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 -----
From: "R Van Noort"
To: "Keith P Walsh"
Cc:
Sent: Wednesday, May 28, 2003 4:07 PM
Subject: Re: The Electrical Properties of Dental Amalgams
Dear Dr Walsh
> Please could you explain why it is you want to measure rthe Seebeck
> Coefficient for a dental amalgam?
> Prof van Noort
>
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:
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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:
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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:
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(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:
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).
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:
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Reply to
Keith P Walsh
Loading thread data ...
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.
Reply to
jbuch
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..
Reply to
madiba
True, but why can I only get hip hop on my amalgam fillings .....?
>Keith P Walsh wrote: > >> 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. >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..
Reply to
Joel M. Eichen D.D.S.
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 ....)
Reply to
Joel M. Eichen D.D.S.
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.
Reply to
jbuch
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
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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 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
Reply to
Keith P Walsh
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
Reply to
jbuch
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.
Reply to
Keith Walsh
(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?
Reply to
John Popelish
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?
Reply to
jbuch
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:
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Reply to
Keith P Walsh
350 millivolts is the magnitude of the electrical potentials which have been measured in amalgam fillings. See:
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I'd say that further experimental investigation would be necessary in order to determine the extent of the contribution, if any, made by the thermoelectric behavior of the material.
Would you agree?
Keith P Walsh
Reply to
Keith P Walsh

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