US2473515A - Artificial tooth - Google Patents

Description

June 21,1949. l I --EGGER "2,473,515,

ARTIFICIAL TOOTH.

Filed Aug. '7, 1947 /n vena/or.-

Leo/ao/d fgger 3 il @y Patented June 21, 1949 UNITED Section 1, tP-ublie Law 690, August8,=1946 This invention relates to lartificial teeth .las may be used for whole -or parti-al tiental .plates as well as for bridge work.

It is an object oi this .invention to .provide san artificial tooth whose crown isrcapaioleof yielding tochewing pressure tosubstantially-the `same limited extent as do the natural teeth.

A further object of the invention to provide a composite artificial tooth whose elements @are constructed and associated .in such a :manner as to permit a limited swinging movement oi `the crown of the tooth relative to the base of the 'denture without rendering by such construction the appearance of `the `tooth noticeably dierent from that of .ordinary artificial teeth.

A further object of the invention vtis to provide an articial tooth which combines y:limited relative movability of its cro-wn with suiiifcient strength to take up any chewing pressure.

Still a further object of the :invention fis to pro- L vide a composite artificial tooth having .a Icrown whose active rim or 'surfacemay .swing iorrelatively wide amounts due to a deeply located pivot for said crown.

Other objects oi the invention lappear .as `f` the description proceeds, reference had to the accompanying ldrawing which illustrates r-by way of example three embodiments of vthe inventvtion and in which-- Fig. 1 is va vertical section through Lan anterior tooth as secured to a base plate;

Fig. 2 is a section along the line 12`2foi Fig. i.; Figs. 3 and 4 are, respectively, vertical isectional views of the crown of a molar tooth vand y'of the vand --I2 may be polymerized tog-ether to form ya unitary body of uniform .appearance and .the tooth may, through the intermediary fof its part I0, be bonded or fused to the conventional :base

plate I3 of the denture also by the polymerization method, if this plate `also consists of polymeri'able material, e. g. an `acrylic resin.

The support :I I) is in the form cfa substantially conical pin which is rounded ou at rits apex to i 2 form a :rolling vsurface I4 and is provided at its base with a marginal flange I5. The crown II has at its lower .side -a conical cavity IB whose ^apex is shaped into a rolling surface I'I adapted to `cooperate with the rolling surface I4 of the pin I0.

The slopes of the `conical surfaces of the fpin .I0 'and the lcavity `I6 are so chosen that, when the axes of these two conical :surfaces coincide, which position is .shown 1in Fig. 1, :an yannular gap is present between 'the .pin IIJ and the Acrown Ill which accommodates lthe intermediate layer |12 'and whose width increases -steadily from :the rolling `.surfaces M, -I .'I towards the mouth vof the gap 7 Aat `the lateral 4surface of `the tooth. While `the Aarmular gap does not have to have lthe exact vform shown in Fig. r1., -it `is essential that its shape iris such as to .permit the crown II which bears with its rolling 'surface il fdirectly, that is without an intervening elastic cushion, upon the rolling `suriace I4, 'to carry outfa apendulous movement in fall 'directions during chewing. Under this `condition the crown I`-II can react :to the chewing .pressures in the same Imanner as would a natural tooth.

While the linear Aextent of the swing voi" the crownedge may be'varied by lengthening or short- :ching this crown edge, the tooth will in any case he 'ableduring the `chewing Aaction to slightly give wayto the food seized :by the teeth, and to adapt `it'sel to natural articulation. The 4similarity to natural teeth becomes 'practically .perfect if the pala-tal surface, in particular that of the iront 'teeth,is shaped soasto exactly correspond to the shape of the palatal surface of the natural teeth.l In the :conventional artificial teeth this surface is-either -shortened or rarbitrarily modified. -It being, however, the task of just the front teeth to out up the food, the heretofore inadequate function of these articial front teeth is the main cause of the unpleasant vexations with which the wearer of an artificial `denture has often to put Aup .in chewing.

In the modied'form ofthe tooth shown in Figs. 3 and 4 there are only tw'o parts, the crown I8 and the intermediate layer 2|, which have to be Aformed separately from the base plate l2'2. While there is again a conical support 23 corresponding to the lpin illifof Fig. 1, this Vsupport or pin `is an integral partfof the base plate 22, and the pins for all the teeth 'carried by the base plate :may be .formed with the latter in the same molding operation. The crown I8-of non-elastic synthetic material has again a conical cavity AI9 whose bottom Aisshaped `so as to form a bearing cup having a rolling surface 20. The cavity I9, except for the rolling surface 20, is lined with a. layer 2| of elastic synthetic material whose cross-section, starting from the bearing cup 20, increases uniformly. At its lower end the layer 2| is shaped into an annular flange 24 whose upper surface 25 rests against the bottom surface 26 of the crown i8 and whose lower surface 2l corresponds in shape approximately to the surface 28 of the base plate 22 so that, when the crown together with its lining is placed upon the support 23, the surface 28 of the base plate 22 affords a. suitable seat for the surface 21 of the lining.

The plate 22 which is made of non-elastic synthetic material is shaped so as to present a support in the form of a conical pin 23 for each tooth of the set of teeth to be carried by the plate. After the tooth shown in Fig. 3 has been placed on its coordinated pin shown in Fig. 4, a permanent connection between the tooth and the base member 22, 23 is brought about by a suitable bonding method, such as by polymerizing.

The break in the profile of the annular gap shown in Fig. l at 40 as well as in Fig. 3 at 4| providing surfaces of small slope at the wide end of said gap improves the seat of the crown on the pin.

Fig. shows a modification of the new tooth permitting for the same distance of the tip of the tooth from the base plate a wider swing of said tip than the constructional forms shown in Figs. 1 to 4. In the latter, the bearing point of the crown on the support or pin is situated at vabout one-half of the total height of the tooth which arrangement is ordinarily sufficient to allow for pendulous movements of proper extent of the chewing rim or surface of the tooth. The chewing rim or surface can swing out the wider, the deeper the bearing point of the crown is located. Lowering this bearing point reduces the height of the supporting pin, but it also reduces the height of the elastic intermediate layer. It is not desirable to reduce this elastic layer below a certain height. In order to permit a lower location of the bearing point of the crown on its support without reduction of the elastic intermediate layer, I have devised the tooth shown in Fig. 5. This tooth is composed of a support 30 which forms a bearing cup 3i open towards the top, a crown 32 whose lower half is in the form of a conical pin 33, and an intermediate layer 3Q. The apex of the conical pin 33 is rounded off so as to form a rolling surface 35 which cooperates with a rolling surface 36 formed at the bottom of the bearing cup 3l. The annular gap between the support 30 and the pin portion 33 of the crown 32 which is occupied by the intermediate layer 34 increases in width uniformly towards its mouth. Due to this reversed arrangement of pin and bearing cup, as compared with the arrangements shown in Figs. 1 to 4, the bearing point of the crown becomes situated much lower so that any desired maximum amplitude of the swing of the crown may be provided for by proper dimensioning of the cushion 34.

The invention proves of particular advantage when applied to molar teeth since with these teeth it is especially important that they can yieldingly adjust themselves to such natural teeth as the wearer of the denture may still possess.

The swing bearing of the crown prevents, particularly if the palatal surface of the artificial teeth conforms exactly with that of the natural teeth, any displacement of the denture and allows for a completely natural chewing action so that the denture satisfies all demands which may be made upon a biotechnically perfect denture.

While I have mentioned synthetic materials for the various parts of the new teeth, I desire it to be understood that also other materials may be used, such as metal or porcelain for the support and the crown and rubber for the elastic intermediate layer. The resiliency of this intermediate layer preferably corresponds approximately to that of rubber for erasers.

What I claim is:

l. A composite artificial tooth -comprising a supporting member, a crown, an elastic layer interposed between said supporting member and said crown, a rolling surface on said supporting member, a rolling surface on said crown, said supporting member and said crown being shaped so that one of said two parts comprises a pin and the other a bearing cup which pin and bearing cup interact at said rolling surfaces, and said supporting member and crown forming between themselves an annular gap occupied by said elastic layer.

2. A composite artificial tooth as claimed in claim l, wherein said pin is part of said supporting member and said bearing cup is part of said crown.

3. A composite articial tooth as claimed in claim l, wherein said pin is part of said crown and said bearing cup part of said supporting member.

4. A composite artificial tooth comprising a supporting member, a crown, an elastic layer interposed between said supporting member and said crown, a rolling surface on said supporting member, a rolling surface on said crown, said supporting member and said crown being shaped so that one of said two parts comprises a pin and the other a bearing cup which pin and bearing cup interact at said rolling surfaces, said pin and said bearing cup having each substantially conical shape with the slopes of the two conical surfaces being different so as to form between them an annular, towards the side wall of the tooth substantially steadily widening, gap occupied by said elastic layer.

l5. A composite artificial tooth as claimed in claim 4, wherein the end portion of said annular gap at the wide side thereof is or reduced slope as compared with the rest of said gap.

6. A denture comprising a base plate and at least one composite artificial tooth, said base plate having integral therewith a pin-shaped extension for each artificial tooth carried by said plate, a rolling surface on each said pin-shaped extension, each tooth consisting of a crown having a cavity and an elastic layer fitting into said cavity, a rolling surface delimiting a portion of said cavity adapted to cooperate with said rolling surface on the coordinated pin-shaped extension of said base plate, said elastic layer fitting into said cavity and onto said pin-shaped extension to the exclusion of said rolling surface of said cavity and said extension.

7. As an article of manufacture an artificial tooth unit consisting of a crown having a substantially conical cavity whose apex is rounded off, and an elastic layer lining the conical wall of said cavity with the exception of said rounded off part at the apex of said conical wall.

8. As an article of manufacture an artificial tooth unit consisting of a non-elastic crown having a substantially conical 'cavity whose apex is rounded off, and an elastic layer lining the conical wall of said cavity with the exception of said rounded off part at the apex o f said conical wall, the thickness of said layer increasing towards the open end of said cavity.

9. A composite artificial tooth comprising a supporting member and a crown consisting of nonelastic polymerizable synthetic material and an intermediate layer of elastic polymerizable synthetic material interposed between said supporting member and said crown, a rolling surface on said supporting member, a rolling surface on said crown, said supporting member and said crown being shaped so that one of said two parts comprises a pin and the other a bearing cup which pin and bearing cup interact at said rolling surfaces, said supporting member and crown forming between themselves an annular gap occupied by said elastic layer, and said supporting member, crown, and intermediate layer being polymerized together.

10. A denture comprising a base plate of polymerizable synthetic material and at least one composite artiiicial tooth comprising a supporting member and a crown, both consisting of nonelastic polymerizable synthetic material, and a layer of elastic polymerizable synthetic material interposed between said supporting member and said crown, a rolling surface on said supporting member, a rolling surface on said crown, said carrier and said crown being shaped so that one of said two parts forms a pin and the other a bearing cup which pin and bearing cup interact at said rolling surfaces, said supporting member and crown forming between themselves an annular gap which is occupied by said elastic layer, said supporting member, crown, and intermediate layer being polymerized together, and said supporting member being polymerized to said base plate.

LEOPOLD EGGER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,460,691 Williams July 3, 1923 2,380,468 Sar July 31, 1945 Certificate of Correction Patent No. 2,473,515 June 21, 1949 LEOPOLD EGGER It is hereby certified that error appears in the above numbered patent requiring correction as follows:

In the heading to the printed specication, line 5, for the foreign filing date July 7, 1946 read July 6, 1946*;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. Signed and sealed this 28th day of March, A. D. 1950.

THOMAS F. MURPHY,

Assistant ommzssz'oner of Patents.

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