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Peter Varley BDSc, FDSRCS, DFHom(Dent.) and Jack Levenson
LDSRCS(Edin). (profile)
Poisons
Given the very large human exposure to mercury, how poisonous is it? The
University of Tennessee has a renowned toxicity centre where they grade poisons
based upon the least amount necessary to kill a human. Plutonium is the most
deadly and is rated on the scale as 1900.
- Plutonium 1900
- Mercury 1600
- Lead 900
- Nickel 600
Mercury, except in severe allergic reactions, is not a drop dead poison.
It is insidious in its action and accumulates in tissues and organs. This
renders diagnosis more difficult. Coupled with the fact that since the use
of mercury by physicians has been drastically reduced in therapeutic medicine,
the ability to diagnose mercury poisoning has shown a similar decline.
History of Mercury in Medicine
Mercury was used as a medicine in India as early as 500BC. Due to its bactericidal
effects it was introduced as a drug by Arab physicians in the tenth century
for the treatment of chronic skin disease. The use of mercury in medicine
spread to Europe and by the 16th century was widely prescribed as an effective
treatment for syphilis.
By the 18th century as mercurial treatment became established in medical
practice, so opposition to its use increased. The argument became a major
topic for press and public. Doctors were so convinced that mercury cured
venereal disease that it was perceived to be a panacea for a variety of ailments.
Mercuric chloride was used as an antibacterial solution in disinfectant.
This and other salts were used as purgatives and fungicides, as ointments
in treatment of eye and skin diseases and in worm chocolate as treatment
for intestinal parasites. Mercury increases urinary flow and found favour
as a diuretic.
Today mercury is still used in skin lightening creams. They were banned
in Nigeria as the mercury content can cause miscarriage and affect the brain
and kidneys. Mercury is in some throat lozenges and is widely used as a fungicide
and preservative in vaccines and contact lens sterilising solutions.
History of Mercury in Dentistry
In 1812 Joseph Bell, a British chemist, introduced the forerunner of the
modern amalgam filling. This consisted of a paste which was formed by filings
from silver coins and mercury, which due to impurities in the coins tended
to expand, sometimes resulting in a fractured tooth or an uneven bite.
American Dental Association
Aggressive advertising by some practitioners in New York led to an increase
in demand which in turn led to a reaction, which precipitated what has become
known as the first amalgam war. The opponents were the American Society of
Dental Surgeons (ASDS) founded by Dr C A Harris in 1840.
The society vigorously opposed the use of amalgam
and in 1845 they passed a resolution ‘pronouncing the use of all amalgams as malpractice’.
So, in effect, dental amalgam was banned for some 15 years. But an increasingly
vociferous minority defied the ban. They had found a commercially viable
material, inexpensive and easy to use, durable and with no apparent side
effects.
Economics won the day. The ASDA collapsed and a new organisation, the American
Dental Association (ADA) was founded to support the argument that mercury
was locked into fillings and could not escape. Dentists found this easy to
believe, conscience and commerce were satisfied.
Chemistry and Mechanism of Action
Mercury has a high affinity for sulphydryl (thiol) groups. Mercurials, even
in low concentrations are capable of inactivating sulphydryl groups present
in biologically active agents. These include proteins, enzymes and enzyme
inhibitors, and allow mercurials to interfere with cellular metabolism. The
binding with various groups results in cell membrane permeability, poor cellular
nutrition and interference with enzyme reactions in the cell.
In the lungs mercury vapour tends to oxidise into free radicals i.e. mercury
ions. These ions are an electrically charged form of the element and will
react quickly with Haemoglobin, Insulin, Thyroxin, Co-Enzyme A
When it reacts with haemoglobin the result is chronic fatigue. When it reacts
with insulin, the pancreas is stressed. When it binds to Co-enzyme A, which
converts food to blood sugar, the result is hypo-glycaemia.
Dental Galvanism
The presence of different metals in the same tooth, or in different teeth,
acts as a battery, producing an electric current with saliva as an electrolyte.
This current with its attendant electromagnetic fields is inches from the
brain and cranial nerves and can influence a variety of disorders e.g. Bell’s
Palsy, Migraine, Trigeminal Neuralgia, Neuromuscular Pathologies (MS) and
Epilepsy.
Research
Bacterial Resistance
A strong correlation between mercury and multiple antibiotic-resistant intestinal
bacteria had been observed by researcher Anne Summers in 1981. At that time
it was not linked to dentistry as it was believed that mercury could not
be released from fillings. Mercury-resistant
bacteria recirculate mercury as vapour and block elimination. Antibiotic-resistant
bacteria - the super bugs - are a serious escalating problem. It is time
the possible causes are reconsidered.
Mercury and the Central Nervous System
Nylander has demonstrated surprisingly high post mortem concentrations in
the pituitary glands of dentists, out of all proportion to other areas of
the brain. Stortbecker explains, ‘this is because the pituitary has an extra
dose by direct transport from the nasal cavity’.
Mercury and Multiple Sclerosis(MS)
The Swiss neurologist Basch hypothesised that MS is a neuro allergic ailment,
the allergen being a heavy metal, probably mercury. Britt Ahlsot-Westerland
showed that mercury levels in the cerebo-spinal fluid (CSF) of MS patients
was 7-8 times higher than the controls, both groups having similar amounts
of amalgam filling.
Mercury and Parkinson’s Disease
Subjects with Parkinson’s disease had significantly higher mean levels of
mercury than controls.
Mercury and Motor Neurone Disease
Motor Neurone Disease is a chronic neuro-degenerative disease also known
as Amyotrophic Lateral Sclerosis (ALS). Brown reported 6 cases of ALS in
farmers dusting seeds with methyl mercury. In the Iraq disaster large groups
of patients demonstrated neurological conditions similar to ALS.
Mercury and Alzheimer’s Disease
In a recent study on the brains of Alzeimher’s Disease (AD) autopsied cases,
concentrations of trace elements were measured. They consistently found the
highest trace element to be mercury. In comparison with age matched controls,
the mercury content was found to be significantly higher. The mercury concentration
was found in areas of the brain associated with memory.
Mercury and Infertility
This work was carried out at The Department of Gynaecology, University of
Heidelberg. The chelating agent for mercury, DMPS, was given to women with
hormonal irregularities, to remove mercury from the body. Since recognising
and treating the environmental contamination burdens of the women 70% became
pregnant without the use of hormonal therapy.
Safety of Dental Amalgam
No research has ever been produced to demonstrate the safety of amalgam
fillings. No long term studies have ever been carried out. There have been
a number of reviews of published research papers, with questionable conclusions.
The latest comprehensive review was published by the British Dental Association
in 1993 in which it was suggested that there was a need for further research
63.
World Reaction to Mercury Fillings
Sweden
The government concluded in 1987 that mercury fillings were unsuitable from
a toxicological point of view. On 18th February, 1994 the Swedish Ministry
of Health announced in a press release that the use of amalgam would be totally
banned for children and adolescents up to age 19 by 1st July 1995 and for
adults by 1997.
Germany
In 1992 the German Ministry of Health, inspired by the Drasch paper issued
a pamphlet recommending that amalgam should be avoided for the following
people.
- Children
under six.
- Individuals
with kidney disease.
- Pregnant
women.
- Any
women of reproductive age.
Austria
The Austrian Minister of Health announced that the use of mercury fillings
in children would be banned in 1996 and discontinued for all Austrians by
the year 2000.
World Health Organisation
In a document on environmental mercury, their determinations regarding human
daily retained intake of mercury from various sources are:
- DENTAL AMALGAM = 3.0-17.0 ug/day (mercury vapour)
- FISH & SEAFOOD = 2.3 ug/day (methylmercury)
- OTHER FOOD = 0.3 ug/day (inorganic mercury)
- AIR & WATER = Negligible traces
The committee also noted that ‘a specific No-Observed-Effect Level( NOEL)
cannot be established’, meaning that no level of exposure to mercury
vapour that can be considered harmless has been found.
Mercury and the
Dentist
Mercury Regulations
Few people are aware of the stringent recommendations of Mercury Hygiene
as documented by the Council on Dental Materials and Devices.
- Store
mercury in unbreakable, tightly sealed containers.
- Perform
all operations involving mercury over areas that have impervious and
suitably lipped surfaces so as to confine and facilitate recovery of spilled
mercury
or amalgam.
- Clean
up any spilled mercury immediately. Droplets may be picked up with narrow
bore tubing connected (via a wash-bottle trap) to the low-volume aspirator
of the dental unit.
- Use
tightly closed capsules during amalgamation.
- Use
a no-touch technique for handling the amalgam.
- Salvage
all amalgam scrap and store it under used x-ray fixer.
- Work
in well-ventilated spaces.
- Avoid
carpeting dental operatories as decontamination is not possible.
- Eliminate
the use of mercury-containing solutions.
- Avoid
heating mercury or amalgam.
- Use
water spray and suction when grinding dental amalgam.
- Use
conventional dental amalgam compacting procedures, manual and mechanical,
but do not use ultrasonic amalgam condensers.
- Perform
yearly mercury determinations of all personnel regularly employed in
dental offices.
- Have
periodic mercury vapour level determinations made in operatories.
- Alert
all personnel involved in handling of mercury, especially during training
or indoctrination periods, of the potential hazard of mercury vapour
and the necessity for observing good mercury hygiene practices.
The above recommendations provoked the comment from
one dentist, ‘It would
seem that the only safe place for mercury is in the patient’s mouth’.
The degree of exposure to mercury would vary in different surgeries, however
it would seem from from the literature that both dentists and their personnel
are at risk.
Removal of Amalgam Fillings
Fillings should be removed in a predetermined sequence depending on electrical
readings. Quadrants having the highest reading should be removed first. This
is important when there are high differentials.
Priority Order for Amalgam Removal
- Root
canal-treated teeth with pins or screw-posts of non-precious metals and
metal crowns with amalgam cores should be treated first
- Next
are amalgams in direct constant contact with gold. Often the amalgam
can be removed while the gold inlays, the crown or the bridge, can be left.
What
to do with the gold can be decided later.
- Where
there is direct intermittent biting contact between amalgam and gold
in opposing teeth.
- Where
there is direct contact between amalgam and other metals like partial
chromium-cobalt dentures.
- Other
teeth with root canal fillings of N2 and gutta-percha. The latter often
contains cadmium. The filling materials and sealers generally contain an
amazing array
of highly toxic compounds.
- Retrograde
amalgam fillings must be removed. These fillings can be seen on x-rays
at the root apex.
- Most
patients have several different types of amalgam fillings, and the ones
containing the newer types of amalgam high in copper (non-gamma 2 amalgam)
should be
removed first. The priority order between different fillings can be based
on the patient’s own opinions or visible signs of corrosion and
discoloration.
- Amalgam
fillings in contact with gum tissue. It might be necessary to remove
metal-impregnated gum tissue surgically.
Pre-treatment Plan
-
Vitamins
A, C, E, selenium, copper, zinc and manganese.
- A
course of Homeopathic Dental Amalgam or Merc Sol is helpful
- Charcoal
tablets should also be used immediately before amalgam removal, to absorb
mercury from any amalgam particles that may pass into the stomach.
- Increase
fluid intake
Protection of the Patient During Amalgam
Removal
The surgery should have good ventilation and an efficient filtration system.
Where possible, rubber dam should be used in conjunction with efficient high-volume
evacuation to protect the patient from the aerosol of water coolant spray
used with the high speed cutting (see diagram). When drilling, the filling
should be sectioned into chunks and elevated where possible. If any metal
has been used as a restorative material, then all amalgams should be removed
first. Patients should wear clothes covering as much skin as possible.
For sensitive patients, when drilling out amalgam cover the eyes with wrap
around goggles and use an RA nosepiece with tubing attached to extend out
of operating area to protect against nose inhalation of mercury vapour. Some
practitioners use oxygen flow.
Scheduling of appointments depends very much on the reaction of the patient
after the first treatment. Patients should be monitored and supplementation
varied as necessary.
PARTICULATE INHALATION DURING THE REMOVAL
OF AMALGAM RESTORATIONS
Post-Treatment Protocols
Continue supplements for 2-3 months. Warm baths, low-heat saunas, acupuncture,
massage, counselling and healing have all proved useful. Any remaining Candida,
food allergies and digestive disorders usually become more amenable to treatment.
Conclusion
Mercury is the only cumulative vaporising poison permanently implanted
in the human body
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