IMPROVEMENTS IN THE CONSTRUCTION OF DENTAL ARTICULATORS
Year: 1876

page_text: LETTERS PATENT to George Genese Davidson, of 415, Old Kent Road, in the
Borough of Lambeth, Dentist, for the Invention of "IMPROVEMENTS IN THE
CONSTRUCTION OF DENTAL ARTICULATORS."
COMPLETE SPECIFICATION filed by the said George Genese Davidson at the
Office of the Commissioners of Patents, on the 5th January 1876.
GEORGE GENESE DAVIDSON, of 415, Old Kent Road, in the Borough of Lambeth,
Dentist. "IMPROVEMENTS IN THE CONSTRUCTION OF DENTAL ARTICULATORS."
This Invention has for its object to provide an instrument of the kind known as
dental articulators, by means of which any dentist or dental operator may be
enabled to fix or adjust the casts or models of a patient's jaws in a position accu-
rately corresponding to that of the jaws themselves, and having done so to turn or
revolve such casts or models in every direction; also to remove the holders or frames
of these models from the instrument and replace them at any angle or in any
position or direction required for the purpose of fitting artificial teeth, so that the
casts or models once duly taken and mounted on these holders or frames may be
worked upon by any operator in the absence of the patient; and the whole of the
work for which the models are intended may be performed with greater facility and
accuracy than by any of the modes or methods at present in use of fitting artificial
teeth to models.
The leading feature of the apparatus constructed according to my Invention is
that each of its component parts is separable from the remaining parts or organs
thereof, and may whenever required be fitted to or removed from the remainder of
the instrument.
In constructing a dental articulator according to my Invention I provide a stock
or stand formed of two tubes placed at right angles to one another. I make two
separable model holders, one for the model of the upper and the other for the model
of the lower jaw. The lower model holder I so furnish with a rod or bar as to
allow it to slide longitudinally within the horizontal part of the stock or stand,
and to be secured in its proper place or position by means of a thumbscrew or
other appropriate appliance. To the top of a vertical bar sliding within the

page_text: vertical tube of the stand or stock I fit directly or indirectly a ball-and-socket
joint, or an equivalent hinge furnished with a rod or tube, upon or within
which the upper model holder may slide longitudinally.
I so arrange the various slides and jointe as to enable the operator to place
the two models in any correlative position to one another that may be required 5
for the dental work for which such models are intended.
the same.
DESCRIPTION OF DRAWINGS.
In the accompanying Sheet of Drawings I have shewn in Figure 1 a longitudinal
section of a dental articulator constructed according to my Invention; Figure 2
represents an end view of the same apparatus; Figure 3, a plan shewing the upper 1
part of the instrument; and Figure 4, a sectional plan shewing the lower part of
In these Figures A is the stock or stand of the instrument, consisting of
two tubes placed at right angles to one another. The vertical tube B I furnish with
two lips, lugs, or flanges b, separated from each other by a slit d, and which may be
brought close to one another by means of a thumbscrew or similar appliance D. 1
Within this tube I place a rod E surmounted by a head piece F, and which may be
fixed at any height by means of the binding screw D.
For the model or cast of the upper jaw I provide a frame or holder G of circular
or longitudinal form furnished with a tube H, having a pair of lips b¹, b', a slit d¹,
and a binding screw D¹ to it like the tube B. This tube H slides upon a rod I, and 2
its position with respect to this rod is adjustable by means of the screw D¹. At
the end of the rod I I provide a ball J within a socket K furnished with a
fork L, L, fitted to the head F of the rod E, upon which the whole socket is
thus suspended by means of the axis N, the ball itself being adjusted in the
position required within the socket by means of the female screw M.
For the cast or model taken of the lower jaw I provide a frame or holder
similar to the top model holder or suspender G, but furnished with a rod P
sliding within the horizontal tube C of the stock or stand A. This horizontal
tube C I furnish with lips 62 and a binding screw D2 similar to the corre-
sponding appliances adapted to the vertical tube B, and intended to admit of a
longitudinal movement of the frame and of its being fixed in any desired
position. Instead of the top model holder or suspender G being furnished with
a tube and sliding upon a rod it may be furnished with a rod sliding within
a tube ending in the ball J, and the same interchange may be made in the
case of the lower frame O, which may be furnished with a sliding tube and
made to slide upon a rod instead of having a rod attached to it which slides
within the tube C.
By the arrangement just described it will be seen that each of the organs
which form the component parts of the articulator constructed according to my
Invention has a movement of its own. The holder G, with the upper model
fitted thereon, may slide to and fro on the rod I, and also rotate or gyrate so
that it may be placed at any angle to the vertical plane passing through the
axis of the rod I. The rod I may vary its positions indefinitely by virtue of
the ball-and-socket arrangement J, K. The socket K may describe any arc
around the axis N on which it is suspended, and to the vertical rod E to which the
fork L of the socket K is fitted both a longitudinal and an angular motion may be
imparted in the same inanner as to the model holder G. The same duplex motion
may be given to the lower model holder O sliding within the tube C and adjustable
at any angle. In this manner any one point of either of the two models may
have its coordinates varied indefinitely.
Both model holders G and O being separable from the stock or stand and from
the rest of the instrument, the models mounted thereon and held together by means
of wax or other agglutinating material may be readily transferred to another instru-
ment, and thus the same apparatus may do service for several fresh sets of models
without the old ones being taken off their holders.. For the rod E, shewn in

page_text: Figure 1, another of greater length may be substituted, so as to become applicable
to different heights of models, as made by different dentists.
For the ball-and-socket arrangement shewn in Figures 1, 2, and 3, I reserve to
myself to substitute any description of mechanism by means of which the same
combination of movements may be achieved. Of these various mechanisms I have
shewn one example in a longitudinal section, Figure 5, where identical parts are
denoted by the same letters of reference as in the previous Figures. Upon the
head F of the rod E I mount a fork piece L in the same way as in Figure 1. To
this fork piece I fit an eye Q, whereon I suspend a fork R, on which the rod I,
Figure 1, or an equivalent tube S may be suspended. In this case the rod I or
tube S moves up and down around the centre T of the fork piece R, which rotates
or gyrates horizontally around its axis U secured by means of a set screw D³, and
forming likewise the center of the eye or lug Q, which may be moved up and down
like I or S.
In those cases in which the rotating motion of the tubes around the rods, or vice
versâ, may not appear essential, and where it may be expedient to sacrifice this
feature for the advantage of being able to fix the organs at once in the position
required, I substitute bars of a square or polygonal cross section for the rods shewn
in the Figures 1 to 4, and I form the tubes of a corresponding cross section, so that
these bars shall be capable only of a sliding or longitudinal motion, but on the
other hand the fixing gear b; d, D, may be dispensed with, although a fastening
screw may be preserved. In the same manner a rack and pinion may be sub-
stituted for the tube and slide or bar arrangement, and a worm wheel and screw
may also be employed for producing the longitudinal motion and fixing the model
holders in their proper positions without any extra appliance.
By another modification in the arrangements herein-before described I substitute
a longitudinal form of model holders for the circular form shewn in Figures 3 and 4.
Figure 6 is a longitudinal section and Figure 7 a plan of an upper; Figures 8 and 9
are a longitudinal section and a plan respectively of a lower frame or model holder
of this description. In both cases I form the body of the model holder, in such
a manner as to be able to cast a mould or model thereon directly. I also pro-
vide a screw W, around which the moulded material gathers, and which being
withdrawn by means of a screwdriver or key allows of the model being removed
from the holder and another substituted in its place. In the case of these model
holders I likewise reserve to myself to tit them either with tubes or with rods, and
also to confine myself to the longitudinal motion by substituting prismatic bars for
the rods and suppressing the fixing gear, as well as by using racks and pinions,
worm wheels and screws, or similar appliances.
Having now described the nature of my said Invention and the method of
practically working or using the same, as well as illustrated my said Invention in
the accompanying Sheet of Drawings, I wish it to be understood that what I
claim is,―
First. The use or employment of a stock or stand, consisting of two tubes placed
at right angles to one another, in the manner and for the use and purposes herein
described and illustrated in Figures 1 to 4 of the accompanying Sheet of
Drawings.
Secondly. The use or employment of the ball-and-socket arrangement for varying
the positions of the casts or models in the manner and for the purpose herein
described and illustrated in Figures 1 to 3 of the accompanying Sheet of
Drawings.
Thirdly. The use or employment in lieu of the ball-and-socket arrangement of a
hinge joint, in the manner and for the purpose herein set forth and exemplified in
Figure 5 of the accompanying Sheet of Drawings.
Fourthly. The use or employment of circular or longitudinal model holders
separable from the remainder of the apparatus, in the manner and for the purpose
set forth in the foregoing and illustrated in the accompanying Sheet of Drawings.
Fifthly. The use or employment of set screws for securing casts or models upon

page_text: and removing them from their holders, in the manner herein set forth and illus-
trated in Figures 6 to 9 of the accompanying Sheet of Drawings.
Sixthly. The use or employment for the purposes herein set forth of a vertical
rod or spindle of variable length fitted with a hinge joint and pin, as herein-
before described and illustrated in Figures 1, 2, 3, and 5 of the accompanying
Sheet of Drawings.
Seventhly. The interchange of rods and tubes in the sliding motion of the
various parts or organs of the apparatus, in the manner and for the purposes
herein described.
Eighthly. The substitution herein-before described of prismatic bars and
corresponding tubes, of racks and pinions, or of worm wheels and screws for
the cylindrical bars and corresponding tubes, shewn in the accompanying Sheet of
Drawings.
And generally I claim the Invention of such an instrument or apparatus as is
berein-before described and specified, for the use and purpose herein recited, with
such a combination of mechanical appliances and with such variations, substitutions,
interchanges, or suppressions of parts or organs thereof as are also herein set
forth.
In witness whereof, I, the said George Genese Davidson, have hereunto set my
hand and seal, this Twenty-eighth day of December, in the year of our Lord
One thousand eight hundred and seventy-five.
Witness.
J. T. DANN,
1, Crawshay Road,
Brixton,
S.W.
GEORGE GENESE DAVIDSON. (L.S.)