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PubMed1990

[Amalgam fillings and T-lymphocyte changes].

Dental amalgam and nickel alloys have been considered quite safe. Previous authors reported the effect of dental amalgam and nickel alloys on human T-lymphocytes modifications after amalgam dental fillings, into dose-dependence of any modifications and into possible temporary. Eight patients were subjected to dental care with amalgam dental fillings. Drawings of blood were executed at start, fifteen days after late fillings and two months later. The results about modifications of T-lymphocytes were not univocal. We believe, at now, that temporary modifications of the immunity seem to be related to a cytotoxic mechanism.

Adolescent↗
PubMed1996

Corrosion of amalgams under sliding wear.

OBJECTIVES: During mastication, dental amalgams are simultaneously subjected to corrosion by the oral environment and to a sliding-wear process by biting forces. In the present study, the effect of sliding wear on the corrosion behavior of two high-copper dental amalgams was investigated. METHODS: An experimental apparatus was utilized that allows electrochemical testing under sliding-wear conditions. Corrosion potential measurements and anodic polarization scans were conducted in 0.1 M NaCl solution under sliding wear to characterize the behavior of two commercial, high-copper, single composition dental amalgams. In addition, long duration tests were conducted to assess possible corrosion and wear synergistic effects. RESULTS: The results showed that sliding wear caused a sharp reduction in the corrosion potential, a significant increase in the corrosion rate and a decrease in the repassivation rate of both amalgams. These effects are due to the mechanical removal by the wear process of the surface protective film formed on dental amalgams. The simultaneous action of sliding wear and corrosion can also induce embrittlement that leads to cracking. SIGNIFICANCE: The present evidence suggests that this cracking may be one of the major contributors to marginal failures of dental amalgam restorations.

Copper↗
PubMed1998

[Illnesses caused by amalgam?].

BACKGROUND: As side effects of dental amalgam have been mentioned allergy, oral lichen, electro-galvanism, amalgam tattoos of gingiva or oral mucosa, and undesirable esthetics. Patients with amalgam restorations show increased mercury levels in different body fluids compared to amalgam-free controls. An intoxication due to dental amalgam fillings, however, is not to be expected-despite equivocal statements in the literature. SCIENTIFIC RESULTS: In contrast, recent studies revealed that dental amalgam contributes to mercury exposure less than assumed few years ago. Therefore, amalgam will stay an option as a restorative material in future. The removal of intact amalgam fillings in the intention of "detoxification" is not science-based. CONCLUSION: Successful caries prevention (e.g. due to the widespread use of fluoride) and the further development of esthetic restorative materials based on composite resins will limit the utilisation of amalgam. Thus, alternative materials have not been shown to have a lower rate of side effects (e.g. allergy) compared to amalgam.

Dental Amalgam↗
PubMed2000

The value of extended-setting-time amalgam in pre-clinical practice in undergraduate dental training.

This is a single-blind controlled study investigating the advantages of extended-setting time dental amalgam compared to a standard amalgam in the training of undergraduate dental students. 50 dental students were randomly assigned 1 of the 2 alloys for each restoration placed in the study. Each student placed class I and class II restorations in extracted human teeth mounted in typodont arches. 449 completed restorations were available for assessment, 228 restorations in the experimental group and 221 restorations in the control group. The test restorations were overall marginally inferior to those of the control group. There appears to be no advantage in using extended-setting time dental amalgam in undergraduate training.

Dental Amalgam↗
PubMedDate not supplied

Microleakage of bonded amalgam restorations: effect of thermal cycling.

This study examined the effect of thermal cycling on the microleakage of bonded amalgam restorations. Three dental amalgam alloys and a gallium alloy were tested with two adhesive resin systems and copal varnish as a control. Class V cavity preparations were prepared on 168 freshly extracted premolars or molars. The preparations were placed parallel to and 1.0 mm occlusal to the cementoenamel junction (CEJ). Four groups of 42 teeth each were treated with one of the following adhesive dentin systems: Bond-It, All-Bond 2/Resinomer or a copal varnish (Copalite). The four groups of 42 teeth each were then restored with one of three dental amalgams: Orosphere Plus, Indiloy, Oralloy or a Gallium alloy (Galloy), resulting in 12 test groups of 14 teeth each. The specimens were stored in double distilled water at 37 degrees C for 24 hours. Final contouring and polishing of the restorations were performed under water spray. Half of the restorations in each group were thermocycled for 3000 cycles (5 degrees C-37 degrees C-55 degrees C-37 degrees C) with a dwell time of 15 sec at each temperature. The other half were stored in double distilled water at 37 degrees C for 24 hours. Then all 168 restorations were stained with dye, sectioned and scored for microleakage. Results showed that the adhesive dentin systems reduced microleakage in amalgam restorations compared to copal varnish only in non-thermocycled specimens. Statistical analysis of the results showed that there was an extremely significant difference (p < 0.001) in microleakage between the non-thermocycled and the thermocycled specimens in all test groups, whereas, there was no significant difference (p > 0.05) among thermocycled specimens. The reduction of microleakage was not significantly different between Bond-It and All-Bond 2/Resinomer in non-thermocycled specimens. Oralloy showed the most microleakage in the non-thermocycled groups when compared to the other alloys using the same adhesive liner.

Analysis of Variance↗
PubMed2006

Amalgam waste management.

Dental amalgam has been extensively used as a tooth filling material for many decades and has beyond doubt saved millions of teeth that otherwise would have needed to be extracted. The release of amalgam particles into dental office wastewater is a matter of particular concern as amalgam particles could then be discharged into the environment. Amalgam waste discharges contribute to mercury in the environment through direct wastewater discharge, incineration, land-filling and sewage sludge incineration, although the discharge from dentistry is probably responsible for less than 1% of the total mercury discharged annually into the environment as a result of human activities. Nevertheless, dentists, by being producers of amalgam waste, have a responsibility and a duty of care for the proper management of this waste within their practices. Appropriate measures should be taken to minimise the amount of waste where possible or take action to ensure that all generated waste is disposed of in accordance with environmental legislation.

American Dental Association↗
PubMed1976

[Resistance to traction forces in different brands of amalgam].

In a previous study the initial tensile strength of several dental amalgams after 15 minutes has been investigated. The present study scrutinized a large number of dental amalgams for the tensile strength after 15 minutes up to 60 minutes. All the dental amalgam specimens used in this study were prepared according to A.D.A. specification no. 1. The results obtained from this study show that out of the twenty three dental amalgams only approximately the half conformed to the minimum value of 2.0 MN/m2 as required for the tensile strength after 15 minutes by A.D.A. specification no. 1. Contrary to the results obtained by other investigators, the dental amalgam obtained from the spherical type of alloys does not acquire a superior initial strength in comparison with those from the conventional types of amalgam alloys. In this study the new dental amalgam alloy Indiloy (n.z.) (Shofu Corporation, Japan) demonstrated a superior tensile strength for all the testing times. If the tensile strength after 15 minutes is taken as a selection criterion, the five best alloys in this investigation are Indiloy (n.z.), Optalloy II, Micro II, Revalloy and Cavex SF. If the previous study is considered likewise. Dispersalloy (fast setting form) should be taken into account as well.

Dental Amalgam↗
PubMed1985

Maximum contents of mercury in dental silver amalgams.

The maximum content of mercury forming intermetallic compounds has been determined in dental amalgams prepared from alloys with different copper contents. In amalgams made from alloys with silver contents less than about 42% there is a risk of occurrence of free mercury if an effective condensation technique has not been used.

Copper↗
PubMed1999

No evidence for specific in vitro lymphocyte reactivity to HgCl2 in patients with dental amalgam-related contact lesions.

Blood lymphocytes from 20 patients with oral contact lesions to dental amalgam and 10 healthy individuals were analyzed for HgCl2-induced proliferation in vitro, using both a modified assay and a conventional assay. The release of interferon-gamma (IFN-gamma) was measured in cell supernatants. Six patients displayed positive reactions in patch tests to mercuric compounds. No significant differences were recorded in HgCl2-induced proliferation in cells from patients and controls, since only few in the whole material responded to submitogenic concentrations. IFN-gamma was detectable in cell supernatants from some patients but also from controls and is not predictive of mercury allergy. Neither the phenotypes of peripheral lymphocyte subsets, the frequency of circulating cells expressing the interleukin-2 (IL-2) receptor, spontaneous lymphocyte proliferation nor concentrations of serum interleukin-6 differed between patient and control samples. In contrast to what has been claimed before, we did not find any evidence for specific in vitro lymphocyte reactivity in patients with oral contact lesions.

Adult↗