Faradaic Activity in Dental Amalgams



I had an MRI of my head. I noticed no effects in my teeth with the fillings nor any other ones including my gold cap.
Al
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

one anecdotal comment does not offset 100 years of experiments and scientific observation. YES, there will be currents in the metal fillings when exposed to an electromagnetic wave.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Al wrote:

The excitation of atomic nuclei in MRI procedures is achieved by matching the frequency of the incident electromagnetic radiation with the corresponding "resonant" frequency of the target nuclei for the chosen electromagnetic field strength.
The variation of resonant frequencies for varying field strengths is different for the nuclei of different elements. In fact each element (more accurately each isotope of each element) has its own characteristic profile of "resonant" frequencies (called Larmor frequencies after the British scientist Sir Joseph Larmor, 1857-1942).
A table of MRI (NMR) frequencies at different field strengths for different elements can be found on the website of the Massachusetts Institute of Technology at:
http://web.mit.edu/speclab/www/nmrfreq.html
You can see that the field strengths for this table have actually been chosen to match with convenient values of Larmor frequencies for hydrogen - H(1).
So, for argument's sake, if an MRI scan was set up with a field strength of 5.8717 Tesla and a frequency of incident radiation of 250 MHz, then you would expect the hydrogen nuclei in the region of the body under examination to "resonate" accordingly.
However, you would not expect the nuclei of the mercury, silver or tin atoms in your amalgam fillings to resonate significantly at all.
Many people mistakenly presume that the reason for this must be that the field strength is not great enough.
But this is not the case.
The true explanation is that the combination of the frequency and the field strength (both of which can be very precisely controlled) does not correspond to the conditions required for producing resonance in any of the atomic nuclei in the material which constitutes the fillings.
In our example (a field strength of 5.8717 Tesla), the Larmour frequencies of Ag(107), Ag(109), Sn(115), Sn(117), Sn(119), Hg(119) and Hg(201) are 10.116, 11.630, 81.749, 89.063, 93.181, 44.568, and 16.499 MHz respectively, and not 250MHz.
The Larmor frequencies for these nuclei will always be different from that of hydrogen, whatever the strength of the field. And it is therefore possible to ensure that only hydrogen nuclei are excited in an MRI procedure simply by determining that the incident radiation matches the Larmor frequency for H(1) at the chosen field strength.
However, I think that to suggest that this may be taken as a general indication that electromagnetic energy is not capable of inducing electrical currents in metal amalgam dental fillings would be silly.
Do you not agree?
Keith P Walsh
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

of course not. you have again grasped at straws and missed. the 250mhz will induce currents in any conductor within range. and since fillings are conductors they will have currents induced in them and these will of course produce potential differences.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Do you think that it should be possible to determine whether or not the electrical potentials thus generated in amalgam fillings are able to dissipate electrical energy through the nerves in people's heads?
Keith P Walsh
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

it should be possible to determine that. i have had tests that measure the normal nerve pulses and stimulated signals when testing for carpal tunnel syndrome. there is probably no reason the same type of test couldn't be used to test for nerve impulses in the head... there would be two problems though, getting access to the nerves with the probes, and preventing interference from the electromagnetic field you are testing with. there would be a big problem with the probes actually injecting signals from the emf instead of measuring the effect on the nerves themselves, some tricky shielding or processing to cancel out the rf effects on the probes would be needed to see the actual nerve impulses.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

As an aside, I have read about people receiving radio broadcasts within the vicinity of high power AM transmitters. Supposedly the corrosion, of whatever chemical means, had created rectifiers. The resultant DC and I suppose a loose part of a filling resulted in audio being generated and conducted via bone to the inner ear. I have not experienced this.
If this is true, might not people who have this defect in their fillings also experience some kind of sound. Or is the noise of the damn machine so loud and synchronized with the "tooth generated" audio that it is not detected by the patient.
The only effect I remember from the procedure is that I saw pink clouds floating in a light blue background when I closed my eyes.
I might add that they found nothing wrong. But my left ear still rings.
Al
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Would you presume that the medical profession has enough scientific evidence to conclude that the ringing in your ear is not the result of a neurological injury caused by the discharge of elecrical energy through the nerves in your head resulting from the generation of electrical potentials by the metal fillings in your teeth?
Keith P Walsh
PS, remember that it has been demonstrated experimentally that metal amalgam dental fillings generate electrical potentials with magnitudes of up to 350 millivolts. See:
http://book.boot.users.btopenworld.com/dutch.htm
And the resting potential of the human neurological synapse is only 70 millivolts.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Keith P Walsh wrote:

Are you also concerned about the electrical potentials generated in the nerves in people's heads (they are conductive material, after all) dissipating energy in their fillings?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Do you think it's possible to pose these questions to the experts at your local college/university?
Do you think it's possible to specifically identify which nerves YOU are talking about?
As I've mentioned previously, I have done just that. You could do it or you could arrange to pay me for my time and effort. The price keeps going up.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dave wrote:

Keith, aren't you saying that the MRI process itself cannot be taken as a negative on other types of EM radiation? It seems Dave has suddenly focused in on the EM radiaiton in an MRI which is probably a very small amount of energy. The point is what the Magnetic field does during an MRI, not the tiny dose of RF radiation they give you. Let's also not forget that this (magnetic) field probably isn't switching at a very high rate at all, even if it is large, (because, remember a constantly CHANGING field is need to induce voltage,).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Good grief... An MRI will suck up a floor buffer; forget about it rattling your fillings. Patients are constantly exposed to huge amounts of EMR during an MRI. -- See: http://www.simplyphysics.com/flying_objects.html# for some piccies :^) An MRI will generate 25,000 times the earth's magnetic field, and aside for avoidable mishaps, patients always survive. The human body is VERY resilient.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
billkatz wrote:

Sigh...Bill your understanding of physics seems to be a little, well off. A magnet will fly into a refrigerator, that doesn't mean that the magnet is generating any substantial emf in the refrigerator or itself. of course if you spun the magnet around real fast so it generated a changing magnetic field...
Magnets create attraction with magnetic materials because the little tiny weeny magnetic domains align to become one great big, huge magnetic domain when exposed to a magnetc field, no changing flux requred!
Patients are constantly exposed to huge amounts

That is apparently caused by the magnetic field, not electromagnetic radiation. If so you cold point an attenna at a nail and watch it fly across the room. Do you see cars lifting up into the air when they drive by a radiostation anntena, or a microwave dish. That's EMR! My understanding is that MRI's do not use substantial electromagnetic radiation but only a little in the RF range. If they do, a lot of people would like to know because on of the big selling points of MRI's is that they are safer than x-rays because of the small-low energy EMR exposure.

It's the change in the flux that matters, not the total strength of the field, for the purpose of induced voltage. You would think that for a while, while it powers up some voltage would be generated, but I don't even know how long it takes the machine to reach full strength. I could sit in a magnetic field 1,000,000 times the earth strength and still not generate a voltage in a wire
A magnetic field attracts objects because they have miniature currents loops inside them, aligned with exposure to the magnetic field and force equals B(H)x(current). this is not the same mechanism by which a magneic field induces a voltage. A changing magnetic field will induce an electric field in AIR, but it won't exert a force on the air molecules, otherwise we would have tornado's near power generators!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've read what you have to say. Keep rationalizing. You'll finish digging your own grave, soon enough.
Bye!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
billkatz wrote:

I don't like threating language like that. By the way telling someone to dig their own grave can be construed as a direct threat according to google laws, say "bye bye" to your account.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@hotmail.com wrote:

google laws? LOL
google has become the largest haven for spammers, what makes you think they care about newsgroup postings
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Okay, lets simplify a bit. TAke two magnets near each other and hold them in place with say a wooden clamp. Now you would agree that the voltage one induces in the other is zero?
In fact it's obvious that since everything is static no energy is being put into the system so it would be hard to see how a voltage could be induced, if say one of the magnets was connected in a loop with a wire and was doing work!
Now imagine the clamps were suddenly removed from the magnets. Note that no voltage is induced, the instantaneous velocity is zero, no change in flux going through the magnet etc, yet there WILL be a strong force on the magnet. The generation of force on the magnet is not the same thing as the induction of voltage and current. Thus the fact that an MRI can exert a large force on an object does not imply that it induces a large voltage, although, when the object moves and depending on changes in the field strength some production of voltage is likely to occur. (I have no idea how much becaue I don't know that field strengths and changes of the magnetic field in an MRI)
This concludes kindergarten physics 101.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Do you think that it would be possible to engineer a constantly changing electromagnetic field which induces an electrical potential in a metal amalgam dental filling?
And, if so, how might you determine what the characteristics of the field should be for producing, say, the maximum effect?
Keith P Walsh
PS, further enquiries regarding the electrical properties of dental amalgams can be found at:
http://book.boot.users.btopenworld.com/intro.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Keith P Walsh wrote:

At one time I could hear the local AM Radio station via the fillings in my teeth. I lived fairly close to the transmitter. Proof is in the pudding; potentials can be produced. A fork in contact with them could also produce a current, quite uncomfortable at times, depending upon saliva ph. I doubt however that there were any dangers involved in either r of these side effects.
BTW, the wife was skeptical, so I convinced her by having her turn on the radio to the local station. When repeatedly the song playing was perfectly in sync with my ongoing rendition of it, she was finally convinced.
If however, yours is an attempt to produce some sort of panic over amalgams, then I suggest that you don't get any, and then stfu about those that other people have, because it isn't hurting you, nor is it hurting them. I'm speaking from experience. The effects can be irritating at times, however.
Richard Perry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
RP wrote:

You able to actually hear the station? I wonder how that worked, maybe the nerves in the ears where stimulated at the right frequency.
How did you know there was a correlation between salvia ph and the current?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.