I have some anecdotal evidence. I recently had an MRI of my head. Yeah,
yeah, they found nothing! Anyway, I felt absolutely no effects from the
high magnetic field in my fillings nor in my caps.
The technician told me that some people insist on wearing their shoes
with nails in them. He reported that their feet then levitate. So the
field is damn strong.
My 2 cents worth.
There's never enough time to do it right the first time.......
Thank you for your reply.
The excitation of the nuclei of atoms in MRI procedures is not simply
dependent upon field strength.
The field strength influences the frequency at which the targeted
nuclei will resonate, but the frequency of the incident radiation must
also match this "resonant" frequency for the excitation required for
MRI purposes to take place.
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
A table of NMR frequencies at different field strengths for different
elements can be found on the website of the Massachusetts Institute of
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 your MRI scan had been set up with a field
strength of 5.8717 Tesla and a frequency of incident radiation of 250
MHz, then you would have expected the hydrogen nuclei in the region of
your body under examination to "resonate" accordingly.
However, you would not have expected the nuclei of the mercury, silver
or tin atoms in your amalgam fillings to have resonated significantly
This is because the Larmor frequencies of Ag(107), Ag(109), Sn(115),
Sn(117), Sn(119), Hg(119) and Hg(201) at this field strength 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 can
therefore be ensured that only hydrogen nuclei are excited in an MRI
procedure simply by ensuring that the incident radiation matches the
Larmor frequency for H(1) at the chosen field strength.
Do you think that it should be possible to determine whether or not
the nuclei of the atoms in your amalgam fillings might be excited by
other, perhaps less mindfully engineered electromagnetic fields, such
as those produced by visual display units, electrified railway lines,
cellular telephones, etc., etc., etc.?
Keith P Walsh
Unlikely for many reasons: reflection/absorption by tissue
surrounding mouth; FCC interference rules which guarantee
weak EM fields from consumer products; the inverse square
law of dissipation of EM radiation away from a source; and
low-Q resonances of metals and compounds which means they
may be strongly attenuated and not significantly "ring".
And after all this, there is still no reason to claim that
a lonely resonating tin atom implies a harmful health effect.
The MRI is not mutating H atoms or causing people to die.
I suspect your reasoning has become inverted. You hate
amalgams and thus think they must be harmful.
For God's sake, why don't you do a little homework then? Just
look up the component compounds of amalgam in a CRC handbook,
jot down their permittivity and permeability constants, and
use the rule of mixtures to arrive at a composite material
Maybe if you did a few calculations your argument would be
better received. My guess is that you are afraid that the
hard science will prove you wrong. Why is it that fanatics
never take the time to do the research themselves? For all
the effort they spend promoting these crazy views, you would
think they would have performed a little effort to make sure
that their theories are on sound scientific ground. Instead,
they try to dredge up the same old papers that have been
refuted so many times in the past.
SiFe = Ferrous Silica ?
Am unfamiliar with mumetal and supermalloy.
Are these metals that considered 'ferrous' metals ?
Just want to know because I don't believe that
any of these metals are contained in any formulation
of dental amalgam.
Some dental casting alloys do contain small ammounts
of Indium, any magnetic properties there ?
Thanks for you time,
Take out the G'RBAGE to reply
Sorry SiFe is my lazy way of writing silicon iron. It's
used a lot in transformers.
Check a CRC manual (I don't have one handy right here).
Look up permeability which also might be referred to
as mu (unit = henries/meter). Run of the mill iron has
a mu of around 5000, and purified iron is around 200000.
Supermalloy has a mu around 1 million. The general rule
of thumb is that most materials on the face of the earth
have a mu of 1.0 (essentially no magnetic susceptibility).
Strangely enough, just now on the Discover Channel program, Mythbusters,
they measured a few millivolts being generated between gold and amalgam
in a solution of vinegar and water with the same PH as a human mouth.
They were trying to prove or disprove that Lucille Ball once received,
as she claimed, WWII Japanese Morse code through her fillings.
73, Cecil http://www.qsl.net/w5dxp
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