The term 'silver filling ' is a misnomer as a 'silver filling' contains 50% pure mercury and 35% silver with the remainder being made up of copper, tin and zinc. The mercury is the same metal that has been banned from thermometers in hospitals, schools and throughout industry because of its toxicity.

These fillings were originally used about 150 years ago as a cheap alternative to gold - the most common material in use at the time - which was too expensive for the vast proportion of the population. Consequently, 'silver fillings' were seen as the cheap alternative to gold. Even then, there was concern about the toxic affects of the mercury in the fillings and, although various dental associations banned its use at the time, economic forces won the day.

As each 'silver filling ' contains approximately 750-1000 milligrams of mercury, and other metals in the filling include silver, copper, zinc and tin (1), these fillings would more accurately be called mercury fillings. 75-80% of all tooth fillings are of this type (2).

At Dental School we were told that, once the filling was mixed, the mercury was locked into the filling and would not escape! Recently the British Dental Association admitted that the mercury in the filling does indeed escape.

The escape of mercury is affected by many things:

• Once covered with saliva the fillings begin to corrode (commonly known as rusting) and this releases mercury from the filling as well as ionic silver, copper and tin, which in themselves are toxic.
  
  
• Chewing and grinding releases more mercury vapour and microscopically small pieces of filling break off which are swallowed and then retained in the gut and slowly absorbed into the body.
  
  
• Increases in temperature cause more mercury vapour to be released, so hot food and drinks increase the amount of mercury vapour released. So each time you eat or drink you are increasing your exposure to mercury.
  
  
• If your mouth has more than one type of metal in it, i.e. gold crowns or fillings as well as 'silver fillings', then a battery is set up which causes currents 100-1000 times stronger than the electrical currents utilised by the brain. In addition, due to the currents released, the more volatile of the metals is released from the filling, in this case mercury vapour!
  

The above reasons explain why 'silver fillings' continuously release mercury vapour and its compounds into your mouth.

This low level, continuous, exposure to mercury vapour may be adversely affecting your health as even minute amounts of mercury vapour are very toxic.

The Environmental Health Criteria 101: methylmercury (WHO 1990) gives the following as estimated daily intakes of elemental inorganic and methylmercury.

Estimated average daily intake and retention (ug/day) of total mercury and mercury compounds in the general population not occupationally exposed to mercury, the figures in parenthesis are the estimated amount (ug) retained by the body of an adult.

No government department or authority anywhere in the world has ever certified 'silver fillings' as safe for use in humans, so we have no assurance that these filling are safe to use.

A risk assessment was recently carried out for the Canadian government by Dr. Richardson, a well respected risk assessor, who used all the available scientific data and came to the conclusion that up to 2 fillings in children and 4 fillings in adults would be an acceptable risk. Any more than this would be an unacceptable risk to the health of the patient.

Dental opinion

Once the mercury is mixed with other metals in the filling it is 'locked in'.

Scientific fact

Mercury vapour is continuously released from 'silver fillings' (4), more vapour is released by chewing (3-5); tooth brushing (6); and eating hot, salty or acidic foods or drinks (7).

The more 'silver fillings' you have, the more your daily exposure to mercury (4).

Once you have stopped chewing, it takes 90 minutes for the rate of mercury release to drop back to its pre-chewing rate (4,5). Thus you are susceptible to a roller coaster of mercury vapour all day. Breakfast will cause the release of mercury to rise, and just as it falls it's time for the mid-morning coffee break so the mercury release goes up again. This pattern goes on all day with lunch, mid-afternoon coffee, dinner and supper.

Dental opinion

Mercury from 'silver fillings' is not retained and is in such small doses that it has no effect on the health of the body.

Scientific fact

German (6), Swedish and American investigations (8) have found that human brain and kidney tissues from people with 'silver fillings' contained more mercury than those tissues of people without 'silver fillings'. The amount of mercury in the brain tissue of the people with 'silver fillings' correlated to the number of fillings they had i.e. the more fillings the person had, the higher the concentration of mercury in the brain tissues.

It has now been established that the mercury from dental 'silver fillings' constitutes the largest single source of inorganic mercury exposure to the general population - greater than all the other environmental sources combined (10). Despite replicated scientific findings, dental authorities maintain that 'silver' dental fillings are safe. They base this on the fact that the fillings have been in use for 150 years. They do not recognise that sickness or death might arise as a result of such fillings, and dentists are nether trained or licensed to determine mercury toxicity (11).

However, from the medical perspective 'silver fillings' are considered a significant source of mercury with significant potential for toxic impact. Medical researchers are now investigating the possible health risks of mercury from 'silver fillings'.

The latest medical research shows that mercury from 'silver fillings' accumulates in all the adult tissues, with the highest levels being found in the kidney and liver (13); and that, during pregnancy, mercury will cross the placenta and accumulate in the developing baby within two days of having a filling placed (14).

Although there have been reports to suggest a relationship between the presence of 'silver fillings' and human health, it is only recently that science has established a direct cause and effect link between 'silver fillings' and pathology.

Experiments carried out at the Departments of Medicine, Pathology and Physiology at Calgary University by M.J.Vimy, N.D.Boyd, D.E.Hooper and F.L.Lorscheider show a 50% reduction in kidney function in sheep one month after placement of 'silver fillings' and continues to fall after 60 days. The kidneys remove harmful substances from the blood, and maintain blood pressure and fluid balance. They also reabsorb essential nutrients and minerals. The loss of 50% of kidney function is like losing one kidney, and although healthy people can usually survive on one kidney, at times of stress it may not be ideal.

In another experiment, where mercury fillings were placed in the teeth of monkeys, it was shown that mercury from the 'silver fillings' dramatically altered the normal bacteria of the gut (16). In their place appeared mercury-resistant strains, which can also be resistant to antibiotics. Exposure to mercury may explain the rise in antibiotic resistant bacteria and the ineffectiveness of antibiotics which is a alarming problem in medicine.

Recent reports implicate mercury in certain brain dysfunctions. Autopsy data from patients who died while suffering from Alzheimer's disease show higher concentrations of mercury in brain areas associated with memory than an age-matched group who did not have Alzheimer's disease (17,18). Others have isolated a biological defect caused by mercury (19) which results in nerve tangles characteristic of Alzheimer's disease.

Scientific conclusions

In general

1. Mercury vapour is an extremely dangerous poison.
2. There is no absolutely safe level of mercury vapour exposure in humans.
3. 'Silver' dental fillings contain 50% mercury.

Specifically

• Mercury is released continuously from 'silver' dental fillings.
• 'Silver' dental fillings release a pharmacologically significant daily dose of mercury in humans, as shown by the work of Dr. Richardson on the risk assessment of amalgam fillings commissioned by the Canadian government.
• 'Silver' dental fillings are the largest source of mercury exposure in the general population, as shown in Environmental Health Criteria 101:Methylmercury (WHO 1990 ) outlined earlier.
• Mercury from 'silver fillings' collects in all the adult tissues of the body, with the highest concentration being in the liver and kidneys.
• During pregnancy, mercury from 'silver' dental fillings crosses the placenta and collects in the developing baby, with the highest concentrations being in the liver and kidneys.
• Mercury from 'silver' dental fillings reduces kidney function.
• Mercury from 'silver' dental fillings alters the normal bacterial population in the gut, producing antibiotic resistance.
• Mercury has been implicated in Alzheimer's disease, and the likely source is 'silver' dental fillings.

Scientific evidence overwhelmingly confronts the unsupported opinion of the dental profession.

The issue of the safety of 'silver fillings' is no longer open to debate.

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Exposure to low level chronic mercury vapour can cause a number of non-specific, seemingly unrelated symptoms leading easily to misdiagnosis. Indeed, mercury exposure has been labeled 'the great masquerader'; the similarity of mercury related symptoms to other medical conditions makes it very difficult for doctors to make a correct diagnosis.

Unfortunately, only a very few doctors are aware of the release of mercury from dental fillings so therefore the correct diagnosis is even less likely.

Symptoms

1. Psychological disturbances

• Irritability
• Nervousness
• Shyness or timidity
• Loss of memory
• Lack of attention
• Loss of self confidence
• Decline in intellect
• Lack of self control
• Fits of anger
• Depression
• Anxiety
• Drowsiness or insomnia

2. Mouth symptoms

• Bleeding gums
• Loose teeth
• Bone loss around teeth
• Excessive salivation
• Foul breath
• Metallic taste
• White patches
• Inflammation of the mouth:
• Ulceration of the gums, palate and tongue
• Burning mouth
• Tissue pigmentation

3. General health symptoms

(a) Gastrointestinal symptoms

• Regular abdominal cramps
• Chronic constipation or diarrhoea
• Chronic gastrointestinal problems including colitis

(b) Cardiovascular symptoms

• Irregular heartbeat
• Feeble or irregular pulse
• Alterations in blood pressure
• Pain and/or pressure in the chest

(c) Neurological symptoms

• Fine tremors (hands, feet, lips, eyelids or tongue)
• Chronic headaches
• Dizziness
• Ringing in the ears
• Numbness of hands or feet

(d) Respiratory symptoms

• Persistent cough
• Emphysema
• Shallow or irregular breathing

(e) Immunological symptoms

• Allergies
• Asthma
• Rhinitis
• Sinusitis
• Swollen lymph nodes, especially the neck
• Auto-immunity - rheumatoid arthritis, lupus, etc.

(f) Endocrine symptoms (glandular or hormonal)

• Sub-normal body temperature
• Cold clammy skin
• Excessive perspiration

(g) Skin symptoms

• Sores on the skin, especially face and shoulders

(h) Kidney symptoms

• Electrolyte imbalance (minerals)
• Reduction in kidney function
• Renal failure in severe cases
• Glomerular nephritis

(i) Other symptoms

• Muscle weakness
• Chronic fatigue
• Joint pain
• Anaemia
• Loss of appetite
• Constriction of visual field

The symptoms of mercury exposure are very varied and confusing as they cover such a wide and diverse picture that mimics many other diseases.

Mercury is a toxic heavy metal which in small doses can be very detrimental to human health. It affects the body in 4 main ways:

1. Poisoning
2. Allergic reactions
3. Induction of auto-immunity
4. Idiosyncratic reactions

1. Poisoning

Mercury is a heavy metal which, like lead and arsenic, is very toxic to the human body. Mercury is liquid at room temperature and so vapourizes very easily. The vapour is odourless, colourless, tasteless and when inhaled is very rapidly taken up by the blood and passes to all the other tissues of the body. Once in the tissues it enters the cells where it is converted into inorganic mercury. This highly reactive chemical reacts with sulphur containing enzymes. Enzymes are special molecules that promote chemical reactions that keep the cells, and therefore the tissues and body, alive. Without enzymes we would not be alive. Mercury's main mode of action is as an enzyme poison, with the final result being metabolic disease.

2. Allergy

Allergic reactions to mercury and other compounds in 'silver fillings' can occur locally around the teeth, gums, or oral tissues. These reactions may occur immediately or take up to several years to develop. Symptoms may appear on other parts of the body (systemic) and, as with local symptoms, may appear immediately or take several years to appear. Typical systemic reactions would be eczema and sores on face or shoulders. General dental opinion is that less than 1% of the population is sensitive to mercury. Unfortunately scientific fact shows that approximately 5% of the population is allergic to mercury - that means that 5 out of every 100 patients in a dental practice may be allergic to mercury.

3. Mercury induced auto-immunity

The immune system is the body's defense system and protects 'you' from things that are 'not you' such as infections and cancer. Autoimmunity is a reaction in the immune system where it can't tell the difference between 'you' and 'not you' and so starts to attack healthy tissues. There are many specific auto-immune diseases e.g. Multiple Sclerosis, Lupus, Rheumatoid Arthritis. If you have any of these diseases, and are told that having your 'silver fillings' removed will cure you, please be very cautious. Choosing to have the mercury removed is a very positive health move and will reduce the mercury levels in your body, but it is not a scientifically proven cure for the disease.

4. Idiosyncratic reactions

Some people may be immunologicaly hypersensitive or toxicologicaly sensitive to very low doses of mercury and some individuals have idiosyncratic (strange) reactions. Often the symptoms are bizarre and difficult to diagnose, and may be included in a whole range of environmentally induced reactions totally unique to that individual.

Conclusion

One of the important issues facing medical research today is whether mercury from 'silver fillings' causes specific diseases. Many diseases today have no known cause and none of these have been shown to be caused by mercury from fillings. However mercury exposure, no matter how small, will cause mercury poisoning to some degree and so one should not ignore the negative effect mercury will have on your health. Removal of the mercury will be a positive health move. Remember mercury is more poisonous than both lead and arsenic.

Showing the impact that low level exposure to mercury vapour has on your health is very difficult. There is neither a single test that can show this, nor indeed any number of tests that are 100% accurate.

Lab tests will help to evaluate the following:

• Overall health status
• Environmental & life style factors
• Co-existing medical factors
• Need for therapeutic nutrition
• Liver & kidney function during removal
• Excretion from the body

When should fillings be removed?

In this practice we do not use 'silver fillings'. If a filling needs to be removed we do not replace it with another' silver filling'. Where possible, it is replaced with a metal free restoration, preferably a composite. Options for fillings will be outlined to you later in the booklet. Other times when 'silver fillings' should be removed are outlined below:

• At your own request, having decided to make a positive health choice. After all it's your body and you have the choice of what you fill your teeth with.
• At the recommendation of your Doctor where, in their opinion, your general health is being affected by mercury and removal of your fillings will aid your recovery.
• If you have a positive patch test for mercury or have other proof of an allergic reaction to the mercury in your fillings. At present approximately 5% of people are allergic to mercury.
• If you dentist feels that mercury is having a detrimental affect on your teeth, gums & oral tissues.

The above represents reasonable criteria for the removal of 'silver fillings' based on current published scientific data and clinical experience.

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'Silver fillings' have been the material of choice for the last 150 years because they are relatively cheap and simple to use, their biocompatability was of little or no importance in bygone days. The alternatives tend to be a little more expensive and clinically more demanding in the application.

They fall into 3 main types:

• Gold alloy restorations
• Porcelain restorations
• Composite restorations

Gold alloys are a mixture of gold and other metals to make the gold harder, they are usually cast to make inlays, onlays or crowns.

The advantages of gold restorations are:

• They can be used on the biting surface of teeth
• They do not corrode very readily
• They fit very accurately
• They are made in the lab and the bite is made to fit correctly
• They fit between the adjacent teeth so food will not get stuck between your teeth

The disadvantages with gold restorations are:

• They require a high level of skill to prepare and fit
• They are held into place with dental cement and this does not strengthen the tooth
• They are not tooth coloured and some people find them unsightly
• Some people are sensitive to the metals in the alloys

Porcelain is made by fusing minerals like feldspar silica and alumina in a glass matrix at high temperatures to form a translucent material that is very tooth like in appearance.

The advantages of porcelain restorations are:

• Natural tooth-like appearance
• They are very durable and collect very little plaque

The disadvantages of porcelain restorations are:

• They are very brittle
• They tend to wear the opposing teeth excessively
• It is very difficult to get an accurate fit

Composite fillings are made from a mixture or finely ground quartz and Bis-GMA resin. hey have very tooth-like qualities in both appearance and hardness. They were originally developed for anterior (front) teeth because of their tooth-like appearance, but more recently the amount of quartz filler has been increased and the particle size decreased to give them increased wear resistance for use in posterior (back) teeth. The composite restorations may be fabricated either directly in the mouth (direct), or made in the lab (indirect).

The advantages of direct composites are:

• Bio-compatibility
• Tooth-like in appearance and strength
• Reduced electrical currents
• Enhances tooth strength due to bonding of the fillings to the tooth
• Cost effective

The disadvantages of direct composites are:

• 70% of the material polymerizes in the mouth, the remaining material does not react and so stops the filling from being quite as strong as it might be
• Some people have an allergic reaction to the unpolymerized material, especially those sensitive to petroleum products
• The composite shrinks slightly on setting and so if the bond is not good it may leave an open margin which may lead to sensitivity or the filling not to last as long as we might hope
• Composites are very demanding of the dentists skill

Indirect composite fillings are processed in the lab using heat, light and pressure this allows more of the material to be polymerised and the shrinkage to be controlled.

The advantages of indirect composite fillings are:

• The lab controls the shrinkage so when the filling is bonded there are no open margins
• The lab processed filling look like teeth, wear like teeth and are able to be made exactly - they are the most compatible tooth restoration
• They have all the advantages of the gold and porcelain restorations with none of the disadvantages
• They are a cost effective durable restoration.

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The ability to measure toxic materials has always been difficult, and their affect on the body almost impossible to determine due to the individuality of each person. When Dr Richardson carried out equivalent tests on composites to those he did on amalgam for the Canada Health 2000 group he found no significant risk in the use of composites. Antibodies are usually produced when toxic elements are introduced to the body. One way of assessing the toxic affect of a material is to measure these antibodies, as carried out in the Clifford Materials Reactivity Test. This test is useful when treating environmentally compromised or highly allergic patients. Applied kinesiology is a well researched technique that we use in the practice to help asses the biocompatability of the various materials we use. It involves testing the body's reaction to a material by using the strength of various muscles as the indicator.

What precautions are taken during silver amalgam filling removal?

When the fillings are drilled out, heat and small particles of filling are produced. Consequently there is a high risk of mercury exposure at these times. This risk can be minimized by taking a few precautions:

• The use of rubber dam, which is a thin sheet of rubber that isolates the teeth from the rest of the mouth, and protects the patient from swallowing particles of filling. It also reduces the amount of vapour inhaled
• The use of special suction devices that cover each individual tooth as it is drilled, and provide high volume vacuum suction
• The use of an alternative source of air to breath which reduces the chance of inhaling mercury vapour produced from the drilling
• Using room fans and ionizers to keep the air moving and carry the vapour away from the patient
• The use of protective covering and eye protection for the patient as the skin, and especially the eyes, absorb mercury when it is in contact with the skin
• The use of copious amounts of cold water when drilling as this reduces the amount of vapour produced as well as reducing the trauma to the tooth from the heat produced while drilling
• In our practice we also use a chelating agent to bind with the vapour and make it less available to the body.
• By sectioning the filling, instead of grinding it out, the amount of vapour is reduced.

Nutrition and Detox

As described earlier in the article, mercury affects the body in different ways. To minimize the metabolic affect of the mercury, specific nutrition can be taken. Minerals and vitamins affect the way in which the mercury is metabolized and taken up by the body. Simply put, vitamins and minerals are either used to make new enzymes to replace the ones destroyed by the mercury, or they attach to the mercury and make it less bio-valuable. This is a very complicated subject, if you wish to know more about it please ask and we can give you more information.

Supplements should be taken before during and after 'silver filling' removal. A typical supplementation regime is outlined below:

• General B vitamin complex formula 15-25 mg of each of the B vitamins each day taken with breakfast
• Vitamin C 1000mg, 2xday
• Zinc 13 -30 mg (amino acid chelate) after evening meal
• Selenium (150-200 micro grams) with lunch
• Vitamin E (400iu), 1 capsule with lunch
• Acidophilus capsule, 1 before breakfast & 1 after supper

Preparatory complexes are available for nutritional supplementation. Please ask at the practice.

There are other therapies available to help with removing mercury from the body:

• Sweat therapy - one of the main excretion pathways for mercury is through the skin by sweating. Steam baths and saunas, plus exercise, are good ways of increasing the amount of mercury eliminated
• Chelation therapy uses drugs that have a strong affinity for mercury and eliminate it from the body. These drugs are not without side affects and should be given under the supervision of a doctor. They are very efficient at reducing the body's mercury burden.

Bibliography

1. Phillips, R. W. (1982):Skinners science of dental materials 8th Ed. Philadelphia: W. B. Saunders Co, 311

2. Paterson, N. (1994) The longevity of dental restorations Br Dent J 157:23-25

3. Vimy, M.J. & Lorscheider F.L.(1985) Intra-oral air mercury release d from dental amalgam. J dent Res 64 :1069-71

4. Vimy.M.J. & Lorscheider F.L. Serial measurments of intra-oral air mercury :Estimation of daily dose fron amalgam J Dent Res 64; 1072-5

5. Patterson, J.E. ; Wiessberg, B.G. ; & Dennison, P.J. (1985)Mercury in human breath from dental amalgam. Bull Environ Contam Toxicol 34, 111-123.

6. Vimy, M.J. & Lorschieder, F.l. (1990) Dental amalgam mercury daily dose estimated from intra-oral vapour measurements: A predictor of mercury accumulation in human tissue. J. Exper. Med. 3,111-123

7. Fredin, B. (1988) Studies on the mercury release from dental amalgam fillings. Swed. Dent J. 3; 8-15.

8. Nylander,M., Friberg, l. ,& Lind, B. (1987) Mercury concentrations in the human brain and kidneys in relation to exposure from dental amalgam fillings. Swed. Dent J. 11; 179-187.

9. Eggelston,D.W. & Nylander, M. (1987) :Corrilation of dental amalgam with mercury in brain tissue. J Prosth Dent 58: 704-707.

10. Clarkson, T.W., Friberg, L., Hursh, J.B. & Nylander, M. (1988)The prediction of intake of mercury vapour from amalgams. In Biological Monitoring of Toxic Metals pp.247-260 Plenum Press, New York.

11. Truono, E.J. (1991) letter of importance JADA 122;8-14.

12. ADA News Release (1990): ADA Reaffirms Safety & Effectiveness of Dental Amalgam.

13. Denscher, G.Horsted-Bindslev, P. & Rungby,J. (1990): Traces of mercury in organs of primates with amalgam fillings. Exp. Mol. Path. 52, 291-299.

14. Vimy, M.J. , Takahashi, Y. & Lorschieder, F.L. (1990): Maternal-fetal distribution of mercury (203-Hg) released from dental amalgam fillings. Am. J. Physiol. 258,R939-R945.

15. Vimy, M.J., Boyd, N.D., & Lorscheider, F.L. (1990) Glomerular filtration impairment by mercury released from dental 'silver' fillings in sheep. Am. Physiol. Soc. Fall meeting Orlando Fl. Oct. 9. 1990 The Physiologist 33(4), 94, 1990.

16. Summers, A.O., Wireman,J., Vimy, M.J., Lorscheider, F.L., Marchall, B., Levy, S.B., Bennet, S., & billard, L. Mercury released from dental 'silver' fillings provokes an increase in antibiotic resistant bacteria in primate oral and intestinal flora. Antimicrobial Agents & Chemotherapy,37: 825-834, 1993.

17. Thompson, C.M. Markesbery, W.R., Ehmann, W.D., Mao, Y-x. & Vance, D.E. Regional brain trace-element studies in Alzheimar's disease. Neurotoxicol 1988 9, 1-7.

18. Wenstrup, D., Ehmann, W.D., & Markesbery, W.R. Trace element imbalances in isolated subcellular fractions of Alzheimer's disease brains. Brain Res 1990 533, 125-131.

19. Duhr, E., Pendergrass, C., Kasarskis, E. Slevin, J. & Haley, B. Hg2+ induces GTP-tubulin intractions in rat brain similar to those observed in Alzheimer's disease FASEB J 1991; 5 A456.

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