Improvements in Dental Plates and their Manufacture.
Year: 1898

page_text: Date of Application, 28th Mar.. 1898-Accepted, 28th May. 1898
Improvements in Dental Plates and their Manufacture.
I, JOHN HUTCHENS GARTRELL, of 47, Chapel Street, Penzance, 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:-
It relates to an improved composite sheet metal for dental plates, made of pure
gold on one side and an alloy of silver and platinum on the other, and the method
of perforating this sheet metal with a punch in order to unite the metal to a
vulcanite plate and forin a metal lining to its palatal surface, and also a strengthener
for the same.
I am aware that attempts to make a composite sheet metal similar to my invention
have been made, but have failed owing to the use of silver only, which becomes
completely changed to silver sulphide during the vulcanizing of the rubber, and the
gold is consequently easily pealed off the plate :-I avoid this result by alloying the
silver with platinum, preferably a 10 per cent. alloy of platinum, or, silver 90, to
10 of platinum: A thick plate made of this alloy is united to a plate of fine gold
by heat and pressure; the two plates are placed together and heated to redness,
pressure is then applied with a hydraulic press, and the combined piece of metal is
afterwards rolled in a flatting mill to the gauge desired; a suitable thickness is
No. 2 plate gauge.
The proportions of the silver and platinum alloy to the gold
may vary, but I find that 4 of the alloy to 1 of gold makes a suitable combination.
The sheet metal is cut to pattern, and swaged with the gold side next the model.
In the finished plate the alloy side will be covered with vulcanite, and united to it
by peculiar perforations made with the punch as shewn in the drawings herewith
wherein Figs. 1 & 2 indicate a pair of forceps with cutter punch A & matrix or
counterpart fixed therein. The cutter point is in one view thereof triangular
vertically, and works into a slot in the counterpart or matrix B. A & B are shewn
in detail in Fig. 3 & Fig. 4 while Fig. 5 and 54 indicate the plate with portions as
at C & D as forced through by the action of the cutter & forming the projections on
the plate necessary for the purpose to be attained. The point of the flat triangular
cutter entering the metal plate drives two strips thereof before it one each way, into
the slot of the counterpart or matrix as fixed in the other jaw of the forceps or press,
curling them as they go as shewn in Figs. 1 2 and in two stages of the
process at C & D Fig. 5. The rubber when vulcanized in the slots and around the
curled projections thus formed becomes firmly attached to the metal plate.
The perforations and projections can be varied in size at will by adjusting a
thumbscrew to limit the action of the punch cutter, as for instance at E Fig. 1.
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 :-
1. A peculiarly perforated dental plate made up of two plates united, the one of

page_text: fine gold and the other of a special alloy of silver and platinum; substantially as
herein described and shewn by accompanying drawings.
2. The special alloy essential to the purpose; substantially as herein described.
3. A special punch-cutter, as being essential to the making of the peculiar
perforations and projections necessary for the special dental plate; substantially
as herein described and shewn by accompanying drawings.
Dated this 28th day of March 1898.
JOHN HUTCHENS GARTRELL.