The Austrian company Ogussa manufactures an alloy called Starfill NG2.
This alloy is intended for use by dentists in mixing solid particles
of it together with liquid mercury to form a dental amalgam.
Starfill NG2 is not the amalgam. It is an alloy which must be mixed
with liquid mercury in order to form the amalgam.
The composition of the alloy Starfill NG2 is as follows:
Ag - 70%
Cu - 15%
Hg - 3%
Sn - 12%
Since it contains 3% mercury, Starfill NG2 can be accurately described
as "an alloy of mercury with other metals".
However, as we have already established, it is NOT an amalgam.
Even dentists (in fact, especially dentists) will recognise that you
cannot make an amalgam with only 3% mercury.
Therefore, logically, it must be concluded that "an alloy of mercury
with other metals" is NOT an adequate definition of an amalgam.
In spite of this, it appears that many dentists, as well as a
significant number of editors of various types of dictionary, have
been misled into believing that an accurate definition of an amalgam
is ""an alloy of mercury with other metals".
In fact this definition is inaccurate on two counts.
Firstly, an amalgam is not an alloy. True metallic alloys are formed
by heating ALL of the constituent metals to a temperature which is
higher than the melting point of each of them. The molten metals are
mixed together thoroughly and then allowed to solidify by cooling at a
controlled rate. That's how the "alloy of mercury with other metals"
called Starfill NG2 is produced.
In contrast, an amalgam is formed by mixing bits of a solid metal, or
solid metal alloy, together with a liquid metal at a temperature which
is below the melting point of the solid component.
Secondly, it is perfectly possible to form an amalgam in which the
amalgamating agent is a liquid metal other than mercury, so that the
resulting amalgam does not have any mercury in it at all.
Do we have any examples of such amalgams?
Well of course we do. If you go to:
- you will find a paper describing amalgams formed by mixing liquid
gallium (melting point 29.7 celsius), with different amounts of
aluminium (that's "aluminum" to Americans).
There is NO MERCURY in these amalgams.
Amalgams can also be formed by using indium as the liquid metal
amalgamating agent. There is NO MERCury in these amalgams either.
And therefore the widely supported definition of an amalgam which is
given as "an alloy of mercury with other metals" is at best
inadequate, and at worst downright wrong.
So I would suggest that any dozy dim-witted dunce in the dental
pofession who has been fooled into believing this definition should
stop believing it, and stop using it, now.
And they should also recognise that because there are different types
of amalgams, formed by using different liquid metal amalgamating
agents, then it makes perfect linguistic, scientific and logical sense
to differentiate between them by referring to them as gallium
amalgams, indium amalgams and MERCURY AMALGAMS, etc.
And those dozy dim-witted dunces in the dental pofession who are in
the habit of telling people that the term "mercury amalgam" is a
pleonasm should realise that the teachers who taught them to believe
this in dental school were confused and ignorant, and they have simply
passed on their confusion and ignorance to you.
(When I use the term "mercury amalgam" it doesn't mean that I think
that I can form an amalgam by mixing liquid mercury with liquid
mercury - it means I'm referring to an amalgam formed using liquid
mercury rather than liquid gallium, or liquid indium, etc. - by the
way, I'm sure that this is all very obvious to you guys at
sci.materials - It's the DDS dopes at sci.med.dentistry who appear to
have difficulty in accepting that what they were taught in dental
school was garbage.)
However, this is not simply an argument about semantics.
The reason why it is important to distinguish between amalgams and an
alloys is because these are two distict types of mixtures of metals.
When you mix liquid mercury together with a powdered metal alloy at
room temperature what you end up with is a solid which has a much more
inhomogeneous microstructure than any true alloy has. A large
proportion of that microstructure consists of solid cores of unreacted
alloy which has not fused with any mercury at all, see:
This material would be more accurately described as a mixture of at
least two different alloys. But it cannot be accurately described as
And, because of its significantly different microstructure, you might
also expect such a material to differ from a true alloy in its
electrical, electromagnetic and thermoelectric behaviour (that's
"behavior" to Americans).
In 2007 a team of Czech researchers set out to measure the magnetic
susceptibility and electrical resistivity of a range of metallic
dental materials (a bit late in the day don't you think?).
You can read their report at:
At the top of page 717 they list 6 different materials included in the
study which are describerd as "Amalgams".
These materials are not amalgams. They are the alloys used to form
dental amalgams by mixing them with liquid mercury. And as a matter of
fact it is not obvious from the report whether it was in fact amalgams
or just samples of the alloys that were measured in the tests. (You
would expect the physical properties of an amalgam to vary
significantly from point to point within the material according to the
inhomogeneous nature of the material's microstructure. It appears that
the researchers made no attempt to take account of this variation in
their study. Also - there is no mention anywhere of the % Hg content
of the "amalgams" that they measured. Did they simply receive samples
of the alloys from the manufacturers - and their results were from
measurements of the alloys and not representative of the properties of
amalgams at all? I'm trying to find out and I'll report later.)
Anyway the case is made pretty clearly. An amalgam is not an alloy.
If anyone has any opinions on the Czech study I'd be interested to
hear them. (Remember that you wouldn't be able to repeat this study
without knowing what percentages of Hg were used in the "Amalgams"
Keith P Walsh.
PS, I have noticed in recent years that attempts have been made to
develop amalgams ustilising liquid metal amalgamating agents other
than mercury (e.g. gallium) for use in dentistry. I also gather that
these attempts are generally inspired by the perception that mercury
should not be used in dental materials because of its toxic
properties. My own belief is that any "gallium amalgam" intended for
use in dentistry would, as a newly developed dental material, have to
satisfy rigorous testing for its physical properties to satisfy public
bodies, such as the US FDA, that it is acceptable from the point of
view of bio-compatibility. And, presuming that such tests would
include a thorough examination of its electrical, electromagnetic and
thermoelectric behaviour, it would be unlikely to gain the required
approval. The principal reasons why the electrical, electromagnetic
and thermoelectric properties of mercury amalgams have never been
subjected to similar scrutiny are because, firstly, when mercury
amalgams were first developed for use in restorative dentistry the
significance of these properties was not as well recognised as it is
today; and, secondly, in the case of mercury amalgams there appears to
apply a wholly unscientific principle that, because they have been
used for so long in dentistry now, if they were causing any
significant problem it would have been widely recognised (remember
that the widespread adoption of mercury amalgams for use in
restorative dentistry was quickly followed by the rise to prominence
of psychiatric "medicine" in our societies, and at present there is
insufficient scientific evidence to support any assertion that the two
are not significantly linked by the relationship of cause and effect.)
- posted 12 years ago