Mercury

“Exposure of the neonate to toxic metals occurs because of their presence in foods and the human biosphere. Nursing infants may ingest these metals in mother’s milk. After weaning, their presence in formula, cow’s milk and weanling foods is of major importance. Additional environmental metal contaminant sources become important when the infants begin to creep on the floor and have access to objects which they can chew or mouth. Infants are at particular hazard when their environment is contaminated by vapors, by metal-containing dust and particulate fallout or entrainment on articles brought into the home, or by building materials, such as plaster or lead-containing paints.”

“This report is a critical evaluation of the use of dental amalgam with special consideration of the possibility of chronic mercury poisoning. The description of psychic and somatic symptoms associated with corrosion of amalgam might help people with similar symptoms to recognize the possible source of their problems. Medical practitioners need to recognize the characteristic manifestations of mercury poisoning and it is also my hope that this report might help dentists to a better understanding of the hazards of amalgam and combinations of metals.”

“The capacity of the oral bacteria Streptococcus mitior, S. mutans and S. sanguis to methylate mercury was investigated in vitro. Mercuric chloride and pulverized dental amalgam in distilled water, respectively, were used as sources of mercury. Methylmercury was found in the bacterial cells of all three tested strains. The results indicate that organic mercury compounds may be formed in the oral cavity.”

“29 patients with oral lichen planus and amalgam fillings were patch tested for contact allergy to dental materials. 18 of these patients (62%) had a contact allergy to mercury. In a control material, the frequency of mercury allergy was 3.2%. In 3 of the patients the lesions healed completely after removal of the amalgam fillings. On the basis of these findings it is recommended that all amalgam fillings be removed after a positive patch test to mercury, as a step in the treatment of oral lichen planus.”

“Fifty-seven prenatal patients with no known exposure to the element mercury, or any of its compounds, were observed for change in whole blood total mercury concentration from the initial prenatal clinic examination through delivery and postpartum hospitalization. On hospital admission for labor and delivery, whole blood total mercury averaged 1.15 parts per billion (ppb), compared to 0.79 ppb from the first prenatal clinic visit; these levels represent a 46% increase and significant difference in maternal concentration of a substance previously recognized for its peculiar ease at crossing the placental barrier. Previous stillbirths, as well as history of birth defects, exhibited significant positive correlation with background mercury levels. Search of the literature of the last 5 years revealed no other report of cohort heavy metal surveillance throughout pregnancy.”

“In a study of the relation between cumulative exposure to mercury and chronic health impairment 298 dentists had their mercury levels measured by an X-ray fluorescence technique. Electrodiagnostic and neuropsychological findings in the dentists with more than 20 micrograms/g tissue mercury levels were compared with those of a control group consisting of dentists with no detectable mercury levels. 30% of the 23 high mercury dentists had polyneuropathies. No polyneuropathies were detected in the control group. The high mercury group had mild visuographic dysfunction; they also had more symptom-distress than did the control group. These findings suggest that the use of mercury as a restorative material is a health risk for dentists.”

A New instrument has been developed suitable for making measurements of the potential and the polarization resistance of the metallic restorations in the oral cavity. An improved measuring electrode has been constructed. The equipment is convenient in clinical routine measurements.

“Conclusion: A review of the literature indicates that the use of mercury in dental amalgam is relatively safe. The potential for mercurial poisoning exists; however, its occurrence is negligible. Of concern to the dental patient and personnel is the occurrence of mercurial hypersensitivity, the allergic response to mercury in amalgam restorations and from restorative procedures. Since the allergic reaction is self-limiting, it may be necessary for the dentist only to be aware of its symptoms for an adequate diagnosis and palliative treatment.”

The amounts of certain metallic components (Ag, Cu, Hg,Sn and Zn) in saliva possibly derived from dental metallic restorations and due to galvanic actions, were studied in twelve females. Three of these subjects were selected as they complained of certain oral mucosal symptoms and as, upon clinical examination, they were found to have enhanced galvanic action in terms of increased calculated currents at metallic contacts between restorative materials. The rest oflhe subjects did not experience any such symptoms and served as control groups by different criteria. The saliva concentrations of the various metallic components were determined by atomic absorption spectrophotometry. They were not found to vary between the different groups. The results do not forward any support to the view that galvanic action in the oral cavity can give rise to increased metallic contents in saliva. They therefore question the suggestion that increased galvanic action will cause general toxic reactions through the saliva.

115 persons were studied from a body of patients referred to the Faculty of Odontology, University of Umeå, for investigation regarding any occurrence of oral galvanism. Potential and polarization of metallic restorations and dentures were recorded using a method and equipment previously described. Data regarding distribution of potential ranges with respect to number of patients and type of alloy are presented. The distribution of calculated intraoral currents in relation to number and type of metallic contacts is stated. Relevant parameters for the study of oral galvanic (bimetallic) cells are discussed.