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Mercury in the Mouth

Amalgam and Mercury; their use and health implications in dentistry.

What is Amalgam?

Amalgam is the silver filling material widely used in dentistry, it is not an alloy, but a mixture of materials. This allows a continuous change in the percentage of it’s constituents with the potential release of metals including mercury when undergoing chemical reactions inside the alloy in the mouth.

What is Mercury and what is the danger?

The presence of mercury within amalgam restorations has lead to controversy, mercury is a recognised heavy metal toxin, mercury poisoning is well understood and the dangers of mercury is not disputed, however there is disagreement on how great a health risk it poses when held within amalgam restorations in the mouth.

Mercury is unique amongst metals in that it is a liquid at room temperature, a slight rise in temperature causes it to vapourise. It is a toxin, given a score of 1600 by the American Toxicology Centre. Plutonium, the most toxic material known to man, has a score of 1900, Lead has a score of  900. While Mercury can cause an immediate reaction if a patient is hypersensitive to mercury, however this is not common. But Mercury it is a cumulative toxin and is found to collect in many tissues including the, brain, nervous system, breast tissue, thyroid, adrenal, pituitary, and prostate glands.

Why is Mercury used in Dentistry?

Mercury is used in dentistry to “dissolve” the various metals that make up amalgam into a paste, that will then solidify to form the filling, it is a cheap and easy to use filling material,needing little skill to place. When an amalgam filling is initially placed in the mouth, it is rich in mercury. This surplus Mercury rises to the surface as the material is pushed into the cavity, and is then removed. However the amalgam is still rich in mercury which potentially leaches from the filling over it’s lifetime.

How much of a risk does Mercury pose to me?

Mercury is very much a product of the industrial age, with associated environmental pollution so that it is now found within the food chain. Many counties have banned the use of amalgam, because of concern in relation to it’s impact on the environment as opposed to our  individual health. In surgeries we are no longer allowed to store mercury, amalgam comes in sealed capsules in it’s constituent parts, it must be mixed in airtight containers, unused amalgam and old removed fillings are stored in airtight containers under inert oils and disposed of by specialist contractors. All surgeries must have specialist mercury/amalgam spillage kits and operate a “no touch” policy for all staff that may handle amalgam. The only place a dentist can legally store amalgam in non airtight situations is in the mouth of a patient.

Mercury, may be lost from an amalgam filling and released in the mouth as, amalgam particles, free mercury or mercury vapour.

Amalgam particles are the least damaging as they will mix with foods, pass through the digestive system and be excreted.

Free mercury, is lost as a result of galvanic action,  a basic chemical reaction. This requires an electrolyte and two metals of differing composition. Saliva is a good electrolyte and  no two amalgams have exactly  the same composition (this depends on many variables such as the mixing time, pressure of placement etc). Therefore all the required ingredients coexist in the mouth and as a result amalgam fillings can start to corrode. This can be exacerbated further by other metals present in the mouth ,such as gold crowns,  allowing mercury to be released.The mercury which releases  is quickly oxidised in the mouth to toxic ions and absorbed by the tissues.

Finally mercury vapour is released as a result of temperature increases in the mouth as well as when fillings grind over each other. The amount of vapour released is dependant on the surface area of fillings and the temperature, but levels can be raised significantly for 30 mins after eating. Vapour levels of mercury have been recorded in the mouth at a concentration that would force evacuation of any building if mercury were to be released accidentally.

Mercury vapour is quickly absorbed in the lungs passing into the blood stream and then into various tissues. It will cross the membranes surrounding the brain, where it alters in composition and hence remains effectively locked in. Traces of mercury are found both in the brain and nerve tissue. Hatters working in the early19th century used mercury to stiffen top hats, the toxicity they suffered lead to the phrase “as mad as a hatter”

How do I know if mercury is affecting me?

Everyone shows sensitivity to Mercury, this will vary from slight sensitivity to hypersensitivity as shown by a patch test, however this is different from toxicity and a patch test does not give information on toxicity.

Toxicity develops when the accumulated mercury damages the tissues with which it is associated, or interferes with the bodies biochemistry. Toxicity reaction is dependant on the dose of mercury, the time of exposure and the  individual body’s response.

There is no debate that mercury is a highly toxic material, there is no argument whether or not the population is exposed to mercury from restorations, the environment and the food chain. the debate is over to what degree does the mercury contained in the amalgam fillings contribute to our chronic low level mercury exposure and how damaging is that exposure to us.

Is there an alternative to Amalgam fillings?

At Crescent Dental Health, we have not used amalgam in over 15 years.  We have alternative filling materials to use instead of amalgam, these perform better than amalgam, do not contain mercury and so the decision not to use amalgam seemed very clear , straightforward and imperative for all our team.

At the practise we will certainly remove all amalgam restorations if a patient feels they are being affected by the mercury, or we replace them only as the amalgams deteriorate and clinically require removal, at which time we replace them with non mercury containing alternatives. This is  assessed on an individual basis with the patient.

As the amalgams are removed, we use charcoal tablets to help remove amalgam. There are a number of other measures which can be taken for those who have serious concerns about the mercury they may be exposed to including the use of various chelating agents to remove mercury from the system and blood or saliva tests  to assess mercury levels within the body after all the amalgam has been removed.