Lining The Cavity And Filling Root Canals
For the last ten years the writer has been using tin at the cervical
margin of proximal cavities in bicuspids and molars, especially in deep
cavities (now an accepted practice), and he finds that it prevents
further caries oftener than any other metal or combination of metals he
has ever seen used. In filling such cavities, adjust the rubber, and use
a shield or matrix of such form as to just pass beyond the cervical
rgin; this will generally push the rubber out of the cavity, but if it
does not, then form a wedge of wood and force between the metal and the
adjoining tooth, thus bringing the metal against the cervical margin,
and if a small film of rubber should still remain in the cavity, it may
be forced out by using any flat burnisher which will reach it, or it can
be dissolved out with a little chloroform. Fill from one-fourth to
one-half of the cavity with tin, and complete the remainder with gold
when the tooth is of good structure; this gives all the advantages of
gold for an occlusal surface.
Before beginning with the gold, have the tin solid and square across the
cavity, and the rest of the cavity a good retaining form, the same as
for gold filling; then begin with a strip of gold slightly annealed and
mallet it into the tin, but do not place too great reliance upon the
connection of the metals to keep the filling in place.
On the same plan, proximal cavities in the anterior teeth can be filled,
and also buccal cavities in molars, especially where they extend to the
occlusal surface. The cervical margin should be well covered with tin
thoroughly condensed, thus securing perfect adaptation, and a solid base
for the gold with which the filling is to be completed. Time has fully
demonstrated that the cervical margin is most liable to caries, and here
the conservative and preservative qualities of tin make it specially
"Electrolysis demonstrates to us that no single metal can be decomposed,
but when gold and tin are used in the above manner they are united at
the line of contact by electrolysis. The surface of both metals is
exposed to the fluids of the mouth, and the oxid of tin is deposited on
the tin, by reason of the current set up by the gold; thus some atoms of
tin are dissolved and firmly attached to the gold, but the tin does not
penetrate the gold to any great extent." (Dr. S. B. Palmer.)
This connection of the metals assists in holding the filling in place,
but it is more likely to break apart than if it was all gold. After
electrolysis has taken place at the junction, it requires a cutting
instrument to completely separate the tin and gold.
For filling by hand pressure, use instruments with square ends and
sides, medium serrations, and of any form or size which will best reach
For filling with the hand mallet, use instruments with medium
serrations, and a steady medium blow with a four-ounce mallet; in force
of blow we are guided by thickness of tin, size of plugger, and depth of
serrations, strength of cavity-walls and margins, the same as in using
gold. The majority of medium serrated hand mallet pluggers will work
well on No. 10 tin of one, two, or three thicknesses. If the tin shows
any tendency to slide, use a more deeply serrated plugger. The
electro-magnetic, and mechanical (engine) mallet do not seem to work tin
as well as the hand mallet or hand force, as the tendency of such
numerous and rapid blows is to chop up the tin and prevent the making of
a solid mass, and also injure the receiving surface of the filling. In
using any kind of force, always aim to carry the material to place
before delivering the pressure, or blow.
In order to obtain the best results, there must be absolute dryness, and
care must be exercised, not thinking that because it is tin it will be
all right. Skill is required to make good tin fillings, as well as when
making good gold fillings. Always use tapes narrower than the orifice of
the cavity; they are preferable to rolls or ropes. After a few trials it
is thought that every one will have the same opinion. A roll or rope
necessarily contains a large number of spaces, wrinkles, or
irregularities, which must be obliterated by using force in order to
produce a solid filling; thus more force is employed, and more time
occupied in condensing a rope, than a flat tape; the individual blow in
one case may not be heavier than in the other, but the rope has to be
struck more blows. The idea that a rope could be fed into a cavity with
a plugger faster and easier than a tape has long ago been disproved.
Many of the old-fashioned non-cohesive gold foil operators used flat
tapes, as did also Dr. Varney, one of the kings of modern cohesive gold
The tape is made by folding any portion of a sheet of foil upon itself
until a certain width and thickness is obtained. This tape is very
desirable in small or proximal cavities where a roll or rope would catch
on the margin and partially conceal the view.
In the form of a tape, perhaps more foil can be put in a cavity, and
there may be more uniform density than when ropes are used. Tapes can
also be made by folding part of a sheet of foil over a thin, narrow
strip of metal. Fold the tin into tapes of different lengths, widths,
and thicknesses, according to the size of the cavity; then fold the end
of the tape once or twice upon itself, place it at the base of any
proximal cavity, and begin to condense with a foot plugger of suitable
size, and if there is a pit, groove, or undercut which it does not
reach, then use an additional plugger of some other form to carry the
tin to place; fold the tape back and forth across the cavity, proceeding
as for cohesive gold. In small proximal cavities a very narrow tape of
No. 10, one thickness, can be used successfully. For cavities in the
occlusal surface, use a tape as just described, generally beginning at
the bottom or distal side, but the filling can be started at any
convenient place, and with more ease than when using cohesive gold. In
any case if the tin has a tendency to move when starting a filling,
"Ambler's left-hand assistant" is used, by slipping the ring over the
second finger of the left hand, letting the point rest on the tin. This
instrument is especially valuable in starting cohesive gold (see Fig.
6). This is the easiest, quickest, and best manner of making a good
filling, relying upon the welding or cohesive properties of the tin.
Many operators have not tried to unite the tin and make a solid mass;
they seem to think that it cannot be accomplished, but with proper
pluggers and manipulation it can be done successfully.
For large occlusal or proximal cavities, the tapes may be folded into
mats, or rolled into cylinders, and used on the plan of wedging or
interdigitation, and good fillings can be produced by this method, but
the advantage of cohesion is not obtained, and more force is required
for condensing. They are, therefore, not so desirable as tapes,
especially for frail teeth. When using mats or cylinders, the general
form of the cavity must be depended upon to hold the filling in place.
To make the most pliable cylinders, cut a strip of any desired width
from a sheet of foil and roll it on a triangular broach, cutting it off
at proper times, to make the cylinders of different sizes.
A cylinder roller, designed by the author, is much superior to a broach.
(See Fig. 7.) When the cavity is full, go over the tin with a mallet or
hand burnisher, being careful not to injure the cavity-margin. Cut down
occlusal fillings with burs or carborundum wheels, and proximal fillings
with sharp instruments, emery strips or disks. After partially
finishing, give the filling another condensing with the burnisher, then
a final trimming and moderate burnishing; by this method a hard, smooth
surface is obtained.
Fillings on occlusal surfaces can be faced with No. 20 or 30 tin, and
burnished or condensed, by using a burnisher in the engine, but do not
rely upon the burnisher to make a good filling out of a poor one.
By trimming fillings before they get wet, any defects can be remedied by
cutting them out; then with a thin tape (one or two layers of No. 10)
and serrated plugger proceed with hand or mallet force to repair the
same as with cohesive gold.
Another method of preparing tin for fillings is to make a flat, round
sand mold; then melt chemically pure tin in a clean ladle and pour it
into the mold; put this form on a lathe, and with a sharp chisel turn
off thick or thin shavings, which will be found very tough and cohesive
when freshly cut, but they do not retain their cohesive properties for
any great length of time,--perhaps ten or twenty days, if kept in a
tightly corked bottle. After more or less exposure to the air they
become oxidized and do not work well, but when they are very thin they
are soft, pliable, and cohesive as gold, and any size or form of filling
can be made with them.
Among the uses of tin in the teeth, the writer notes the following from
Dr. Herbst, of Germany: "After amputating the coronal portion of the
pulp, burnish a mat of tin foil into the pulp-cavity, thus creating an
absolutely air-tight covering to the root-canal containing the remainder
of the pulp; this is the best material for the purpose." There has been
a great deal said about this method, pro and con, notably the latter.
The writer has had no practical experience with it, and it need not be
understood that he indorses it.
If a pulp ever does die under tin, perhaps it will not decompose as
rapidly as it otherwise would, owing to its being charged with
The Herbst method of filling consists in introducing and condensing tin
in cavities by means of smooth, highly tempered steel engine or hand
burnishers. In the engine set of instruments there is one oval end
inverted cone-shaped, one pear-shaped, and one bud-shaped. The revolving
burnisher is held firmly against the tin, a few seconds in a place, and
moved around, especially along the margins, not running the engine too
fast. Complicated cavities are converted into simple ones by using a
matrix, and proximal cavities in bicuspids and molars are entered from
the occlusal surface. The tin foil is cut into strips, and then made
into ropes, which are cut into pieces of different lengths; the first
piece must be large enough so that when it is condensed it will lie
firmly in the cavity without being held; thus a piece at a time is added
until the cavity is full. The hand set of burnishers has four which are
pear-shaped and vary in size, and one which is rather small and
roof-shaped. In filling and condensing they are rotated in the hand
one-half or three-quarters of a turn.
Dr. Herbst claims a better adaptation to the walls of the cavity than by
any other method. Proximal cavities in bicuspids and molars can easily
be filled; the tin can be perfectly adapted against thin walls of enamel
without fracturing them; less annoyance to the patient and less work for
the dentist; can be done in half the time required for other methods.
Fees should be reasonably large, certainly more than for amalgam, for
we can save many teeth for a longer time than they could have been
preserved with cohesive gold. Many are not able to pay for gold, but
they want their teeth filled and saved, and it is expected that we
will do it properly and with the right kind of material; thus it is our
duty in such cases to use more tin and less amalgam.
We should always take into consideration the amount of good accomplished
for the patient,--the salvation of the tooth,--and if we are sure, from
experience and observation, that the tin filling will last as long as a
gold one in the same cavity, or longer, then the fee should be as much
as for gold, with the cost of the gold deducted. The amount of the fee
ought to be based upon the degree of intelligence, learning, and skill
required; upon the amount of nervous energy expended; upon the draft
made on the dentist's vitality; upon what benefit has been given the
patient; upon the perfection of the result; and, everything else being
equal, upon the time occupied; the value of this last factor being
estimated in proportion to the shortness of it.