US2203226A - Artificial denture - Google Patents

Description

June 4, 1940. R, K I K 2,203,226

ARTIFICIAL D EEEE RE Filed June 29, 1939 Patented June 4, 1940 UNiTED STATES mm orFicE 6 Claims.

My invention relates to dentistry and consists in improvements in artificial teeth.

A set of artificial teeth embodying theinvention is illustrated in the accompanying drawing. :Fig. I is a view of the set in side elevation, showing the teeth of the upper and lower dentures in the interdigitated relationship that exists when the jaws of the user are tightly closed. Fig. II is a view comparable to Fig. I, showing the teeth slightly separated, as is the case when the jaws are opened part way. Fig. III is a view to larger scale, illustrating in perspective two of the posterior teeth of the lower denture and; one of the teeth of the upper denture, as seen from the buccal side. Fig. IV is a View of the teeth of Fig. III, as they appear in perspective from the lingual side. Fig. V shows in elevation, as viewed on the planes indicated by the lines VV of Fig. II, one of the posterior teeth of the lower denture and a cooperating tooth of the upper denture; the two teeth appear in vertically spaced-apart relation, with the teeth-carrying bodies or plates of the upper and lower dentures omitted for the sake of simplicity in illustration. Fig. VI is a View comparable with Fig. V, showing the two teeth in closed pos1tion. Fig. VII is a fragmentary view, showing in plan the occlusal surfaces of four of the teeth of the lower denture. And Fig. VIII is a view in plan of the occlusal surface of one of the posterior teeth of the upper denture.

The upper and lower teeth in the human mouth must be properly oriented with the points of articulation of the lower jaw or mandible with the skull, and the individual teeth must be so formed and arranged as to admit of natural jaw movements. Otherwise, the biting and chewing of food can not be accomplished most effectively, and over a greater or less period of time serious anatomical and functional disorders will develop.

Dr. Gysi and others have perfected apparatus and methods, by virtue of which it has become possible to construct artificial dentures that are theoretically perfect, that is to say, dentures that may be perfectly oriented with the points or centers of mandible articulation, while providing perfect registry of the occlusal surfaces of the upper and lower teeth. I say that the dentures are theoretically perfect, because, with no food in the mouth, the mandible may be moved naturally, and the jaws may be forcefully closed in the usual biting and chewing positions, without the slightest malarticulation of the mandible condyles in the sockets or glenoid fossae in the skull. However, when food is in course of mastication between the dentures, this condition of perfection is not always maintained.

More particularly, I have discovered that the usual artificial teeth, even though they meet all theoretical requirements hitherto considered sufficient, do not in fact function with perfection. During the chewing of food the distribution of stress upon the dentures is not uniform, and varies with each bite, with the consequence and effect that the condyles do not articulate properly in the glenoid fossae. I have found that in many cases the condyles, pressing the cartilages out of normal positions, bear immediately upon the posterior walls of the glenoid fossae, and cause painful irritations in the face and head. Indeed, in some cases the distal lobes of the condyles pierce the posterior walls of the glenoid fossae and enter the auditory canal, causing partial or complete deafness.

My invention consists in particular refinements and elaborations in the form or shape of artificial teeth. More specifically, the artificial dentures of the invention, otherwise constructed in accordance with known practice, are provided with bicuspids in place of molars. Preferably, all of the posterior teeth (the food-masticating teeth) of the dentures are bicuspids. As will presently appear in minute detail, the buccal cusps of the lower bicuspids and the lingual cusps of the upper bicuspids are of sharp pyramidal form, while the lingual cusps of such lower teeth and the buccal cusps of the upper teeth are each formed as a section of a pyramid-a section approximating that which is obtained by dividing a square-base pyramid on a vertical plane extending between its diagonally opposite corners. The pyramidal cusps of each tooth are relatively deep, and provide substantially one-half, and preferably more, of the body of the tooth that extends between the gingival lines represented in the upper and lower plate members of the dentures. Preferably, if not essentially, the apical axes of the pyramidal cusps extend perpendicularly to the occlusal plane of the dentures, and two of the sides or facets of one cusp intersect two of the sides or facets of the companion cusp of the same tooth, and form between the cusps a groove that extends between the mesial and distal faces of the tooth. .The groove is of V- shape in cross section and of inverted V-shape in longitudinal section; the groove in fact consists in two V-shaped' grooves that, extending in common vertical plane, are inclined relatively to one another from the center of the tooth downward to the mesial and distal faces of the tooth.

The cusps of the several lower bicuspids, thus formed, provide between successive teeth pockets of inverted pyramidal form, and such pockets are adapted to receive the lingual cusps of the upper bicuspids. In the same general manner the inclined occlusal surfaces of the upper bicuspids provide pyramidal pockets that are adapted to receive the buccal cusps of the lower bicus pids. By virtue of these features I obtain an abnormally deep interdigitation of the posterior teeth of the upper and lower dentures, and I have found that such deep interdigitation, particularly when combined with certain other refinements described below, insures natural articulation of the mandible, even during mastication of the toughest foods.

It is characteristic of the teeth of the invention, and this may in large measure explain why the desired articulation of the mandible is not de stroyed, that food undergoing mastication is cut and chopped rather than ground between the teeth. The sharp corners or edges of the deeply interdigitated teeth out into and through the food, and mastication is effected by a simple opening and closing movement rather than by a grinding action of the jaws. The deep pointed cusps of the teeth of one denture cut and pierce the food being chewed and enter the complementary sockets formed by and between the teeth of the cooperating denture. Turning to a mechanical analogy: consider the body of a leather gasket or the like seated upon a rigid flange including a dowel-receiving recess, and then visualize how a pointed dowel pin under axially applied pressure will pass through the body of the gasket and enter the recess. Such is a homely example of the manner in which the pyramidal cusps of the teeth of one denture pierce the food being masticated, and enter the sockets formed by the teeth of the opposing denture, so that, even through the food is between the teeth, there is such an interdigitation as will prevent malarticulation. While certain of the stresses of chewing act laterally of the cusps of the teeth, they are minor stresses; the principal or major stresses of chewing react vertically upon the two dentures, and the dentures in their entirety are not subjected to objectionable lateral stresses, as is the case when food is crushed and ground between natural molars, or molars of the sort that have been hitherto embodied in artificial dentures.

Referring to the accompanying drawing, the upper and lower dentures l0 and 20 of a set of artificial teeth are illustrated. Inasmuch as the invention has to do primarily with the posterior teeth of the dentures, I shall pay no particular attention to the usual incisors and cuspids, other than to say they may be of usual form and organization in the dentures. The posterior teeth, it will be noted, are all bicuspids. The lower denture in this case includes five bicuspids 1 on each side, while the upper denture includes four bicuspids 2 on each side. The upper bicuspids are arranged in staggered relation with respect to the lower, so that the cusps of the upper teeth 2 nest between the cusps of successive lower teeth I. (Note Figs. I, III and IV.) The buccal cusp C of each lower bicuspid is of sharply point-- ed pyramidal form, including four sides or facets a, b, c, and (1, while the lingual cusp Cl is of semi-pyramidal form, including two faces orfacets e and f.

It will be understood that the individual teeth may be formed of the usual. materials, m l d and vitrified in known ways. At variance with usual practice, however, the pyramidal cusps of the teeth of my invention are, preferably, brought to ultimate shape or form in a precision grinding operation, with the good effect that the usual glassy finish is removed from the occlusal surfaces of the teeth; minute accuracy is obtained in the shape or form of the cusps, and the corners or edges of the cusps are sharpened to a degree that is unattainable in teeth that are brought substantially to ultimate form in the usual molding and vitrifying operations.

Other than in the particulars described herein, the dentures may be designed and constructed for a patients mouth in accordance with recognized good practice.

The facets a and b of the buccal cusp C of each lower bicuspid meet in a relatively sharp edge at; the facets c and d of cusp C meet in a sharp edge cd; and the facets e and f of the lingual cusp C extending in parallelism with the facets a and b of cusp C, respectively, meet in an edge ef. As viewed in plan (Fig. VII), the three edges ab, cd, and ef are aligned; they extend in the transverse, medial, vertical plane of the tooth, and in such plane the edges ab and ef extend in parallelism, with the edge cd extendingangularly between them. Note Figs. V and VI. It is important to note that the angle between the aligned edges ab and cd is of a value within the range between 60 and 100, and preferably of a value of approximately as shown. The value of the angle between the edges cd and 6 is of the same order. The facets a and d, and b and 0 meet in ridges or edges ad and be, respectively, and such edges of the several bicuspids of the denture extend (as viewed in plan, Fig. VII) in alignment with, or in parallelism with, the ridges (the center line of bite) of the jaws for which the teeth are made. The ridges or edges ad and he need not be sharp, although they may be, as shown. It will also be noted that the facets c and d of the buccal cusp C, and the facets eand f of the lingual cusp C form a groove or valley 3 between the two cusps; such valley, extending between the mesial and distal faces of the tooth, is

of V-shape in transverse or linguo-buccal section (see Fig. V), and of inverted V-shape in longitudinal or mesiodistal section (of. Figs. III and IV). .The two lines ed and cf of intersection of the four facets e, d, c, and 1 that form such valley or groove 3 are aligned (as viewed in plan), and extend in substantial parallelism with the longitudinally aligned edges ad and be already mentioned. As viewed in side elevation (Fig. II), the edges ad and be extend angularly to one another, as do the lines of intersection ed and of of the facets that form groove 3. I have found that the angle between the corners or edges ad and be of the pyramidal cusp should lie within the range specified for the angular relation of the transverse edges ab and cd; that is, between 60 and And the same holds true for the angle of intersection of the two lines ed and cf that form the bottom of the V-shaped valley or groove 3.

The facets c and f of each lower bicuspid cooperate with the facets d and e of the next-succeeding tooth in the lower denture in forming a pocket P of inverted pyramidal form, while the facets b and a form between the successive teeth V-shaped notches N that slope downward and outare formed to fit snugly in said notches formed by the facets b and a of succeeding lower bicuspids. (Cf. Figs; VII and III). The drawing clearly shows the specific form of the cusps of the upper bicuspids 2, and it is needless to dwell at length upon features thatare perfectly intelligible in the illustration. Suffice it to say that the lingual cusps of the upper teeth -2 are the counterparts of the buccal cusps of the lower teeth I, while the buccal cusps of the upper teeth are the counterparts of the lingual cusps of the lower teeth. Each upper bicuspid includes six facets that are complementary in form-and relation to the six facets a to j that form the occlusal surface of each lower bicuspid. The cusps of two adjacent lower teeth form a pyramidal pocket and a half-pyramidal pocket or notch that are adapted severally to receive the pyramidal lingual cusp C and the half-pyramidal buccal cusp C of the opposite upper tooth. In like manner the aligned upper teeth form pockets and notches that receive the cusps of the lower teeth.

As indicated by the broken line A in Fig. I, the occlusal plane of the dentures will be understood to lie midway between the upper and lower plates I and 20, and in further describing the teeth of this invention it may be noted that the vertical or apical axes of the pyramidal cusps of the osterior teeth I and 2 extend normal to such plane. Characteristically, the pyramidal cusps of each lower bicuspid 5 form over one-half of the body of the tooth that extends above the gingival ridge or gum line represented in the lower plate or denture, as at a. As shown in this case such cusps may form substantially the entire body of the tooth above'such gum line. Similarly, the cusps of the upper teeth 2 form over one-half of the bodies of the teeth extending below the gum line represented in the upper plate or denture, as at Ma. Whereas in the usual artificial teeth, and in anatomical teeth, the mesial and distal marginal ridges of the teeth lie at a substantial interval above the gum line, in the teeth of this invention such marginal ridges of the teeth are in effect deleted. The inclined facets of the pyramidal cusps extend to, or almost to, the gum line.

The interdigitation of the posterior teeth of my dentures is so deep that the pyramidal cusps extend (with the dentures in closed position) through over one-half of the vertical interval, and preferably through substantially the entire vertical interval, between the gum lines 18a and 20a. Note Fig. I. The cusps of the teeth I on the lower plate extend over half way to the line or ridge lilo of the upper plate, and the cusps of the upper teeth 2 extend through substantially the entire interval between the lines or ridges Illa and 21m. By virtue of such form and organization of the bicuspids I and 2, I obtain advantages of the nature indicated.

The high pyramidal cusps that afford the desired deep interdigitation of the teeth, insure proper dental registration as the teeth close upon and cut (as distinguished from crushing and grinding) the food. This inhibits such tendency 'as exists for the condyles to move into unnatural positions, and insures normal articulation of the mandible during the food mastication. The sharp-edged pyramidal cusps readily out and chop the food, and simplify and improve mastication.

While I have said that all of the posterior teeth of the dentures are biscupids, I have this qualification to note: At Variance with the showing in Figs. I and II, the last tooth VI in the line of biscuspids on each side of the lower denture 20 need include only the facets b, c, and f. The facets a, d, and e lie to the rear of the last bicuspid in the upper denture and in no Way affect the interdigitation of the teeth, and thus such facets may be eliminated, leaving the top of the tooth, to rear of facets b, c and 1, Smooth and round-edged.

The particular embodiment of my novel features of tooth construction in bicuspids, and the particular organization of the bicuspids described, afford advantages that could not be enjoyed if such features were incorporated in teeth made in the form of molars. However, it will be clear to those skilled in the art that several of the above-described features will prove valuable in teeth other than bicuspids, and within the terms of certain of the appended claims such modifications are held in contemplation.

The application for this patent comprised acontinuation in part of application Serial No. 255,081, filed by me February '7, 1939.

I claim as my invention:

1. A set of artificial teeth including upper and lower dentures whose posterior teeth each include a sharp-edged pyramidal cusp that stands substantially normal to the occlusal plane of the dentures and forms over one-half the body of the tooth above the gum line represented in the plate member of the denture that carries the tooth, two of the diagonally opposite edges of such pyramidal cusp extending angularly to each other between the mesial and distal faces of such tooth, the cusps of successive teeth in the lower denture forming pyramidal pockets arranged to receive the pyramidal cusps of successive teeth in the upper denture in an interdigitation that is effective through an interval exceeding one-half of the vertical interval between the gum lines represented in the plate members of the upper and lower denturesin closed position.

2. An artificial denture whose posteriorteeth consist in two rows of bicuspids, the two cusps of each tooth being in substantially right pyramidal form, with the axes of the pyramids substantially parallel to the axis of the tooth, the two cusps on each tooth being aligned between the buccal and lingual sides of the tooth, such cusps forming between successive teeth in said rows pyramidal pockets, and V-shaped notches that extend downward between the teeth, the depth of said pockets exceeding one-half the extent of the teeth above the gum line represented in the plate member of said denture.

3. A tooth for use in an artificial denture consisting in a bicuspid whose cusps are of a fiatfaceted, right pyramidal form, with the axes of the cusps substantially parallel to the axis of the tooth, one of said cusps comprising a foursided pyramid, two of the diagonally opposite edges of said cusp extending angularly to one another in aplane that extends between the mesial and distal faces of the tooth, and the other two of the diagonally opposite edges of such cusp extending angularly to one another in a plane that extends between the buccal and lingual sides of the tooth.

4. A tooth for use in artificial dentures consisting in a bicuspid whose cusps are of flat-- faceted right pyramidal form, with the axes of the cusps substantially parallel to the axis of the tooth, two of the facets of one cusps form ing with two of the facets of the other cusp a groove that is of V-shape in linguo-buccal section and of inverted V-shape in mesio-distal section.

5. A set of artificial teeth including upper and lower dentures whose posterior teeth consist of bicuspids, the buccal cusp of each of such teeth in the lower denture being in the form of a right pyramid whose axis is substantially normal to the acclusal plane of the dentures and the lingual cusp being shaped to provide between the two cusps a groove that is of V-shape in linguo-buccal section and of inverted V-shape in mesiodistal section, said buccal and lingual cusps forming over one-half of the body of the tooth above the gum line represented in the teeth-carrying plate of said lower denture, a plurality of pockets formed by and between the buccal and lingual cusps of the several posterior teeth in said lower denture, said pockets including each a plurality of facets inclined in downward convergent relation, the buccal cusps forming between successive teeth, on the buccal sides of such lower denture, notches of V-shaped cross section; the lingual cusps of the bicuspids in said upper denture being complementary in form and relation to said pockets in the lower denture, and the buccal cusps of such upper bicuspids being complementary in form and relation to said notches, with the consequence that the interdigitation of said upper and lower bicuspids is efiective through over one-half the vertical interval between the gum lines represented in the teeth-carrying plates of the dentures.

6. A tooth for use in artificial dentures consisting in a bicuspid whose cusps are of pyramidal form, one cusp comprising a four-sided right pyramid whose axis is substantially parallel to the vertical axis of the tooth and whose diagonally opposite edges extend from the apex of the pyramid angularly to one another, the value of such angle being between and two of the sides of said four-sided cusp forming with its companion cusp a groove that is V-shaped in cross section and that extends longitudinally from the mesial to the distal face of the tooth and is of inverted V-shape in mesio-distal section.

RUDOLF KLICKA.

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