Improvements relating to the Manufacture of Dentures and to Apparatus therefor.
Year: 1891

page_text: Date of Application, 16th June, 1891-Accepted, 8th Aug., 1891
COMPLETE SPECIFICATION.
[Communicated from abroad by ROBERT EMANUEL ZELLERS, Gentleman, and
EDWARD CASPERSONX, Doctor of Medicine, both of Philadelphia, Penn-
sylvania, United States of America.]
Improvements relating to the Manufacture of Dentures and to
Apparatus therefor.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
45 Southampton Buildings, in the County of Middlesex, do hereby declare the
nature of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
My invention relates to the process of, and apparatus for making cast dentures of
magnesium, aluminum or aluminum alloys or analogous material; to the removal
of porcelain teeth from a magnesium, aluminum or other metal plate; to casting
solid metal plates and teeth of magnesium, aluminum or other metal with the desired
color and shade of teeth and gum; and also to repairing a metal plate of magnesium,
aluminum or other metal with or without porcelain teeth.
My invention consists in the improved process and apparatus hereinafter fully
described whereby the several results above enumerated are effected.
In the accompanying drawing,
Figure 1, is a vertical sectional view of my improved apparatus.
Figure 2 is a cross sectional view of the same on line of Figure 1.
Figure 3, is a detail showing in elevation the crucible and two-part flask.
Figure 4 is an elevation of the flask and crucible showing one section of the flask
removed.
Figure 5, is a detail of the crucible and flask showing the latter broken away.
Referring to the drawing, A indicates a flask formed preferably of two sections A¹
and A united together by bolts, one of said sections A¹ being cast integral with a
crucible B as shown in Figure 3. The flask A is designed to contain the model
made of plaster-of-paris or analogous material and taken from an impression of
either jaw in the usual manner.
The section A of the flask has its upper wall formed with three holes a band c
the former of which is centrally disposed and leads up through the centre of the
bottom of the crucible, while the two others are outside of the crucible, one on each
side. In the mold is cut a canal or passage e which extends around the mold as
shown and has its ends communicating with the holes b and c, and from said canal
or passage extend a series of lateral branch canals or passages e¹ which lead direct
to the mold.
The short canal or passage at the bottom of the mold being slightly larger than
the others, and the main and branch canals forming an air space or passage leading
from the exterior direct to the mold.
The holes and before mentioned are adapted to receive metal tubes C, to the
upper ends of which is attached a forked mouth picce D, or if preferred a rubber
bulb may be substituted for the mouth piece, the purpose of which will be herein-
after stated.
The crucible is provided with a top or cover E to prevent the escape of heat
therefrom, and said top or cover is provided with a tube f forming a passage for the
escape of hydrogen and gas while the mold is drying. From the description thus
far given it will be seen that when the ingot of metal is fused in the crucible, and
the tubes C are inserted in the holes b and c the operator exhausts the air in the
mold (through the canals or passages before described) by an inhalation of the lungs
or by the rubber bulb and thereby creates a vacuum in the mold.

page_text: When the vacuum is thus created the fused metal instantly begins to flow through
the opening a from the crucible into the mold.
When metal of a heavier specific gravity than aluminum is used, it is desirable to
insert a plug in the hole in the bottom of the crucible until the metal is fused, the
said plug to be withdrawn, as the vacuum is created; and to arrest the flow of
metal into the tubes connected with the mouth piece, I secure over the inner
ends of the air holes or passages b and c fine wire gauze or like material, see
Figure 4.
The burner F has an open centre to receive the crucible whereby the latter
is heated, and from the bottom of the burner project suitable spaced lugs 10,
which are designed to receive and form bearings for suitable trunnions 11,
projecting from the sides of the flask and held within the bearings by means of
removable pins or like devices whereby the flask and crucible are held in position
within the burner; the crucible being centrally held within the open centre of
the burner, and the flask below the same as shown.
A sheet metal cylinder G, is bolted to and surrounds the burner projecting
above and resting upon the lower burner H so that the flask as well as the
crucible is practically within the burner so as to receive heat therefrom equally
on all sides; each burner having a hollow passage 12, with a series of outlets 13
leading therefrom, the lower burner H having an oblong opening in its centre
in which the lower portion of the flask lies as shown, and the upper burner
having a flange F¹ provided with holes for the passage of the heat from the
lower burner, while the sheet metal cylinder is formed with openings G¹ to
provide for a proper circulation of air.
From each burner extends a pipe I, to which is attached a forked tube. J
provided with valves or cocks 14, and said forked tube is connected with a
single tube L, which in turn is suitably connected with a suitable source of heat
such as a gas supply, the flow of which, to the burners, is regulated and
controlled by the valves or cocks 14 in the forked tube.
By this means the gas may be equally distributed to both burners at the same
time, or a greater or less amount may be conducted to one than to the other, or
one burner may be cut off, and the whole flow of gas or any portion thereof
may be conveyed to a single burner.
may
am thus enabled to concentrate the heat at any desired part, and prevent
any material loss of the same by providing the crucible with the top or cover
before mentioned. I also dispense with the heretofore objectionable furnaces
and connect my. apparatus directly with the gas supply.
From this description it will be observed that when the operator wishes to
make a cast, he will first shut off the flow of gas by means of the valves or
cocks after which he will insert the air tubes attached to the mouth piece or
bulb, remove the top or cover from the crucible so as to obtain the natural air
pressure, then exhaust the air and create the vacuum as before mentioned, when
the cast is made.
I will now describe the process of casting solid dentures of aluminum or of
other metal Any operator skilled in the well known rubber work may produce
the above: The first step will be to select the desired size and shape of teeth,
and then proceed as in the rubber work, investing in that portion of the
flask which is integral with the crucible, with the palate side down. He
will now cut the air canals, varnish and oil, and let dry; after which he
will cover the plate and teeth with the investiment material, then fill the other
side or section of the flask, and close and lock the sections of the flask so that
the surplus investment material will escape through the openings 15 in the sides
of the flask. After the material has "set or hardened the flask is opened, and
the paraffin plate and teeth are picked out or removed by any of the well
known means, thereby forming a mold for a solid plate of any metal desired.
"
When teeth are required of a different color and shade, to that of the gum and
the rest of the plate, I first select plain teeth without roots, and invest as usual to

page_text: form a mold for the teeth above, after which the metal of the desired shade and
color of teeth is run into the mold. I now invest the teeth as made, and wax the
model of mouth, the gum and other parts of the plate in the manner common to the
well known rubber work, after which the trial plate is removed leaving the teeth in
the mold, and finally the metal of the appropriate color and shade is run into the
mold thereby making a plate of solid metal, and doing away with porcelain teeth.
When, however, porcelain teeth are used the operator will proceed as in rubber
work, leaving the teeth in the mold and run in the desired metal, instead of packing
with rubber.
The process and apparatus previously described is also used for repairing a
broken denture, and when such an object is in view I invest the broken denture and
proceed as if intending to make a new plate. Through the side of the flask is
formed a hole 16, say of one-eighth inch diameter, and which leads through the
investment material to the broken denture (in case of repairing only) and by with-
drawing the wire 18 from said hole I am able to ascertain when the metal of the
invested plate is fused. When the wire 18 is withdrawn I insert in its place a brass
or other metal plug, which snugly fits the holes and expands by reason of the heat
in the mold until it makes the hole absolutely air tight. An ingot of metal is now
placed in the crucible, the cocks in the forked tube are turned to admit a greater
supply of gas, and consequently an increased heat to fuse the ingot as soon as
possible. I now create a vacuum in the main and branch canals e and e¹ in the
manner previously stated so that the metal of the old plate will flow into these
canals, and the new metal will flow from the crucible into the mold and fill the same
thus making a new plate or denture exactly like the broken one.
By my process and apparatus I am also enabled to remove porcelain teeth from
metal plates, and in doing this I invest the metal denture from which the teeth are
to be removed, and cut two canals only, one leading from the hole in the crucible to
the denture, making said canal approximately A-shape with its sinaller end about
the size of the crucible opening, and its larger end of sufficient width to take in the
full width of the plate.
In this part of my process I employ a hole 20 made in the bottom of the flask,
with a canal in the mold leading thereto, therefore when the metal is fused
in the mold, as when in the repairing, I plug the hole 16, and then insert
one of the air tubes attached to the mouth piece or bulb in the hole in the
bottom of the crucible, and by forcing a current of air through said tube into the
mold, the fused metal within the latter is forced out of the opening 20 in the bottom
of the flask, leaving the teeth in the mold clean and free of metal.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me by
my foreign correspondents, I declare that what I claim is :-
First. The process herein described of making cast dentures which consists
essentially in forming a mold from the trial plate in the usual manner; investing the
same in a flask; then closing the flask, and creating a vacuum therein, by exhausting
the air so that the fused metal will flow into the flask, then removing the cast and
finished in the usual manner, substantially as herein described.
Second. The process herein described of casting sofid dentures of magnesium,
aluminum or analogous material which consists essentially in selecting the desired
size and shape of teeth and forming a mold in the usual manner; investing
the same in a flask, and when dry covering the plate and teeth with investment
material then closing the flask and allow the material to harden; then removing
the trial plate and teeth, and again closing the flask; then exhausting the air
therefrom and run the fused metal into the mold; and finally removing and
finishing the cast in the usual manner, substantially as herein described.
Third. The process herein described of repairing a broken denture which
consists essentially in investing the broken denture in a flask; forming air
passages or canals in the flask; then applying heat to fuse the broken denture,

page_text: and the ingot in the crucible; then creating a vacuum in the mold so that the
fused metal of the broken denture will be drawn into the air canals, and the
fused ingot will simultaneously enter the mould; and finally removing and
finishing the cast, substantially as herein described.
Fourth. In an apparatus for making dentures, the combination with suitable
burners connected with a source of heat supply, of a two-part flask within one
of said burners having air canals or passages formed therein; air tubes communi-
cating with said canals for exhausting the air therefrom, a crucible within the
other burner and a passage therefrom to the interior of the mold, substantially
as herein described.
Fifth. In an apparatus for making dentures, the combination with suitable
burners connected with a source of heat supply of a two-part flask within one
of said burners having openings bc in its upper wall, an air canal or passage
formed in the flask having branch canals or passages leading to the mold within
the flask, a crucible in the other burner having an outlet leading to said mold
air tubes let into the openings be and connected with means for exhausting the
air and creating a vacuum in the mould, substantially as herein described.
Sixth. In an apparatus for making dentures, the combination with burners and
means for supplying heat thereto of a two-part flask within one of said burners,
a crucible within the other burner formed integral with one of said parts, means
for locking the sections of the flask together, the air tubes communicating with
the interior of the flask for exhausting the air therefrom, and a passage leading
from the crucible to the mold, substantially as herein described.
Seventh. In an apparatus for making dentures, the combination with the
burners and means for supplying heat thereto of a two-part flask adapted to
contain the mold, a crucible integral with said flask a passage leading from the
crucible to the mold, a second passage leading from the lower part of the mold
through the bottom of the flask, and an air tube adapted to enter the upper
passage whereby a current of air may be forced through the mold, substantially
as herein described.
Eighth. In an apparatus for making dentures, the combination of a flask for
containing the mold, a crucible integral with the flask and communicating with
its interior, the lower burner within which the flask is suspended, the upper
burner for receiving the crucible, pipes leading from said burners to a source
of heat supply and valves or cocks in said pipes for directing and regulating
the low of heat, substantially as herein described.
Ninth. In an apparatus for making dentures, the combination of the flask, a
crucible integral therewith a cover for said crucible to prevent the escape of
heat therefrom, the upper and lower hollow burners having open centres for
receiving the crucible and flask respectively, a forked pipe connected with a
source of gas supply having a branch pipe leading to each burner, and valvės
or cocks in said pipe for directing and regulating the flow of gas, substantially
as herein described.
Tenth. In an apparatus for making dentures, the combination of a flask having
a crucible formed integral therewith the hollow lower burner having an open
centre to receive the flask, the hollow upper burner having an open centre to
receive the crucible and having a surrounding flange provided with openings for
the escape o heat from the lower burner, a cylinder surrounding the upper
burner, Hask and crucible, pipes leading from the burners to a source of heat
supply, and having valves or cocks by which the heat is directed and controlled,
substantially as herein described.
T
1001
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.