US2417965A - Artificial tooth - Google Patents

Description

March 25, 1947.

M. BERESINI ARTIFICIAL TOOTH File d May 18, 1942 2 Sheets-Sheet l INVENTOR MORRIS BERESIN ATTCRNEYS March 25, 1947. M BERE5|N 2,417,965

ARTIFICIAL TOOTH Filed May 18, 1942 2 Sheets-Sheet 2 R O T N E V m MORRIS BERESIN A'ITORNEYS Patented Mar. 25, 1947 UNITED STATES PATENT OFFICE ARTIFICIAL TOOTH Morris Beresin, Philadelphia, Pa.

Application May 18, 1942, Serial No. 443,447

Claims.

This invention relates to artificial teeth, and has particular reference to full dentures and to posterior teeth especially adapted for use in such dentures.

At the very outset, it should be stated that there are two general types of artificial teeth. The first type is the anatomic, which is so-called because the teeth are designed to simulate natural teeth not only in non-functional and esthetic features as shape, form and general contour but also in configuration of the occlusal or masticating surfaces. The second type is the non-anatomic or mechanical teeth, which do not simulate natural teeth, but which are intended to function more effectively than artificial teeth of the anatomic type. The present invention concerns itself particularly with artificial teeth of the nonanatomic or mechanical type.

At first blush, it would appear that artificial teeth should simulate natural teeth as much as possible. However, as will be hereinafter pointed out, artificial teeth do not function in quite the same manner as do natural teeth, and the very features that make for maximum comfort and eflectiveness in a mouth containing natural teeth produce discomfort and may even result in serious damage when embodied in an artificial denture. For this reason, many attempts have been made with more or less success to devise a form of artificial teeth that would function as well in the mouth as do the teeth given us by nature.

The reason that natural teeth function as they do is that the occlusal or masticating surfaces of the posterior teeth are provided with external cusps having inclined planes. These planes serve a two-fold purpose. First, they maintain the proper vertical dimension, 1. e. the maxillo-mandibular relationship. Second, the inclined planes assist in guiding the movementsof th mandible or lower jaw in its masticatory movements. In addition to the external cusps, the occlusal surfaces are provided with grooves and fossas. These serve to cut, mash and grind the food during the masticatory process. The form, shape and contour of the natural teeth as well as the grooves, fossas and cusp inclines of the occlusal surfaces vary with the individual and are the result of the growth and development of the entire masticatory apparatus.

The mandible or lower jaw has several principal movements during mastication. It moves up and down, and in addition has two grinding movements, namely, from side to side (lateral), and back and forth (retrusive and protrusive). The mandible also has what are known as intermediary movements. As has been stated, the inclined planes of the cusps assist in guidin the mandible in its several movements. In normal natural dentition, each tooth is individually embedded in bone, and the forces of mastication are absorbed by each tooth separately. Hence, movements of the mandible in any or all directions do not ordinarily cause any unbalanced condition or disturbance in the oral cavity.

Artificial teeth, instead of being individually embedded in bone, are fixed as a unit to a denture base, which rests on the soft tissue covering the alveolar bone. In the case of a fully edentulous mouth, there are twenty-eight teeth carried by two bases, each one of which acts as a unit. Hence, pressure applied at one point affects the entire denture base, in contradistinction to a mouth of natural teeth wherein pressure at one point is absorbed by the particular tooth involved. If during mandibular excursion, there is unbalanced porcelain contact, tilting or teetering of the denture inevitably results. It follows, therefore, that external cusps, which are so essential in natural teeth, are undesirable in artificial teeth. For they cause interference and interlocking between the upper and lower dentures, resulting in instability and eventual damage to the underlying structure. Y It should also be noted that due to the fact that natural teeth are individually and firmly embedded in the alveolar bone, they are capable of exerting much greater force during the mastication process than are artificial teeth. This is another factor that must be taken into consideration when devising an artificial denture.

The following are the principal problems in designing artificial teeth:

1. To so shape the occlusal or masticating surfaces of the posterior teeth and to arrange them on the denture base in such manner as to insure multiple tooth contact during all the normal horizontal movements of the mandible, thereby providing the maximum of balance and stability;

2. To eliminate interference and interlocking of the dentures within the normal mandibular range; and

3. To obtain the greatest cutting, grinding and mashing capacity possible with the limited transmission of force available in the case of artificial dentures.

In practicing the teachings of the present invention, I provide posterior teeth, the occlusal or masticating surfaces of which conform to a portion of the surface of a sphere having a radius between three and a half and four inches. The

occlusal surface of each upper tooth is spherically convex, buccolingually and mesiodistally in conformity with the designated sphere, and the occlusal surface of each lower tooth is spherically concave, buccolingually and mesiodistally in conformity with the same sphere. Hence, the posterior teeth may be readily set up on the ridge of the denture base so that the occlusal surfaces of all the posterior teeth are on the surface of the same sphere and so that the plane of occlusion is substantially at right angles to the direction of stress. As a natural consequence, the two dentures when in contact maintain each other in a stable position, and the two dentures may move freely and harmoniously over each other in accordance with mandibular movement without interlocking or tilting. The occlusal surfaces of the two dentures will always be in contact during said movement, thereby eliminating any tendency of the dentures to tilt.

, At this point, I may state that I am aware that it has been proposed to arrange artificial teeth of conventional form so that their occlusal surfaces will conform to a sphere. This can be done only imperfectly and with great difficulty. Usually, part of the occlusal surfaces of the teeth have to be ground or cut away in order to produce the required spherical congruency. This necessarily mutilates the external cusps, which, as has been indicated, perform certain very important functions in the masticatory process.

An essential feature of the present invention consists in providing the spherical occlusal surfaces with what may best be termed internal cusps. These cusps, which may advantageously be frusto-conical in shape are surrounded by a peripheral rim separated from the cusps by a groove or channel. By means of this construction, the conventional external cusps, grooves and fossas are entirely eliminated, thereby also eliminating cuspal interference and interlocking.

It is important to note that the upper surfaces of the peripheral rim and of the internal cusps are on the surface of the designated sphere, while the floor of the groove or channel is below this surface. It is also important to note that the occlusal surfaces of the teeth are preformed to provide the rims, cusps and, grooves, so that the teeth may be readily set on the crest of the ridge of the denture base with their occlusal surfaces on the surface of the same sphere, and with the plane of occlusion at right angles to the direction of stress, thereby eliminating any necessity for grinding the occlusal surfaces.

In the preferred form of the invention, each of the bicuspids is provided with a single internal cusp, and the first molars are each provided with two cusps. The second molars may also be provided with two cusps each, unless means are provided to control the mandibular movements. In such case, each second molar is provided with but a single cusp, the rest of the space being taken up by a projection or cooperating recess depending upon whether the molar is an upper or lower.

The internal cusps serve to mash or grind the food, while the peripheral rim assists in cutting the food. The rim may for this reason be provided with fairly sharp edges. The rim may also be provided with a sluiceway on the lingual side to permit the escape of food from the groove or channel between the cusps and the peripheral rim. In the case of the molars, a second sluiceway may also be provided on the buccal side for the same purpose.

In the preferred form of the invention, the occlusal surface of the lower teeth is about twothirds of the occlusal surface of the upper teeth buccolingually. In this manner, the area of contact on the lower denture is considerably decreased, With a resultant preservation of the bone of the alveolar ridge.

The posterior teeth are set on the crest of the ridge of the denture with their long axes converging to the center of the designated sphere so that the occlusal surfaces of all the upper posterior teeth as a unit conform to the surface of the designated sphere and all of the lower teeth do likewise. In the case of each denture, the plane of occlusion is substantially at right angles to the direction of stress. As has been stated, the fact that the occlusal surfaces of all the posterior teeth conform to the surface of the designated sphere eliminates any tendency for either denture to tilt.

The arrangement of the posterior teeth as stated and the proportioning of the buccolingual dimensions of the upper and lower dentures tend to throw the masticatory forces to the inside of the ridge of the denture or on the lingual portion of the occlusal surface. This fact renders it possible to design the buccal portions of the dentures to simulate natural teeth without decreasing their effectiveness. This is a very important consideration for esthetic reasons. It should be noted that also for esthetic reasons the anterior teeth preferably do not conform to the designated sphere, and they may be of conventional construction. In order to avoid interference, the upper anterior teeth may be arranged to provide an over-bite or over-jet.

As thus far described, the teeth of my invention have many important advantages over artificial dentures of the prior art. In order to obtain additional advantages, I may provide the second molars with means to secure greater control of the mandibular movements. As has been previously stated, in the case of natural teeth the inclined planes of the external cusps assist in guiding the movements of the mandible. When cuspless mechanical teeth are used, the wearer has a decided tendency to make exaggerated, extensive and unnecessary movements of the lower jaw. By providing the second molar on each side of the lower denture with a projection or protuberance, and the second molar on each side of the upper denture with a recess to receive the projection or protuberance, sufficient control of mandibular movements is provided for practically all purposes. By properly proportioning the projection and recess, this desirable result can be accomplished without any interference or interlocking between the dentures.

Brief reference will now be made to the drawings forming part of the application.

Figure 1 is a plan view of an upper denture, which constitutes one embodiment of the invention;

Figure 2 is a plan view of the lower denture corresponding to the upper denture of Figure 1;

Figure 3 is a side elevation of the two dentures of Figures 1 and 2, the dentures being shown separated vertically;

Figure 4 is a side elevation of the two dentures of Figures 1 and 2, said dentures being shown in occluded relationship;

Figure 5 is a cross-sectional view taken on line 5-5 of Figure 3.

Figure 6A is a plan view of one of the molars of the upper denture (Figure 1) Figure 6B is a cross-section along line BB of Figure 6A;

Figure 6C is a cross-section taken along line CC of Figure 6A;

Figure 7A is a plan view of one of the molar of the lower denture (Figure 2) Figure 7B is a cross-sectional view along line BB of Figure 7A;

Figure 7C is a cross-section taken along line CC of Figure 7A;

Figure 8A is a plan view of one of the bicuspids of the upper denture;

Figure 8B is a cross-section taken along line BB of Figure 8A;

Figure 8C is a view in cross-section along line CC of Figure 8A;

Figure 9A is a plan view of one of, the bicuspids of the lower denture;

Figure 9B is a cross-section taken along line BB of Figure 9A;

Figure 9C is a cross-section on the line CC of Figure 9A;

Figure 10 is a cross-section taken buccolingually through an upper and lower molar in occlusal relationship;

Figure 11 is a similar section through an upper and lower bicuspid in occlusal relationship;

Figure 12 is a cross-section taken mesiodistally through two dentures in occlusalrel ationship and showing the first molars and second bicuspids;

Figure 13 is a plan view of an upper denture provided with means to control mandibular movement;

' Figure 14 is a plan view of a lower denture corresponding to the upper denture of Figure 13;

Figure 15 is a side view of the two dentures of Figures 13 and 14, the dentures being shown separated vertically;

Figure 16A is a plan view of one of the second upper molars of Figure 15;

Figure 163 is -a cross-sectional view taken on line BB of Figure 16A;

Figure 160 is a cross-section taken on line CC of Figure 16A;

Figure 17A is a plan view of one of the lower second molars of Figure 15;

Figure 173 is a cross-section taken along line BB of Figure 17A;

Figure 170 is a view in cross-section taken along line CC of Figure 17A; and

Figure 18 is a cross-sectional view taken mesiodistally through the upper and lower second molars in occlusal relation.

Referring with greater particularity to Figures 1 to 5 inclusive, the reference numeral I designates the upper denture and the numeral 2 denotes the lower denture of a full set of artificial teeth. The anterior teeth of the upper denture are indicated by l, 2, 3, 4, 5 and 6 and the corresponding teeth of the lower denture are desi nated by la, 2a, 3a, 4a, 5a and 6a. As previously stated, the anterior teeth may be of conventional form and construction and for esthetic reasons their occlusal surfaces preferably do not conform to the designated sphere. As indicated in Figures 3 and 4, the upper anterior teeth may advantageously be arranged with reference to the lower anterior teeth to provide an over-bit or over-jet.

In the upper denture, the bicuspids are denoted by the numerals I, 8, I and 8, and the molars are designated by 9, l0, 9' and III. In the lower denture, the bicuspids are indicated by Ia, 8a, Va and. 8'11, and the molars by 9a, Illa, 9'0 and l0'a.

As has been stated, the occlusal surface of each upper posterior tooth is spherically convex both buccolingually and mesiodistally in conformity with the surface of a designated sphere, and the occlusal surface of each lower posterior tooth is spherically concave both buccolingually and mesiodistally in conformity with the surface of the same sphere. This spherical congruency is shown clearly in Figures 3, 4 and 5. Figure 5 is taken at right angles to Figures 3 and 4. and the radius B" of Figure 5 is the same dimension as radius A" of Figures 3 and 4. It will be understood from these figures of the drawing that the occlusal surfaces of the posterior teeth of each denture are on the surface of the designated sphere both individually and as a unit. Furthermore, as was previously stated, the posterior teeth are set on the crest of the ridge with their long axes converging to the center of the sphere and with the occlusal plane substantially at right angles to the direction of stress.

The essential details of the second molar l0 of the upper denture are shown in Figures 6A, 6B

and 6C, and the essential features of the corresponding molar l0'a of the lower denture are shown in Figures 7A, 7B and 70.

Referring to Figures 6A, 6B and 60, it will be seen that the upper portion of the molar is provided with a peripheral rim l I, two frusto-conical internal cusps l2 and I3, and a groove or channel Id separating the cusps from the peripheral rim. As has been stated, the upper surfaces of the peripheral rim H and of the internal cusps l2 and I3 are on the surface of the designated sphere, while the floor of the groove or channel M is below this surface. This is clearly shown by means of radius A" and "radius B in Figures 63 and 6C. As shown in Figure 6A, the two cusps l2 and I3 are arranged diagonally, the mesial cusp I2 being nearer to the buccal face of the tooth and the distal cusp 13 being nearer to the lingual. As also shown in Figure 6A, two sluiceways l5 and I6 may be provided in the peripheral rim, one on the buccal side and the other on the lingual side.

Referring to Figures 7A, 7B and 70, wherein are shown the essential features of the lower molar corresponding to the upper molar of Figures 6A, 6B and 60, it will be noted that the upper portion of the tooth is provided with the peripheral rim [6, two frusto-conical internal cusps l1 and I8, and a groove or channel is separating the cusps from the peripheral rim and from each other. As in the case of the upper molar, the upper surfaces of the peripheral rim l6 and of the internal cusps are on the surface of the designated sphere, while the fioor of the groove or channel I9 is below this surface. The two cusps are arranged in line with each other on the arch of the denture instead of diagonally as in the upper molar. A sluiceway 20 is provided on the lingual side of the tooth.

It is important to note that the occlusal surface of the lower molar is about two-thirds of the occlusal surface of the upper molar buccolingually. The upper buccal portion of the tooth l0a may be curved as shown at 2|, to provide for the smaller buccolingual dimension. It is also important to note that the occlusal surface of the upper molars is spherically convex, while the occlusal surface of the lower molars is spherically concave.

The first molars of both the upper and lower dentures differ from the second molars merely in being somewhat large mesiodistally.

The essential details of the bicuspids are illustrated in Figures 8A, 8B, 8C, and 9A, 9B, 90, the

first set of figures showing an upper bicuspid and the second set of figures showing the corresponding lower bicuspid.

Referring to Figures 8A, 8B and 8C, wherein is illustrated the upper bicuspid 8', it will be seen that the upper bicuspids are each provided at its upper portion with a peripheral rim 22, a single -frusto-conical internal cusp 23, and a groove or channel 24 separating the cusp from the rim. The upper surfaces of the peripheral rim 22 and of the internal cusp 23 are on the surface of the designated sphere, while the floor of the groove or channel 24 is below this surface. A sluiceway 25 is preferably provided on the lingual side of the rim.

One of the lower bicuspids is shown in Figures 9A, 9B and 9C. The tooth is designated by the reference character lla, and as illustrated, is provided at its upper portion with the peripheral rim 26, a single frusto-conical internal cusp 21, and a groove r channel28 separating the cusp from the rim. As in the case of the previously described teeth, the upper surfaces of the peripheral rim and of the internal cusp are on the surface of the designated sphere both buccolingually and mesiodistally, while the floor of the groove or channel is below this surface. The numeral 29 indicates a sluiceway in the rim, which is preferably provided on the lingual side.

It is to be noted that as in the case of the molars, the occlusal surfaces of the upper bicuspids are spherically convex, while the occlusal surfacesof the lower bicuspids are spherically concave; also that the occlusal surfaces of the lower bicuspids are about two-thirds of the occlusal surfaces of the upper bicuspids buccolingually. To provide for this difference in dimension, the upper buccal portions of the lower bicuspids are curved lingually as indicated at 30.

Figure is, as has been stated, a cross-section taken buccolingually through an upper and lower molar in occlusal relationship, and Figure 11 is a similar view through an upper and lower bicuspid. The same reference numerals are used -asinFigures7,8and9.

Figure 12 is a cross-section taken mesiodistally through two dentures in occlusal relationship and showing the first molars and second bicuspids. The upper molar and bicuspid are designated as 9' and I respectively, and the lower molar and bicuspid are indicated by 9'a and 8'a respectively. The peripheral rim on the upper molar is denoted by l I and the rim on the lower molar by '11. The peripheral rims on the upper and lower bicuspids are indicated by 22 and 26 respectively. The internal cusps on the upper molar are l2 and I3, and those on the lower molar are' I1 and I8 respectively. The internal cusps on the upper and lower bicuspids are denoted by 23 and 27 respectively.

It is important to note that in Figures 10, 11 and 12 the occlusal surfaces of the molars and bicuspids are shown as being on the surface of the designated sphere both buccolingually and mesiodistally. As clearly indicated in Figures 3, 4 and 5 the occlusal surfaces of the molars and bicuspids are on said sphere both individually and as a unit. Hence, the occlusal surfaces of the right molars and bicuspids are on the same sphere as the left molars and bicuspids. It is also to be noted that the upper posterior teeth are spherically convex, while the lower posterior teeth are spherically concave.

Reference will now be made to Figures 13 and 14, which differ from Figures 1 and 2 in that the dentures 3| and 32 are provided with means to secure better control of the mandibular movements. The means to be described are embodied in the second molars 33 and 33' of the upper denture and the second molars 34 and 34' of the lower denture. The other teeth of both dentures are exactly the same as in Figures 1 and 2, and hence need not be described.

The details of the upper second molars are shown in Figures 16A, 16B and 16C, the illustrated molar being designated by 33'. The molar is provided on its occlusal surface with a peripheral rim 35, an internal cusp 38 and a recess 39, the cusp being nearer the mesial portion and the recess nearer the distal portion. The numeral 40 is a groove or channel separating the cusp from the recess and the rim. The numerals 38 and 31 designate two sluiceways provided in the buccal and lingual sides of the rim.

The details of the lower second molars are shown in Figures 17A, 17B and 17C. .The illustrated molar is denoted by 34, and is shown as being provided on its occlusal surface with a peripheral rim 42, an internal cusp 43 and a protuberance or projection 44. The cusp is nearer the mesial portion of the tooth and the protuberwoe is nearer the distal portion. A groove or channel 45 separates the cusp and protuberance from the peripheral rim. Slulceways l6 and 41 may be provided on the buccal and lingual sides of the rim. I

It is to be noted that the upper surface of the peripheral rim 35 and of the internal cusps of the tooth 33' are on the surface of the designated sphere, while the floor of the groove or channel 40 and of the recess 39 are below this surface. It is also to be noted that in the case of the tooth 34, the upper surfaces of the rim 42 and of the internal cusp 43 are on the surface of the designated sphere, that the floor of the groove or channel is below the surface of the sphere, and

that the protuberance or projection extends be-' yond the surface of the sphere. It is also to be noted that the occlusal surface of the upper tooth 33' is spherically convex both buccolingually and mesiodistally, while the occlusal surface of the lower tooth M is spherically concave both buccolingually and mesiodistally,

As shown in Figure 18, the projection or-protuberance 44 is intendedto fit into the recess 39 when the two dentures are in contact. The relative proportions of the protuberance and recess are such that the protuberance fits loosely and freelyin the recess when the dentures are in contact and permits all the normal masticatory movements without any interference or interlocking, but prevents the exaggerated, extensive and unnecessary movements that are characteristic of mouths fitted with cuspless teeth,

It is thought to be clear from the foregoing disclosure that I have provided an entirely new form of non-anatomic or mechanical teeth having many advantages over artificial teeth of the prior art. It is to be particularly noted that the teeth of the invention are of relatively simple and very sturdy and rugged construction, may be manufactured inexpensively on a large commercial scale from the usual dental materials, and may be adapted to the mouths of individual patients without any radical change in dental technique.

Terms such as anterior," posterior, buccal, "lingual," "mesial, "distal," occlusal, etc., are used with the same meanings as in the dental art. The 'term upper surface refers to the surface of the tooth or denture which is uppermost when the tooth or denture is disposed with its occlusal surface uppermost.

I claim:

1. An artificial posterior tooth, the occlusal portion of said tooth being provided with a peripheral rim, an internal cusp and a protuberance, said cusp and protuberance being separated from each other and from said rim by a channel, the upper surface of both the peripheral rim and the internal cusp being on the surface of a sphere both buccolingually and mesiodistally and said protuberance extending beyond the surface of said sphere.

2. An artificial tooth, the occlusal portion of an internal cusp and a recess, said internal cusp and recess being separated from each other and from said rim by a channel, the upper surfaces of both the peripheral rim and said internal cusp being on'the surface of a sphere both buccolingually and mesiodistally.

3. A full set of artificial dentures, both the upper and lower dentures consisting of anterior and posterior teeth, the posterior teeth of which are each formed on their occlusal portions with a peripheral rim and a frusto-conical internal cusp, the internal cusp being separated from the rim by a V-shaped channel, the upper surfaces of all the peripheral rims and the internal cusps of the denture being on the surface of a sphere both buccolingually and mesiodistally, the occlusal surfaces of the posterior teeth of the upper denture being spherically convex and the occlusal surfaces of the posterior teeth of the lower denture being spherically concave, the occlusal surfaces of the upper and lower posterior teeth being congruent, the upper second molars and the lower second molars being provided with cooperating means to control mandibular movement.

4. A full set of artificial dentures, both the upper and lower dentures consisting of anterior and posterior teeth, the posterior teeth of which are each formed on their occlusal portions with a peripheral rim and a frusto-conical internal cusp, the internal cusp being separated from the rim by a V-shaped channel, the upper surfaces of all the peripheral rims and the internal cusps of 10 the denture being on the surface of a sphere both buccolingually and mesiodistally, the occlusal surfaces of the posterior teeth of the upper denture being spherically convex and the occlusal surfaces of the posterior teeth of the lower denture being spherically concave, the occlusal surfaces of the upper and lower posterior teeth being congruent, the upper second molars being each provided with a recess and the lower second molars being each provided with a projection, each of said projections being adapted to be received in the corresponding recess. 7 Y

5. A full set of artificial dentures, both the upper and lower dentures consisting of anterior and posterior teeth, the posterior teeth of which are each formed on their occlusal portions with a peripheral rim and a frusto-conical internal cusp, the internal cusp being separated from the rim by a V-shaped channel, the upper surfaces of all the peripheral rims and the internal cusps of the denture being on the surface of a sphere both buccolingually and mesiodistally, the occlusal surfaces of the posterior teeth of the upper denture being spherically convex and the occlusal surfaces of the posterior teeth of the lower denture being spherically concave, the occlusal surfaces of the upper and lower posterior teeth being congruent, the buccolingual dimension of the occlusal surfaces of the posterior teeth of the lower denture being about two-thirds of the corresponding dimension of the occlusal surfaces of the posterior teeth of the upper denture.

MORRIS BERESIN.

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

UNITED STATES PATENTS OTHER REFERENCES.

Maxwell, George H., Contact occluding Number Sphere, copyright 1934, pages 2-6, 4-3, and Figures 23-4 and 25-4.

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