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Amalgam fillings normally contain 50 per cent mercury
small studies have suggested that dentists and dental assistants who experience mercury exposure through handling amalgam do have a higher than average risk of neurological disturbance. ("Dentists have the highest rate of suicide among the health professions " - CW)
The mouth is not a nice environment for materials. It's warm, wet and full of an effective electrolyte (chloride ions in saliva) that encourages galvanic corrosion. The jaw musculature is immensely strong, giving rise to huge pressures and displacement forces. For dentists challenged with working here, access to the mouth is sometimes near impossible. To cap it all, the sensitivity of the tongue, teeth and oral mucosa is such that their patient can feel (and complain about) minute changes or differences too tiny for diagnostic techniques to detect.Developing materials that can survive this environment is no easy task, but one success story is dental amalgam. These ubiquitous 'silver' fillings have remained more or less unchanged since the late 19th century.Dental amalgamDental amalgam comprises a powder, mainly a silver-tin alloy often with copper and zinc, and liquid mercury. In use, the powder and liquid are thoroughly mixed, or triturated, to ensure that all the solid alloy particles are completely wetted by the mercury.The amalgamation process is usually described in terms of the reaction of the silver-tin g-phase with mercury:Ag3Sn (g) + Hg ® Ag2Hg3 (g-1) + Sn7Hg (g-2) + Ag3Sn (g remnant)This mixture, initially the texture of wet sand, is placed into the tooth cavity. The compaction of amalgam into the cavity is not simply a matter of filling the hole. Dentists use repeated pressure to bring the metallurgically weak and mercury-rich g-2 phase material to the surface of the amalgam. This can then be skimmed from the surface and removed with a suction tube. What is left behind is not only very strong, but also contains very little free mercury. Increasing the copper content of the amalgam reduces the amount of weak g-2 phase, so improving the load bearing properties of amalgam, whilst adding zinc improves the working time.Over a period of minutes, the amalgam passes through a phase during which the dentist can carve it into its final form before it sets hard. Once set, amalgam fillings are immensely strong and durable but attention has recently focused on the possible long term side-effects of mercury on the patient.There is no question that low-grade exposure to inorganic mercury over a long period of time can lead to chronic poisoning (Chem. Br., August 1994, p646). The expression 'as mad as a hatter' dates from the days in which hat-makers dipped material into solutions of mercuric nitrate to render the felt easier to shape - and suffered varying degrees of neurological damage as a result.But with workers in over 60 industries having occupational exposure to mercury, and high levels of mercury found in food, the real question must be whether the mercury used in dental fillings poses any additional threat. Small amounts of mercury are released from amalgam fillings during their insertion and removal from a tooth. However, modern water-cooled drills and high volume suction ensure that a negligible amount of this free mercury is swallowed.Research from the late 1970s onwards has shown that very small amounts of mercury are released during the lifetime of the filling, particularly when chewing. Estimates of this amount vary between 2 and 10µg per day. Whilst this may sound worrying, bear in mind that the daily dose of mercury from this source is only 10 per cent of the normal daily intake from food, air and water. It's also worth pointing out that such apparently innocent products as antiseptic ointments and face creams may also contain mercury products that can be absorbed through the skin.In fact, the main route of mercury absorption for most people is via the food chain. This is the result of global industrial dumping of large quantities of mercury and its derivatives into the sea, where bacteria and algae convert it into a more toxic substance called methylmercury. This can find its way into the higher reaches of the food chain and the human population. Not surprisingly, seafish contain a lot of this methylmercury, and people who eat a lot of seafish may have up to 10 times more mercury in their blood than control groups.Research on this subject makes a very clear distinction between the effects of elemental mercury (as released from a dental filling) and those of its organic derivatives such as methylmercury. Of the two, these organic forms of mercury are by far the most biologically active and potentially toxic compounds.The mercury released from fillings is inorganic, and in ionic or elemental form. This means that the metal is in its least toxic state, and research suggests that transformation from this state to the organic form probably does not occur to any significant degree in the body. Whilst mercury may be swallowed, its extremely poor absorption by the gut means that it is rapidly and easily excreted.Inhalation of mercury vapour is a slightly different matter, because this can rapidly cross alveolar membranes in the lung and directly enter the bloodstream. Even so, this mercury vapour has a limited lifetime in the body because it is quickly oxidised to a harmless form. If an amalgam filling is releasing mercury during chewing, then this will inevitably show up as an increase in the level of mercury in saliva. One study carried out in Tokyo in 1985 measured saliva mercury levels in people both with and without amalgam fillings. From the results, the researchers estimated that the amount of mercury swallowed corresponded to 1/30 of the total mercury intake from food for those with no amalgam fillings and 1/13 of the intake for a person with amalgam fillings.Health and well-beingSo what does this mean for well-being of the patient? There seems to be a consensus from various studies that the presence of amalgam fillings will lead to an increase in blood and urine mercury levels. But compared with our normal intake of mercury from other everyday sources these increases are relatively small.The problem facing the patient is that mercury is sometimes now being blamed for a whole host of conditions from insomnia and anxiety to multiple sclerosis and autism, without any real scientific evidence upon which to base such conclusions. Such problems, if they exist at all, are of much less import to patients than to dental staff who spend much of their working lives in the presence of mercury.Amongst the hyperbole of the amalgam debate, some very real and scientifically valid results have come to light regarding the relationship of amalgam to a condition known as lichen planus, which manifests itself as white plaques on oral tissues.Whether such lesions are due directly to mercury sensitivity, or whether mercury sensitivity subsequently develops due to mercury penetration into the deeper tissues once the integrity of the oral mucosa is breached is unclear. However, there is very positive evidence that many oral lichen planus sufferers test as hypersensitive to mercury. Going one step further, there is also a research study that demonstrates convincingly the remission or disappearance of the plaques once amalgam fillings were removed and replaced with other materials.In the light of evidence such as this, and despite a healthy amount of cynicism, one must at least consider the possibility that time and research will demonstrate other problems arising from mercury.A new generation of amalgams is now being researched in which a gallium-indium-tin liquid replaces mercury completely. Until then, amalgam, and in particular the modern high copper varieties which are less prone to corrosion, is likely to continue as the most widely used and most forgiving filling material.
A Question of EthicsHad a chat with my new dentist today while having 2 teeth filled with white fillings. [:0]The discussion followed a suggestion that I might want amalgam in my teeth. I replied of course, definitely not! Adding I paid a fortune to have all amalgam removed from my teeth previously.He said, I have to mention this to patients as I am unable to offer white fillings on the NHS? He then added I don’t blame you for not wanting mercury put in your mouth and I certainly would not have it put in my mouth. [V]Which got me thinking about the ethics behind putting highly toxic mercury into the mouths of the people who are unable to pay for their own dentistry. More to the point, why is it more expensive to have white fillings than highly toxic mercury fillings? [V]My bill came to £123 for the two fillings paying privately, which to me is a lot of money for a couple of fillings.My wife just suggested something that made a lot of sense. She said, many people go on holidays abroad, some of who are registered disabled, some who are in between jobs and many who pay privately for dental work anyway. She said, from now on when we go oversees on holiday, we should get our teeth done in Spain, France, or for example Thailand. This makes a hell of a lot of sense to me and for anyone who is being lined up to part with a few thousand pounds for dental work it should make even more sense to them. Thailand for example has some of the best dentists and plastic surgeons in the world, operating at a fraction of the cost over in the U.K. And no other country in the EU to my knowledge forces the poor to have poisonous metals inserted into their teeth because they are too poor to afford white fillings. [!]I hope someone with some influence reads this if only to prevent this totally unethical practice from continuing.http://www.harmonikireland.com/index.php?topic=amalgams A Mercury overview
We have also evolved with arsenic, but I wouldn't stick that in my mouth!
Quote from: Don_1 on 01/07/2009 08:14:51We have also evolved with arsenic, but I wouldn't stick that in my mouth!Yes you do.It might be difficult, but I bet that I could analyse the food you eat and measure the arsenic concentration in it.If you happen to like fish it would be easy since it often contains quite a lot, though it's usually in a form that's not very toxic.Incidentally, I could do the same with mercury, uranium, lead and all the other "nasty" things that are, and always have been, part of our environment.
" So why risk adding a top up 24/7 from amalgum fillings when using white fillings should at least prevent mercury overload."False dichotomy. There is no reason to suggest that amalgam fillings are causing "mercury overload" so there's no way to justify the assertion that something else can prevent it.As I have said before there has been a whole lot of research in this field and it all points one way. The only threat from mercury in fillings is to careless dentsists making the amalgam.There isn't a problem so there's no point wasting effort trying to solve it.
Dr. Robert Kelly, a spokesman for the ADA from the University of Connecticut School of Dental Medicine, said the ADA's position supporting the safety of dental amalgam has been formed from a lot of people outside the field of dentistry.He said the amount of exposure to mercury from amalgam fillings is minuscule relative to exposure from a normal diet or "from the air we breathe."…Kelly said at best having amalgam fillings adds one microgram of extra exposure per day, compared to some 10 micrograms of exposure per day in a normal diet.
QuoteDr. Robert Kelly, a spokesman for the ADA from the University of Connecticut School of Dental Medicine, said the ADA's position supporting the safety of dental amalgam has been formed from a lot of people outside the field of dentistry.He said the amount of exposure to mercury from amalgam fillings is minuscule relative to exposure from a normal diet or "from the air we breathe."…Kelly said at best having amalgam fillings adds one microgram of extra exposure per day, compared to some 10 micrograms of exposure per day in a normal diet.http://www.msrc.co.uk/index.cfm/fuseaction/show/pageid/1596
... why not take into account the other text on the same site?
There is no evidence that mercury causes MS or that the removal of dental amalgam improves the course of MS. It has been estimated that amalgam accounts for ten per cent or less of mercury intake. Dental amalgam removal is generally expensive, though there are few risks associated with it. On rare occasions it may cause injury to nerves or tooth structure.