US2328575A - Artificial tooth - Google Patents

Description

Sept. 7, 1943. s. MYERSON ARTIFICIAL TOOTH 1 73226726 07 fz'rrzow/yyez'aow 5 @1 Q 2 :2?

Filed March 14, 1939 Patented Sept. 7, 1943 UNITED STATES PATENT OFFICE ARTIFICIAL TOOTH .Simon Myerson, Brookline, Mass.

Application March 14, 1939, Serial No. 2.61.717

4 Claims.

This invention pertains to artificial teeth and though of broader utility relates particularly to teeth of the crown type, that is to say, those having both lingual and labial contours simulating those of natural teeth, and concerns improved anchorage means readily adaptable to different conditions of use and which provide a strong and reliableattachment of the tooth to-its supporting member, for example, a plate.

In accordance with the invention, the anchorage meanscomprises a pin so associated with and fixed to the tooth as to permit the tooth to be ground away so as properly to abut the alveolar ridge and to obtain the desired bite without injuring or impairing the efiectiveness of the attaching means or weakeningthe pinor its connection tothe tooth.

A furtherfeature of the invention resides in the provision of anchorage means so devised .as to furnish a firm and direct attachment of the tooth to the support without unduly thickening the material of the denture adjacent to the il netion of the tooth therewih.

The invention further contemplates the provision of attaching pin which enters the substance of the tooth at the basal portion of the latter, and which is so devised that though normally substantially rigid it may be bent or otherwise adjusted so that, although a substantial part of the tooth may be ground away to fit the tooth to the gum ridge, the pin may nevertheless be so located as to afford secure anchorage of the pin to the support.

Heretofore it has been common. to provide artificial teeth, in particular anterior teeth, with substantially vertical rear surfaces for engagement with the material of the support, such. vertical surfaces usuall terminating at a substantially horizontal shoulder or ledge defining the upper limit of the exposed lingualsurface of the tooth. Ordinarily one or more pins (having their forward ends embedded in the body of the tooth) project rearwardly and substantially perpendicular to said vertical rear surface. said pins ordi- 1 narily being located about the mid-point of ,said vertical surface, as measured in vertical direction.

When an anterior tooth is subjected to biting pressure, it tends to tip upwardly and forwardly. 1

In order effectively to prevent such action, it is requisite that the rear end of the anchoring pin be firmly embedded in a substantial. thickness of the material of the support. The forward portion of the inner surface of the roof of the plate 1 should curve upwardl and rearwardly from the lingual surface of the tooth, following the normal curvature of the roof of the mouth, while the upper surface of the plate should follow a similar curvature and should be as near to the inner sur- 1 face as is possible without unduly weakening the plate. However, the ordinary pin which projects substantially horizontally from the tooth does not even approximately follow the general direction of the thin roof of the platebut projects into the latter at such an angle that its rear end, where it should find firm anchorage, would come very close to and might even protrude through the inner surface of the plate material if the latter were of the desirable curvature. It is thus usually necessary to depart from this desired and proper curvature in building up a mass of material adjacent to the location of the tooth into which the pin may project and find secure anchorage.

In accordance with the present invention the improved tooth is preferably so externall contoured as to afford a firm and reliable grip for the material of the support, so that the pin need not be relied upon as the only dependable connection between the tooth and the supporting material. Furthermore, the pin is so arranged that, when the tooth is in the position of use, the axis of the pin substantially follows the slope of the palate portion of the plate and thus the rear portion of the pin is embedded to its full depth in a solid mass of the material. 1 the-support, thereby providin firm and adequate anchorage. The lingual surface of the tooth may be contoured as desired to provide the most natural eifect, while at the same time the pin is so located as to provide a great mechanical advantage in resisting stress in response to biting pressure.

In accordance with a preferred construction, the pin is so mounted in the tooth as to provide a certain degree of freedom of movement for its projecting rear end, for instanceby bending, so that if the tooth be ground down to fit it to a particular condition, the direction of the rear portion of the pin may be varied at will by the dentist so as to insure its properembed ding in the plate material without necessitating an undue thickening of the latter, and without weakening the retention of the pin in the tooth.

In the accompanying drawing, wherein certain desirable embodiments of the improved tooth are illustrated by way of example,

Fig. l is a diagrammatic view showing a portion of a plate in vertical section with a tooth embodying certain features of the invention mounted in the plate;

Fig. l is a diagrammatic side elevation, to smaller scale, showing the improved tooth as mounted in a lower denture;

Fig. 2 is a rear or lingual elevation of the tooth of Fig. 1;

Fig. 3 is a diagrammatic view illustrative of a common prior construction;

Fig. 4 is a side elevation of a tooth embodying the invention but of somewhat modified construction;

Fig. 5 is a rear or lingual elevation of the tooth of Fi 4.;

Fig. 6 is a side elevation of a tooth of a further modified. construction, a portion of the plate being indicated in broken lines;

Fig. '7 is a fragmentary section through the rear part of the tooth of 6, substantially in the plane of the line l-7;

Fig. 8 is a vertical section illustrating a modified construction;

Fig. 9 is a rear or lingual elevation of a tooth illustrating a further modification;

Fig. 10 is a vertical section on the line lii-lfi of Fig. 9;

Fig. 11 is a view similar to Fig. 10, but showing the tooth as having been shortened by grinding, the rear end portion of the pin having been bent down to a position different from that shown in Fig. 10;

Fig. 12 is a sectional view generally similar to that of Fig. 1, but showing a further modification;

Fig. 13 is a composite view illustrating pins of different lengths which may be supplied for use with the tooth of Fig. 12;

Fig. 14 is an elevation illustrating an attaching pin of different type; and

Fig. 15 is a fragmentary vertical section showing another form of pin.

Referring to Fig. l, the numeral l designates a tooth embodying certain features of the present invention. As illustrated this tooth forms part of an upper denture comprising a plate 2 having the roof or palate portion 3 provided with upper and under surfaces l and 5 respectively. The forward part of the roof 3 inclines downwardly and forwardly with a slope generally indicated by the line X-Y. The surface t merges with the downwardly concave surface which defines the gum-receiving recess i In Fig. 1 a lower denture is illustrated having the lingual lip 3 and the gum-receiving recess The tooth illustrated in Fig. 1 comprises the labial or front surface 7, the incisal edge 8, the upper or gingival surface 9, the lingual surface Ill, and an inclined rear surface H which. eX- tends from the gingival surface to the lingual surface. The gingival surface :3 and the surface H collectively constitute what may be termed the basal surface of the tooth. As illustrated in Fig. l, the surface I i has a shoulder U where it intersects the gingival surface. The surface H is inclined downwardly and rearwardly from. the gingival surface, as respects the substantially vertical line VV passing through the upper and lower extremities of the tooth, and as here illustrated, the surface i l makes an angle of approximately 90 with the lingual surface ill.

The tooth is furnished with an attaching pin I2 of an appropriate non-corrosive material, usually metal, having an enlargement 3 at its forward end which is embedded in the substance of the tooth. The rear end portion of the pin projects outwardly beyond the surface H and is furnished with an anchoring head M designed to be embedded in the material of the support. The axis of the pin it. is so arranged as to be substantially parallel to or to coincide with the line X-'Y, representing the slope of the extreme forward part of the roof 3 of the plate. It may be noted that the under surface 5 of the roof 3 of the plate merges smoothly and uninterruptedly with the lingual surface it of the tooth so that there is no shoulder, crevice or abrupt change in contour for contact by the tongue of the wearer. It may also be noted that the lingual surface 3 of the lower denture (Fig. l likewise merges smoothly with the lingual surface of the tooth I fixed therein.

In Fig. 3 a usual prior construction is indicated diagrammatically for contrast with the present improved arrangement. Thus in 3 the tooth T has a substantially plane rear surface R parallel to the vertical line VV and terminating at an abrupt shoulder L. The anchoring pin A has its axis substantially perpendicular to the line VV and to the surface R. With such an arrangement, in order to provide adequate material to abut the surface R and for securely embedding the attaching pin A, it is necessary to increase the vertical thickness of the forward part of the roof of the plate, so as to form a mass M of the plate material at this point. This added mass of material takes the place of a portion of the natural tooth and impairs the naturalness of feel when contacted by the tongue and may even interfere with clear enunciation of certain sounds in speaking or singing.

While the construction illustrated in Figs. 1, l and 2 provides a better and more dependable anchorage than usual prior constructions, it is preferred, in accordance with the present invention, to provide additional anchorage by a proper contouring of the rear part of the tooth itself. Thus, as illustrated in Figs. 4 and 5, the lateral faces of the tooth t'- are recessed or depressed at E5, the recesses being so shaped that the rear edge ill of the tooth is somewhat wider than the rear part of the tooth at the point ll, so that, when the tooth is embedded in the material of the plate, a positive key or dovetail effect results, whereby the tooth is very firmly anchored in position, and the pin is relieved of some of the stresses to which it is commonly subjected.

In Figs. 6, 7 and 8, a further modified construction is illustrated, wherein the tooth l is furnished with lateral recesses E8 of more or less triangular form, said recesses being disposed with their narrow ends adjacent to the surface ll, and becoming gradually shallower as they increase in width toward the front of the tooth. These recesses are preferably defined by upper and lower shoulders l9 and 29 (Fig. 8) which are quite abrupt at the rear end of the tooth, and thus provide very effective keys for engagement by the material of the plate, thus affording substantial resistance to the rocking of the tooth in response to biting pressure. Preferably the recesses it, as above noted, grow shallower toward the front of the tooth, eventually merging, as indicated approximately at the line 25, with the lateral surface of the tooth.

Fig. 8 is a sectional view illustrating a modifled construction in which the rear face i i of the tooth has a recess 23 concentric with the pin E2. The surface it is concave and the head M of the pin does not project substantially beyond the rim or margin of the concave surface it. With this arrangement it is possible to bend a substantial length of the rear part of the pin in any desired direction without disturbing its firm anchorage to the substance of the tooth, while at the same time permitting this bendable rear part of the pin to be firmly mbedded in the material which forms the support, such material readily entering the recess 23 and filling the space surrounding the head i l of the pin.

In Figs. 9, 10 and ll, which illustrate a still further modification, the tooth I is furnished with a vertical slot 23 which extends downwardly from the surface 9 to the surface l and which is open at the rear surface I! of the tooth. The slot 23 has an inner or forward wall at which the pin l2 emerges from the substance of the tooth, the rear portion of the pin being within the slot 23. A substantial length of the pin is thus free so that it may be bent upwardly or downwardly from its normal position. As illustrated in Fig. 11, the upper or basal portion of the tooth has been ground away but preparatory to so doing the pin may be bent as indicated at 12 so as to avoid injury thereto in the grinding operation, and after the tooth has been cut away to the desired extent it is still possible, by properly disposing the rear part of the pin, to obtain a firm and secure anchorage of the pin to the material of the plate.

In Fig. 12 a still further modification is illustrated wherein the tooth I is furnished with an elongate bore 25 extending inwardly from its base, for instance from th rear surface H, a suitable anchorage element 25, concentric with the axis of this bore being fixed in the substance of the tooth at a considerable distance from the surface H. If preferred, the bore may extend beyond the anchorage element, as indicated at 25". The bore 25 is designed to receive an attaching pin I2 (Fig. 14), the inner end of which may be secured to the anchorage 26 by solder or equivalent means. By extending the bore at 25 beyond the anchorage it is possible to adjust the pin longitudinally in the bore before solder ing it in place, so that its rear or head end H may project to the desired distance beyond the basal surface of th tooth. Thus the tooth may be used just as it is furnished to the dentist or ground away at its basal portion as much as desired, for instance as illustrated in Fig. 11, the pin being removed during such treatment of the tooth, and then the pin may be fitted into the bore and secured in place with as much or little of the pin projecting as may be desired. Instead of depending upon solder for uniting the pin to the anchorage. the pin and anchorage may hav complemental screw threads, such a pin being indicated for example in Fig. 14 at l2. In adjusting the length of the pin with such an arrangement it is merely necessary to screw it into the anchorage to a greater or lesser extent. On the other hand, if preferred the dentist may be provided with a plurality of pins l2 of diiferent lengths, as indicated in Fig. 14, and may then select a pin of the proper length for use with the tooth which has been made ready for mounting in the denture, the selected pin being slipped into the bore and secured to the anchorage.

In 15 a pin or a further type is illustrated. This pin I2 has an inner head which is embedded in the substance of the tooth. The rear end portion of the pin is located in a recess '23 opening at a basal surface of the tooth and the thus exposed shank portion of the pin is screw threaded for the reception of a nut 14* which may be screwed along the threaded shank so as to occupy any desired position, for example, as indicated at M or 14*, so that if the tooth be shortened, for instance by grinding it to the line G, the head Hl may still be located advantageously for obtaining a secure anchorage in the substance of the support.

While certain desirable embodiments of the invention have herein been illustrated by way of example, it is to be understood that the invention is not necessarily limited to the precise constructions herein shown, but is to be regarded as broadly inclusive of any equivalent constructions falling within the terms of the appended claims.

I claim:

1. An artificial tooth of the kind having a basal surface from which projects a pin for attaching the tooth to a plate, said basal surface including a downwardly concave gingival portion designed to engage that part of the plate which receives the gum ridge, the tooth also having an upwardly and rearwardly directed lingual surface substantially all of which is exposed when the tooth is mounted in the plate and which is so contoured as closely to simulate the entire exposed lingual surface of a natural tooth, characterized in that the basal surface of the tooth also includes a rear portion which inclines downwardly and rearwardly from the rear edge of the gingival portion to the lingual surface and intersects the latter at substantially a right angle, said inclined rear portion of the basal surface being designed to contact the material of the plate when the tooth is mounted in the latter and to define the forward boundary of the under surface of the plate and further characterized in that the rear end portion of the pin projects rearwardly beyond said downwardly sloping rear portion of the basal surface with the axis of the pin substantially midway between the upper and lower edges of the said inclined rear surface and normally substantially perpendicular to said inclined rear surface and normally substantially parallel to the rear portion of the lingual surface, the relative slopes of the gingival and rearwardly inclined portions of the basal surface being such that the length of the tooth may be varied by grinding away material from the gingival portion of the basal surface without damaging the free, exposed rear end portion of the pin.

2. An artificial tooth substantially as set forth in claim 1 further characterized in that the pin and the adjacent parts of the tooth are so designed and arranged as to permit said rearwardly projecting portion of the pin to be displaced from normal position preparatory to removing material from the gingival portion of the basal surface whereby a substantial body of material may be removed from said gingival surface without damage to the pin.

3. An artificial tooth as set forth in claim 1 further characterized in that the tooth has a slot of substantial vertical depth open at said rearwardly inclined portion of the basal surface and whose inner wall is spaced a substantial distance forwardly from said inclined rear surface, the pin extending rearwardly from its anchorage in the tooth through said slot and free from contact with the walls of the slot whereby a substantial part of the length of the pin may be bent away from the gingival portion of the basal surface thereby to permit removal of material from said gingival surface without injury to the pin.

4. An artificial tooth as set forth in claim 1 further characterized in that there is an abrupt shoulder at the junction of the gingival and rearwardly inclined portions of the basal surface whereby the gingival surface may be cut away to a substantial extent without cutting away any of the rearwardly inclined surface.

SIMON MYERSON.

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