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Antiquity Of Tin And Medical Use
Dealing With Sensitive Cavities
Discoloration Of Tin And Decomposition Of Food
Fibrous And Textile Metallic Filling
History Of The Use Of Tin Foil Pre 1850
History Of Tin Foil In The Era 1845-1895
Lining The Cavity And Filling Root Canals
Opinions On Tin Foil And Reasons For Using
Starting The Filling


Tin Foil And Its Combinations For Filling




Discoloration Of Tin And Decomposition Of Food








In some mouths tin does not discolor, but retains a clean, unpolished
tin color, yet when there is a sesquioxid of the metal formed, fillings
present a grayish appearance. In the same mouth some fillings will be
discolored, while others are not. As a general rule, proximal fillings
are most liable to show discoloration. Perhaps one reason is that on
occlusal and buccal surfaces they are subject to more friction from
mastication, movements of the cheeks, and the use of the brush.

We have seen a large number of fillings which were not blackened, yet
were saving the teeth perfectly, thus proving to a certainty that
blackening of tin in the tooth-cavity is not absolutely essential in
order to obtain its salvatory effects as a filling-material.

Where there is considerable decomposition of food which produces
sulfuretted hydrogen, the sulfid of tin may be formed on and around the
fillings; it is of a yellowish or brownish color, and as an antiseptic
is in such cases desirable. To offset the discoloration, we find that
the sulfid is insoluble, and fills the ends of the tubuli, thus lending
its aid in preventing further caries. A sulfid is a combination of
sulfur with a metal or other body. A tin solution acted on by
sulfuretted hydrogen (H{2}S) produces a dark-brown precipitate (SnS),
stannous salt, which is soluble in ammonium sulfid (NH{4}){2}S{2};
this being precipitated, gives (SnS{2}) stannic salt, which is yellow.
Brown precipitates are formed by both hydrogen sulfid and ammonium
sulfid, in stannous solutions. Yellow precipitates are formed by
hydrogen sulfid and ammonium sulfid in stannic solutions. The yellow
shade is very seldom seen on tin fillings; the dark brown is more
common.

An oxid is a combination of oxygen with a metal or base destitute of an
acid. In oxidation the oxygen that enters into combination is not
sufficient to form an acid. The protoxid of tin (SnO) is black, and can
be obtained from chlorid of tin, or by long exposure of tin to the
atmosphere. The oxygen in the saliva helps to blacken the tin, and the
metallic oxid penetrates the dentin more or less, acting as a
protection, because it is insoluble. Oxygen is the only element which
forms compounds with all others, and is the type of electro-negative
bodies; it combines with all metals, therefore with tin, and in many
cases only the metal is discolored, and not the tooth. Steam boilers are
made tight by oxidation.

Where there is complete oxidation, the tooth is blackened to but a very
slight depth, and the oxid fills the ends of the tubuli, thus affording
an additional barrier to the entrance of caries. The filling itself will
prevent caries, but oxidation acts as an assistant.

"In the mouth, a suboxid is more likely to be formed than a protoxid,
but both are black; sulfur and oxygen are capable of acting on tin under
favorable circumstances, such as warmth, moisture, full contact,
condensation of elements, and their nascent conditions; the first three
are always present in the mouth. The protosulfuret of tin is black."
(Dr. George Watt.) Others give the color as bluish-gray, nearly black.

Experiments show that slight galvanic currents exist between fillings of
dissimilar metals in the mouth, and practical experience demonstrates
that these currents occasionally produce serious results.

Direct galvanic currents do not decompose normal teeth by true
electrolysis, but acids resulting from decomposition of food and fluids
react upon the lime constituents of the teeth and promote secondary
caries.

When two metals are so situated in the mouth that the mucous membrane
forms a connecting conductor and the fluids are capable of acting on
one metal, galvanic action is established sufficient to decompose any of
the binary compounds contained in these fluids; the liberated nitrogen
and hydrogen form ammonia, which being exposed to the action of oxygen
is decomposed and nitric oxid formed, resulting in nitric acid. We also
have in the mouth air, moisture, and decomposing nitrogenous food to
assist in the production of nitric acid.

"Galvanic action is more likely to develop hydrochloric acid, for the
chlorids of sodium and potassium are present in the normal saliva and
mucus, and when decomposed their chlorin unites with the hydrogen
derived from the water of the saliva." (Dr. George Watt.)

The fact should also be noted that both nitric and hydrochloric acids
are administered as medicine, and often assist in producing decay.

When there is a battery formed in a mouth containing tin fillings and
gold fillings, and the fluids of the mouth are the exciting media, tin
will be the positive element and gold the negative element; thus when
they form the voltaic pair, the tin becomes coated or oxidized and the
current practically ceases.

There is more or less therapeutical and chemical action in cavities
filled with tin, and its compatibility and prophylactic behavior as a
filling-material depends partly upon the chemical action which occurs.

Some dentists fill sensitive cavities with tin, in order to secure
gentle galvanic action, which they believe to be therapeutic,
solidifying the tooth-structure.

"Tin possesses antiseptic properties which do not pertain to gold for
arresting decay in frail teeth; it not only arrests caries mechanically,
but in chalky (imperfect) structure acts as an antacid element in
arresting the galvanic current set up between the tooth-structure and
filling-material." (Dr. S. B. Palmer.) If the metal is acted on, the
tooth is comparatively safe; if the reverse, it is more or less
destroyed. The galvanic taste can be produced by placing a piece of
silver on the tongue and a steel pen or piece of zinc under it; then
bring the edges of the two pieces together for a short time, rinse the
saliva around in the mouth, and the peculiar flavor will be detected.

"In 1820 attention was called to the injurious effects of the galvanic
current on the teeth, and dentists were advised never to use tin and
amalgam in the same mouth.

"A constant galvanic action is kept up in the mouth when more than one
kind of metal is used in filling teeth, and galvanism is often the
cause of extensive injury to the teeth. The most remarkable case I ever
saw was that of a lady for whom I filled several teeth with tin. After a
time decay took place around some of the fillings. I removed them and
began to refill, but there was so much pain I could not proceed. I found
that by holding a steel plugger an inch from the tooth I could give her
a violent galvanic shock. I observed that the exhalation of the breath
increased the evolution of galvanism." (Dr. L. Mackall, American
Journal of Dental Science, 1839.)

"When a faulty tooth in the upper jaw had been stopped from its side
with tin, the interstice between it and the adjoining tooth being quite
inconsiderable, while the upper surface of a tooth not immediately
beneath it in the lower jaw was stopped with the same metal, I have
known a galvanic shock regularly communicated from one tooth to the
other when by the movement of jaws or cheeks they were brought near
together." (Dr. E. Parmly, American Journal of Dental Science, 1839.)

"An interesting debate here sprung up on the action where two metals are
used in one filling, such as gold and tin, the saliva acting as a
medium, and where the baser metal is oxidized by exhalents and by
imbibition through the bony tooth-structure." (Pennsylvania Society of
Dental Surgeons, 1848.)

"A patient came to me and complained of pain in the teeth. Upon
examination I found an amalgam filling next to one of tin. With a file I
made a V-shaped separation, when they experienced immediate relief from
pain." (Dr. Nevill, American Journal of Dental Science, 1867.)

In regard to the decay of teeth being dependent on galvanic action
present in the mouth, Dr. Chase, in 1880, claimed that a tooth filled
with gold would necessarily become carious again at the margin of the
cavity, wherever the acid secretions constantly bathe the filling and
tooth-substance. A tooth filled with amalgam succumbs to this
electro-chemical process less rapidly, while one filled with tin still
longer escapes destruction. The comparative rapidity with which teeth
filled with gold, amalgam, or tin, are destroyed is expressed by the
numbers 100, 67, 50. He prepared pieces of ivory of equal shape and
size, bored a hole in each, and filled them. After they had been exposed
to the action of an acid for one week, they had decreased in
weight,--viz, piece filled with gold, 0.06; amalgam, 0.04; tin, 0.03.

"With tin and gold, some have the superstition that the electricity
attendant upon such a filling will in some way be injurious to the
tooth; it matters not which is on the outside, when rolled and used as
non-cohesive cylinders each appears. We say that neither experimentally,
theoretically, nor practically can any good or bad result be expected
from the electrical action of a tin-gold filling on tooth-bone, and
neither will the pulp be disturbed." (Dr. W. D. Miller, Independent
Practitioner, August, 1884.)

"When the bottom of a cavity is filled with tin which is tightly
(completely) covered with gold, there is practically no galvanic
action and there is no current generated by contact of tin and
gold,--i.e., no current leaves the filling to affect the dentin. That
portion of tin which forms the base is more positive than a full tin
filling would be. The effect is to cause the surface exposed to dentin
to oxidize more than tin would do alone; in that there is a benefit. In
very porous dentin there is enough moisture to oxidize the tin, by
reason of the current set up by the gold." (Dr. S. B. Palmer.)

Electricity generated by heat is called thermo-electricity. If a cavity
with continuous walls is half filled with tin and completed with gold,
or half filled with silver and completed with gold, and the junctions of
the metal are at 20-1/2 deg. C. and 19-1/2 deg. C., if the electrical action
between the tin and gold be 1.1, the action between the silver and gold
will be 1.8, thus showing the action in silver and gold to be nearly
two-thirds more than in the tin and gold, a deduction which favors the
tin and gold.

Rubbing two different substances together is a common method of
producing an electric charge. Is there not more electricity generated
during mastication on metal fillings than when the jaws are at rest?
Friction brings into close contact numerous particles of two bodies, and
perhaps the electrical action going on more or less all the time through
gold fillings (especially when other metals are in the mouth) accounts
for a powdered condition of the dentin which is sometimes found under
cohesive gold fillings, but not under tin.





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Previous: Opinions On Tin Foil And Reasons For Using



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