Amalgam and Seebeck Coefficient

The following is my reply to the question as to why one might wish to measure the Seebeck coefficient of a typical dental amalgam, as posed by
Professor Richard van Noort, dental Materials scientist at the University of Sheffield, UK.
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----- Original Message -----
Sent: Wednesday, May 28, 2003 4:07 PM Subject: Re: The Electrical Properties of Dental Amalgams

Dear Professor van Noort,
It has been demonstrated experimentally that dental amalgams generate electrical potentials with magnitudes of up to 350 millivolts (slightly more than one third of a volt). See:
http://book.boot.users.btopenworld.com/dutch.htm
However, it appears that experimental investigations to determine whether or not these potentials are able to dissipate electrical energy through the nerves in people's heads have never been carried out.
In his "Master of Dental Surgery" thesis Peter Sheridan asserts that, "Electrical Reading of Restorations is particularly worthless", on the grounds that, "there is no consensus as to what these devices are actually measuring". See:
http://book.boot.users.btopenworld.com/sheridan.htm
I disagree with this argument.
Metal amalgam dental fillings are placed in children's teeth.
I think that it is therefore more consistent with the established principles of scientific understanding, and incumbent upon the dental profession, that further investigations into the electrical behaviour of amalgams should be carried out until there IS consensus regarding what these measurements are telling us.
In my experience, the one aspect of the electrical behaviour of dental amalgam which dentists and dental material scientists feel most confident in being able to discuss is its electrochemical behaviour. Briefly, this is that the exposed surfaces of a newly placed amalgam tarnish as the result of a small degree of electrochemical corrosion. This action produces a thin layer of metal oxide (and/or chloride) which adheres to the surface and effectively prevents further electrochemical corrosion from taking place.
However, it appears that some if not all dentists and dental materials scientists are under the impression that this accounts for all of the electrical behaviour of the material.
Again I disagree.
For a start, metal oxides do not necessarily make good electrical insulators. So, whilst they may effectively seal the surfaces of amalgams from further corrosion, they would not necessarily prevent the passage of electrical currents arising as a result of electrical potentials generated by other electrical phenomena.
Moreover, it has been known for more than 160 years that metals, mixtures of metals, and dissimilar metals in contact with each other are able to dissipate electrical energy to their surroundings as a result of their thermoelectric behaviour, and that it is not necessary for there to be any electrolysis taking place in order for this to happen. See:
http://book.boot.users.btopenworld.com/thermo2.htm
(It has also been known for more than 160 years that when an electrical conductor moves in an electromagnetic field an electromotive force is induced in the conductor; and that when a stationary conductor is subjected to a varying electromagnetic field an electromotive force is again induced in the conductor.
The inter-relation of thermoelectric and electromagnetic phenomena in inhomogeneous materials can be seen at:
http://www.finoag.com/fitm/n6.html
).
In view of these facts I believe that a responsibility lies with those who advocate the use of metal amalgams in restorative dentistry to take all reasonable steps to demonstrate that these materials are not able to dissipate electrical energy through the nerves in people's heads as a result of their thermoelectric (not to mention electromagnetic) behaviour.
And according to the established principles of scientific understanding this would mean carrying out experimental studies to measure the thermoelectric properties of amalgams.
And the principal thermoelectric property of a material is its Seebeck coefficient (sometimes called "thermoelectric power", and measured in volts per kelvin).
If such investigations were to then demonstrate experimentally that the thermoelectric potentials generated by amalgam dental fillings are, for example, not large enough on their own to dissipate electrical energy through the nerves in people's heads then the assertion that this is the case would have some scientific basis.
Otherwise we are just guessing.
And amalgam fillings are placed in children's teeth.
It should be neither necessary nor possible for anyone to guess these things.
They should have been measured.
That is science.
I put it to you that the fact that you don't know what the thermoelectric properties of dental amalgams are is the principal reason why you appear to have concluded that they cannot be of any significance.
That isn't science.
It's just sheer blind arrogance.
You might more honestly consider that you are not allowed to know what the thermoelectric properties of dental amalgams are.
And you might also consider that if you yourself were to try to find out what these properties are, you too would be met with nothing but ridicule, sarcasm and derision.
I think that you would prefer to preserve your reputation as a dental materials "scientist", even if you do recognise that without the science then what you might actually be is an unwitting dental materials "apologist".
This reply has been posted to the usenet newsgroups sci.med.dentistry, sci.physics and sci.materials
Keith P Walsh
PS: Some scientifically coherent enquiries regarding the possible effects of the electrical behaviour of dental amalgams can be found at:
http://book.boot.users.btopenworld.com/intro.htm
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Keith P Walsh wrote:

You are certainly of a One Track Mind.
How come it took you from May 28, 2003 to November 30, 2003 to make your reply?
Seems like the subject isn't of that much priority to you. And it is hard to maintain continuity of thought for that long.
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I don't think they let him out very often anymore.
carabelli
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Orthodontics bands may be 175 millivolts .......... WATCH OUT!

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Joel M. Eichen, .
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Are you kidding? Walsh has asked 1,000,0000 times about the350 millivolts ........ I personally thought it was some kind of religious mantra or something ..........
(I was always under the impression that amalgams never went above 349 millivolts ....)

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Joel M. Eichen, .
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This is probably correct. I recall hearing something about 350 millivolts somewhere before but I cannot remember where.
Joel
On Sun, 30 Nov 2003 15:10:30 +0000 (UTC), "Keith P Walsh"

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Joel M. Eichen, .
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Good stuff, thanks. In fact it should be van Noort explaining why he doesn't find it interesting, teeth being the well-innervated structures that they are..
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madiba

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True, but why can I only get hip hop on my amalgam fillings .....?
On Sun, 30 Nov 2003 18:14:55 +0100, snipped-for-privacy@thekraal.com (madiba) wrote:

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Joel M. Eichen, .
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madiba wrote:

The "Scientific Letters" appeared to be someone equally ignorant as himself, writing to someone like himself.
To the science illiterate, even jingles will look good.
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wrote:

Thank you for your support.
I find that the kind of unscientific response from dentists and dental materials "scientists" to enquiries concerning the electrical behavior of dental amalgams, as exemplified by Professor van Noort's apparent indifference, is very common.
The dismissal of concerns regarding, for example, the thermoelectric properties of these materials usually appears to be based upon the principle that if the these properties are not known then this somehow constitutes sufficient scientific evidence for concluding that they cannot be of any significance.
Even more alarming, perhaps, is the apparent tendency to extrapolate from this to the further conclusion that the correct scientific position on the thermoelectric behavior of dental amalgam is maintained by NOT carrying out experimental investigations to find out what these properties are.
I call this the "pro-ignorance" argument, and it is in fact the exact antithesis of scientific method.
And I rather suspect that the reason for its prevalence has more to do with the preservation of reputations than with science.
Any real scientist in Professor van Noort's position would not only feel an obligation to at least try to establish a proper scientific understanding (i.e. one based on experimental observation) of the physical properties of the material in question, but would also be driven by a scientific curiosity to determine the degree to which the thermoelectric behavior of dental amalgams contributes to the electrical potentials which they generate - measured at up to 350 millivolts in magnitude (see http://book.boot.users.btopenworld.com/dutch.htm ).
It has been known for more than 160 years that metals, mixtures of metals, and dissimilar metals in contact with each other are able to dissipate electrical energy to their surroundings as a result of their thermoelectric behavior.
And amalgam fillings are placed in children's teeth.
I believe that the thermoelectric properties of dental amalgams should therefore have been measured.
And I am confident that I am correct.
Keith P Walsh
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No need to be unscientific. I think amalgams account for 350 millivolts.
Joel

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Joel M. Eichen, .
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Keith P Walsh wrote:

You have it wrong.
The dismissal is of YOU and your abrasive presumptive ways.
The psuedoscience you sometimes couple to your plea ( really, your demand) is an additional aggrivation.
Just to repeat.
The dismissal is of YOU and your abrasive ways.
Jim
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But we cannot refute the 350 millivolts ....... even Einstein and Fermi agreed on that. (according to Keith).
Joel

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Joel M. Eichen, .
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It has been known for more than 160 years that metals, mixtures of metals, and dissimilar metals in contact with each other are able to dissipate electrical energy to their surroundings as a result of their thermoelectric behavior (and that it is not necessary for there to be any electrolysis taking place in order for this to happen).
And metal amalgam dental fillings are placed in children's teeth.
I believe that the thermoelectric properties of dental amalgams should therefore have been measured.
Are you saying that you agree with me?
Or are you saying that you disagree with me?
Keith P Walsh
PS, the principal thermoelectric property of a material is its Seebeck coefficient (sometimes called "thermoelectric power), and it is measured in volts per kelvin.
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I was thinking 349 millivolts, but I was wrong It is 350.
On Sun, 7 Dec 2003 08:31:33 +0000 (UTC), "Keith Walsh"

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Joel M. Eichen, .
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Keith Walsh wrote:
(snip)

I think that is volts per delta kelvin. In other words, thermoelectric potential develops across a piece of metal that has a thermal gradient across it (i.e. two parts must be at different temperatures). How many degrees kelvin difference do you imagine there might be between various parts of a dental filling?
--
John Popelish

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We agree. It should be at least 349 millivolts per delta kelvin or even possibly as high as 350 millivolts per delta kelvin..

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Joel M. Eichen, .
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Keith Walsh wrote:

How can you possibly think that my statement that you are abrasive can be either an agreement or disagreement with you?
Either incredible stupidity, or incredible tenacity no matter what is said.
Either way, it appears pointless to continue.
You haven't changed a bit, have you?

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The wording of my question was in fact intended to convey the idea that you hadn't actually stated whether or not you agreed with my point.
However, I shall be happy to put it more directly if you wish:
It has been known for more than 160 years that metals, mixtures of metals, and dissimilar metals in contact with each other are able to dissipate electrical energy to their surroundings as a result of their thermoelectric behavior (and that it is not necessary for there to be any electrolysis taking place in order for this to happen).
And metal amalgam dental fillings are placed in children's teeth.
I believe that the thermoelectric properties of dental amalgams should therefore have been measured.
Do you agree with me?
Or do you disagree with me?
Keith P Walsh
PS, enquiries concerning the electrical behavior of dental amalgams can be found at:
http://book.boot.users.btopenworld.com/intro.htm
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Keith P Walsh wrote:

Same old cheap tricks.
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