Improvements in Moulds for and the Method of Making Tooth Crowns.
Year: 1899

page_text: Date of Application (in United Kingdom), 11th May, 1899
Complete Specification Left, 11th May, 1899-Accepted, 26th Aug., 1899
Improvements in Moulds for and the Method of Making Tooth
Crowns.
I, CLYDE SYLVANUS PAYNE, residing at No. 18, West 102nd Street, in the
City and State of New York, United States of America, Dentist, 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 novel devices and the method employed in connection
therewith for shaping blanks and making seamless metallic tooth crowns, and in
carrying out my invention I employ a cylindrical mould in which are placed inter-
secting plates. The metal forming the matrix is cast into this mouid and upon the
intersecting plates, and the tooth form or die is placed in the center of the mould
and plates, either before the methal is cast or the same is pressed into the metal
while it is still in a molten condition.
The inner surface of the cylindrical mould and the outer edges of the inter-
secting plates are slightly inclined or tapering so that after the metal forming
the matrix is set, it can be removed from the mould and the intersecting plates
are taken away from the matrix, so that the matrix is left with edge and base
grooves. A suitable tool is introduced into these grooves and the matrix is
split up into sections and the tooth form or die is removed. A cylindrical holder
is provided for the divided matrix, the inner surface of which is also slightly
tapering to conform to the surface of the matrix and the diameter of the holder
is slightly in excess of the diameter of the cylindrical mould in which the matrix
was cast, the difference in diameter being equivalent to the thickness of the metal
of the seamless metallic tooth crown.
The tooth crown blank is placed in the matrix and the matrix is placed in the
cylindrical holder and upon a suitable support, and thereafter the tooth crown
blank is swaged outwardly against the walls of the matrix until the same fills
and fits closely within the cavity in the matrix and conforms to the surface
configuration thereof and agrees with the outline of the tooth form or die, so
that the tooth crown will fit the tooth stump and fill the office of a complete
tooth. This swaging operation is preferably effected by filling the tooth crown
blank with such suitable material as a block of rubber, small metallic balls, shot

page_text: or metal filings, and by using a plunger or rammer upon the same and giving
the blows with a mallet or similar tool.
I prefer in connection with these means and this method, to form a groove
around the tooth form or die, which groove indicates the outline or configuration
of the surface of the gum around the tooth stump upon which the crown is to
be placed. This groove forms a rib around the surface of the matrix and in
the swaging of the tooth crown blank the form of the rib of the matrix produces
a groove in the tooth crown indicating the line upon which the same is to be
trimmed so as to fit the gum when the crown is in place..
In the drawing,. Figure 1 is a vertical cross section through the cylindrical
mould and matrix and an elevation of the tooth form or die and part of the
intersecting plates. Fig. 2 is a plan. Fig. 3 is a vertical cross section of the
cylindrical holder, the divided matrix and the seamless metallic tooth crown
after the swaging operation. Fig. 4 is a plan of the same. Fig. 5 is a plan of
the parts of the matrix separated. Fig. 6 is a plan of the tooth crown alone.
Fig. 7 is an elevation of the same ready for trimming, and Fig. 8 is a vertical
cross section through the mould, matrix, tooth crown blank and rubber block
and elevation of the rammer and mallet.
The cylindrical mould a has an inner, slightly tapering surface, and 6 repre-
sents the crossing or intersecting plates. These are in the form of an X which
is across the lower end of the mould with rising arms that extend to the upper
edge of the mould. These parts are placed upon a suitable bed or support f and
the molten metal forming the matrix e is cast into this mould and between the
plates. The tooth form or die d is made in any suitable or desired manner well
known in the dental art, the same conforming to the size and configuration of
a complete tooth, a reproduction of which in metal is desired. This reproduction
in metal is the tooth crown and when the stump is capped therewith the same,
take the place of an original natural tooth.
A cavity corresponding to this tooth form or die is made in the center of the.
metal forming the matrix, either by holding the tooth form or die in place and
casting the metal around it, or by forcing the die down into the metal while in
a molten condition. After the metal is cooled, it and the intersecting plates b
and the tooth form d, are removed from the cylindrical mould and the intersecting
plates are, readily separted from the matrix, and when so separated, the matrix
has crossing grooves at the bottom and vertical grooves at the sides. The matrix
thus scored is broken apart into sections by any suitable tool, or in other words,
the walls between the grooves and the open center are broken through to divide:
up the matrix and allow the tooth form à to be removed. A cylindrical holder e,
now receives the divided matrix and the diameter of this cylindrical holder' is
slightly greater than that of the cylindrical mould a, that is, it is approximately
as much larger as the thickness of the metal forming the tooth crown f', and
to show this plainly the drawing has been slightly exaggerated.
The blank forming the seamless metallic tooth crown fl is placed in the open
center of the matrix and the matrix is placed in the cylindrical holder e, and
in the operation of forming the tooth crown, the blank is filled partially or
wholly with such suitable material as a soft rubber block h, small metallic balls,
shot, or metal filings, and a rammer i and mallet are employed to cause. the
blank to spread outwardly and fill the inequalities of the matrix c and conform
to the configuration of the tooth form or die d. The excess of diameter of the
cylindrical holder and the consequent spread and separation of the sections forming
the matrix cause the tooth crown when made to have an internal diameter con-
forming to the exterior diameter of the tooth form or die d, and also a surface
configuration conforming thereto. The spaces between the parts of the matrix
are so slight that no impression is made on the tooth crown in the swaging
operation, it being found in practise that the swaging adjacent to any crack
or division has a tendency to bring two parts of the matrix momentarily together:
The tooth form or die d is preferably made with a groove 2 of irregular

page_text: outline, in any manner well known in the dental art and conforming to the gum
ine around the tooth and of course when a tooth form or die with this groove
s placed in the molten metal, the cast matrix is made with a rib that conforms
to the said groove, and this rib is shown at 3, consequently when the seamless
metallic blank forming the tooth crown is swaged or expanded to fill the cavity
in the matrix, the same has a groove 12, which indicates the place where the
tooth crown shall be cut so as to cause the crown to fit around the tooth base
upon which the crown is placed.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
First: In the manufacture of seamless metallic tooth crowns, a cylindrical
mould and intersecting plates within the same into which mould the metal form-
ing the matrix is cast around the tooth form or die, a cylindrical holder for
receiving the divided matrix and means for swaging the tooth blank in the
cavity of the matrix to cause it to conform to the surface configuration thereof,
substantially as set forth.
Second: In the manufacture of seamless metallic tooth crowns a mould with
an inner surface tapering slightly and intersecting plates within the same and
conforming thereto, and into which mould the metal forming the matrix is cast
around the tooth form or die, a holder for receiving the divided matrix also
with an inner surface slightly tapering and slightly larger than the mould and
means for swaging the tooth crown blank in the cavity of the matrix to cause
it to conform to the surface configuration thereof, substantially as set forth.
Third: In the manufacture of tooth crowns, the method herein specified of
making the same, consisting in casting metal forming a matrix around a tooth
form or die and into a mould containing intersecting plates, removing the tooth
form or die, the intersecting plates and the matrix when cold from the mould,
separating the plates from the matrix, and leaving grooves in the base and
surface of the matrix, breaking up the matrix upon lines predetermined by the
grooves, placing the divided matrix into a holder of slightly greater diameter
than the first mould in which the matrix was cast, placing the tooth crown blank
in the cavity of the matrix and swaging or enlarging the same outward to cause
it to conform to the surfaces of the matrix cavity, substantially as set forth.
Fourth In the manufacture of tooth crowns, the method herein specified
of forming the same, consisting in making a tooth form or die with a circum-
ferential groove indicating the gum line of the tooth, casting a matrix around
the form in a mould having intersecting plates, removing the tooth form or
die, the intersecting plates and the matrix when cold from the mould, separa-
ting the plates from the matrix so as to leave grooves in the base and sides of
the matrix, breaking up the matrix upon the lines predetermined by the grooves
to remove the tooth form and expose the internal rib therein, placing the divided
matrix into a holder of slightly greater diameter than the mould in which the
matrix was cast, placing the hollow tooth crown blank in the cavity of the matrix
and swaging or enlarging the same outward to cause it to conform to the surfaces
of the matrix cavity, whereby the seamless metallic tooth crown when swaged
has a groove to indicate the line to which the tooth crown is to be trimmed to
cause it to conform to the gums, substantially as set forth.
1000
BREWER & SON,
London & Leeds,
Agents for the Applicant.