Faradaic Activity in Dental Amalgams



Clinton,
It is possible that you may have confused some of your readers here by the careless editing of your reply.
Your post gives the impression that it may have been me who wrote the above account of receiving a radio station signal with metal fillings.
I should like to make it clear that it was not.
I have never heard, nor have I ever claimed to have heard, any radio signals coming from any of the fillings that I have ever had in any of my teeth.
The account of the experience which you have replied to above was written by RP.
Having said that, I should add that I have no reason to doubt that RP's story is genuine.
It is well known that radio signals are attenuated by metallic objects, and there is no scientific reason that I know of for suggesting that metal amalgam dental fillings can be considered exempt from the laws of nature.
The following is from "Frank", who writes the digest for the Yahoo newsgroup bioelectromagnetics (you'd have to be a member to access it):
"the old saw about people receiving radio stations from fillings in teeth is not a hoax. occassionally the composition is such that it creates audible sound. Have never had it myself but have met two people who had it and it was possible to actually hear it with a small mike. . for the most part, they don't have it long. they go back to the dentist and get it fixed. needless to say dentists don't advertise this. frank"
Keith P Walsh
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how might you determine what the characteristics of this field should be for producing, say, the best reception?

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I want to know what to do to receive frequency modulation rather and amplitude modulation. I can only take so much talk radio and country music.
And of course, would this affect the nerves in people's heads, ie, you pick up a FM station playing Uncle John's Band (long version).
carabelli
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In article

I'm waiting for the XM specs myself
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Clinton wrote:

The mere fact that orange juice would light up my nervous system and produce the reflex action of spewing what was left across the kitchen. I didn't have that problem for more than a few days. I'm now 100% ceramic, even the dentist can't tell the real from the fake. It's nice to be able to sink your front teeth into an Eskimo Pie and chase it with a sip of scalding coffee :)
Richard Perry
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wrote:

I see Robert could NOT answer the questions as usual.
Rather dense, he is.
What is*your* position on the safety of amalgams, Robert?
What is *your* position on the electromagnetic properties of typical dental amalgams, Robert?
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Have you any proof that I CANNOT answer the questions?
BTW, I have already answered them...can't help it if your mind is too fogged to realize it.
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I see that lolly could not answer the questions as usual:
What is your position on Keith Walsh's inability to muster the courage to ask the physicists at his local college/university his questions about determining field characteristics and induction of electrical potential in amalgam dental fillings?
Why have you not urged keith to ask the physicists at his local college/university to answer his questions?
What is your position on Toxic Shock Syndrome and tampooooooooons?
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Keith P Walsh wrote:

The field which generates voltage is the magnetic field. (Any electric field present automatically counts toward the voltage)
So Yes, any changing magnetic field or electromagnetic field which is changing will induce some voltage. The question is how much? To maximize the effect, your would have to generate a field with the maxium rate of change of the magnetic field, per unit area possible, I would guess probably cutting perpendicualr to one of the filling faces, (if the filling is seen as rectangle) as it cuts through the filling.
However there is another way of generating a changing magnetic field, which is, in fact an electromagnetic wave. EM waves travel through space with their amplitude, (which includes Electric and magnetic fields that point perpendicular to each other) constantly changing, so as the wave passes through an area it generates a changing magnetice and electric field. But there is another effect. In the vicinity of atoms EM waves may obey what is known as the photoelectric effects, which means that the wave is suddenly absorbed completely and it's energy is converted to voltage/current that way as well.
Predicting the exact effect of either a magnetic field or Em wave on a filling is a difficult task requiring solving differntial equations and setting boundary conditions, and applying probably antenna theory for an EM wave.
However you could make some approximations, for example you know that for a magnetic field , whose amplitude is perpendicular to a metal sheet, the voltage in any closed circuit in the sheet will equal the change in flux in the enclosed circuit , times some factor which takes into account, the material properties of the sheet. The physicists on sci.phys can help you to solve this problem.
For an EM wave you can use an energy argument. Since you should be able to compute the energy of an EM wave, and the amount of EM wave energy passing through the area of the filling, you can estimate that the total energy generated by the filling, in terms of voltage times current in whatever circuit it is in, cannot be larger than this amount of energy. The paper you cited did mention an intruiging fact however, which is that some of the EM energy near the filling which passes through the mouth might also be aborbed, so you could ask not just how much voltage is induced in the filling but in the vicinity of the filling. Maybe this effect is significant in some cases and maybe not.

For Em radiation wavelength will be the key since the filling will act as an antenna. YOu could ask someone experienced in antenna theory, (either a physicist or an electical engineer specializng in antennas) how to compute this. They can acutally solve the problem using computer software.
For a pure magnetic field, the main effect will be both it's magnitude and how fast it changes. An MRI , might in fact be good for this, the magnitude is certainly very large, but you would have to see how quickly the field changes, and determine for how long it is changing.
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Do you?

Do you think the physicists at your local college/university might be able to answer those questions if you asked them?

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wrote:

any changing em field will induce currents and potentials in fillings. for maximum effect just look at maxwell's equations and all will become clear.
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Dave wrote:

By the way, the US congress and indeed legislatures around the world are constantly changing their laws and statutes. But which laws have never changed in the the last 100 years?
Answer: Maxwells laws! (gravity was modified after 1905)
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This would require Keith having to do some research on his own without asking for others to do it.
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By the way "Dave", a few weeks ago our fellow newsgroup contributor billkatz wrote this:
"Amalgam is a metallic compound but because of the high resistance of amalgam, it cannot truly be classified as a conductor. "
This appears to directly contradict what you are saying with regard to amalgam fillings being conductors.
It looks as if one of you must be mistaken.
Is it you or is it him?
Keith P Walsh
PS, I'd guess that it's him.
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But your inability to state categorically that this is true shows how little faith or knowledge you have in the subject.
--

I fear that I will be walshed

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On Mon, 10 Oct 2005 18:22:17 -0700, Robert Morien

No it doesn't.
It simply allows (deliberately) for the fact that after a long time looking and asking the right questions I have not been able to find an experimentally determined value for the electrical conductivity (or resistivity) of a typical dental amalgam.
And I think it shows that my own scientific thought process is perhaps more rigorous than yours.
Would you yourself describe amalgam dental fillings as "conductors"?
And, if so, would you be able to quote an experimentally determined value for the material's electrical conductivity - measured in siemens per metre - (or its electrical resistivity - measured in ohm-metres) in support of it?
Keith P Walsh
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wrote:

Robert's not good at answering questions.
He can't answer the below ones either.
What is*your* position on the safety of amalgams, Robert?
What is *your* position on the electromagnetic properties of typical dental amalgams, Robert?
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Much better than Keith. I see that you still refuse to urge keith to pose his questions to the physicists at his local college/university. Why is that? Are you afraid of the answer or is it that you know that keith will never do anything that would crumble his theories?

Your wrong. There is a world of difference between can't and won't. Learn that difference.

Do you think tampons should be forbidden for sale as they cause more deaths per year than mercury poisoning?

What is your position on the 30000 children who die every day of hunger?
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Asking the right questions? Who have you been asking? Certainly not the Physicists at your local college/university. Inquiring minds want to know.

Please describe the experiments that you have performed or asked to have performed by legitimate scientists. Please explain your refusal to ask the physicists at your local college/university for their help in determining these values.

What scientific thought process is that? What experiments have you conducted and what were the results? How can you say your "thought experiments" are more rigourous than mine when yours are just theories and I have had the actual experiments performed?

I am not about to provide you with any useful info prior to proper payment for my research.

Yes.
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Wrong, or at least sloppily worded. The frequency of the electromagnetic field is matched to the frequency of precession of nuclei with magnetic moments in the _static_ magnetic field.
[snip irrelevant information about nuclear precession]

And even if they did, it wouldn't be relevant. Nuclear magnetic resonance has nothing to do with whether the radio-frequency part of the scanning technology induces electric currents in conductive materials. That's down to Maxwell's equations and Ohm's law.
--
Richard Herring

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