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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




Starting The Filling








White caries, the most formidable variety known, may be produced by
nitric acid, and in these cases all the components of the tooth are
acted upon and disintegrated as far as the action extends. In proximal
cavities attacked by this kind of caries, separate freely on the lingual
side, and fill with tin. When such fillings have been removed the dentin
has been found somewhat discolored and greatly solidified as compared to
its former condition; this solidification or calcification is more
frequent under tin than gold, which is partly due to the tin as a poor
conductor of heat. Nature will not restore the lost part, but will do
the next best thing--solidify the dentin. In some cases, under tin, the
pulp gradually recedes, and the pulp-cavity is obliterated by secondary
dentin. In other cases the pulps had partly calcified under tin. It has
been known for years that tin would be tolerated in large cavities very
near the pulp without causing any trouble, and one reason for this is
its low conducting power. Attention is called to the fact that gold is
nearly four times as good a conductor of heat as tin, and more than six
times as good a conductor of electricity. Where tin fillings are
subject to a large amount of attrition, they wear away sooner or later,
but this is not such a great detriment, for they can easily be repaired
or replaced, and owing to the concave form produced by wear the patient
is liable to know when a large amount has been worn away. That portion
against the wall of the cavity is the last removed by wear, so that
further caries is prevented so long as there is any reasonable amount of
tin left. If at this time the tooth has become sufficiently solidified,
proper anchorage can be cut in the tin or tooth, one or both, as
judgment dictates, and the filling completed with gold. A tin filling,
confined by four rather frail walls, may condense upon itself, but it is
so soft and adaptable that the force which condenses it continually
secures the readaptation at the margin; thus there will be no leakage or
caries for years. Owing to its softness and pliability, it may be driven
into or onto the tubuli to completely close them from outside moisture,
and with a hand burnisher the tin can be made to take such a hold on
dry, rough tubuli that a cutting instrument is necessary to remove all
traces of it.

Tin foil has been found in the market that under a magnifying glass
showed innumerable tiny black specks, which, upon being touched with an
instrument, crumbled away, leaving a hole through the foil. More than
likely, some of the failures can be attributed to the use of such foil.
Good tough foil, well condensed by hand or mallet force, stays against
the walls of a cavity and makes a tight filling, and ought to be called
as near perfect as any filling, because it preserves the tooth, and
gives a surface which will wear from five to twenty years, depending
upon the size and location of the cavity and tooth-structure. Buccal
cavities in the first permanent molars, and lingual cavities in the
superior incisors, filled for children from six to eight years of age,
are still in good condition after a period of twenty years. Perhaps the
limit is reached in the following cases, all in the mouths of
dentists: One filling forty years old; one forty-two; four on the
occlusal surface, fifty; in the latter case gold had been used in other
cavities and had failed several times. Lingual cavities in molars and
bicuspids can be perfectly preserved with tin. Tapes of No. 10 foil,
from one to three thicknesses, can be welded together and will cohere as
well or better than semi-cohesive gold foil, and it can be manipulated
more rapidly; therefore, if desirable, any degree of contour can be
produced, but the contour will not have the hardness or strength of
gold, so in many cases it would not be practicable to make extensive
contours with tin, owing to its physical characteristics.

No. 10 will answer for all cases, and it is not as liable to be torn or
cut by the plugger as a lower number, but one need not be restricted to
it, as good fillings can be made with Nos. 4, 6, or 8. More teeth can be
saved with tin than with any other metal or metals, and the average
dentist will do better with tin than with gold. It is invaluable when
the patient is limited for time or means, and also for filling the first
permanent molars, where we so often find poor calcification of
tooth-structure. In cases of orthodontia, where caries has attacked a
large number of teeth, it is well to fill with tin, and await further
developments as to irregularity and caries.

If cavities are of a good general retaining form, that will be
sufficient to hold the filling in place; but if not, then cut slight
opposing angles, grooves, or pits. Cavities are generally prepared the
same as for gold, except where there is a great deal of force brought
upon the filling; then the grooves or pits may be a little larger;
still, many cavities can be well filled with less excavating than
required for gold, and proximal cavities in bicuspids and molars, where
there is sufficient space, can be filled without removing the occlusal
surface, and here especially should the cavities be cut square into the
teeth, so as not to leave a feather edge of tin when the filling is
finished, as that would invite further caries and prove an obstruction
to cleansing the filling with floss.

In proximal cavities involving the occlusal surface, cut the cervical
portion down to a strong square base, with a slight pit, undercut, or
angle, at the buccal and lingual corners; where there is sufficient
material, a slight groove across the base, far enough from the margin so
that it will not be broken out, can be made in place of the pit,
undercut, or angle; then cut a groove in the buccal and lingual side
(one or both, according to the amount of material there is to work
upon), extending from the base to the occlusal surface; in most of these
cases the occlusal grooves or pits would have to be excavated on account
of caries; thus there would be additional opportunity for anchorage. In
place of the grooves the cavity may be of the dovetail form. In nearly
all proximal cavities in bicuspids and molars, some form of metal
shield, or matrix, is of great advantage, as they prevent the tin from
crushing or sliding out. By driving the tin firmly against the metal, a
well-condensed surface is secured; and as the metal yields a little, we
can with a bevel or thin plugger force the tin slightly between the
metal and the margin of the cavity, thus making sure of a tight filling,
with plenty of material to finish well. After removing the metal,
condense with thin burnishers and complete the finish the same as for
gold. Where no shield or matrix is used, or where it is used and removed
before completing the filling, it is often desirable to trim the
cervical border, for in either case there is more light and room to work
when only a portion of the cavity has been filled. Tin cuts so much
easier than gold, it is more readily trimmed down level with all
cervical margins.

Be sure that all margins are made perfect as the work progresses, and if
the cavity is deep and a wide shield shuts out the light, then use a
narrow one, which can be moved toward the occlusal surface from time to
time.

In filling the anterior teeth when the labial wall is gone, and the
lingual wall intact or nearly so, use a piece of thin metal
three-quarters of an inch long and wide enough to cover the cavity in
the tooth to be filled, insert it between the teeth, and bend the
lingual end over the cavity; the labial end is bent out of the way over
the labial surface of the adjoining tooth, as shown in Fig. 4. When the
labial wall is intact or nearly so, access to the cavity should be
obtained from the lingual side, and in this case the bending of the
shield would be reversed, as shown in Fig. 5. The shield is not
absolutely essential, but it helps support the tin, and also keeps a
separation.


It is preferable to save the labial wall and line it with (say) five
layers of No. 4 semi-cohesive gold folded into a mat and extended to the
outer edge of the cavity; this gives the tooth a lighter shade, and
bicuspids or molars can be filled in the same manner. Cases are on
record where incisors with translucent labial walls, filled by this
method, have lasted from twenty-three to thirty-seven years.





Next: Lining The Cavity And Filling Root Canals

Previous: Discoloration Of Tin And Decomposition Of Food



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