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PubMedDate not supplied

An in-vitro investigation of variables influencing mercury vapor release from dental amalgam.

Controversy regarding patient exposure to mercury from dental amalgam is more than 150 years old. Researchers continue to investigate the amount of mercury vapor released from amalgam both in vivo and in vitro. In this investigation, an in vitro testing method previously described in the literature was used to quantify the effect of operator-controlled variables on mercury release from dental amalgam. The variables tested were alloy morphology (spherical, admixed or atomized irregular particle), operator skill (inexperienced, novice and expert), operator technique (overfill and evenly fill) and cavity design (standard Class I, double volume and double surface area). Preparations fabricated in sections of acrylic rod were filled with dental amalgam, placed in 25 mL glass bottles and sealed. Mercury vapor concentrations were measured using a Jerome M-411 at specified times. Standardized mean concentrations for each time and total mercury released over time were calculated and analyzed with ANOVA and Tukey HSD. Statistically significant differences ((alpha = 0.05) were identified for all variables tested. Total mercury vapor release was consistently found to be greater for admixed as compared to spherical amalgam. Amalgam restorations prepared by an inexperienced operator demonstrated statistically less mercury vapor than a novice or experienced clinician for both spherical and admixed morphologies. A statistically significant difference in mercury vapor using different condensation and carving techniques was found for the spherical amalgam but not for the admixed material. Restoration design demonstrated significant differences in total mercury vapor dependent on volume and exposed surface area of the amalgam restoration. In this in vitro investigation, mercury vapor release from amalgam was dependent on alloy morphology, operator experience, operator technique and restoration design.

Analysis of Variance↗
PubMed1989

[The history of dental amalgam].

This article reviews the history of dental amalgam. There are indications that dental amalgam was used in the first part of the T'ang Dynasty in China (618-907 A.D.), and in Germany by Dr. Strockerus in about 1528. Ever since its introduction in the Western World in the 1830s, amalgam has been the subject of recurrent controversies because of its mercury content. Early amalgam was made by mixing mercury with the filings of silver coins.

Dental Amalgam↗
PubMed1975

Electrochemistry of the saline corrosion of conventional dental amalgams.

The electrochemical behaviour of the component phases of dental amalgam, viz. Ag3Sn(gamma),Ag2Hg3(gamma1), Sn7-8Hg(gamma2),Cu3Sn, Cu6Sn5 and a composite of gamma1 + gamma2 phases were evaluated in saline solution by standard anodic polarization techniques. Using multi-electrode theory a theoretical polarization diagram was constructed from the composite phases and compared with an anodic polarization profile attained from conventional dental amalgam. A strong agreement was obtained. From analysis of the electrochemical reactions it was found that the passivity of gamma2 is due to the formation of stannous and/or stannic oxide (hydroxide) and that the corrosion failure of dental amalgam occurs through the dissolution of this passive oxide in gamma2 at potentials of minus 250 mV Vs. SCE with the formation of tine oxychloride. The corrosion behaviour of Cu6Sn5 is similar to that of gamma2 phase and its presence impairs the corrosion resistance of dental amalgam. If the copper containing phase is Cu3Sn, it will be passive in Ringer's solution, possibly as a result of Tamman's "multiple rule of eight".

Copper↗
PubMed2002

The weight of wastes generated by removal of dental amalgam restorations and the concentration of mercury in dental wastewater.

OBJECTIVE: To determine the amount of amalgam entering the waste stream during removal of dental amalgam restorations. METHODS: Dental amalgam restorations were removed from anatomic replica teeth and natural teeth by means of a tungsten carbide bur, a high-speed handpiece and a conventional suction system. The weight of amalgam particles trapped in the primary and secondary solids separators was determined. Amalgam particles were filtered from wastewater with 15-microm filter paper and weighed. The concentration of total mercury in the effluent collected (by instantaneous flow-through) during the removal of amalgams, with and without an ISO-certified separator, was measured by means of cold-vapour atomic absorption spectrophotometry. RESULTS: About 60% by weight of the amalgam removed was found in the effluent, about a third was retained in the primary solids separator and less than 10% was retained in the secondary solids separator. The ISO-compliant separator reduced the concentration of mercury in the instantaneous flow-through discharge by 99.4%, from 31.2973 mg/L to 0.1800 mg/L. CONCLUSIONS: About 60% of the waste generated during the removal of amalgams escaped the primary and secondary solids collectors and was released into the wastewater. An ISO-certified amalgam particle separator was effective in removing the amalgam from the wastewater.

Canada↗
PubMed1976

Dental amalgam stabilization by selective interfacial amalgamation.

The purpose of this investigation was to explore the feasibility of enhancing the electrochemical stability of dental amalgam restorations by a process of "selective interfacial amalgamation." If dental amalgam restorations can be selectively alloyed at the tooth-amalgam interface, to a minor thickness as compared with the dimensions of the bulk amalgam, so as to present a more electrochemically stable phase than psi2 to the oral environment, corrosion will be reduced and desirable qualities of existing amalgams can be utilized. It was found that selective interfacial amalgamation was indeed possible and that it could be readily accomplished using a silver suspension as a cavity liner. By then placing a conventional silver-tin amalgam according to ordinary dental techniques, mercury expressed during hand condensing reacted with the silver in the liner resulting in the formation of an integral amalgam restoration with the more noble psi1 phase adjacent to tooth structure. In vitro corrosion tests of samples so prepared exhibited corrosion resistance far superior to unlined control samples.

Corrosion↗
PubMed1978

Toxic effects of dental amalgam implants. Optical histological and histochemical observations.

Dental amalgam and porcelain control discs were implanted in the subcutaneous tissue of rats. Amalgam implants exerted a toxic effect caused by release of metal ions which was characterized by prolonged inflammation, delayed granulation and disordered collagen formation. Dental porcelain was found to be a suitable biocompatible control which provided a bulk similar to that of dental amalgam but induced only an uncomplicated granulation response.

Animals↗
PubMed1983

Mercury toxicity and dental amalgam.

There is adequate evidence that dental amalgam restorations, during and after placement, results in the release of Hg into the patient's body. Whether the Hg released from amalgam is due to placement procedures, surface abrasion, or later corrosion breakdown, there is evidence that a low level Hg release continues for years. It is generally agreed that if amalgam was introduced today as a restorative material, they would never pass F.D.A. approval. With new and more accurate techniques of measuring Hg levels, especially in tissue and blood, additional studies are necessary to relate blood-Hg levels with dental amalgam restorations. Studies must relate existing restorations as well as the placement of new restorations to body-Hg levels. It is possible that we have accepted a potentially dangerous material as being safe.

Dental Amalgam↗
PubMed2004

Dental amalgam: regulating its use and disposal.

Although dental amalgam has been a restorative material for more than 150 years, government regulation of its use and disposal came much later with the creation of new federal laws and agencies. None of the federal laws regulating dental amalgam today were written specifically to regulate amalgam. Instead, these new laws and agencies were created to address broad public safety concerns, where little or no regulation existed before, in the areas of medical devices and drugs and environmental pollution. It is the interpretation and implementation of environmental laws that recently have had the greatest impact on dental practices.

California↗
PubMed2006

The safety of dental amalgam in children.

The safety of mercury-containing dental amalgam has been hotly debated for well over a century. Dental exposures from mercury have been suggested as the cause of numerous diseases including multiple sclerosis, autism and many others. Known health effects of mercury exposure include CNS and renal damage. However, these effects have only been shown at occupational or higher levels of exposure, and have not been conclusively shown to be present at levels of mercury exposure consistent with that from dental amalgam fillings. The use of mercury amalgam fillings remains a state-of-the-art treatment for dental caries throughout the world. Although there have been a small number of peer-reviewed reports examining the health effects of dental mercury in children, only very recently have the only randomised, controlled clinical trials (two) of the safety of mercury amalgam been published. The purpose of this review is to discuss the scientific evidence on the safety of the use of mercury-containing dental amalgam as a treatment for dental caries.

Child↗
PubMed1998

The biocompatibility of non-amalgam dental filling materials.

Non-amalgam filling materials may release substances which have been shown to be toxic in cytotoxicity tests and implantation studies. However, results from systemic toxicity tests do not indicate any unacceptable risk to the patient's general health, but data for non-amalgam dental filling materials are scarce in comparison to amalgam. Although estrogen-like effects of one fissure sealant have been claimed, no conclusions can be drawn at present for the patient from these in vitro data because of the limitation of the test methods and materials used. Some components of composite resins/dentin adhesives and a resin-modified glass ionomer cement were mutagenic mainly in in vitro tests. Due to the limitations of the test systems and the comparatively high concentrations needed to elicit the reactions, no unacceptable risk can yet be derived from those data for the patient. However, a no-touch technique is recommended for the dental personnel. As with amalgam, local reactions of the pulp are not expected with alternative filling materials, if the pulp tissue is not exposed and if bacterial penetration is avoided. The latter requirement is still difficult to fulfill, especially for composite resin systems and related materials in posterior teeth situations. Slight gingival reactions to alternative filling materials and to amalgams are mainly attributed to plaque accumulation. From all these data it can be concluded that, for the time being, it is not possible to rank dental filling materials in respect to their biocompatibility, and it is evident that biocompatibility must be considered to the same extent for both amalgams and commonly used or recommended alternative filling materials.

Adhesives↗
PubMed2006

The effect of hydrogen peroxide concentration on metal ion release from dental amalgam.

OBJECTIVES: The aim of this study was to investigate the effect of hydrogen peroxide (HP) concentration on metal ion release from dental amalgam. METHODS: Dental amalgam discs (n=25) were prepared by packing amalgam into cylindrical plastic moulds (10 mm diameter and 2 mm height). The discs were divided into five equal groups and each group was immersed in 20 ml of either 0%, 1%, 3%, 10% or 30% HP solution for 24 h at 37 degrees C. Samples were taken for metal ion release determination (Hg, Ag, Sn and Cu) using inductively coupled plasma mass spectrometry (ICP-MS). The surface roughness of each disc was measured before and after bleaching. RESULTS: The differences in concentration of metal ions released after treatment with 0% (control) and each of 1%, 3%, 10% and 30% HP were statistically significant (p<0.05). Metal ion release for the elements (Hg, Ag, Sn and Cu) increased with exposure to increasing concentrations of HP. Surface roughness measurements of the samples before and after treatments with HP solutions were not significantly different (p>0.05). CONCLUSIONS: Exposure to HP bleaching agent was associated with increased metal ion released from dental amalgams compared to treatment with a control solution. Ion release was in proportion to the peroxide concentration tested, with the highest concentration associated with the greatest metal ion release for all elements investigated.

Copper↗
PubMed1995

Dental amalgam: toxicological evaluation and health risk assessment.

Dental amalgam releases small amounts of mercury, which is absorbed by the body. Available data are not sufficient to indicate whether this poses a health hazard to the general population. There is an urgent need for research into the potential health effects of mercury absorption from this source. However, considering the multiple benefits of dental amalgam, unless new scientific research dictates otherwise there is currently no justification for discontinuing the use of this material. Placing a priority on the preservation of healthy tooth structure through preventive strategies and the judicious use of all restorative materials could lessen current concerns over toxicity and unnecessary treatments.

Absorption↗
PubMed1999

Alzheimer's disease, dental amalgam and mercury.

BACKGROUND: Mercury, or Hg, is a neurotoxin that has been speculated to play a role in the pathogenesis of Alzheimer's disease, or AD. Dental amalgam releases low levels of Hg vapor and is a potential source of Hg for a large segment of the adult population. METHODS: The authors studied 68 subjects with AD and 33 control subjects without AD to determine Hg levels in multiple brain regions at autopsy and to ascertain the subjects' dental amalgam status and history. The subjects were from central Kentucky and Elm Grove, Wis. The authors conducted dental amalgam assessments during the lives of the majority of subjects and in some subjects at the time of autopsy only. The authors also determined three dental amalgam index scores--Event (placement, repair or removal of amalgam), Location and Time In Mouth--in addition to the numbers of and surface area of occlusal amalgam restorations. The authors determined Hg levels in multiple brain regions and performed full neuropathologic evaluations to confirm the normal status of the brain or the presence of AD. RESULTS: The authors found no significant association of AD with the number, surface area or history of having dental amalgam restorations. They also found no statistically significant differences in brain Hg level between subjects with AD and control subjects. CONCLUSIONS: Hg in dental amalgam restorations does not appear to be a neurotoxic factor in the pathogenesis of AD. The authors found that brain Hg levels are not associated with dental amalgam, either from existing amalgam restorations or according to subjects' dental amalgam restoration history. CLINICAL IMPLICATIONS: Dental amalgam restorations, regardless of number, occlusal surface area or time, do not relate to brain Hg levels.

Adult↗
PubMed1994

[Amalgam. XVII. Associations between views on dental amalgam and other variables].

Bivariate associations between views on amalgam in the Netherlands and other variables, such as preventive health measures and environmental ones, information on amalgam in the mass media, knowledge of the composition of amalgam, socio-demographic variables, visits to alternative healers, regularity of dental attendance, number of teeth, etcetera, appear in general to be low, yet significant, and even very low.

Attitude to Health↗
PubMed1989

[Antibacterial properties of two conventional and two high copper dental amalgams].

Two conventional and two high copper dental amalgams (Non gamma 2) has been investigated for their antibacterial properties. The high copper dental amalgam, Ana 2000 possessed a very small range of antibacterial propertie against Lac. acidophilus and Staph. epidermidis, while other amalgams found to have no antibacterial activity against the ten tested microorganism strains.

Bacteria↗