Tissue uptake of mercury from dental fillings. Recent investigations in sheep and monkey animal models demonstrate that dental mercury accumulates in all tissues of the adult, being highest in the kidney and liver. This accumulation is so extensive that it can be visualized on a whole-body image scan. [26,27] Research also shows that a high level of dental amalgam mercury in monkey kidney is still present at one year after mercury filling placement. [28] Also, mercury from dental amalgam will cross the placenta and begin accumulating in the developing fetus within two after the filling placement in pregnant sheep and is highest in the fetal liver then the kidney. The mother's milk also showed evidence of mercury, suggesting that the newborn would have an additional exposure to mercury.[29] Recent human chelation studies show a association between urinary mercury excretion and the presence of mercury fillings.[30-33] For example, one study showed that, after a chelation challenge with DMPS, urinary mercury excretion is significantly higher from subjects with mercury fillings than from those with no such fillings. It was concluded that at least two-thirds of the excreted mercury originates from the dental restorations.[30]

On the basis of the research cited here, there is now international scientific consensus that the mercury from dental tooth restorations constitutes the largest non-occupational source of mercury in the general population, being greater than all other environmental sources combined! [34-36] Yet, the dental profession still insists, without evidence, that the exposure is insignificant and has no potential to produce harm.

Pathophysiological consequences of mercury from dental fillings. During the last several years, medical research has demonstrated a relationship between mercury exposure and pathophysiology in various animal models. In sheep exposed to mercury from in situ tooth fillings, kidney function has been shown to be impaired. After 30 days of chewing the sheep lost 50% of their kidney filtration ability; they began to have difficulty regulating sodium and they demonstrated a reduced albumin excretion. Control sheep teated with non-mercury dental fillings did not show such effects.[37] In a study of 10 humans with mercury fillings, it was demonstrated that the plasma mercury level dropped by 50% and the urinary mercury level declined by 25% over a twelve month interval after filling removal compared to the pre-removal level. Most notable was the finding that 12 months after removal, the urinary albumin level was significantly higher than the level 4 months prior to removal.[38] In the sheep, the placement of mercury fillings caused a fall in the urinary albumin, signifying renal pathophysiology. In humans, the removal of mercury fillings results in an elevation in urinary albumin, indicating a renal homeostatic readjustment. The agreement between this sheep and human data is remarkable.

In a recent collaborative paper between three North American universities, it was demonstrated in a primate model that oral and intestinal bacteria (eg. streptococci, enterococci, enterobacteriaceae) exhibit a significant increase in mercury and antibiotic resistance within two weeks following mercury filling placement.[39] The mercury resistant bacterial species exhibited resistance to various antibiotics such as, ampicillin, tetracyclines, streptomycin, kanamycin, erythromycin, and chloramphenicol, which they had not demonstrated prior to placement.. This is the first direct experimental confirmation of a non-antibiotic factor, mercury, producing antibiotic resistance. This occurs because in some bacteria mercury-resistance and antibiotic-resistance are encoded adjacent small genetic sites within plasmids. [40] When exposed to environmental mercury, this genetic material is activated to protect the bacteria from the lethal mercury. The plasmid is also replicated and passed on to other bacteria, insuring species survival. In so doing, the antibiotic resistance also spreads to the other bacteria. Antibiotic resistance is a important issue in medicine today. [41] It has been estimated that 80% of mercury-resistant bacterial strains also show an increased resistance to one or more conventional antibiotics. Thirty percent of all hospitalized patients in North America receive antibiotic therapy [42] and antibiotics compromise 10% of the total $5.1 billion drug sales in Canada during 1992. [43] Moreover, ten of the top 20 generic drugs prescribed during 1990 in the U.S.A. were antibiotics. [44] Yet, antibiotics appear to be losing their clinical potency and stronger antibiotic medications at increasing dosages are necessary to combat many common infections.[41]

Recently, investigations have suggested that mercury may be involved in common brain pathologies and that the source of the mercury is likely the dental fillings [45-47] In a human autopsy study, tissue from persons having Alzheimer's Disease at death were compared to an age-matched group of control brains from subjects without Alzheimer's Disease. The only significant difference in metal content between the two groups was mercury, being considerably higher in the Alzheimer group. The mercury concentration was prominent in the hippocampus, the amygdala and particularly in the nucleus basalis, all brain structures involved in memory function. Other metals examined were not significantly different in the two groups of subjects. The effect of mercury on cental nervous system neuron membrane integrity has been examined and shown that mercury specifically affects tubulin, a brain neuronal dimer protein responsible for proper microtubule formation of brain neurons.48 Both in vivo and in vitro experiments demonstrated that mercury chelated to amino acids maintains an abnormal polymerization state of tubulin. This effect may produce neurofibrillar tangles. Such tangles are a recognized lesion of Alzheimer's Disease. Inorganic mercury affects ADP-ribosylation of the rat brain neuronal proteins tubulin, actin and B-50, in both in vivo and in vitro experiments. [49] ADP-ribosylation is the rate limiting process involved in polymerization of tubulin and actin monomers into the structure of the neuron membrane. Most recently, our laboratory demonstrated that ionic mercury and elemental mercury vapour markedly diminishes the binding of tubulin to GTP and thus inhibits the polymerization of tubulin which is essential for the formation of microtubule in the central nervous system [50] These studies are direct quantitative evidence for a connection between mercury exposure and neurodegeneration.

Other investigations have examined the mercury hypersensitivity from dental amalgam in patients with and without oral lichen planus lesions. [51-53] These studies showed that patient groups having oral lichen planus had a much higher incidence of mercury patch-test reactivity (16-62%) than did control groups (3-8%). Removal of the mercury fillings resulted in amelioration of the oral symptoms.

Governmental regulatory action concerning mercury fillings. In 1987, the government of Sweden commissioned an "expert panel" to evaluate the available evidence regarding mercury filling safety. The panel concluded that mercury fillings were "unsuitable from a toxicological point of viewBased on this panels advice, the Swedish Socialstyrelsen announced that steps would be taken to eliminate dental amalgam usage and recommended that comprehensive mercury filling treatment on pregnant women should be stopped to prevent mercury damage to the fetus. [54] Shortly thereafter, the German Ministry of Health (Bundesgesundheitsamt, BDA) issued an similar advisory. [55] In October of 1989, the Swedish Director of Chemical Inspection (KEMI), responsible for environmental protection, declared that amalgam would be banned. [56] In January of 1992, the German Ministry of Health (BDA) informed manufacturers of its intention to ban the production of amalgam. [57] The BDA removed low copper non-gamma-2-amalgam from the market and published a pamphlet recommending avoiding mercury filling use in individuals with kidney disease, children to age 6, and pregnant women. [58] In August of 1992, the Swedish government suggested a timetable to phase out mercury fillings. Environmental concerns were used as the official reason for amalgam discontinuation, but the government did acknowledge the toxicological risk to patients and stated that mercury fillings should no longer be used in children by July 1993, in adolescent to age 19 by July 1995, and in all Swedish citizens by 1997. [59] The Austrian Minister of announced that the use of mercury fillings in children would be banned in 1996 and discontinued in all Austrians by the year 2000. [60] In 1994, the Swedish Dental Association acknowledged that its leadership had previously been incorrect in their position regarding mercury filling safety. They now support a discontinuation of mercury use in dentistry. [61] Other industrialized countries, for what ever reason, appear to be side stepping the issue.

Also make sure to read these books: Poison in Your Teeth: Mercury Amalgam (Silver) Fillings...Hazardous to Your Health! and Mercury Detoxification by Tom McGuire