AN IMPROVED MODE OF MOULDING AND CASTING THE PLATES OR BASES OF ARTIFICIAL TEETH."
Year: 1857

page_text: LETTERS PATENT to Alfred A. Blandy, M.D., D.D.S., of the City and
County of Baltimore, and State of Maryland, in the United States of
America, for the Invention of "AN IMPROVED MODE OF MOULDING AND
CASTING THE PLATES OR BASES OF ARTIFICIAL TEETH."
PROVISIONAL SPECIFICATION left by the said Alfred A. Blandy at the
Office of the Commissioners of Patents, with his Petition, on the
1st May 1857.
I, ALFRED A. BLANDY, M.D., D.D.S., of the City and County of Baltimore,
5 and State of Maryland, in the United States of America, do hereby declare
the nature of the said Invention for "AN IMPROVED MODE OF MOULDING AND
CASTING THE PLATES OR BASES OF ARTIFICIAL TEETH," to be as follows:-
This Invention relates, firstly, to a peculiar process of moulding the plate
or base of the teeth, by which a correct articulation can be had. upon
0 casting.
Secondly, to the use of an alloy suitable from its chemical and physical
properties to form the plate or base of artificial teeth that will not practically
shrink or expand in cooling or solidifying after being cast, whereby an accurate
fit of the plate to the gums can be had.

page_text: And, thirdly, to the use of a matrix, which, from the nature of its com-
ponent parts, will not shrink or expand on being heated or cooled.
To illustrate the moulding process, let it be supposed that a case of teeth for
the upper jaw is required. An "impression" of the upper jaw is first taken in
wax, and recast to form the upper half of the matrix. Upon this cast a thin
plate of metallic foil coated with wax is pressed down in a careful manner to
represent the plate or base of the teeth, after which a rim of wax of about
one quarter of an inch thick is fitted upon it to represent the teeth; the plate
and rim thus prepared are then removed from the model and inserted in the
mouth of the patient to obtain the just acclusion or bite, by cutting down or
trimming the rim of wax, as circumstances may require.
When properly trimmed the plate is removed from the mouth, and the
teeth requisite to supply the want are then carefully fitted upon the wax rim,
after which the redundant wax is removed. The plate and rim thus armed
with the teeth are placed upon the model or upper half of the matrix ready
to receive the composition which is to form the lower flask of the matrix.
The latter when solidified and sufficiently hardened may be removed from the
upper flask, carrying with it the plate, the rim of wax, and the teeth which
are imbedded in it. The wax and foil may now be carefully removed and
withdrawn from around the teeth and the lower flask. A gate or aperture is
then cut in the flask to permit a free influx of the metal to form the plate of
the teeth and to allow the air and gas to escape. The two flasks are now
brought together and firmly secured by means of wire. The mould thus
formed is heated, and the molten metal may be poured into it with perfect
safety to the teeth. To prevent the shrinking or expansion of the matrix the
following composition is used, viz., equal parts or nearly so of feldspar and
.plaster of Paris thoroughly incorporated with each other..
The metallic alloy used for forming the plate is composed of bismuth and
antimony combined, either singly or together with tin, cadmium, and silver in
suitable proportions.
The expansive properties of the antimony and bismuth on cooling are intended
to neutralize the shrinkage on the part of the other metals. They also serve
in conjunction with the silver and cadmium, to give that hardness, strength,
and rigidity to the alloy necessary to render it suitable to form the dental
plate. The plate when completed, if desired, may be readily and durably
coated with pure gold.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alfred A. Blandy in the Great Seal Patent Office on the
29th October 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALFRED
A. BLANDY, M.D., D.D.S., of the City & County of Baltimore, State of
Maryland, in the United States of America, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of May, A.D. 1857 in the twentieth year
of Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Alfred A. Blandy, Her special license that I, the said Alfred A.
Blandy, my executors, administrators, or assigns, or such others as I, the said
Alfred A. Blandy, my executors, administrators, or assigns, should at any
time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "AN
IMPROVED MODE OF MOULDING AND CASTING THE PLATES OR 'BASES' OF ARTIFICIAL
TEETH," upon the condition, amongst others, that I, the said Alfred A. Blandy;
by an instrument in writing under my hand and seal, should particularly
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said Alfred A. Blandy, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the Drawing hereunto annexed, and to the
letters and figures marked thereon (that is to say):-
My Invention consists in four separate and distinct features, all of which
are required to form'a perfect denture by the process of casting, as contra-
distinguished from the process of swaging, altho' either of these features may
be used separately with a beneficial effect upon the old plans or processes.
The first of these consists in a peculiar process, by means of which a correct
articulation of the teeth can be had, and an absolute fit of the plate to the
mouth obtained. The second consists in so forming the roots, or that part of
the tooth intended to be imbedded in the plate, as to adapt it to the process of
casting, so that a firm retention of the plate to the tooth is obtained by the
simple act of casting the plate. The third consists in the use of a matrix so

page_text: composed of certain ingredients so that when exposed to the action of heat at
a given temperature it will neither shrink nor expand, thus removing the
possibility of the plate when cast being either too large or too small. And
the fourth consists in casting the plates or "bases" of an alloyed metal,
which after being cast will not shrink or expand on solidyfying or cooling.
These I will now proceed to describe in detail and in connexion with cach,
reference being had to the accompanying Drawing, in which Figures 1 & 2
represent side elevations of a jointed plaster cast, technically termed the
"articulator," the front half of which may be taken to represent the upper and
lower jaw during my process preparatory to the adjustment of the teeth
thereon.
In Figure 1 the wax rim is represented as being too long in front, and in
Figure 2 as properly trimmed; Figure 3 represents a vertical longitudinal
section of Figure 2; Figure 4 represents a side elevation of the upper half of
the "articulator" after the teeth have been adjusted, and the wax reduced to
the proper shape and thickness preparatory to moulding. Figure 5 represents a
vertical longitudinal section (through a central incisor tooth) of the moulding
flask with the teeth and pattern plate enclosed; and Figure 6, a similar view
of the same, but showing the pattern plate removed and prepared for pouring
the metal intended to form the "base" or plate. Figure 7 represents a view
in perspective of a tooth adapted to the process of casting, and Figures 8 & 9
a plan and section of the same respectively. Figure 10 represents a plan of a
block of teeth adapted to my process; and Figuro 11, a transverse vertical
section of the same, taken centrally through it. Figure 12 represents a view
in perspective of an upper sett of teeth completed out of my improved alloy,
and by my peculiar process; and Figure 13, a similar view of the same, but
represented as being electro-gilded.
An impression of the mouth in wax is first obtained as in other processes,
from which a plaster cast is taken, which subsequently forms one-half (A),
Figures 5 & 6, of the moulding flask; upon this cast a pattern plate (a) (made
of rolled wax, and to of an inch thick, and lined on the side next the cast
with metallic foil by tobu of an inch thick,) is carefully pressed and trimmed
to the required shape, after which a rim (b) of wax of about of an inch wide
is placed upon the alveolar ridge of the samo. When this is completed the
process is repeated for the lower jaw in cases of entire loss of teeth, in which
event both plates with their wax rims are then introduced into the mouth and
the wax trimmed down until the two rims touch at all points, as shown in
Figure 2, due attention being had to the correct closure and proper spacing of
the jaws, points essential to the natural appearance of the artificial teeth,

page_text: as also to their comfort and utility. The two plates while thus in the mouth
are then so marked upon the wax rims 6 that when withdrawn they may
be replaced in precisely the same relation to each other. The double cast,
technically termed the "articulator," Figure 2, is then formed upon them pre-
paratory to the adjustment of the teeth upon the wax rim (b,) which adjustment
will require the removal more or less completely of said rims, the plates mean-
while being held securely in proper position by the "articulator." By this
process the plate adapts itself with unerring accuracy to the teeth, whereby
great expenditure of time, trouble, and patience necessary in the articulation of
teeth other methods are saved where each tooth requires to be ground to fit
the plate or base.
The teeth having been arranged, they are for greater security again tried in
the mouth, and any slight changes necessary made, after which all superfluous
wax is removed, leaving only so much as is designed to be replaced by metal
in order to secure a plate of proper thickness for strength and durability and a
firm retention of the teeth. The upper pattern plate is represented in section
in Figuro 5; this, if made rightly at first and carefully handled, will require no
further alteration. In this Figure c represents the wax added or placed
around the teeth, which when replaced by the metal used for the formation of
the plate or "base" will secure for them a strong attachment to the plate,
and give to teeth thus mounted a superior cleanliness, as, it furnishes no
crevice or other place for lodgement of extraneous matters. The wax having
been properly smoothed, and the slightest change in the position of.the teeth
carefully avoided, the pattern plate is placed upon the original cast A, Figure 5,
and the other half of the matrix made by pouring the composition over it, in doing
which care must be taken to fill every crevice: between the teeth not occupied
by wax. When hardened, the two parts of the matrix are separated and the
fuil and wax carefully removed, disregarding minute portions of the latter,
which the matrix when heated will absorb. A gate (d) is then cut (see.d,
Figures 5 & 6,) to give free access to the metal, with suitable vents whenever
required for the escape of air or gas during the act of casting, after which the
two parts of the matrix are closed and secured firmly together with binding
wires (e,) and the joint luted with composition similar to the matrix, except on
the end containing the gate. The matrix thus prepared is then subjected for
two or three hours to a dry heat, ranging from 250° to 350° Fahrenheit, which
drives off the moisture (which otherwise would interfere with the flow of the
molten metal) and absorbs such particles of wax as may have been too
tedious or impossible to remove, and by gradually heating the teeth renders it
impossible for the metal to fracture them, as so often happens under other

page_text: processes. The matrix thus heated is then ready to have the metal intended
to form the base or plate poured into it, when the sett will be completed, with
the exception of the finishing process, which is substantially the same as in the
old methods.
For the different varieties of work required the manipulations are sub-
stantially the same, and hence do not demand a separate description; but as
an absolute & accurate fit to the mouth could not be obtained did the metal
used for the purpose of forming the base or the material used in the formation
of the matrix shrink or expand in solidifying or cooling.
I will now proceed to describe them, commencing with the matrix, which is 1
composed of nearly equal proportions of plaster of Paris and feldspar. This
compound enables the moulds to endure a certain amount of heat without
shrinking or breaking, and at the same time sustain and give the exact
characteristics of the impressions of the mouth, upon which depends the practical
result of the operation, especially when taken in connection with the metal used 1
in forming the plate or base of the teeth, which for the purpose of an accurate
fit must not shrink or expand in solidifying on being cast, and yet possess
sufficient hardness, strength, rigidity, and durability to render it suitable for
the formation of dental plates.
A metal possessing such qualities I form by alloying in certain proportions, s
according to the strength and rigidity of the plate required, suitable metals, to
be hercin-after named, in which the expansive property of one or more will
counteract the tendency of the others to shrink in cooling after being cast, as, for
example, an alloy of this nature may be formed by combining tin, bismuth,
antimony, and silver in the following proportions, to wit:-Tin, ten to twenty
parts; bismuth, one to five parts; antimony, one to two parts; and silver, one to
two parts; to those might be added from five to fifteen parts of cadmium if a
still greater strength and rigidity are required, as in cases of partial setts;
or, for the same purpose, an alloy composed of tin, twenty to twenty-four
parts; antimony, four to six parts; and silver, two to four parts, may be used.
In these examples the expansive properties of bismuth and antimony on
cooling are used to neutralize the shrinkage on the part of the other metals.
These metals (bismuth and antimony) also serve in conjunction with the silver
& cadmium to give that hardness, strength, and rigidity to the alloy, which
renders it suitable for forming the dental plate, the bismuth also acting in
conjunction with the tin and cadmium when used to lower its melting point,
great fusibility being an indispensable quality as well in the successful
formation of the dental plates by the process of casting, as in the repair of
accidents, and in the repair of mistakes. The plates when completed, if

page_text: desired, may be readily and durably coated with pure gold by the process
known as electro-gilding; but as a general rule, the plate when made of the
above-described alloys will be worn pure, as it is almost devoid of all taste,
and is not liable to tarnish or corrode by the secretions of the mouth. From
the foregoing it will be apparent that these alloys may be slightly varied in
their relative proportions in order to suit the circumstances of the case,
without departing materially from the principle of my Invention, or the metals
themselves might be substituted by others possessing the same characteristic
properties.
The matrix & the metal used for casting the plates, & the process by which
an accurate fit to the month and correct articulation of the teeth are obtained,
having been described, it is now only necessary to describe the formation of
the tooth, by which it is adapted to the process of casting, the object of which
is so to encase the teeth with the metal that they shall virtually form but
one piece, thus rendering it utterly impossible for a tooth to work loose or drop
out. The teeth employed by me for this purpose are constructed with a
channel (f) running vertically through them, into which a piece of wire of
alloyed tin may be inserted if desired; altho' I frequently omit the use of
such, merely permitting the metal of the base to flow in it. When the wire
is used it is allowed to project at either end about 1 of an inch, which, upon
the metal being poured in the matrix to form the plate, secures the positive
union or connection of the tooth with the plate. The outer end of this piece
of wire may be afterwards fused by n.cans of a blow pipe to make it a headed
bolt, so as to rivet each tooth as it were to the plate.
In order to effect a more positive union of the teeth with the plate, a neck (9)
and side projections are formed, which are perfectly encased by the metal,
the neck and sides being so shaped as to act as a dovetail, thus rendering it
impossible for the tooth to work loose or drop out, unless broken, or the plate
by some accident ruptured. Or, the teeth may be formed with a dovetailed
groove extending through the teeth, there being a vertical hole or channel
formed in the teeth and connecting with the groove, or a channel may be
formed around the exterior periphery of the tooth near its bottom, thus forming
a species of a dovetail round which the metal flows, firmly securing the teeth
to the plate, as the large end is embedded in it. This process is also adapted
to the securing of block teeth to the plate, which has the effect of rendering
them more enduring, and at the same time giving to them a more elegant and
finished appearence than by the old processes. For this purpose the upper
surface of the block is grooved and perforated (either in part or entirely)
through with a series of holes, as shown in Figures 10 & 11, one for every

page_text: tooth, for the reception of a fusible pin, which being melted by the liquid
metal as it is poured in the flask ensures a perfect metallic connection between
cach with the plate. Around the upper edge of the block is accurately cut a
narrow curvilinear channel, which forms the limit of the metal, and another
bond of connection between it and the plate, there being a similar groove for
the same purpose in the rear sido of the block. By theso grooves the block is
firmly secured, that is to say, dovetailed in the metal of the plate, thus
rendering it at once strong and neat.
Having thus fully described my Invention; what I claim as new, and desire
to secure by Letters Patent, is,-
First, moulding the plates or bases of artificial teeth in such a manner as to
obtain an accurate fit to the gums and a correct articulation of the teeth.
Second, I claim forming artificial teeth in the manner described so as to
adapt them to the process of casting, as set forth.
Third, I claim a matrix composed of plaster of Paris and feldspar in the
proportions substantially as specified for the purposes set forth.
And, lastly, I claim casting the plates or "bases" of artificial teeth of an alloy
suitable for such a purpose from its chemical & physical properties which
practically will not shrink or expand on solidifying or cooling, substantially as
set forth.
In witness whereof, I, the said Alfred A: Blandy, have hereunto set my