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PubMedDate not supplied

The influence of amalgam fillings on urinary mercury excretion in subjects from Apulia (southern Italy).

The purpose of this study was to assess the role of dental amalgams and diet upon urinary mercury (U-Hg) excretion. 98 subjects (50 men and 48 women) not exposed to inorganic mercury, for either occupational or environmental reasons, and living in coastal and inland districts of Apulia (Southern Italy) were considered. All the subjects were administered a questionnaire with questions concerning life style, medical history, and occupational activity. Dental amalgams were evaluated with respect to their number and their surface areas. Urinary mercury was measured by the cold vapour atomic absorption technique. Expressed in terms of arithmetic mean, U-Hg excretion was found to amount to 1.03 micrograms/g creatinine (5th and 95th percentile: 0.31 and 2.40; range 0.30-3.25). Multiple linear regression analysis showed that, of the several tested independent variables (dental amalgams, age, body mass index, consumption of tuna, bass, swordfish, etc.), only the number of amalgam fillings (T = 5.25; p = 0.025) and the number of restored surfaces (T = 2.33; p = 0.020) were found liable to affect urinary mercury excretion in a significant manner. In conclusion, the results of this study confirm the primary role of amalgam fillings in affecting urinary mercury excretion in those subjects who are not occupationally exposed to inorganic mercury, The resulting urinary mercury levels can no doubt be taken as the reference values for the population of Apulia.

Adolescent↗
PubMed2001

Mercury and selenium concentrations in maternal and neonatal scalp hair: relationship to amalgam-based dental treatment received during pregnancy.

Mercury and selenium concentrations were determined in scalp hair samples collected postpartum from 82 term pregnancy mothers and their neonates. Maternal mercury and selenium had median concentrations of 0.39 microg/g (range 0.1-2.13 microg/g) and 0.75 microg/g (range 0.1-3.95 microg/g), respectively, and corresponding median neonatal values were 0.24 microg/g (range 0.1-1.93 microg) and 0.52 microg/g (range (0.1-3.0 microg/g). Amalgam-based restorative dental treatment received during pregnancy by 27 mothers (Group I) was associated with significantly higher mercury concentrations in their neonates (p < 0.0001) compared to those born to 55 mothers (Group II) whose most recent history of such dental treatment was dated to periods ranging between 1 and 12 yr prior to pregnancy. In the Group I mother/neonate pairs, amalgam removal and replacement in 10 cases was associated with significantly higher mercury concentrations compared to 17 cases of new amalgam emplacement. Selenium concentrations showed no significant intergroup differences. However, the selenium/mercury molar ratio values were lowest in the Group I neonates, compared to their mothers and to the Group II mother/neonate pairs. This ratio decreased as mercury concentration increased, and this interrelation was statistically significant in both groups of mother/neonate pairs. The data from this preliminary study suggest that amalgam-based dental treatment during pregnancy is associated with higher prenatal exposure to mercury, particularly in cases of amalgam removal and replacement. The ability of a peripheral biological tissue, such as hair, to elicit such marked differences in neonatal mercury concentrations provides supporting evidence of high fetal susceptibility to this form of mercury exposure. The data are discussed in relation to the differences between maternal and fetal mercury metabolisms and to mercury-selenium metabolic intereactions in response to mercury exposure.

Dental Amalgam↗
PubMed1989

New dynamic corrosion test for dental materials.

A new laboratory technique has been developed in an effort to simulate the deterioration processes occurring in dental amalgam restorations while they are exposed to attack by the oral environment and simultaneously subjected to biting forces during mastication. This combined mechanical wear and corrosion action may be one of the major contributors to the degradation of dental amalgam restorations. The technique provides the capability of varying and measuring electrochemical and mechanical parameters during a sliding-wear process in a corrosive environment. A high-copper dental amalgam was selected and tested to demonstrate the applicability of the method in evaluating and studying the effects of the combined action of wear and corrosion processes on dental materials. For the particular amalgam material tested in the present study, it was found that sliding-wear significantly lowered its corrosion potential and increased corrosion rates by at least one order of magnitude.

Copper↗
PubMedDate not supplied

[Evaluation of the dose of mercury in exposed and control subjects].

OBJECTIVES: The aim of this paper was to analyse the concentrations of HgU and HgB in three different groups: 122 workers exposed, 18 workers formerly exposed and 196 subjects not occupationally or environmentally exposed to mercury. METHODS: All the subjects filled out a questionnaire concerning personal data, lifestyle, occupational or non-occupational exposure to Hg and medical history. The amalgam fillings area was measured by a standardised method. RESULTS: Urinary mercury excretion was significantly greater in the group of the exposed workers respect to the group of subjects not occupationally exposed (Median value of 8.3 micrograms/g creatinine and the 5 degrees and 95 degrees percentile respectively of 2.66 e 23.50 micrograms/g creatinine against Median value of 1.2 micrograms/g creatinine and the 5 degrees and 95 degrees percentile respectively of 0.18 and 5.42 micrograms/g creatinine). U-Hg in formerly exposed workers were comparable to U-Hg in non-occupationally exposed subjects, with a median value of 1.6 micrograms/g creatinine. B-Hg values were similar in the three groups: the median value was 3.1 micrograms/l in the non-occupationally exposed, 4.0 micrograms/l in the exposed workers and 3.9 micrograms/l in the past exposed. These value were not significantly different. Among the considered variables (amalgam fillings, fish consumption, age, sex, alcohol intake, chewing-gum and smoking) dental amalgam and fish consumption were significantly related with the Hg urinary excretion and the B-Hg levels. This is particularly true considering the subjects altogether: for the exposed workers, indeed, the occupational exposure was the most relevant variable. CONCLUSIONS: The results of the present research confirmed that the U-Hg excretion in non-occupationally exposed subjects is influenced by amalgam dental fillings. Furthermore, in our study Hg urinary excretion was significantly related with fish consumption. This fact can be explained, according to several recent experimental human and animal trials, considering that methylmercury contained in fish is partially converted, through breakage of the carbon-Hg bond, into Hg inorganic forms, which accumulate in the kidney and have a urinary excretion pathway.

Absorption↗
PubMed1984

Toxic effects of Cu implants on liver.

In an effort to identify possible systemic effects due to dissolution of Cu from the experimental use of dental amalgam, specimens of pure Cu and several dental amalgams containing various concentrations of Cu were implanted into the peritoneal cavity of rats for 4 weeks. Concentrations of Cu in the liver varied from 33.3 to 156.2 micrograms Cu/dry g of liver tissue after implantation of the Cu-containing amalgams. Histopathological changes in the liver confirmed the presence of Cu within the lysosomes of hepatocytes. The histopathological and chemical changes in the liver after implantation indicated the need for subsequent investigations of long-term systemic toxicity to the use of Cu-containing implants.

Animals↗
PubMed1990

Cuspal flexure associated with amalgam restorations.

Cavity preparation causes cuspal flexure under simulated occlusal loads. During amalgam condensation, the dentist exerts forces on the tooth. After condensation, dental amalgam undergoes dimensional changes. We measured possible changes in the cuspal position of premolars during and after their restoration with dental amalgam. Strain gauges were attached to the buccal surfaces of the teeth, and a direct reading of the strain and a simultaneous time-strain curve were obtained. Measurements were taken at the onset of amalgam condensation and continued for 24 hours. The amalgam was then removed from the teeth, and a subsequent reading was made. On the basis of this model, we found that the use of amalgam as a restorative material caused a static load on the cusps of the teeth brought about their consequent permanent deformation. After amalgam removal, we observed complete elastic recovery for all the treated teeth.

Biomechanical Phenomena↗
PubMedDate not supplied

In vitro comparison of the shear bond strength of amalgam to tooth structure using two bonding agents--lutting glass ionomer and 4-META.

Bonding dental amalgam to tooth structure using 4-META has become an accepted clinical procedure. Glass ionomer cements possess the ability to bind to tooth structure as well as to the components of dental amalgam. The present in vitro study evaluates the shear bond strength of amalgam to tooth structure using luting glass ionomer as a bond mediating agent, and compares with that obtained using 4-META. Results indicate that it is possible to bond amalgam to tooth structure using a thin layer of glass ionomer cement. The shear bond strength of glass ionomer cement mediated bond is significant and may be adequate for clinical application.

Bicuspid↗
PubMed1998

Mercury concentrations in urine and whole blood associated with amalgam exposure in a US military population.

Minute amounts of mercury vapor are released from dental amalgams. Since mercury vapor is known to be associated with adverse health effects from occupationally exposed persons, questions regarding the margin of safety for exposure to mercury vapor in the general population continue to be raised. To address this issue, one needs information regarding exposure to mercury vapor from dental amalgam fillings and its possible consequences for health in the general population. The NIDR Amalgam Study is designed to obtain precise information on amalgam exposure and health outcomes for a non-occupationally-exposed population of US adults. One hypothesis was that in a generally healthy population a significant association between amalgam exposure and Hg levels in urine and/or whole blood could be detected. The cohort investigated was an adult military population of 1127 healthy males. Their average age was 52.8 years, and their ages varied from 40 to 78 years. Ninety-five percent of the study participants were white males, and slightly over 50% had some college education. Five percent were edentulous. The dentate participants, on average, had 25 natural teeth, 36.9 decayed or filled surfaces (DFS), and 19.9 surfaces exposed to amalgam, with amalgam exposure varying from 0 to 66 surfaces. Their average total and inorganic urinary mercury concentrations were 3.09 microg/L and 2.88 microg/L. The average whole-blood total and inorganic mercury concentrations were 2.55 microg/L and 0.54 microg/L. Significant correlations were detected between amalgam exposure and the total (r = 0.34, p < 0.001) and inorganic 0.34 (r = 0.34, p < 0.001) urinary mercury concentrations on the original scale. Stronger correlations were found for total (r = 0.44, p < 0.001) and inorganic (r = 0.41, p < 0.001) urinary Hg on the log scale, as well as for creatinine-corrected total (r = 0.43, p < 0.001) and inorganic (r = 0.43, p < 0.001) urine concentrations. In whole blood, statistically significant, but biologically weak, correlations were detected for total (r = 0.09, p = 0.005) and inorganic (r = 0.15, p < 0.001) Hg concentrations, respectively. Based on these cross-sectional data, it is estimated that, on average, each ten-surface increase in amalgam exposure is associated with an increase of 1 microg/L mercury in urine concentration.

Adult↗