IMPROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL TEETH, AND IN APPARATUS THEREFOR
Year: 1879

page_text: LETTERS PATENT to Gerard Wenzeslaus von Nawrocki, of the Firm of J.
Brandt and G. W. von Nawrocki, Patent Agents, of No. 124, Leipzigerstrasse,
Berlin, Germany, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF ARTIFICIAL TEETH, AND IN APPARATUS THEREFOR." A communication by
Robert Telschow, of Berlin, in the German Empire.
Sealed the 30th December 1879, and dated the 7th July 1879.
PROVISIONAL SPECIFICATION left by the said Gerard Wenzeslaus von
Nawrocki at the Office of the Commissioners of Patents on the 7th July
1879.
GERARD WENZESLAUS VON NAWROCKI, of the Firm of J. Brandt and G. W. von
Nawrocki, Patent Agents, of No. 124, Leipzigerstrasse, Berlin, Germany. "Iм-
PROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL TEETH, AND IN APPARATUS
THEREFOR." [A communication by Robert Telschow, of Berlin, in the German
Empire.]
In such
This Invention relates to the mode of producing sets of artificial teeth wherein
the teeth are first imbedded in a plastic material such as wax, which is moulded
to the shape of the mouth, and then has plaster of Paris cast round it, on the
hardening of which the wax is melted by the application of heat, and is run out of
the mould through a channel, the mould being then filled with celluloid or other
composition for the setting in which the teeth are to be imbedded.
manufacture, as heretofore carried on, the plaster of Paris mould being of a single
piece and closed, access could not be gained to the interior thereof after the wax
setting had been removed, in order to observe whether the teeth were held in proper
position in the plaster of Paris, so that it frequently happened that after intro-
ducing the compound for the setting and opening the mould, it was found that the
teeth were not in the desired position, and that the article was consequently
useless.
The present improvements have for their object, firstly, to obviate this defect by
so constructing the plaster of Paris mould that it can be opened before the intro-
duction of the compound for the setting; and, secondly, an improved mode of
introducing the said compound so as to insure that the teeth shall not become
displaced thereby, and that the setting shall be formed without flaws.
For these purposes, the plaster mould of the jaw or gums to which the teeth are

page_text: to be fitted having been formed in the usual manner, a setting composed of gutta
percha and wax is moulded on to it, and into this the single artificial teeth are
Limbedded. The mould, together with the setting and teeth, is then imbedded in
semi-liquid plaster of Paris contained in a half mould box, and the surface of the
plaster bed having been-scraped_level_and_smooth, it is oiled. A hole having pre-
viously been drilled through the centre of the mould and setting, and a wire rod
fitted therein, such rod on the mould being imbedded in the plaster as described
passes through the mass and into a hole in the bottom of the mould box, so that
after the plaster has solidified-and-the-wire is--withdrawn, a channel is thereby
formed through the mould and box, through which the composition for the setting
is afterwards introduced. Wires are also placed so as to extend laterally from the
mould of the setting through the sides of the mould box to form channels in the
plaster filling, through which the compound for the setting can escape somewhat
when forced in, so as to prevent imperfect filling. The second half of the mould
box having been fitted upon the first half, it is filled with semi liquid plaster of
Paris, and the cover having been fitted on and the plaster allowed to solidify, the
entire box is subjected to slight heat, whereupon the two halves of the mould box
are separated; the wax and gutta percha setting having become soft, is then readily
removed, leaving the teeth partly imbedded in the plaster exposed to view, so that
any misplacement thereof can be rectified. The two half boxes are then fitted
together again, and are placed in a frame consisting of a stirrup piece attached to a
bed plate having a central recess, in which is fitted a cylinder that is attached to
the cover of the box, and is filled with the liquid composition that is to be forced
into the hollow mould to form the teeth setting. Over this cylinder a second
cylinder is fitted to the bed plate containing a plunger or piston, which by means
of a screw is forced down into the lower cylinder, so as to force the composition
into the mould through the before mentioned channel formed through the plaster in
the mould box. While performing this operation the mould box is kept hot by being
placed inside a casing containing gas jets arranged so as to play against the sides
and bottom of the box. Or spirit lamps may be used for this purpose. The mould
having been filled with the. composition this is allowed to cool and solidify, after
which the mould box is opened, and the teeth with their setting removed.
Any composition that may have remained in the cylinder can be readily forced
out of it after removal from the frame.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Gerard Wenzeslaus von Nawrocki in the Great Seal Patent Office
on the 6th January 1880.
GERARD WENZESLAUS VON NAWROCKI, of the Firm of J. Brandt and G. W. von
Nawrocki, Patent Agents, of No. 124, Leipzigerstrasse, Berlin, Germany.
"IM-
PROVEMENTS IN THE MANUFACTURE. OF ARTIFICIAL TEETH, AND IN APPARATUS
THEREFOR." A communication by Robert Telschow, of Berlin, in the German
Empire.
This Invention relates to the mode of producedg sets of artificial teeth wherein
the teeth are first imbedded in a plastic material such as wax, which is moulded to
the shape of the mouth, and then has plaster of Paris cast round it, on the hardening
of which the wax is melted by the application of heat, and is run out of the mould
through a channel, the mould being then filled with celluloid or other composition
for the setting in which the teeth are to be imbedded. In such manufacture as
heretofore carried on, the plaster of Paris mould being of a single piece and closed,
access could not be gained to the interior thereof after the wax setting had been
removed, in order to observe whether the teeth were held in proper position in the
plaster of Paris, so that it frequently happened that after introducing the compound
for the setting and opening the mould, it was found that the teeth were not in the
desired position, and that the article was consequently useless.
The present improvements have for their object, firstly, to obviate this defect by
so constructing the plaster of Paris mould that it can be opened before the intro-
duction of the compound for the setting; and, secondly, an improved mode of
introducing the said compound so as to insure that the teeth shall not become
displaced thereby, and that the setting shall be formed without flaws.
For these purposes, the plaster mould of the jaw or gums to which the teeth are
to be fitted having been formed in the usual manner, a setting composed of gutta-
percha and wax is moulded on to it, and into this the single artificial teeth are
imbedded. The mould, together with the setting and teeth, is then imbedded in
semi liquid plaster of Paris contained in a half-mould box, and the surface of the
plaster bed having been scraped level and smooth, it is oiled.
A hole having pre-
viously been drilled through the centre of the mould and setting, and a wire rod
fitted therein, such rod on the mould being imbedded in the plaster as described
passes through the mass and into a hole in the bottom of the mould box, so that
after the plaster has solidified and the wire is withdrawn, a channel is thereby
formed through the mould and box, through which the composition for the
setting is afterwards introduced.
Wires are also placed so as to extend laterally from the mould of the setting
through the sides of the mould-box, to form channels in the plaster filling through
which the compound for the setting can escape somewhat when forced in, so as to
prevent imperfect filling. The second half of the mould box having been fitted
upon the first half, it is filled with semi-liquid plaster of Paris, and the lever having
been fitted on and the plaster allowed to solidify, the entire box is subjected to
slight heat, whereupon the two halves of the mould-box are separated; the wax
and gutta percba setting having become soft, is then readily removed, leaving the
teeth partly imbedded in the plaster exposed to view, so that any misplacement
thereof can be rectified. The two half-boxes are then fitted together again, and are
placed in a frame consisting of a stirrup-piece attached to a bed-plate having a
central recess, in which is fitted a cylinder that is attached to the cover of the box,
and is filled with the liquid composition that is to be forced into the hollow mould
to form the teeth setting. Over this cylinder a second cylinder is fitted to the bed-
plate containing a plunger or piston, which by means of a screw is forced down into
the lower cylinder, so as to force the composition into the mould through the before-
inentioned channel formed through the plaster in the mould-box. While performing

page_text: this is allowed to cool and solidify, after which the mould-box is opened and the
teeth with their setting removed...
Any composition that may have remained in the cylinder can be readily forced
out of it after removal from the frame.
*
t
DESCRIPTION OF THE DRAWINGS:
t
Fig. 1 is an elevation and Fig. 2 a vertical section shewing the apparatus for
beating the mould and forcing into it the caoutchouc, celluloid, or other material
which is to form the bedding for the teeth; Fig. 3 is a plan of gas burners for
heating the mould; Fig. 4 is an elevation of the mould-box with the clamping-frame
partly in section; Fig. 5 is a section and Fig. 6 is a plan of the mould box with the
bedding material in it; and Figs. 7 and 8 are respectively a vertical section and
plan of the mould-box with its covers and a modified form of the git nipple. A is
a casing, open at the bottom and having holes through its sides; its cover B forms
the head of the clamping frame for the mould-box, which is held between it and the
under ring D by bolts and nuts h. F is a tube screwed on to B, and forming at
its upper part a nut for the screw H. In the head B is fixed a cylinder G containing
the bedding material, fitted with a plunger m. The cylinder G may be of one piece
with B, but it is of advantage to make it separate and fit it into B, as shewn. The
mould is heated by jets from perforated pipes o and p, to which gas is supplied by
a pipe q, but when gas is not available spirit or other lamps may be arranged in
the lower part of the casing A. is a thermometer to shew the temperature of the
material in G. The plaster of Paris mould, as above described, consists of two
parts, the upper part held within a ring b with cover a, and the lower part within
a ring d with cover f, the covers being steadied on the rings by dowels y, or other-
wise, and the rings b and d being held together by tongues d' projecting from d, and
entering grooves on b, wherein they are secured by screws or pins e. The rings b
and have also eyes for a steady pin z. It is convenient to make the rings band d
of different depths, so that either may serve for the upper or lower part of the
mould, and thus one mould be made to serve for teeth settings of different heights,
the covers a and f being in this case made to fit either ring. The cover a has on
its upper side a boss i, into which screws the end of the cylinder G and also the
nipple which forms the git for the passage of the fused bedding material from
the cylinder G to the interior of the mould, the surplus material escaping laterally
by the wire holes, as indicated by the black lines in Fig. 5, which shews the
artificial teeth s in the plaster of the lower part of the mould covered by the
bedding material, which occupies the space between the two parts of the mould.
The nipple.x.may_be_modified, as shewn in Fig. 7, the hole in it being somewhat
enlarged at its upper part to receive a plug x¹, projecting from a screwed collar 2
that can be screwed into the boss i. The operation with this apparatus is as
follows-The two parts of the plaster of Paris mould having been prepared, as
above described, the one part or upper part within the ring b, and the other part or
lower part within the ring d, the two parts are put together and clamped between
the head B and the ring by the bolts h, the cylinder G charged with the bedding
material having been screwed into the boss i. The mould-box thus clamped is
placed within the casing A, and the tube F is screwed on B, as shewn in Fig. 2.
The mould is now heated till the material in G has attained a suitable temperature;
'when it is celluloid it should be about 260° Fahr., when it is caoutchouc it should
be about 205° Fahr. By means of the screw H the plunger m is pressed down,
forcing the soft or viscid material through the nipple into the hollows of the mould
until some of it is squeezed out laterally through the wire holes. The tube F is
then unscrewed, and the mould box with its clamping frame is removed from the
casing A, a hand-bar T is passed through a hole in the upper part of the plunger m,

page_text: as shewn in Fig. 4, and the mould-box is plunged in water or otherwise rapidly
cooled.
In order to render the cast of the bedding material in the mould sound and
complete when forming sets of teeth for the lower jaw it is of advantage to provide
in the mould a narrow space &, communicating all round with the inner edge of
the space for the teeth-bedding a, as shewn in Figs. 5 and 6, which bedding in this
case is of horseshoe form, such space forming a runner for the passage of the
material from the inlet ẞ to the bedding-mould a, the thin film thus formed between
the sides of the bedding is afterwards cut away.
By this arrangement the danger of displacing the teeth in the mould when
forcing in the material from a channel at one end or other point of the horseshoe
mould, as at present practised, is avoided.
It has been found that in vulcanizing the caoutchouc bedding it is of advantage
that this shall be subject to a certain degree of compression in the mould.
This is
effected by providing in the mould box cover i a screw plug a², Fig. 7, having a
small plunger x entering the passage or git x, so that after filling the mould, and
while the material is still viscid or plastic, by screwing in the plug a² the material
is compressed to the required degree. The small escape hole in the sides of the
mould d would in this case have to be first closed by small screw-plugs.
Having thus described the nature of the said Invention, and in what manner the
'same is to be performed, as communicated to me by my foreign correspondent; I
would have it understood that no general claim is made to the use of celluloid,
caoutchouc, or analogous material as a bedding for artificial teeth, nor to the
moulding of such material in plaster of Paris moulds in which the teeth to be
bedded have been previously set; but I claim,-
First. The method of moulding the bedding of artificial teeth by arranging the
teeth in the lower part of a divided plaster of Paris mould and forcing in the liquid
bedding material through a passage or channel in the upper part of the mould,
substantially as herein described.
Second. The use for filling the moulds for the bedding of artificial teeth of a
cylinder with piston or plunger removeable from the mould, such cylinder being of
equal diameter throughout so as to admit of the ready removal of its contents,
substantially as herein described.
Third. In apparatus for the manufacture of artificial as set forth in the pre-
ceding claims, so arranging the heating apparatus for the mould that the heat is
also communicated to the cover thereof, and from this to the cylinder, through
which the bedding material is injected, substantially as herein described.
Fourth. The use for clamping, heating, and charging the divided mould above
referred to of the clamping frame B, D, and h, with the charging cylinder G and its
plunger m in combination with the burner O and casing A, arranged and operating
substantially as herein described with reference to the accompanying Drawings.
Fifth. In apparatus for the manufacture of artificial teeth the combination of the
divided mould-box a, b, d, f, cylinder g, piston m, casing A, cover B, cylinder F,
screw H, burner O, and clamping faame D, h, substantially as and for the purposes
herein described with reference to the accompanying Drawings.
In witness whereof, I, the said Gerard Wenzeslaus von Nawrocki, have here-
unto set my hand and seal, this Second day of January, in the year of
our Lord One thousand eight hundred and eighty.
GERARD WENZESLAUS VON NAWROCKI. (L.S.)