powder was rinsed with dilute fluoboric acid and consolidated into a cohesive solid. For tooth cavity restoration and flexural testing, the silver was consolidated with a dental amalgam plugger at a load of 15 N. For wear testing, because of the relatively large specimen size, the silver was pressed at a pressure of 150 MPa, yielding a density similar to that obtained by hand consolidation. RESULTS: The silver had a flexural strength twice that of amalgam. Pin-on-disk wear resulted in a smooth surface and hardening in silver, as measured by indentation inside the wear tracks, in contrast to the damage that was found in amalgam. The wear track cross-sectional area (n = 12) at 10(6) revolutions was not statistically significantly different among amalgam, polished silver, and burnished silver. CONCLUSION: The consolidated silver exhibited work hardening and surface densification during wear and, as a result, was more resistant to wear-induced damage than amalgam.
This thesis is based on seven studies. The aims of these studies were to investigate a series of consecutive patients with orofacial and general sensations and complaints of discomfort, which the patients assumed to be caused by galvanic currents created by metallic dental fillings and restorations, as well as contact allergy to both metallic and non-metallic substances in dental materials. Studies I and II described the patients' symptoms and complaints, as well as the clinical findings of many odontological and medical examinations. A widely varying symptom panorama and numerous clinical findings, both oral and general, have been found which could not be explained by a single etiological factor. A combination of many factors, such as general health problems, side effects of medication, psychosocial problems, including stressful life events and complications due to the chronicity of the pain formed the background to the oral and general complaints of these patients. The salivary and microbiological conditions and patch test results were presented in studies III and IV. The saliva flow rate, pH and cariogenic bacteria level as well as contact allergy to metallic and non-metallic substances known as allergens, were not significantly different, but buffer capacity and saliva conductance did differ. A laboratory investigation of the corrosion behaviour of dental amalgams and gold alloys in natural saliva and saline solutions was performed (Study V) and the corrosion state of dental amalgam fillings and constructions was examined (Study VI). Special laboratory and clinical methods and apparatus were constructed and used. No differences between electrode potentials of the amalgam fillings and constructions in patients with and without orofacial discomfort complaints were measured. Study VII presented an analysis of the outcome of the treatments applied. The treatment was based on each patient's symptoms and signs and probable diagnosis. Besides conventional dental, stomatognathic and medical treatment, metallic constructions were removed in 54% of the patients. The initial treatment result was favourable in 80% but recurrences were frequent. It was concluded that these patients need a careful oral examination and dental treatment of observed local pathosis and defects of dental constructions, but removal of metallic fillings and constructions should be avoided when not indicated. Many of these patients require medical consultation and treatment, and collaboration between dentist and the physician is recommended.
Determining the safety of dental materials through laboratory and animal testing before widespread use of such products in humans is critical to the continued use of many materials in dentistry. The patient and the dentist have the right to expect that a manufacturer has adequately evaluated a product for safety as well as effectiveness for its intended use before making the product commercially available. Although the use of dental amalgam and casting alloys is widespread, there is insufficient documented evidence to recommend discontinuing the use of either dental amalgam or base metal casting alloys. Unless it can be shown that a patient is hypersensitive to the metal and that the hypersensitivity is indeed a causative factor in a systemic disease, replacement of existing restorations is not recommended. Nevertheless, there are specific areas of future research including actions a dentist should implement. The dentist should document cases of sensitivity to metals and become familiar with the symptoms arising from metal exposure. In screening new products for use in dentistry the FDI Technical Report No. 9, Recommended Standard Practices for Biological Evaluation of Dental Materials is relevant. The series of recommended tests for metals to be used in dentistry include initial tests to determine acute toxicity, secondary tests such as those to evaluate irritation to the tissues in contact with the metal and usage tests, i.e. tests in animals simulating intended clinical use in humans.
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Mercury concentrations in morning urine and ejaculate were detected in 80 husbands of women presenting for infertility treatment. Additionally, the number of their dental amalgam fillings was documented. A routine spermiogram was performed, from which a numerical "fertility index" was calculated. Urinary mercury concentrations were in the range of non-exposed populations, only minute Hg concentrations were determined in ejaculate, 75% of the semen sample concentrations were under the detection limit of 5 micrograms/l. In comparison, 7 proven fertile workers with occupational mercury exposure had elevated levels of mercury in their ejaculates (range 10-65 micrograms/l). No positive correlation could be established between subject mercury concentrations in urine or ejaculate and the quality of their semen, expressed as fertility index. Equally, no such correlation could be established between the fertility index and the number of their dental amalgam fillings. From these preliminary data no evidence can be derived for the alleged relation between the mercury burden from dental amalgam fillings and male fertility disorders.
Two alloys for dental amalgams made from lathe-cut powder with high Cu content have been developed. The alloys have been characterized with respect to physical properties and microstructure. The strongest amalgam exhibited minimal dimensional changes during setting and had low flow and creep values. It had the highest Cu content of the two amalgams investigated and no gamma 2 phase. The epsilon and eta' phases may dispersion-strenthen the amalgam which in compressive strength was comparable to the strongest amalgams available. A new mechanism for gamma 2 disappearance is suggested where Cu replaces Hg directly in the gamma 2 phase thus forming the eta' phase.
A random sample of 68 males and 25 females who reside in Mansoura city, Egypt, was examined for concentrations of cadmium, lead, and mercury in blood, urine, hair, and nails. The effect of gender and smoking on such levels was studied. The influence of dental amalgam on the levels of mercury in these biological samples was also examined. The results obtained show that only blood lead, which increased among males, was affected by gender. Blood levels of cadmium and lead as well as hair lead appeared to increase with smoking habit. Mercury levels in blood and urine were related to the presence of dental amalgam fillings. International comparisons between our results and the corresponding levels in other localities in the world showed that there were environmentally related variations in terms of cadmium levels in hair, lead levels in blood, urine, hair, and nails, and mercury levels in blood, hair, and nails. In conclusion, reference intervals of cadmium, lead, and mercury in the biological samples are environmentally related parameters. Some factors, such as gender, smoking habit, and the presence of dental amalgam fillings, may affect such levels and therefore should be considered.
The aim of this article is to present a critical reflection on 'cures of patients' after the removal of dental amalgam fillings, reported in the popular press. It is concluded that, when the removal of dental amalgams in patients with a hypersensitivity to mercury is put aside, possible explanations for these questionable cures are not connected with the removal of amalgam but may involve the functioning of the immune system, the relation between environment and the opinions of patients and the influence of psychological factors on illness and health.
Fractured or ditched margins are the most common problem associated with amalgam restorations. Unfortunately, continuously replacing dental amalgams takes its toll on a tooth. Good restorative practices demand that we limit the number of restorative procedures to which we subject a tooth. This paper looks at an effective technique for sealing the margins of ditched amalgam restorations. This technique allows the practitioner to repair the ditched area of the amalgam without replacing the amalgam restoration.
The employment of dental amalgam in the area of conservative dentistry, in spite of representing an excellent therapeutic solution, is today undergoing criticism more frequently than before because of the potential toxicity of mercury regarding hyman health and environmental salubrity. Mercury is a metal having the tendency to evaporate at ambient temperature and it is just the inhalation of its vapor the most common form of exposure to mercury for man. The absorption may also may also occur through food ingestion or accidental swallowing of metal particles coming from dental amalgam fillings. Mercury poisoning usually turns out to be a chronic process which causes its major toxic effects at the expense of digestive, excretory and neurocentral apparatuses. Several authors have studied mercury exposure on the working places, including in their investigation persons operating in the dentistry departments: they found high levels of mercury existing both in tissues and in biological fluids in people affected by exposure, frequently accompanied by symptoms of chronic intoxication. More recent studies, however, do not fully confirm such conclusions and exclude that coming into contact with mercury vapor on the working place may be in connection with an increase of mortality. Exposure to mercury from amalgam for the most part occurs through ingestion of amalgam particles abraded from restored surfaces, inhalation of vapors generated during dental restorative procedures and deglutition of saliva into which corrosion products have dissolved.(ABSTRACT TRUNCATED AT 250 WORDS)
Inhalation of mercury vapor is a potential hazard when handling dental amalgam. To prove the safety of modern capsule systems, we tested 21 brands of dental amalgam. Mercury vapor emission was measured at different stages during handling: a) immediately after opening of a capsule package, b) cumulative emission over 24 h of storage of an open package, c) during trituration and d) for different methods of waste capsule treatment. Highly significant differences between capsule types were found for the measured parameters. Disposable capsules that could be reassembled showed the most favorable results.