Are silver amalgam ("the infamous lead") fillings bad for my health?
Amalgam “toxicity” hits South Africa
South Africa has recently been exposed to elevated levels of amalgam hype. Carte Blanche on MNet, Huisgenoot and You have reported on the suffering of patients from “amalgam disease” and their “miraculous recovery” after replacement of amalgam with tooth coloured material.
Many dentists are getting onto the “amalgam free” bandwagon leading to a commercial boom in the tooth coloured restorative dentistry. This wave of amalgam anxiety is driven in no small way by the lectures of a South African doctor touring the country. Hundreds of dentists attend his lectures and come away absolutely convinced of the veracity of his statements, sentiments and views, which are not substantiated by science. A dangerous situation is developing with thousands of patients being advised to have their fully functioning, defect free amalgam restorations removed and replaced with resin composite or porcelain. These materials have their own problems, of which the patients are not equally well informed.
Resins and porcelain mostly require more preparation and damage to sound tissue and the use of technique sensitive bonding procedures. An inordinate amount of post-operative sensitivity often develops and this leads to costly root canal therapy and other procedures which in turn produce unhappy patients.
These unhappy patients often demand to know why they should pay for all this “extra treatment”, eg. root canal treatment. If the dentist had been clinically and ethically correct in advising the patient to have the amalgam removed, then there is no problem. The patient has to accept it as a “normal” risk or complication. But, if the dentist’s facts had been incorrect, if perhaps he had indeed misled the patient, the situation reverses. The dentist should be responsible for all the damage he or she had caused.
The question is really – “Are the statements made on Carte Blanche, Huisgenoot, You and by Dr. X true or false?”
What are these statements exactly? The anti-amalgam lobby’s claims range from multiple sclerosis, mental and neural disorders e.g., Alzheimers disease, Parkinson’s disease and renal failure to muscle pains and vague complaints eg., head aches, muscle pains, colds and flu.
Dr. X claims that he works in the realm of the little understood “pro-phase or pathological homeostasis which precedes clinical, organic disease” (author’s interpretation).
Dr. X does not dispute the fact that there exists no scientific evidence for his claims. He does not make use of the scientific method eg. double blind clinical trials. He rather “observes nature”. He does however refer frequently to Chang’s “Metal toxicology”. He is also keen to cite the example of the fall of the Roman Empire due to lead poisoning, an historical fact, which bears no relation to dental amalgam, but succeeds in captivating an audience. He furthermore cites one or two case reports, three teeth which he had had extracted and analyzed and found mercury “even in the apical dentine” and the experiment in which one cow had received amalgam fillings with a concomitant drop in lactation. With this “evidence” he sweeps his audience on a wave of emotion to the utopia of a mercury free environment.
Dr. X has many loyal fans. And several notable opponents. Mainstream academics generally dismiss his theories and claims with contempt.
The general consensus in academic circles is that:
There is no scientific evidence that the removal of amalgam restorations will lead to any improvement in general health.
The academic view is supported by the ADA, FDI, BDA and also SADA. Unlike the Huisgenoot and Dr. X these organizations are keen to use and cite scientific data and studies:
Stromberg et al, 1999 performed a double blind, controlled, clinical study on 39 volunteers with alleged “amalgam disease”, each releasing 0.6-10µg mercury per day from their amalgam restorations. Their amalgam was removed and the patients then re-exposed to either air or mercury vapours. There was no significant difference in the number of reactions after inhalation of mercury vapour or pure air.
In Sweden no differences was found in the renal function of groups with and without amalgam.
Also in Sweden, in 1024 females, there was no relationship between the number or severity of complaints or symptoms and the presence of amalgam fillings.
There was no correlation between raised levels of mercury and performance at school in a group of Inuits (Tulinius, 1995).
There was no correlation between the number of amalgam fillings in a group of Roman Catholic nuns, and their cognitive ability (Saxe et al, 1995).
Dahl et al, 1999 studied fertility of 558 female amalgam placing dentists and 450 female teachers and found no difference.
Herreton et al, 1994 actually found higher numbers of asthma in amalgam free children.
Bjorkman et al, 1993 found no effect of dental amalgam in red blood cell enzymes.
The US Public Health Service in 1993 reviewed 800 papers and recommended no restrictions on amalgam.
Mattison et al, 1994 provoked the oral mucosa of patients who had previously tested positive to mercury in patch tests, with mercury, and performed biopsies at 24 hours. No difference from the control group was noted.
Does all this evidence then give us the green light for the continued and unabated use of amalgam? Perhaps not quite:
It is known that dental amalgam is not inert and mercury vapour is produced in quantities ranging from 0.5-29µg./day. The question however is, is this clinically significant? In the USA 170µg/day is the allowable exposure.
Eggleston and Nylander 1987, performed autopsies on the brains of 83 cadavers ranging in age from 13-59 years:
The control group had 0-1 occlusal amalgam surfaces per individual. The intermediate group had 1.5-4 occlusal amalgam surfaces. The subject group had more than 5 amalgam surfaces.
Control Intermediate Subjects
Grey matter 6.7 10.6 15.2
White matter 3.8 6.6 11.2
Clearly the results are statistically significant, but is this clinically significant? Does it cause disease? There is as yet no evidence that it does.
Nylander et al, 1989 performed autopsies on 8 dental personnel and 27 non-dental controls, all with similar numbers of amalgam surfaces.
Occipital cortex Pituitary gland Renal cortex
Dental 61 1599 1533
Control 11 108 27
The highest levels were found in the older individuals but in the dental group with the highest number of amalgam fillings the lowest levels of mercury were found. Statistically these figures may alarm, especially dental staff, but does it cause disease? There is no evidence that it does, but it may.
There are six studies showing that lichenoid/lichen planus lesions resolve after removal of amalgams:
12 out of 13 patients showed improvement (Smart et al, 1995).
14 out of 16 healed (Pang and Freeman, 1995)
33 out of 49 regressed (Ostman et al, 1996)
130 out of 142 improved (Bratel et al, 1996)
10 out of 11 improved or cleared (Koch et al, 1995)
92% of 159 healed or improved (Henrikson et al, 1995)
So here is clear, circumstantial evidence that dental amalgam is involved in a disease process. Note that this is local as opposed to systemic disease. There is still no scientific evidence that dental amalgam causes systemic disease. The resolution of lichenoid/lichen planus lesions after removal of amalgam is reason for some serious consideration. The extremist views can not be summarily dismissed without acknowledging the fact that there are a small number of individuals who are indeed “hypersensitive” to dental amalgam (and other metals).
Does the lichen planus evidence warrant the removal of amalgam in patients with systemic complaints?
Does all the evidence warrant the routine use of expensive chelating therapy (Dr. X)? Definitely not.
Is routine blood testing eg. metal challenges, MELISA warranted?
Should further testing be conducted?
Definitely yes, but only when following proper scientific guidelines.
Has anything changed and should we still be using amalgam as before? The answer to this question is not so simple.
Dental resin composite has been developed to such extent that it has actually become useful in posterior teeth. When resources (money) are available small resin composite fillings in posterior teeth can be placed with predictability. When large amalgam restorations need to be replaced due to physical reasons (decay, fracture, leakage) patients must be fully involved in the decision making process. The benefits, disadvantages, costs and implications of all dental restorative materials should be truthfully discussed with the patient, empowering him or her to exercise his or her right of choice. Care should be taken not to improperly influence the patient’s choice by emphasizing half truths or by deliberately advocating a lie. When patients, out of their own volition demand the replacement of sound amalgam with any other material, they should be told in no uncertain terms, that there is no scientific justification for doing so. When a dentist actually suggests that amalgam is harmful to a patient’s general health, he or she is treading on very dangerous ground, assuming considerable legal liabilities. When a patient presents with lichen planus or lichenoid reactions, a very careful look should be taken at the patient’s amalgam restorations.
I gratefully acknowledge prof. Stephen Challacombe, president of the IADR and head of Oral Medicine at Guy’s, Kings and St. Thomas, London for his valuable contribution of information and references.
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