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Патент USA US2129922

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Sept. 13, 1938.
Filed April 22, 19.36
04W WW
Patented Sept. 13, 1938
oFFicE '
James P. Franchetti, Santa Rosa, Calif.
Application April 22, 1936, Serial No. 75,746
2 Claims. (Cl. 32—-9)
This invention relates to interchangeable fac
ings and backings for prosthetic dentistry.
A few years ago there was introduced to the
dental profession of a plain type interchangeable
v5 porcelain facing for bridge pontics. This facing
was a radical departure from the old pin type
facings which were at that time almost univer
sally used in this country. The interchangeable
feature was a step forward and in time this type
10 of facing was extensively accepted by the profes
sion. It developed into two types, one known as
the plain type interchangeable facing and the
other as the root tip type interchangeable facing.
The object of the present invention is generally
to improve and simplify the construction and
operation of interchangeable facings of the char
acter described, and more speci?cally stated, to
provide an interchangeable facing so constructed
as to practically overcome most of the defects
above referred to and above all to provide an
interchangeable type of facing which may be
gold-tipped without in any way sacri?cing the
interchangeable feature.
The interchangeable facings employed and dis
closed in this application are shown by way of
illustration in the accompanying drawing, in
It soon became evident to the profession that which—
15 this type of facing was not universally adaptable I
Fig. l is a perspective view of a portion of the 15
and that in certain locations of the mouth and upper jaw showing a pontic applied and in posi
under certain working conditions, which will later
be referred to, the high percentage of breakage of
the facings limited their use almost entirely to
tions of the interchangeable facings removed;
the maxillary arch. Even then the percentage of
breakage was much higher than with the old pin
type facing. Its redeeming feature was the ease
with which it could be replaced and because of
this feature its popularity continued to grow and
for the same reason this type of facing is un
doubtedly used many times in cases known to be
Fig. 2 is a similar View showing the veneer sec
Fig. 3 is a central, vertical section of the veneer
section of an interchangeable facing showing
what will hereinafter be referred to as a “plain
interchangeable facing”; .
Fig. 4 is a central, vertical section of the back
ing plate to which the veneer is to be attached;
Fig. 5 is a front view of the backing plate shown
in Fig. 4;
Fig. 6 is an enlarged cross section of a pontic
unfavorable to its indication.
An interchangeable facing of the character
here referred to consists of a porcelain veneer showing the backing plate and veneer attached
having a dovetailed groove formed in its inner thereto;
face and a metal backing plate having a lug to
Fig. '7 is a central, vertical section of a root tip
enter the groove of the veneer; the backing plate type of veneer;
being soldered or otherwise secured to the casting
Fig. 8 is an enlarged cross section of a pontic
of the pontic and the veneer to the-backing plate showing the root tip type veneer and the backing
35 by means of the lug which enters the groove of
plate attached to the pontic;
the veneer and by cement placed therein. As time
Fig. 9 is a perspective view of the root tip type
went on certain problems and defects developed I shown in Fig. 7;
and among the more important may be men
Fig. 10 is .a perspective view of the backing
plate used in conjunction with a root tip type
Fig. 11 is a perspective view of the veneer em
ployed in conjunction with a common inter
The tendency of the facings to fracture;
Separation of lug from backing;
Separation of backing from casting or pontic;
Excessive bulkiness of facing;
45 (5) All like (same tooth and length) facings not
interchangeable; and
(6) Shade influenced by cement.
the veneer shown in Fig. 11;
Fig. 13 is a perspective view showing the lingual
Problems in the use of root tip interchangeable
side of the backing plate used in conjunction with
5O (1) Separation of lug from backing;
(2) Separation of backing from casting or pontic;
(3) Limited adaptability;
the veneer shown in Fig. 11;
Fig. 14 is an end view of the backing plate
shown in Figs. 12 and 13.
(4) Not truly interchangeable; and
55 (5) Ridge creates interference in replacing.
changeable facing;
Fig. 12 is a perspective view showing the labial
side of the backing plate used in conjunction with 45
Referring to the drawing in detail, and partic~
ularly Figs. 3, 4, 6, 11, 12 and 13, which illustrate
the plain type interchangeable facing, A indicates
the porcelain or veneer portion of the facing and 55
B the metal backing plate. Projecting from the
as this will greatly decrease the number of facings
lingual surface of the veneer is a lug 2 which is
disposed on an angle of substantially 150°, this
a dentist must keep on hand to have a fair selec
tion of facings.
being an important feature as will hereinafter
By investing the anchor portion of the coupling
in the veneer and forming the groove in the back
appear. The lug is dove-tailed shaped in cross
section and is provided with an anchor member 3
which extends into the porcelain a sufficient dis
tance so that when the veneer is baked a rigid
anchorage and attachment will be insured.
The lingual face of the occlusal edge of the
veneer is beveled, as indicated at 4, and the angle
is the same as that of the lug 2, to-wit, 150°.
ing plate, I accomplish several things. First, I do
away with any grooves in the veneer and thereby
reduce tendency to fracture; cement shadows are
eliminated and bulkiness of facings in the plain
type, and a limited use of the root tip type. Also,
by investing the lug in the veneer I overcome the
problem of the lug separating from cast backings.
The backing plate is ?at but terminates inv a . The grooved coupling in the backing plate gives
beveled seat 5 having the same angle as the bevel
15 4 so as to form a support therefor.
The rear or
lingual surface of the backing plate is provided
with a lug 6 which is internally grooved, as shown
at ‘I, and shaped to receive the lug 2. A slot 8
forms a continuation of the groove 1 to receive the
shank 2a of the lug 2. Lug 6 and the groove
formed therein is disposed on the same angle as
the lug 2, thereby permitting ready separation or
assembling of the veneer and backing plate as
conditions may demand.
The backing plate will in actual practice he
the backing plate a mechanical retention to the
casting which overcomes the problem of the back 15
ing separating from the casting.
In the root tip type facing I leave a butt end on
the root tip permitting the same facing or veneer
to be used as a cone end type or as a saddle end
In this type of facing I eliminate any grinding
of the biting edge by the dentist as the veneer is to
be manufactured with a good beveled edge of con
stant angle and distance from the lug. This per
mits complete uniformity in replacing facings to 25
soldered or cast to C forming a bridge, plate, or
previously cast pontics.
whatever type of pontic it may happen to be, but
The elimination of the grooves in the root tip
veneer permits almost unlimited grinding in this
area which, in turn, increases the indication of
this type facing to one hundred percent, the indi
a better attachment will be obtained when com
parison is made with common or standard plates
30 as the lug C will in itself be dove-tailed and shaped
as shown in Fig. 14, and as such will form a
mechanical retention between the backing plate
cation of the plain type interchangeable facing.
This is an important feature of this type of facing.
Another advantage which I accomplish for the
root tip type facing is the fact that the plain type
B and the casting.
The root tip type of interchangeable facing is
best shown in Figs. 7 to 10, inclusive. It'is almost
identical to the plain type but differs at the root
backing can be used for this facing with the same
advantages as the more expensive backing. If
end as that end of the porcelain or veneer is en
the pontic is to be soldered to the backing, the
larged and rounded as shown at It). The lingual
surface is cut or beveled, as at H, to engage the
40 seat I2 formed on the backing plate. The angle
of the beveled face and the seat 12 being the same
as that of lug 2. The seat [2 is formed by an
angular extension at the upper end of the backing
This extension reinforces and strengthens
the veneer as a whole and, furthermore, adds to
the anchorage formed between the backing plate
and the pontic.
While the angle of lug 2 and the other angular
faces described have been speci?ed as substan
50 tially 150", it may be varied considerably one way
or the other; also it will be noted that the occlusal
edge of the veneer and the backing plate is shown
as substantially straight for the front teeth, but it
will be understood that it will be shaped to follow
the contour or slope of the cuspids, bicuspids and
molars, as the case may be.
The outstanding feature of the interchangeable
facing here disclosed is a facing (plain or root tip)
which is gold-tipped without sacri?cing the inter
60 changeable feature.
This is accomplished by
using an attachment which permits a facio lingual
angle of approach of veneer to backing and by
beveling the biting edge of the veneer to the lin
gual at the same degree of angle (or greater) as
the angle of attaching coupling is to the veneer.
With this arrangement the portion of the casting
extended over the biting edge (the gold-tip) is no
longer an interference to the assembly or dis
assembly of the veneer and backing. Having
evolved an interchangeable facing, it was decided
to make the distance between the position of the
lug in the veneer and the position of the linguo
incisal or occlusal angle of the beveled edge con
stant, thereby allowing all like (same tooth) fac
75 ings to be interchangeable with all like‘backings
using of the plain backing with the root tip facing
necessitates furnishing a small piece of coping
gold over the uncovered portion of the root tip 40
before waxing backing in position. If the pontic
is to be cast, as is usually the case, no added pre
caution need be taken.
Summarizing the advantages of the plain type
facing, they are:
(1) Protection to incisal (or occlusal) edge by
Eliminate separation of lug and backing.
Mechanical retention of backing to casting.
No line of fracture in facing.
Like tooth facings interchangeable with all
like backings.
(6) No cement shadow through facing.
('7) Thinner facing (and stronger).
Advantages of root-tip type facing:
(1) Protection to incisal (or occlusal) edge by
Eliminates separation of lug and backing.
Mechanical retention of backing to casting.
No line of fracture in facing.
Thinner facing (and stronger).
(6) Can be used in any case where plain type can
be used.
(7) One facing for cone or saddle type.
(8) Can use plain type backing.
(9) Truly interchangeable in replacing to gold
tipped pontic.
(10) No ridge crest interference in replacing.
The short-bite facing and backing
Because the attachment of the interchange
able facing projects on the lingual of the back
ing, it is advisable to manufacture two kinds of 75
facings and backings for the six anterior maxil
lary teeth; 1. e., the regular facing and backing
having the same position of the lug to the biting
edge as all other teeth, in addition to this a short
bite facing and backing is advisable for the teeth
mentioned to be used in cases of extremely deep
overbite of these teeth with a very narrow over
In such cases the projecting backing might
cause an interference in establishing proper tooth
position. The short-bite facing and backing
10 would have the position of the lug on the facing
and the corresponding female coupling on the
backing in a slightly more gingival position allow
ing a greater depth of overbite to be cleared
without interference by this porjection. The de
15 gree of angle of lug and bevel alike would re
beveled face, and a backing plate having com
plementary upper and lower seats formed there
on and oppositely disposed in parallel relation
to receive thereagainst the upper and lower
beveled surfaces of the veneer, and also hav
ing a groove and recess formed therein between
said seats complementary to said lug and
adapted to receive the lug of the veneer, said
beveled surfaces and seats together with the lug
and the lug receiving groove being disposed on
an occluso-gingival angle from the occlusal end
to the lingual side with relation to the longi
tudinal axis of the veneer, whereby said facing
may be mounted on said backing without inter
ference at an occluso-gingival angle and said 15
root portion may be readily ground and adapted.
main the same as in the regular facings. Such
facings and backings would be designated as
2. In an arti?cial tooth structure of the root
extension type, a veneer or facing member hav
short-bite facings and backings by a conspicuous
marking such as the imprint of the capital letter
ing an intermediate lingual face and a root tip
presenting an occlusally disposed beveled sur 20
face above said lingual face and also having at
its biting edge a lower surface beveled away from
said lingual face between the lingual and facial
sides, the said beveled surfaces being inclined
substantially in parallelism on an occluso-gingival 25
angle from the occlusal end to the lingual side,
and a lug invested in and projecting from the
intermediate lingual face between said beveled
surfaces and spaced from said occlusally dis
posed surface and spaced gingivally from said 30
lower beveled surface, said lug having an en
gaging rib extending on an incline coinciding
with the incline of the two beveled surfaces.
20 “S” on facing and backing.
Having thus described my invention, what I
claim and desire to secure by Letters Patent is:
1. An interchangeable arti?cial tooth of the
root extension type comprising a veneer hav
25 ing an intermediate lingual face and having upper
and lower beveled surfaces formed on the lingual
side thereof at opposite ends of said lingual face
and disposed in parallel relation to each other,
said upper surface forming the occlusally dis
posed portion of the root extension, a lug invested
in and projecting from said intermediate lingual
face and spaced occlusally from the upper beveled
surface and spaced gingivally from said lower
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