IMPROVEMENTS IN ARTIFICIAL TOOTH CROWNS, AND IN THE MANNER OR PROCESS OF CONSTRUCTING AND SETTING OR APPLYING THE SAME TO NATURAL TOOTH ROOTS WHILE IN THE MOUTH
Year: 1881

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for an
Invention of "IMPROVEMENTS IN ARTIFICIAL TOOTH CROWNS, AND IN THE
MANNER OR PROCESS OF CONSTRUCTING AND SETTING OR APPLYING THE
SAME TO NATURAL TOOTH ROOTS WHILE IN THE MOUTH." A communication
from abroad by Cassius M. Richmond, of the City, County, and State of New
York, United States of America.
COMPLETE SPECIFICATION filed by the said Sydney Pitt at the Office of the
Commissioners of Patents on the 26th July 1881.
"IMPROVEMENTS IN
SYDNEY PITT, of Sutton, in the County of Surrey.
ARTIFICIAL TOOTH CROWNS, AND IN THE MANNER OR PROCESS OF CONSTRUCTING
AND SETTING OR APPLYING THE SAME TO NATURAL TOOTH ROOTS WHILE IN THE
MOUTH." A communication from abroad by Cassius M. Richmond, of the City,
County, and State of New York, United States of America.
This Invention relates to certain improvements in artificial tooth crowns for
application to natural tooth roots while in the mouth, and to the manner or
process of constructing and fitting, setting, or applying the crowns to the natural
roots.
It has long been common in dentistry to remove defective or carious crowns
from natural teeth while in the mouth, and to fit, secure, or pivot artificial crowns
(of different material) upon the roots after their proper preparation. A common
way in which this has been practiced has been to connect the porcelain or other
crown with the root by a screw, pin, or pivot passing from an opening in the
crown to an opening in the root. Various other plans of attaching artificial crowns
to natural tooth roots have been suggested or practiced, such as connecting the
crown with the root by cement or amalgam, with or without the aid of pins or
screws, but, as far as I am aware, there has not been suggested or practiced a plan
of setting or attaching the crowns free from serious objections. In some plans of
fitting the crowns, the connection between the crown and root is too weak to
stand the strain to which the tooth is subjected; in others the crown itself is too
D

page_text: weak to stand the strain to which it is some times put; in others a neat appearance
cannot be had, nor artistic results insured; in others again, if not in all the plans
proposed or practiced, full protection is not afforded to the soft parts of the root
against the injurious action of the fluids of the mouth; and in others the crown is
soon darkened or discolored, and presents an ugly appearance. Objections other
than those mentioned exist to some of the plans proposed, which need not be
recited.
The object of this Invention is to produce strong durable crowns to fit, set, or
apply them in such a manner that when fitted and secured to the root the
completed tooth will be a permanent and durable one, capable of the same service
as a wholly natural and uninjured tooth. The crowns which are applied to the
front teeth or the teeth (incisors and cuspids) ordinarily exposed or partially
exposed to view, while being permanent, durable, and artistic, will present a
natural or nearly natural appearance.
This Invention consists,-
First. In an artificial tooth crown for molar and bicuspid teeth composed of a
metallic ring, cup, band, or tube open at one end to closely fit over the natural
tooth root, and closed at the opposite end with pieces of metal securely soldered or
fastened to the ring in other ways to form the grinding, cutting, or wearing surface
of the crown.
Secondly. In a crown for incisor and cuspid teeth composed of a porcelain or
equivalent face or cutting portion backed with metal, and provided at its neck or
base with a metallic ring, band, or cup joined to said metallic backing to fit over
the end of the tooth root, and with an opening through said ring or cup for the
passage of a screw to fasten the crown in place upon the root.
Thirdly. In a crown for incisor and cuspid teeth composed of a porcelain or
equivalent face or cutting portion backed with metal, and provided at its neck or
base with a metallic ring, band, or cup joined to said metallic backing, and with
a pin projecting from within the metallic ring or cup to enter the root and form a
connection between it and the crown.
Fourthly. In an improved process of constructing and fitting artificial crowns to
natural tooth roots, which consists in preparing the root, fitting a metallic ring,
band, cup, or tube at one end accurately to the root to surround its end, removing
said ring and fastening to.its end or edge which projects beyond the root (by
means of a blow-pipe or equivalent means) pieces of metal of the proper shape to
form the cusps or points on the grinding or masticating surface of molars, or to
form the grinding or masticating surface of bicuspids, and then replacing the crown
thus formed upon the root, and fastening it in place by a suitable connection, a
screw and cement or amalgam, for example, for molars, and cement or amalgam
and a pin or loop, for example, for bicuspids.
Fifthly. In an improved process of constructing and fitting artificial crowns to
natural tooth roots, which consists in preparing the root, fitting a ring, band, cup,
or tube at one end accurately to the root to surround its end, removing said ring,
and fastening or joining its outer end or edge (by means of a blow pipe or
equivalent means) to a tooth crown having a porcelain or equivalent face and
a metallic backing, and then replacing said ring and crown upon the root, and
fastening them firmly thereto by means of a screw passing through said ring or
ring and crown into an internally threaded tube secured in the tooth root, or into
the cement or amalgam with which the cavity of the root may be filled.
Sixthly. In an improved process of constructing and fitting artificial crowns to
natural tooth roots, which consists in preparing the root, fitting a ring, band, cup,
or tube at one end accurately to the root to surround its end, removing said ring,
and fastening or joining its outer end or edge (by means of a blow-pipe or
equivalent means) to a tooth crown having a porcelain or equivalent face and a
metallic backing, and then replacing said ring and crown upon the root, and
fastening them firmly thereto by means of a pin projecting rigidly from within the
ring, said pin entering the cavity of the root, so as to be embedded in cement or

page_text: amalgam with which the root cavity is filled, and be locked therein by the
hardening or setting of the cement.
The Invention also consists in certain details which will be hereinafter fully set
forth.
In the accompanying Drawings Figures 1 to 4 inclusive relate more especially
to the improvements as applied to molar teeth; Figure 4 shows a view of a molar
tooth root partly in section with the metallic crown also in section. The molar
tooth root A is prepared for the reception of the metallic crown B by cutting,
grinding, or wearing it off the proper distance, preferably to near the edge of the
gum, or on a level therewith. A cavity is then formed in the root (if the natural
canal is not of sufficient size) for the reception of a mass of plastic cement or
amalgan C, such as is commonly used by dentists, the cavity being preferably an
undercut one, so as to securely retain the cement or amalgam filling when the
same has set or hardened.
A ring, band, or tube of metal b, Figure 1, is fitted at its inner edge to the end
of the prepared root, so as to surround said end and accurately fit it or conform
thereto, as shown in Figure 4, while the outer edge of the ring or band projects
outward a short distance beyond the end of the root. After the ring has been
nicely fitted or shaped to the root it is removed, and to its outer edge or the edge
projecting. beyond the end of the tooth root is joined or fastened by fusion or
heat preferably four metallic corner pieces c, c¹, c², c³, shown clearly in Figure 2.
Said metallic pieces are preferably shaped as shown, that is to say, they have a flat
under surface, a rounded outer surface, and three sides or edges, two of said edges
being straight or nearly so, and one rounded. The straight edges permit close
fitting of the pieces together so as to be united together by fusion, while the
rounded edges conform the crown to the usual shape of the natural crowns of
molar teeth. The said metallic pieces are preferably joined or united together at
their edges and to the ring b by means of an ordinary blow-pipe, which is a
convenient and efficient medium for the purpose. Said metallic pieces c, c', c³, c³,
are for the purpose of forming the grinding or masticating surface of the artificial
crown, and by shaping the separate pieces as shown in Figure 2 the grinding
surface of the crown when completed has grinding or cutting cusps or points like
those of a natural molar tooth. Figure 3 is a plan or top view of the crown when
completed and finished, showing no signs of joints or that its grinding surface is
made up of different pieces of metal of a particular shape. It will be understood,
of course, that instead of forming the grinding surface of a molar crown of four
separate pieces of metal fitted and joined together and to the ring by heat or
fusion, said surface may be formed by the use of a greater or less number of pieces
than four if properly shaped. The number of pieces mentioned are however
preferred as more convenient, and as permitting of a saving of time to the operator
and of the performance of a nicer operation and finish.
It will also be understood that any suitable metal may be used to form the
crowns, but the use of gold is preferred.
A hole or opening d, preferably a conoidal opening, is formed through the centre
of the metallic crown.
To fit and securely fasten the crown to the root, the cavity in the root is filled
with plastic cement or amalgam, and a tube D internally and externally threaded
is embedded in the plastic filling, as shown in Figure 4, which filling, as soon as it
sets or hardens, secures the tube rigidly to the root. The completed crown,
which is of cup shape, is now partially filled with a suitable packing, such as a
plastic cement or amalgam, for example, and it is then fitted accurately over and
pressed down upon the root so as to surround its end and make a water tight joint
with the aid of its packing when hardened to prevent the access of the fluids of
the mouth to the interior of the crown. The soft parts or interior of the tooth
root is thus securely protected against the action of injurious fluids.
A screw E having a preferably conoidal-shaped head is passed through the
opening in the crown and firmly screwed into the tube D so that the head of the

page_text: screw will accurately fit and close the opening in the crown, and at the same time
durably, firmly, and permanently fasten the crown to the root. The head of the
fastening screw is dressed to virtually unite it with the metallic crown, and the
crown is then polished or finished, which completes the operation.
Instead of the fastening screw entering the screw-threaded tube it may be passed
directly into the plastic filling while in a soft condition, so that when said filling
has set or hardened the crown will be firmly held in place upon the root, or the
screw may be entered in an opening formed in the solid dentine itself. So also
may the threaded tube be fastened in the root without embedding it in a plastic
filling, but the tube embedded in the centre of the root by the hardening of a
plastic filling or cement is preferred.
Figures 5, 6, 7, 8, and 9 relate more especially to the imprevements applied to
bicuspid teeth. The bicuspid root A is prepared as before explained, and its cavity
formed for the reception of the plastic filling C. The ring, band, or tube b (Figures
5, 6, and 7) is fitted at its inner edge over the root to surround its exposed end and
conform thereto, as shown more particularly in Figure 8. The outer edge of the
ring or band for bicuspids is cut out or formed, as shown in Figure 6 in section, so
as not to be a flush or true edge. One of the raised sides of the ring, which is to
be the facial side of the crown, is crimped or shaped so as to be given the contour
of a natural bicuspid at that side, while the opposite raised side of the ring or band
is left in a rounded form so as to be upon that side of the same contour as a natural
biscuspid tooth.
So much of the shaping tool or implement F as is necessary to an understanding
of its construction is shown in Figure 9. It is in the form of pliers, the pivotted
jaws of which are constructed to crimp or shape the bicuspid crown in the desired
manner. One jaw of the tool has a widened V shaped groove or recess on its inner
surface, and the other jaw has a corresponding widened V shaped ridge on its inner
surface, so as to fit when the jaws are closed into the groove of the opposite jaw.
The jaw with the ridge is placed inside the ring, band, or tube, and the jaw with
the groove is brought down upon the outer surface of said ring, so that the edge
of the ring is between the two jaws. The requisite pressure is now made upon the
handles of the shaping tool to shape or crimp the ring or band.
The crimped or shaped ring, band, or tube is now in a condition to receive the
pieces of metal which are to form the grinding and cutting surface of the crown.
For bicuspids I preferably use two pieces or plates of metal c, c', as shown in Figure 6,
which are united to the outer inclined edge of the ring or band band to each other by
means of heat or fusion, preferably as before described. The metallic pieces are
then trimmed, shaped, and polished, and the completed crown is virtually of one
piece of metal in the shape shown in plan in Figure 7, and in section in
Figure 8.
To secure the bicuspid crown in place upon the root the cavity in said root is
filled with the plastic filling, and while it is yet soft a loop or pin E, preferably a
loop such as shown in Figure 8, is embedded therein, so that when said filling has
set or hardened the loop or pin will be firmly secured in the root with its outer end
projecting a short distance beyond the end of said root. The cup shaped crown is
now filled with the plastic filling, and its open end forced down firmly over the
upper end of the root so as to nicely fit its sides, and with the aid of the filling
make a tight joint. As soon as the filling of the crown sets or hardens it takes such
hold of the loop as to prevent the displacement of the crown which will be firmly and
durably held in place.
Any of the proper metals may be used for the biscuspid crowns. Gold is
preferred.
In Figures 10 and 11 I have shown the improvements relating more especially to
cuspid and incisor teeth.
The root A. is prepared as before described, and the ring, band, or tube b fitted
thereto so as to nicely envelope and fit the upper end of said root. The crown B
which is preferably composed of a porcelain or equivalent facing b¹ and a metallic

page_text: backing b firmly fastened to said facing, is united with the upper edge of the ring b
by fusion or heat, preferably so as virtually to constitute the ring and backing a
single piece of metal.
In Figure 10 the crown is shown as having a metallic connecting pin b³ projecting
from it through the ring or band b, the pin being rigidly fastened to the crown so
as virtually to form a portion thereof. Said connecting pin is preferably
cylindrical within the ring and square near its outer end, which projects into the
root, so that the filling when set or hardened may take a firm hold of the pin and
lock it in the root, not only by reason of its flat sides, but by reason also of the
shoulders formed at the junction of the square and cylindrical portions of the pin.
The pin may be made in other ways to have retaining points or shoulders for the
enlargement of the filling.
To apply the completed crown shown in Figure 10 the root cavity is filled with
the plastic filling C, as also the cup of the crown, and while said filling is still
soft the open end of said cup is pressed down firmly over the root to surround its
end, the connecting pin of the crown entering the plastic filling in the root and being
embedded-therein. As soon as said filling sets or hardens the connecting pin will be
firmly locked in the tooth root and the crown firmly, durably, and permanently held
in place upon the root.
To apply the crown shown in Figure 11 the root cavity is filled with the plastic
filling C, and while soft an internally and externally screw-threaded tube D is
embedded therein. Upon the hardening of the filling the tube will be securely
locked in the root. The open end of the crown is now fitted firmly and closely
over the root to surround its end and form a tight joint, and a screw E is then
passed through an opening in the crown, or in the ring or band into the tube D
and firmly screwed up. The back of the crown is then finished off and polished so
as to leave no asperities in its surface, and the operation is complete.
It will be observed that there is no packing or filling between the crown and
root in Figure 11, but I prefer the use of such a packing or filling in that instance
also.
I have stated that the crown's in Figures 10 and 11 are preferably composed of
a porcelain face and a metallic back. The porcelain is preferred as a facing as it
gives the mouth a natural or nearly natural appearance, the band or ring b being
the only metal showing in cuspid or incisor teeth, and this may be partially hid
beneath the gums if desired. It will be understood however that other facings
than porcelain may be used, and that in some cases a wholly metallic crown may
be employed.
I claim,
First. An artificial tooth crown consisting of a metallic ring, cup, band, or tube
open at one end to closely fit over the end of a natural tooth root, and closed at
the opposite end with pieces of metal to form the grinding, cutting, or wearing
surface of the crown.
Second. An artificial tooth crown composed of a porcelain or equivalent face or
cutting portion backed with metal, said crown being provided with a metallic
ring, band, or cup joined to said metallic backing so as to fit over the end of the
tooth root, and with an opening through said ring or cup for the passage of a
fastening screw to secure the crown in place upon the root.
Third. An artificial crown composed of a porcelain or equivalent face or cutting
portion backed with metal, said crown being provided with a metallic ring, band,
or cup joined to said metallic backing, and with a pin projecting from within
said ring or cup to enter the root and form a connection between the root and
crown.
Fourth. The improved process of constructing and fitting artificial crowns to
natural tooth roots, which consists in preparing the tooth root, fitting a metallic
ring, band, cup, or tube at one end accurately to the root to surround its end,
removing said ring and fastening to its end or edge, which projects beyond the
root, pieces of metal, of the proper shape to form the cups or points on the grinding

page_text: or masticating surface of molars, or to form the grinding or masticating surface of
molars, or to form the grinding or masticating surface of bicuspids, and replacing
the crown thus formed upon the root and fastening it in place by a suitable
connection.
Fifth. The improved process of constructing and fitting artificial crowns to
natural tooth roots, which consists in preparing the root, fitting a ring, band, or
cup at one end accurately to the root to surround its end, removing said ring and
fastening, or joining its outer edge to a tooth crown having a porcelain or
equivalent face and a metallic backing, and replacing said ring and crown upon
the root and fastening them firmly thereto by means of a screw passing through
said ring or ring and crown into an internally-threaded tube secured in the root, or
into the cement or amalgam with which the cavity of the root may be filled.
Sixth. The improved process of constructing and fitting artificial crowns to
natural tooth roots, which consists in preparing the root, fitting a ring, band, cup,
or tube at one end accurately to the root to surround its end, removing said ring
and fastening or joining its outer end or edge to a tooth crown having a porcelain
or equivalent face and a metallic backing, and replacing said ring and crown upon
the root, and securing them firmly thereto by means of a pin projecting rigidly
from within the ring into the cement filling in the tooth cavity.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand and
seal, this Twenty sixth day of July, in the year of our Lord One thousand
eight hundred and eighty one.
SYDNEY PITT. (L.S.)