US2195370A - Artificial tooth - Google Patents

Description

Mar h 26. 40. J. B. LA DUE ml.

ARTIFICIAL TOOTH Filed Dec. 9, 1938 2 Sheets-Sheet 2 Elm WW5 J0 km .5. La Due Jacob Patented Mar. 26, 1940 UNITED STATES PATENT OFFICE,

3 Claims.

Our invention relates to improvements in artificial teeth, and has to do, more particularly,

with the occlusal and masticating surfaces of posterior teeth intended for the replacement of 5 those natural teeth known as molars and bicuspids. I

In the last decade, much thought and research has been devoted to the development of a more satisfactory artificial tooth construction for the replacement of natural molars and bicuspids, and a number of posterior-tooth designs have evolved. While, from the standpoint of appearance, these suggested structures vary widely-in .point of functional principle, each classifies itself into one of two fundamentally distinct types, as follows:

(A) Posterior teeth in which the occlusal surfaces lie in a single flat or substantially flat plane common to all teeth of the denture, hence are capable of description as geometrically cuspless;" and (B) Posterior teeth the occlusal surfaces of which do not lie in a substantially flat plane but include acclivous and declivous portionswhich function in a manner similar to the cusps of 5 natural teeth and positively induce separativc jaw movements during masticating excursions of the mandible.

Our invention pertains to teeth of the class A" above defined, and has, for its primary object, the attainment therein of a degree of masticating eiiiciency so effective as to render such geometrically cuspless" teeth equal or superior to cusped" teeth in this respect.

Viewed from another angle, our invention may be said to have, as a salient object thereof, the reduction and uniform distribution of stress and effort required for mastication; Corollarially, the individual equipped with such teeth is less subjcct to mandibular fatigue, the possibility of ture parts is greatly reduced. and the division of food intofiner particles is facilitated.

It is another object of our invention to provide a masticating face for posterior replacement teeth which, by its inherent freedom from blind" cavities or culs-de-sac, has far less tendency to become clogged with impacted food. This feature of advantage, while primarily adding to the user's comfort and oral hygiene, also evidences itself in more rapid and thorough food mastication.

Considered from the standpoint of the technicians who construct and fit ,dental restorations to the individual mouth, our invention has another important feature of advantage in that it provides a tooth construction which is adaptable." Not only are the occlusal faces of denturemounted teeth embodying our invention susceptible of grinding to proper occlusal fit with respect to the facial curvature of the teeth which oppose them, but the pattern of the occlusal surfaces of our type of tooth is such that especial alinement of the opposing maxillaryand mandibular teeth of a denture is not so essential to insure either occlusal balance or efficient mastication.

Finally, it is an object of our invention to provide an artificial posterior tooth structure which can be manufactured inexpensively in a wide range of stock sizes and shapes and which may be suitably sculptured on. its buccal and lingual faces to closely simulate the natural teeth.

Further objects, and objects relating to details and economies of manufacture, installation and use will readily appear from the detailed description to follow We accomplish the objects of our invention by the concepts set forth in the following specification. Our invention is clearly defined by the appended claims. Preferred embodiments of our invention are illustrated in the accompanying drawings forming a part of this specification, in which:

Figure 1 is an enlarged view, in side elevation, of posterior denture portions provided with four maxillary and four mandibular teeth embodying our invention, said view disclosing the lingual spillways provided in said teeth;

Fig. 2 is a bottom plan view of the four maxillary. teeth of said denture;

Fig.3 is a top plan view of the four'mandibular teeth of said denture;

Fig. 4 is a transverse sectional view of a pair of such denture portions assembled as parts of maxillary and mandibular plates," the view being takenon the line 44 of Fig. l, but drawn to a somewhat smaller scale.

Fig. 5 is an enlarged plan view of four maxiland is comprised by a boss located centrally with respect to the tooth and a marginal upstanding wall at the periphery of thetooth, substantially encircling said central block and defining a moatlike canal which holds larger particles of food to the masticating surfaces while directing discharge of smaller particles. Functionally considered, such a construction embodied in an appropriate maxillary and mandibular denture distinguishesitself fromheretofore-contemplated tooth structures in that the masticating operation is dual, embracing two distinct food-comminuting steps which co-operate during masticating excursions of the mandible. As these two opieratively-distinguishedsteps contribute to effect the reduction of a bolus of food to a homogene-,

ous, relatively smooth, saliva-saturated plastic mass suitable for facile digestion, they may be defined as the shearing step and the triturating step; the former tearing or shreadlng the food into small particles, and the latter grinding the small particles in a manner similar to that characterizing the use of a mortar and pestle. From the foregoing explanation it may be readily appreciated that we have developeda facial structure, for artificial posterior teeth, which, in point of view of oral food'processing, compares favorably with the eifectiveness of natural molars and bicuspids, yet is basically distinguished thereso from, structurally, in that interdigitation of cusps is entirely precluded.

More specifically, we refer now to Figs. 1 to 4 of the accompanying drawings in which is illustrated a simple form of artificial tooth construe- 35 tion embodying the basic concepts of our invention. Reference to Figs. 1 and 4 reveals the planar disposition of the occlusal surfaces of these teeth. In this connection, it is to be pointed out that the expression planar is used in 4Q its broad sense and includesnot only an absolutelyrgeometrically plane surface, but a slightly spherical surface as well, it being well known that natural teeth generally, occlude spherically on radii which vary, in different individuals, from 5 2 to 15 inches.

Fig. l is a lingual view of eight teeth embodying our invention and secured to mandibular and maxillary denture portions A,-B, by any suitable means (not shown). Fig. 3 is a top-plan 50 view of the first bicuspid C,'second bicuspid D,

first molar E and second molar F of one side of the mandible denture portion A illustrated in Figs. 1 and 4 jointly. Fig. 2 is a bottom plan view of the first bicuspid G, second bicuspid H, first 55 molar I and second molar J of the coacting side of the maxillary denture portion B illustrated in FigsJ-rl and 4 jointly.

While, in actual practice, themolars E, F, I and J as well as the bicuspids'C, D, G and H may vary considerably in relative size, propor- 65 ered identical to its neighbors, as may the molars.

Each bicuspid comprises a body portion I0 provided with any suitable means (not shown) for securing it to the denture mounting A or B, a boss II extending integrally upwardly from the 70 tooth body and terminating in a substantially flat triturating surface Ila disposed in the common occlusal plane for the teeth of the denture. Substantially encircling the triturating boss or block II, and extending upwardly from the pe- 7 riphery of the tooth body Ill, is arelatlvely narrow marginal wall I2 which terminates in a flat edge I2a disposed in the common occlusal plane forthe denture. There is thus defined,'between said triturating block II and the marginal wall l2, a moat-like canal I3 which co-operates with the occlusal portions II, I2 of the tooth in several functional particulars-later to be explained. This I canal communicates with the lingual side of the tooth body through lingual spillways I4, IS.

The structure .of each molar E, F, I and J is generally similar to that of the bicuspids. described. These are each comprised by a body portion 20, a central triturating block 2| and a marginal wall 22 extending upwardly from the tooth body. The surfaces 2Ia and 22a of the molars lie in a plane common to all teeth of the denture. A moat-like canal 23 surrounds" the triturating block 2I and communicates with the lingual and buccal sides of'the teeth through spillways 24 and 25 cut through the marginal wall 22.

Assembled as occlusal maxillary and mandibular elements of a denture, teeth of this construction function to comminute the bolus of food by two distinct methods. The rather sharply occluding edges of the maxillary and mandibular elements II, 2| and I2, 22, as they traverse the canals I3,'-23 of opposing teeth, direct large food particles 'thereinto and, being so directed, these particles are sheared as the teeth continue the traversing movement induced by masticating excursion of the mandible. The end-for-end tumbling of the larger food particles into these canals I3 and 23 is not diflicult to envision from study of the several Figures 1 through 4.

Further subdivision of the food particles produced by this shearing action is effected between the maxillary and mandibular triturating block surfaces Ho. and 2Ia as these move relative to each'other in close proximity. This final division or trituration of food into particles of considerable fineness is analogous to that accomplished by the use of a conventional mortar and pestle. The thus-detrited food particles, particularly when moistened to fluidity with normal salivary secretion administered by the tongue,

'are readily swept into the canals I3 and 23 from whence they reach the mouth proper through the various spillways I4, I5, 24, 25 cut through the marginal walls I2, 22 and preferably extended slightly into the body portions I0 and 20 of the teeth.

Reference to Fig. 1 of the drawings, which discloses the mandibular teeth in a protrusive occlusal association with respect to the maxillaries,

'clearly demonstrates that the shearing function of teeth of this type need not occur only between teeth which are axially alined; a bicuspid being capable of thus coacting with a molar. More than this, though to a far lesser extent, some trituration may take place, during extremes of mandibular excursion, between the marginal wall portions of the occlusal face and the central triturating block of subjacent or superjacent teeth, the marginal wall serving somewhat in the manner of a pestle against the central block as a mortar. In teeth of the basic structural form illustrated in Figs. 2 and 3, this supplemental triturating action is relatively slight as compared with that effected between the central blocks per se. However, by a modification of marginal wall conflguration, this supplemental action may be materially increased, as will appear from the description to follow and relating to the modified 7 and Y are shown in a laterally displaced rela-.

embodiment of the invention disclosed 'in Figs. 5 and 6.

From the foregoing description of the structure and functional operation of the teeth illustrated substantially flat surface common to all teeth of the denture. Cuspal interdigitation with attendant localized stresses tending to displace the tooth supports is impossible; fatigue and trauma are reduced to an irreducible minimum; and f ood mastication-is eflicient to a degree comparable with that achieved by perfectly arranged natural teeth. Due to the generally open pattern inherent to our tooth design, impaction of food in such teeth is not li kely to occur, nor is there likelihood of the creation of a jaw-locking vacuum between the occlusal surfaces thereof. Especially advantageous is the simplicity of the design and the correspondingly reduced cost at which such teeth may be manufactured andinstalled by the reconstructionist. Any suitable buccal and lingual carvings may be applied to our teeth to cooperate with that inherent to the spillway formations l4, I5, 24 or 25 and to disguise the fact of dental restoration. Likewise, the shape and configuration of the occlusal portions ll, l2, 2! and 22 of these teeth may be varied considerably without departing from the basic concepts of our invention. These variations in non-functional configuration are matters primarily of artistry anddo not relate materially to thefunctional principles with which the present invention is concerned.

In Fig. 5 we have disclosed a modified form of tooth structure constituting another embodiment of our invention. Here the central-triturating block 3| of the bicuspids K, L, is supplemented by widened occlusal portions 32b, 320 at the buccal and lingual sides, respectively, of the marginal wall 32. The mesial and distal edges 32a of the wall 32 remain narrow, as in the embodiment disclosed in Figs. 2 and 3. A moat-like food-directing canal 33 separates the central triturating block 3| from the marginal wall 32, as in the pre-.

viously described form of tooth, and lingual spillways 34, 35 facilitate discharge of properly masticated food therefrom.

The molars M, N, which correspond in structure to these bicuspids, each include a relatively elongate central triturating block M which is functionally supplemented by widened occlusa portions 42b, 42c, 42d and 42a of the marginal wall 42. The mesial and distal edges 42a of the wall 42, like those 321: of the bicuspids, remain narrow. The characteristic moat-like food-directing canal 43 separates the central'triturating block 4| from the marginal wall 42 and discharge of properly masticated food particles is facilitated by communicating lingual and buccal spillways 44 and 45. The several occlusal faces 3la, 32a,

, 3217, 320, Ma, 42a, 42b, 42c, 42d and 426 of these form.

For a graphical depiction of this supplemented triturative capacity, reference is made to Fig. 6 in which the occlusal surfaces of two molars x tionship occurring during mandibular excursion.

, These molars X and Y are of the same general molar Y is identical in form and includes corresponding triturating surfaces Y-la, Y-2b, Y-2c, Y-2d and Y-.2e, as well as mesial and distal marginal edges Y-2a. A food canal extends about the central triturating block of each tooth and is designated X-3 of the maxillary and Y-3 of the mandibular molar. vided with a lingual spillway X-4 and a buccal spillway X-5, and the canal Y-3 is provided with corresponding lingual and buccal spillways Y-4 and Y-5, respectively.

A clear understanding of primary trituration afforded between the central occlusal surfaces X-la and Y-la, of these teeth can be gained from the disclosures in Figs. 1 and 4. As the teeth X and Y move from this position of central alinement to the lateral position depicted in Fig. 6, food trapped in the canals X-3 and Y-3 is chopped by the shearing action of canal-defining edges of the occlusal portions Y-2b, Y-Zc across the proximate edge of the central occlusal portion X-la, and by the canal-defining edges of the occlusal portions X-Zd, X-2e across the proximate edge of the central occlusal portion Y-la. While some supplemental shearing is effected by the marginal wall portions X-2a and 86-211 in their traversal of each other and portions of the broader occlusal surfaces of these teeth, these function rather to force the food along the canals Y-3 and X3 and through the spillways Y4 and X-5 during the lateral cycle which terminates in the dental relationship depicted in Fig. 6.

The canal X-3 is pro-' 3. Food urged through the spillway Y-4 is di rected upon the triturating surfaces X-la, i l-2b,

A Y-2c.

4. Fine particles of food are urged to discharge. from the teeth through the spillway X-5.

5. Supplemental trituration is effected between the surfaces X-Ia and Y-Zb, Y-2c; and X-2d, X-2e and Y -la.

During the return cycle of movement to alined occlusion the following salient component masticating functions occur.

1. Trituration constituting a continuance of that (5) above occurs.

2. Food in the canals X-3 and Y-3 is shifted about into positions where shearing of larger particles, and trituration of smaller particles, is assured.

3. Spillways Y-4 and X-5 become intrusion ducts for the portion of the food which remains for, processing by the teeth, spillways Y-5 and X-4 becoming avenues of escape for properly subdividedfood.

4. Shearing of larger food particles occurs between the proximate edges of the occlusal portions X-2b-Y-2b, X-Zc-Y-Zc, X-2d-Y-2d, X-Ze-Y-Ie, X-lw-Y-la, to a lesser. extent, X-2 zY-2a, and various combinations of these X- exponented and Y"-exponented occlusal portions, depending upon the directional characteristics of the mandibular excursion;

5. Primary trituration at the terminal portion of this return cycle is effected between the triturating surfaces X-la--Y-la, X-2b-Y-2b, X-2c- Y-2c, X-Zd-Y-2d, and X-2e-Y-2e.

Lateral mandibular excursion in mastication being generally symmetrical, the return cycle just described follows through to a position of displacement which is the reverse of that disclosed in Fig. 6, during which functional operations generally corresponding to those first described occur. Likewise, return movement from this reversed position embodies functional efiects similar to the return movement from the first cycle. To describe these corresponding cycles is, therefore, unnecessary.

While we have endeavored to point out salient functional effects normal to mastication with teeth of the structural form illustrated, it may be readily appreciated that, due to the intricacy and variation of mandibular movements comprising mastication as practiced by each individual, it would be impossible to discuss all the functional relationships occurrent with our novel teeth. Although mandibular masticating movements embrace protrusive, retrusive, bi-lateral and separative components in a myriad of combinations, the functional effects of teeth embodying our invention have been set forth with sufiicient fundamental particularity to establish primary distinctions which characterize that invention. Inasmuch as the molar construction illustrated in Figs. 5 and '6 is, in a sense, a twinning of the bicuspid construction illustrated in Fig. 5 and a common functional similarity underlies both the single and twinned structures, a'n'understanding of the operation of this bicuspid structure will occur to those skilled in the art without further detailed explanation.

From the foregoing description of the structural and functional concepts which characterize our invention it will be obvious that considerable variation in size, configuration and arrangement is permissible without departing from these concepts. While we have disclosed our invention as embodied in a full restoration of the natural posterior teeth, obviously the invention is applicable to partial restorations supported by crown, plate or bridge. ornamentation of lingual and buccal surfaces of such teeth is also, naturally, contemplated. While we have disclosed only two distinct forms of occlusal patterns which fulfill the structural and functional requirements of our concepts, it is self-evident that other patterns of greater or lesser intricacy might be employed without a departure from essential principles. These and other variants will readily occur to persons skilled in the art and such changes are contemplated as optional practice of our invention. We, therefore, claim our invention broadly, as indicated by the following claims.

What we claim is:

1. An artificial tooth of the geometrically cuspless type the occlusal surfaces of which all lie in a single, substantially fiat plane, comprising; a body portion adapted for anchorage to a tooth mounting member, said body portion terminating at aconsiderable distance from the occlusal plane of the tooth, a substantially continuous annular wall extending occlusally from the periphery of said body portion and terminating as the marginal occlusal edge of the tooth, a relatively broad, centrally-located boss extending occlusally from said body portion and constituting a broad food triturating block the milling surface of which is disposed in said common occlusal plane, and an annular canal isolating said central and marginal occlusal portions and constituting a magazine for the reception and application of food-particles to said triturating block.

2. An artificialtooth of the geometrically cuspless type the occlusal surfaces of which all lie in a single, substantially fiat plane, comprising: a body portion adapted for anchorage to a tooth mounting member, said body portion terminating at a considerable distance from the occlusal plane of the tooth, a boss integral with said body portion and extending occlusally from the central portion thereof to constitute a broad food triturating block the milling surface of which is disposed in said common occlusal plane, a marginal wall extending integrally upwardly from the periphery of said body portion and terminating in an occlusal edge substantially encircling said central triturating block, a supplemental triturating block intermediate said marginal occlusal edge and said central triturating block, said supplemental triturating 'block having its milling surface lying in said common occlusal plane, and an annular canal isolating said central occlusal block from said supplemental block and marginal wall and constituting a magazine for the reception and application of food particles to said triturating blocks.-

3. An artificial tooth of the geometrically cuspless type the occlusal surfaces of which all lie in -a single, substantially flat plane, comprising: a

body portion adapted for anchorage to a tooth mounting member, said body portion terminating at a considerable distance from the occlusal plane of the tooth, a boss integral with saidbody portion and extending occlusally from the central portion thereof to constitute a broad food triturating block the milling surface of which is disposed irpsaid common occlusal plane, a marginal wall extending integrally upwardly from the periphery of said body portion and terminating in an occlusal edge substantially encircling said central triturating block, a supplemental triturating block inbuilt into a lingual portion of said marginal wall, a supplemental triturating block inbuilt into a buccal portion of said marginal wall, each of said supplemental triturating blocks having its milling surface disposed in said common occlusal plane and constituting extensions of the occlusal surface of said marginal wall, and an annular canal isolating said central occlusal block from said other occlusal portions of said tooth and constituting" a magazine for the reception and application of food particles to said triturating blocks.

JOEJ B. LA DUE. JACOB A. SAFFIR.

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