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Results for “DENTAL AMALGAM”

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PubMed1987

Correlation of dental amalgam with mercury in brain tissue.

Data from this project demonstrate a positive correlation between the number of occlusal surfaces of dental amalgam and mercury levels in the brain (p less than .0025 in white matter). This is indirect evidence suggesting that mercury from dental amalgam fillings may contribute to the body burden of mercury in the brain. The toxic levels of mercury in human tissues have not been sufficiently investigated and the amount of mercury in human brain tissue from dental amalgam may or may not be clinically significant. Nevertheless, dental amalgam exposure should be considered in monitoring sources of mercury accumulation in human brain tissue.

Adolescent↗

PubMed2001

Use of inductively coupled plasma-emission spectroscopy and mercury vapor analyses to evaluate elemental release from a high-copper dental amalgam: a pilot study.

STATEMENT OF PROBLEM: The use of dental amalgam as a direct restorative material has been a subject of controversy for many years. The potential safety of amalgam has been questioned because of leakage of elements such as mercury, copper, tin, and silver. PURPOSE: This study evaluated the elemental leaching from Tytin dental amalgam placed in deionized water for 2 months. Both mercury vapor and elemental (silver, copper, tin, and mercury) analyses were performed. MATERIAL AND METHODS: Two capsules of Tytin amalgam were triturated (one for the precipitate and liquid analysis, and the other for the mercury vapor analysis) and stored in a polypropylene tube with 10 mL deionized water for 60 days at room temperature. The amalgam pellet then was removed and rinsed with deionized water. The resulting liquid was separated from a precipitate, and 2 separate analyses were run: one on the liquid without any precipitate and another on the precipitate. Elemental analyses for copper (Cu), tin (Sn), mercury (Hg), and silver (Ag) were determined by inductively coupled plasma-emission spectroscopy with a Perkin-Elmer P2000 spectrometer. Mercury vapor analyses were performed daily for 60 days with a Jerome 431-X vapor analyzer. RESULTS: The maximum amount of copper (80 microg), silver (2.6 microg), mercury (15 microg), and tin (550 microg) was found in the precipitate. The maximum amount of mercury vapor released was 67 microg/m(3)/d. CONCLUSION: Under the conditions of this in vitro study, there was a significant amount of elemental leaching and mercury vapor release from the Tytin amalgam over a 60-day period.

Chemical Precipitation↗

PubMed1995

A comparative electrochemical in vitro evaluation of the corrosion behaviour of dental amalgams.

The electrochemical corrosion behaviour of 16 currently marketed amalgams for dental fillings was studied in vitro. Depending upon the type of amalgam and the treatment of the filling the electrochemical corrosion currents derived from cyclic voltammograms varied over several orders of magnitude. Their change as a function of time was also very different. Suggestions are made for a stability rating of the products based on the results obtained.

Corrosion↗

PubMed1980

Electrochemical characteristics of the S.I.A. dental amalgam cavity liner.

Selective interfacial amalgamation (S.I.A.) has been developed as a dental amalgam cavity liner with the intent of increasing the restoration-tooth adhesion and reducing the debilitating effects of corrosion and marginal leakage. This paper examines the S.I.A. liner's effectiveness as a corrosion preventive cavity liner by two experimental techniques: anodic polarization and differential aeration tests. The results from these tests indicate that S.I.A. does enhance the corrosion resistance of a dental amalgam.

Corrosion↗

PubMed1993

The release, absorption and possible health effects of mercury from dental amalgam: a review of recent findings.

Recently many articles have appeared on the subject of mercury from dental amalgam and some of these have questioned its safety as a dental material. This article reviews critically the evidence on mercury release from dental amalgam restorations, its absorption, accumulation and excretion by the body, and its possible relationship to ill-effects. Finally, brief recommendations are given for the handling and usage of dental amalgam.

Abnormalities, Drug-Induced↗

PubMedDate not supplied

Effect of replacement of dental amalgam on oral lichenoid reactions.

OBJECTIVES: The objectives of this study were to investigate (i) healing of oral lichenoid reactions (OLR) following the selective replacement of restorations of dental amalgam, (ii) whether there were differences in healing between contact lesions (CL) and oral lichen planus (OLP), and (iii) whether there was a difference in healing potential when different materials were selected as a substitute for dental amalgam. METHODS: Patients included in the study presented with OLR confined to areas of the oral mucosa in close contact with amalgam restorations (CL; n = 142) or with OLR which involved other parts of the oral mucosa as well (OLP; n = 19). After examination, restorations of dental amalgam which were in contact with OLR in both patient groups were replaced. The effect of replacement was evaluated at a follow-up after 6-12 months. RESULTS: In the CL group, the lesions showed a considerable improvement or had totally disappeared in 95% of the patients after replacement of the restorations of dental amalgam (n = 474). This effect was paralleled by a disappearance of symptoms, in contrast to patients with persisting CL (5%) who did not report any significant improvement. The healing response was not found to correlate with age, gender, smoking habits, subjective dryness of the mouth or current medication. However, the healing effect in patients who received gold crowns was superior compared to that of patients treated with metal-ceramic crowns (MC; P < 0.05). In the OLP group (n = 19), 63% of the patients with amalgam-associated erosive and atrophic lesions showed an improvement following selective replacement. OLP lesions in sites not in contact with amalgams were not affected. Most of the patients (53%) with OLP reported symptoms also after replacement. CONCLUSION: From these data it can be concluded that the vast majority of CL resolve following selective replacement of restorations of dental amalgam, provided that a correct clinical diagnosis is established. It is also noteworthy that MC crowns did not facilitate healing of CL to the same extent as gold crowns.

Adult↗

PubMed1990

Effectiveness of sterilisation and disinfection procedures for dental amalgam carriers.

The potential for cross infection through dental amalgam carriers was investigated in 37 Dunedin dental practices and in the University of Otago School of Dentistry. Eighteen practitioners had autoclavable carriers, but only 2 autoclaved them at least daily. The School of Dentistry disinfected plastic carriers and autoclaved metal carriers. Microbiological examination, by culturing from the most commonly contaminated carrier site, showed that the School of Dentistry method for disinfection of plastic carriers was unreliable. Autoclaving was confirmed as the preferred method of sterilisation, but many existing carriers are not suited to this technique.

1-Propanol↗

PubMed1997

The future of dental amalgam: a review of the literature. Part 7: Possible alternative materials to amalgam for the restoration of posterior teeth.

This is the last in a series of articles on the future of dental amalgam. It considers possible alternative materials to amalgam for the restoration of posterior teeth. The materials discussed are gold inlays, gold foil, gallium alloys, and tooth coloured non-metal alternatives including glass-ionomer cements, composite resins, glass-ionomer-resin hybrids, compomers and ceramics. The clinical indications for these restorations are first described along with their potential clinical problems and their mean survival rates in comparison with dental amalgam. Secondly, the safety of composite resins is considered and potential toxic and hypersensitive effects of these materials are discussed. Finally, it is concluded that the present evidence does not appear to demonstrate that dental amalgam is hazardous to the health of the general population. It does, however, recommend that in continuing to use amalgam dentists must use strict mercury hygiene procedures to avoid risk to their staff and contamination of the environment. It seems that mercury contamination of the environment is likely to be the main reason for any future government action against the continued clinical use of dental amalgam.

Air Pollutants, Occupational↗

PubMed1989

Effect of admixed indium on mercury vapor release from dental amalgam.

The purpose of this study was to evaluate the effect of admixed indium on the amount of mercury vapor released from dental amalgam. We made amalgam specimens according to ADA Specification Number 1. We added various amounts (0-14% by weight) of indium to the alloy powder. We also tested the commercial amalgams Dispersalloy, Valiant, and Indiloy. Specimens were held at 37 degrees C and 100% humidity. We used a Jerome Mercury Vapor Analyzer (model 411) to measure the mercury vapor released. We analyzed the data by means of ANOVA and Student-Newman-Keuls procedures. Admixed indium significantly decreased the amount of mercury vapor released from dental amalgams; the period of the greatest effect on mercury vapor released was during the setting phase of amalgam; and dental amalgams with greater than or equal to 8% admixed indium released the least amount of mercury vapor.

Air Pollutants↗

PubMed1965

DENTAL AMALGAM.

Explore the source record for details and available documents.

Copper↗

PubMed1985

Serial measurements of intra-oral air mercury: estimation of daily dose from dental amalgam.

Serial measurements of Hg concentration in intra-oral air were made during and after chewing stimulation in 35 subjects with occlusal amalgam restorations. Hg concentrations remained elevated during 30 min of continuous chewing and declined slowly over 90 min after cessation of chewing. By curve-fitting and integration analysis of data during these time periods (including corrections for respiratory volume, retention rate of inspired Hg, oral-to-nasal breathing ratios, and consumption of three meals and three snacks per day), we calculated that all subjects received an average daily Hg dose of approximately 20 micrograms. Subjects with 12 or more occlusal amalgam surfaces were estimated to receive a daily Hg dose of 29 micrograms, whereas in subjects with four or fewer occlusal amalgam surfaces, the dose was 8 micrograms. These Hg dosages from dental amalgam were as much as 18-fold the allowable daily limits established by some countries for Hg exposure from all sources in the environment. The results demonstrate that the amount of elemental Hg released from dental amalgam exceeds or comprises a major percentage of internationally accepted threshold limit values for environmental Hg exposure. It is concluded that dental amalgam Hg makes a major contribution to total daily dose.

Air↗

PubMed1992

Factors influencing mercury evaporation rate from dental amalgam fillings.

Factors influencing mercury evaporation from dental amalgam fillings were studied in 11 volunteers. Air was drawn from the oral cavity for 1 min and continuously analyzed with a mercury detector. In six volunteers the median unstimulated evaporation rate was 0.1 ng Hg/s, range 0.09-1.3 ng Hg/s. After chewing gum for 5 min the highest evaporation rate was 2.7 ng Hg/s. Chewing paraffin wax gave only a small increase in evaporation rate. Changes in airflow rates between 1.5 and 2.5 1/min during the 1 min sampling did not change the amount of mercury drawn from the oral cavity. Sampling with different mouthpieces and closed mouth was compared to open mouth sampling with a thin plastic tube. It was found that the latter method could result in lower values for some volunteers due to simultaneous mouth breathing. After placing individual plastic teeth covers in the mouth, the intraoral evaporation of mercury decreased immediately by 89-100% of previous levels. This technique could be used to detect mercury evaporation from separate amalgam fillings or to reduce the intraoral mercury vapor concentration. Rinsing the mouth with heated water for 1 min increased the mean evaporation rate by a factor of 1.7 when the water temperature increased from 35 degrees C to 45 degrees C.

Adult↗

PubMed1990

[Biocompatibility of dental amalgam].

The purpose of the present review was to present a detailed description of those current scientific results and opinions relative to the biocompatibility of dental amalgam. The first section of the percent review to the pulpar reactions caused by amalgam fillings, especially when no protective base has been used, while the second part concerns itself with the biocompatibility of the dental amalgam per se. Specifically, reference is made to: a) the adverse reactions due to amalgam fillings both on the patient's physiological system and on the dentist's employing the material under consideration. b) those investigation results bearing a relation on the amount of mercury liberated during the amalgam filling procedures, i.e., mixing, condensation, finishing and polishing and/or removal of old amalgam fillings. c) Liberation of mercury, as well as metallic ions in the patients mouth cavity during chewing and/or during the process of intrabuccal galvanization and corrosion, and d) on the amount of mercury traced in the blood and urine of the patient following amalgam fillings. No conclusive evidence on any adverse reactions on the patient's health, attributable to the liberation of mercury from amalgam fillings, could be presented by the scientific investigations under consideration. Moreover, the number of cases reported on toxic reactions due to dental amalgam is negligible compared to the immense number of amalgam fillings performed in practice. It merits mentioning in this connection, however, the fact that the total amount of mercury attained by the patient from any other source, in conjunction with that liberated from amalgam fillings, could by all means contribute to a number of toxic reactions on the patient's health in general. Conclusively, one could state without reservations, that dental amalgam fillings per se are by and large free of toxic reactions on the patient, based on current scientific observations. Mentioning is finally made on several simple but nevertheless imperative precautions for the safety of public health.

Biocompatible Materials↗

PubMed1992

Side-effects: mercury contribution to body burden from dental amalgam.

The purpose of this paper is to examine and report on studies that relate mercury levels in human tissues to the presence of dental amalgams, giving special attention to autopsy studies. Until recently, there have been few published studies examining the relationship between dental amalgams and tissue mercury levels. Improved and highly sensitive tissue analysis techniques have made it possible to measure elements in the concentration range of parts per billion. The fact that mercury can be absorbed and reach toxic levels in human tissues makes any and all exposure to that element of scientific interest. Dental amalgams have long been believed to be of little significance as contributors to the overall body burden of mercury, because the elemental form of mercury is rapidly consumed in the setting reaction of the restoration. Studies showing measurable elemental mercury vapor release from dental amalgams have raised renewed concern about amalgam safety. Mercury vapor absorption occurs through the lungs, with about 80% of the inhaled vapor being absorbed by the lungs and rapidly entering the bloodstream. Following distribution by blood circulation, mercury can enter and remain in certain tissues for longer periods of time, since the half-life of excretion is prolonged. Two of the primary target organs of concern are the central nervous system and kidneys.

Alzheimer Disease↗

PubMed1997

The future of dental amalgam: a review of the literature. Part 4: Mercury exposure hazards and risk assessment.

This is the fourth article in a series of seven on the future of dental amalgam. It first describes toxic mercury hazards from all sources of exposure including dental amalgam. It begins by considering the many problems in accurately estimating daily mercury intakes from these sources. It then describes potential mercury hazards to industrial workers and the calculation of thresholds for the general public from industrial data. The implications of these findings to the production of a safe threshold for patients with dental amalgams are then discussed. It finally discusses the attempts which have been made to carry out a risk assessment of dental amalgam. In this connection it reports the reviews of the United States Public Health Service in 1993, the Swedish National Board of Health and Welfare in 1994 and the risk assessment commissioned from Canada Health which was reported in 1995. It also includes comments on the methods used in this last report.

Adolescent↗

PubMedDate not supplied

[Dental amalgams and urine elimination of mercury in workers exposed to low concentrations of inorganic mercury].

The aim of the research was to assess the contribution of dental amalgams and other non-occupational factors of exposure to inorganic mercury (diet, etc.) to the quantity of mercury excreted with urine in workers exposed to low level concentrations of inorganic mercury. Two groups of workers (Groups I and II) were studied who were exposed to low and different environmental concentrations of inorganic mercury. These two groups were compared with a group of subjects not occupationally exposed to mercury in the same geographical area (Group III). All subjects were administered a questionnaire concerning personal data, lifestyle, recent removal and/or insertion of dental amalgam fillings, presence of nasal obstruction or bruxism and consumption of fish. The number of amalgam-filled teeth was established for each subject. Mean environmental exposure to inorganic mercury was 0.0087 mg/m3 for Group I and 0.0030 mg/m3 for Group II. Urinary excretion in the 3 groups was 4.2 +/- 2.8 micrograms/l for Group I, 3.0 +/- 2.1 micrograms/l for Group II and 1.6 +/- 1.2 micrograms/l for Group III. The results showed that of the factors of exposure to inorganic mercury, only occupational exposure (T = 9.18; p = 0.000) and the number of amalgam-filled teeth (T = 2.03; p = 0.043) were able to influence significantly urinary excretion of mercury; the sources of non-occupational exposure did not appear to play any role. The contribution of each amalgam filling to urinary mercury excretion was calculated to be 0.08 microgram/l. Occupational exposure therefore, even at low level doses, is still the main cause of urinary mercury excretion in workers exposed to inorganic mercury; of the non-occupational exposure factors, a significant role is played by amalgam dental fillings, whose contribution needs to be taken into consideration in order to make a correct interpretation of the results of biological monitoring of exposed workers.

Adult↗

PubMed1985

Intra-oral air mercury released from dental amalgam.

Intra-oral air was analyzed for mercury (Hg) vapor concentration in 46 subjects, 35 of whom had dental amalgam restorations. Measurements were made with a Jerome Hg detector both before and ten min after chewing stimulation. Subjects with dental amalgams had unstimulated Hg vapor concentrations that were nine times greater than basal levels in control subjects with no amalgams. Chewing stimulation in subjects with amalgams increased their Hg concentration six-fold over unstimulated Hg levels, or a 54-fold increase over levels observed in control subjects. Concentrations of Hg measured in intra-oral air larger than those reported in expired air were attributed to the rate and direction of air passage across amalgam surfaces. There were significant correlations between Hg vapor released into intra-oral air after chewing stimulation and the numbers and types of amalgam restorations. It is concluded that intraoral air is a reliable physiological indicator of Hg released from dental amalgam that may reflect a major source of chronic Hg exposure.

Air↗

PubMed1989

A model for the corrosion behavior of dental amalgams.

At high frequencies, electrochemical impedance behavior for corroding dental amalgams cannot be interpreted in terms of a simple Randles equivalent circuit. This may often be ascribed to the imperfect cell geometry resulting in a nonuniform current distribution. However, the insertion of a constant phase element (CPE) in the non-faradaic branch of the equivalent circuit offers a new scope for interpretation as the circuit provides an m-parameter corresponding to the degree of distortion. The decrease of m as a function of time was explained by a mathematical model reflecting an increasing number of pores. Moreover, that same model allows a better understanding of the passivating effect of NaHCO3 and of the differences between conventional and Cu-rich dental amalgams.

Biocompatible Materials↗