US3638309A

US3638309A - Artificial denture

Info

Publication number: US3638309A
Application number: US6904A
Authority: US
Inventors: John P Frush
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-01-29
Filing date: 1970-01-29
Publication date: 1972-02-01
Anticipated expiration: 1989-02-01

Abstract

A denture is constructed with molars in a first denture base having flat chewing surfaces in a common plane. Elongated ridges on opposing molars in a second denture base provide a biting edge which makes continuous linear contact in centric occlusion with the flat surfaces in the same common plane. The plane passes through upper portions of the retromolar pads and the incisal edges of the central incisors, and is also substantially parallel to a line passing through the hamular notches. Parallel transverse ridges on the upper first or second bicuspids engage the lower posterior biting edge in protrusive movement to keep the denture bases seated.

Description

United States Patent Feb. 1, 1972 Frush [54] ARTIFICIAL DENTURE [72] Inventor: John P. Frush, 704 Highland Drive,

Pasadena, Calif. 91 108 [22] Filed: Jan. 29, 1970 [2|] Appl. No.: 6,904

[52] US. Cl ..32/2 [5 1] Int. Cl r ..A6lc 13/00 [58] Field of Search ..32/8, 2

[56] References Cited UNITED STATES PATENTS 2,669,021 2/1954 Bader ..32/2 2,617,192 11/1952 Goddard... ...32/2

Beresin Primary Examiner-Robert Peshock Attorney-Christie, Parker & Hale [57] ABSTRACT A denture is constructed with molars in a first denture base having flat chewing surfaces in a common plane. Elongated ridges on opposing molars in a second denture base provide a biting edge which makes continuous linear contact in centric occlusion with the flat surfaces in the same common plane. The plane passes through upper portions of the retromolar pads and the incisal edges of the central incisors, and is also substantially parallel to a line passing through the hamular notches. Parallel transverse ridges on the upper first or second bicuspids engage the lower posterior biting edge in protrusive movement to keep the denture bases seated.

16 Claims, 5 Drawing Figures PATENTEU H51 1972 I 3338.309

SHEET 1 BF 2 INVENTOR. JOHN P, FRUSH Maw/M A TTORNE V5 ARTIFICIAL DENTURE This invention relates to dentures made with artificial teeth.

Many of the prior art dentures use artificial teeth made to approximate the sizes and shape of natural teeth, and they are somewhat difficult to shape and form. More important, the irregular masticating or crushing surfaces of the prior art teeth present valleys or troughs which are engaged by projections from the crushing surfaces of opposing teeth, and cause locking or bumping of the teeth or dentures. These irregularities in the opposing surfaces of the teeth create cusp rise or occlusal deflections which tend to shift the dentures on the ridges of the patients mouth during mastication or sliding movements of the mandible. This makes the denture uncomfortable and unsatisfactory for efficient crushing of food. In addition, many of the prior art teeth are shaped so that perfect mounting must be achieved to obtain proper crushing. The prior art teeth also require fairly high biting pressures to achieve the desired cutting and crushing effect in chewing. For these reasons, the artificial teeth of the prior art, even when accurately positioned relative to the other teeth in the mouth, cannot prevent undesirable pressure from being transmitted through the teeth to the gums and causing sore spots and sensitive areas which are painful to the patient. People are also prevented from having a normal variety of food which requires these pressures for mastication.

The chewing or crushing motion in a human being is a fairly complex movement about three mutually perpendicular axes, plus a fourth axis parallel to one of the three. The lower jaw or mandible can move up and down about a horizontal axis which extends from left to right approximately through the condyles of the lower jaw. The mandible can pivot about either a right or a left sagittal (fore and aft) axis which extends horizontally through each condyle of the lower jaw. The mandible can also move laterally around a vertical axis which extends vertically through the condyle. When the mandible shifts laterally, the side moving inwardly drops slightly about the sagittal axis on the opposite side, and the side moving outwardly drops slightly, or not at all. This type of movement makes it difficult for a patient wearing prior art dentures to maintain uniform chewing or cutting contact between the teeth without irritating movement of the dentures and without a degree of discomfort. This invention provides in its preferred form opposing teeth with linear or blade contact to modify this movement about the sagittal axis and to provide less interference in the contacting surfaces when the mandible moves away from center position.

Briefly, this invention provides an improved prosthodontic masticatory system for endentulous patients. A lower denture base rests on the gum tissue overlying the mandible of the patient. An upper denture base bears against the gum tissue covering the maxilla (upper jaw bone) of the patient. One of the denture bases includes at least one elongated portion having a flat surface facing the other denture. The flat surface extends over an area substantially corresponding to that previously covered by at least the first and second adjacent natural molars of the patient. The other denture base includes an elongated ridge which extends for a distance at least equal to that previously covered by the span between the mesial edge of the first molar and the distal edge of the adjacent second molar. The ridge projects toward the flat surface to form a biting edge which lies in substantially the same plane as the flat surface when the denture bases are held in centric contact.

Preferably, the upper denture includes a pair of flat surfaces lying in a common plane. Each flat surface covers an area corresponding to at least the first and second upper molars on each side of the patients mouth. The lower base carries a pair of laterally spaced ridges each of which is adapted to bear against a respective flat surface on the upper denture base.

Preferably, the common plane in which the biting edges bear against the flat surface when the dentures are held in centric contact passes through upper portions of the retromolar pads in the patients mouth and through the incisal edges of the upper central incisors mounted in the upper denture base. The common plane is preferably parallel to the transverse axis of the temperomandibular joints of the patient. This axis is difficult to determine in a patient, but a close approximation is made by having the plane substantially parallel to a line passing through the hamular notches in the patients mouth.

To prevent the denture bases from tending to becomes unseated when the patient slides his mandible forward in a protrusive position, a transverse ridge is provided on each of the first or second bicuspids in the upper denture base which also includes the flat surfaces. Thus, as the mandible slides forward, the biting edge opposing the flat surfaces tends to slide across the transverse ridges on the bicuspids. This keeps the anterior teeth from contacting and tending to pivot the dentures inwardly about axes passing through the anterior ridges of the mandible and the maxilla. To facilitate this function, the incisal edges of the lower anterior teeth are spaced slightly below the plane of contact between the biting edges and flat surfaces so that the upper and lower anterior teeth do not intercept when the mandible is moved toward the protrusive position.

These and other aspects of the invention will be more fully understood from the following detailed description and the accompanying drawings in which:

FIG. I is a schematic side elevation showing the masticatory system of this invention mounted in the patients mouth;

FIG. 2 is a view taken on line 2-2 of FIG. 1;

FIG. 3 is a schematic side elevation of the dentures with the mandible in the protrusive position;

FIG. 4 is a view taken on line 4-4 of FIG. 1; and

FIG. 5 is a perspective view of the lower denture made in accordance with this invention.

Referring to FIG. 1, the prosthodontic masticatory system 10 of this invention includes a lower denture base 11 adapted to fit over and rest on the mandibular ridge 12. An upper denture base 14 is adapted to seat on and bear against the maxillary ridge 16. Each base is made of conventional denture plastics and is generally horseshoe shaped in plan view as shown best for the lower base in FIG. 5. Each base also includes a generally U-shaped groove 18 (FIG. 2) opening away from the opposing denture base so as to seat on and grip the mandibulary or maxillary ridge.

Referringto FIGS. 1 and 5, the lower denture includes the following artificial teeth mounted in and projecting upwardly from the upper surface of the lower denture base:

Right and left lower central incisors 20, right and left lower lateral incisors 21, right and left lower cuspids 22, right and left lower first bicuspids 23, right and left lower second bicuspids 24, right and left lower first molars 2S, and right and left lower second molars 26. The six anterior artificial teeth in each denture are shaped and colored to appear like natural teeth. The eight posterior teeth are colored and generally shaped like natural teeth except for the occlusal surfaces 28 (FIG. 2). The buccal edge of each lower posterior tooth carries a longitudinally and upwardly extending ridge 29 which terminates in a relatively sharp biting edge 30. Preferably, the right lower posterior teeth are cast form plastic or the like in an integral block which is shaped to look like four separate teeth. The same is true for the four posterior teeth on the left side of the lower denture. Preferably, each biting edge 30 for each of the sets of four posterior teeth is continuous to form an elongated and substantially linear cutting edge. The upper surface of each lower posterior tooth slopes downwardly and inwardly in a gentle upwardly concave curve to form a lower crushing or masticating surface 31. Each lower posterior tooth also slopes outwardly and downwardly in a relatively steep convex curve to form the buccal side 32 of the tooth. The biting edges 30 on each set of four posterior teeth lie in a common flat plane.

Referring to FIGS. 1 and 4, the upper denture includes the following artificial teeth mounted in and projecting downwardly from the lower surface of the upper denture base:

Right and left upper central incisors 34, right and left upper lateral incisors 36, right and left upper cuspids 38, right and left upper first bicuspids 39, right and left upper second bicuspids 40, right and left upper first molars 42, and right and left upper second molars 43.

In the preferred form of the invention, each set of four posterior artificial teeth on each side of both the upper and lower bases are cast from porcelain or plastic as an integral and continuous unit. For example, the occlusal surfaces 50 on the upper posterior teeth are cast to lie in a common flat plane, and are set on a flat plate or template (not shown), which establishes that plane. The same is true of the biting edges of the lower posterior teeth. An inwardly extending stabilizing bar 51 is formed integrally with each set of upper posterior teeth and rests on the template to stabilize the teeth in the proper position on the template while the teeth are set in the upper denture wax base. Thereafter, the stabilizing bars are removed, say by cutting. The stabilizing bar can be separate as shown in FIG. 4, or can be joined together at their inner portions. It can be fixed to the teeth or separate, fitting into slots formed in the occlusal surfaces to receive same.

As shown best in FIG. 1, when the mandible 52 is in the centric position with respect to the maxilla 54, the biting edges 30 of the lower posterior teeth bear against the flat surfaces of the upper posterior teeth in a common flat intermaxillary plane 56 (shown in phantom line) which passes through the line of contact of the biting edges 30 of the lower posteriors and the flat surfaces 50 of the upper posteriors. Preferably, the intermaxillary plane also passes through the upper portions of the retromolar pads 58 (shown in phantom line) and the incisal edges of the upper central incisors 34. The intermaxillary plane is also preferably parallel to a line (not shown) passing through the hamular notches 60 in the patients mouth.

The lower anterior teeth are placed in the lower denture so that they are spaced slightly, preferably about 0.020 inch, below the intermaxillary plane as shown in FIG. 1, when the dentures are in centric contact.

A separate downwardly facing transverse fulcrum ridge 62 (FIGS. 1, 3, and 4) is formed across the flat surface of each of the first bicuspids. The ridges on the bicuspids are parallel, preferably collinear, and they lie in the intermaxillary plane 56. The ridges provide a fulcrum of stability when the mandible is moved forward to the protrusive position shown in FIG. 3. The fulcrum ridges on the first or second bicuspids and the location of the lower anteriors below the intermaxillary plane permit the mandible to slide forward into the protrusive position shown in FIG. 3 without developing any unseating forces on the dentures, as explained more fully below. The transverse fulcrum ridges 62 can be located on the second bicuspids instead of the first bicuspids. This has the advantage of providing a seating force which is more centrally located than that provided with the transverse ridges on the first bicuspids. If the ridges are on the second bicuspids, the first bicuspids become substantially nonfunctional. This is not a serious disadvantage because most of the chewing is provided by contact between the first molars and second bicuspids of the upper and lower sets of teeth.

The advantage of the dentures of this invention will be more completely understood from the following description with reference to FIGS. 1 and 2 which show schematically how the mandibular condyles 70 fit into the glenoid fossae 72 of the temporal bone to form the temporal mandibular joint 74 in which the mandible is hinged to the maxilla.

In the following description, the term intermaxillary planar contact means that every contact between the upper and lower denture masses, regardless of the position of the mandible,is within a common plane, which for the purpose of this invention is referred to as the intermaxillary plane. Since the intermaxillary plane is flat, the denture masses are noninterceptive, i.e., there is an absence of any mechanical projection in the occlusion, or any part of the denture base which would intercept single plane contact due to movement of the dentures relative to each other.

People who wear dentures which do not include the present invention experience three main problems, namely:

1. Discomfort 2. Inability to chew various foods, and

3. Looseness of the dentures. Pain and discomfort force most patients to leave their lower denture out either all or part of the time. Inability to chew various types of food often forces patients to restrict their diet. Looseness of the dentures often makes it necessary to employ adhesive powders and to endure the flow of food under the dentures while eating a meal.

The dentures of this invention improve the standard of performance of artificial dentures by correcting the main factor which causes the above three problems. The main factor causing tipping, looseness, and discomfort with dentures is movement of the denture bases on the denture-supporting gum tissue (cornified oral mucosa) when the upper and lower dentures make contact. The construction of the dentures of this invention stabilizes the upper and lower dentures of this invention on the tissue, and thus provides new and improved conditions for comfort and health of the gum tissue. This result is obtained because the occlusal surfaces 50 of all the upper posterior teeth are in a flat plane, and the biting edges 30 of the lower posterior teeth are also in a flat plane. Moreover, the dentures are constructed so that all occlusion between them occurs in a common plane at a fixed position regardless of the position of the mandible. Since the plane is flat, all occlusion is therefore noninterceptive, i.e., occlusion takes place in such a way that the dentures tend to remain seated rather than be tipped and become unseated. Also, all forces and counterforces of occlusal contact are vertical to the ridges (see arrows, FIG. 2).

The noninterceptive environment during intermaxillary denture contact releases the condyles of the temperomandibular joint from the various and confused neuromuscular stimuli which result from interceptive contacts of dentures not employing this invention.

The intermaxillary planar contact and the transverse ridges on the first bicuspids provide a noninterceptive intermaxillary contact which decreases or eliminates the need in the joints for the classic mandibular sagittal, vertical and transverse rotations required to accommodate the slanted contacting and intercepting surfaces, as in the conventional dentures. All contacts between upper and lower teeth of dentures prior to this invention have been referred to as various types of occlusion," the posterior teeth being set in different planes of contact, which have created transverse forces, i.e., forces which tend to unseat the dentures, that cause movement of the dentures on the gum tissue.

The dentures of this invention create the noninterceptive environment which permits lateral movements of the mandible without the transverse unseating forces of the dentures. This occurs because all contacts between the anterior and posterior teeth of the upper and lower dentures in every jaw position is of linear origin and occurs in the intermaxillary plane established as described above. In making the dentures of my invention, the intermaxillary plane is established, controlled, and maintained in the upper denture. When proper vertical dimension is supplied, the linear-plane contact allows the condyles to move freely in their glenoid fossae and in a way which allows bilateral balancing without cusp rise during a lateral shift of the mandible. This function has not been previously obtained with prior dentures because the proper noninterceptive environment for the phenomenon has not been supplied.

The proprioceptive nervous system stimulates hyperactive condyle movement which is an accommodation for multiplanar denture contacts, such as occur with dentures prior to this invention. With linear contact in a single plane provided by this invention, the proprioceptive influence on excessive condyle movement is suppressed. This allows the condyles freedom of movement within the fossae. Since the single flat intermaxillary plane of contact influences the pattern of mandibular movement so consistently, I refer to this phenomenon as environmental gnathology.

The precise contact between the denture masses within the flat intermaxillary plane 56 properly oriented with respect to the cranium produces maximum benefit to the patient in comfort, chewing, and stability because linear contact, properly oriented in a single plane, results in comfortable seating forces which hold the denture bases stable and virtually unmoving during any. contact between the dentures. The usual tilting, tipping, and sliding movements of prior dentures ,on the underlying gum tissue is thus minimized. The denture-supporting gum tissue contains proprioceptive nerve endings which respond to the stimuli of denture movement. These stimuli influence the pattern of mandibular movement, condyle position, and the comfort of the entire temperomandibular joint. when the stimuli induced by the movementof the. denture base on the supporting 'tissueare suppressed by-the dentures of this invention, the proprioceptive nerve endings are not activated to change mandibular movement as a'preventative of tissue injury. The proprioceptivenerve, system is a protective mechanism which intercept any-mandibular movement, when artificial teeth touch, which wouldinju'refthe.tissue .if such movement continued. Such injury would be caused by subsequent traumatic movement of the relatively hard denture base on the sensitive gum tissue. Thus, by stabilizing the dentures on the gum tissue through the linear single plane contact between the upper and lower dentures, instead of multiple planes of occlusal contact between individual opposing teeth as with prior dentures, a superior and unique masticatory system is provided for the patient.

As stated above, the location of the flat intermaxillary plane 56 is determined by the incisal edge of the upper artificial central incisors 34 and the patients retromolar pads 58 (upper portion). The position of the intermaxillary plane of contact between the dentures is therefore related to:

l. Anatomic guides provided by the patient (the retromolar pads), and

2. The aesthetic position of the upper central incisor teeth as determined by he dentist or technician. The intermaxillary plane 56 is also established to be parallel to the axis passing through the mandibular condyles. Since this is difficult to obtain directly from the patient, a good approximation of the direction of the axis is accomplished by making a wax rim on the conventional upper cast whose inferior surface is horizontally parallel to a line passing through the maxillary hamular notches 60. Thus, the upper wax rim accomplishes two functional requirements incidental to the establishment of the intermaxillary plane. It is used essentially as the height of the planar contact in the anterior region and it establishes the horizontal level of the planar contact by paralleling it with the hamular notches, which are used as a bench mark because they are readily available on endentulous upper casts, and they are essentially parallel to the axis passing through the mandibular condyles. The intermaxillary plane of contact is made parallel to the transverse axis of the condyles 70 by the use of a flat metal template (not shown) preferably 0.020 inch thick. The template is placed on the lower mounted cast at the retromolar pads 58 in back, and is supported by a softened wax rim, adapted to the lower ridge in front.

As stated above, the mandibular condyles 70 are where the mandible is hinged to the cranium, and are the source of all mandibular movement. Thus, the intermaxillary plane 56 should be parallel to the axis passing through the mandibular condyles. Since a line passing through the same portions of the hamular. notches 60 is substantially parallel to the transverse axis of the condyles in the glenoid fossae, the plane of contact is made essentially substantially parallel to the transverse axis of the condyles by having it parallel to a line passing through the hamular notches.

It is important for the intermaxillary plane 56 to be parallel to the transverse axis of the mandibular condyles 70 to insure tioning integral unit. A movement in one part of the mass produces movement inanother part of the same mass. Therefore, it is. necessary to realize thatthe movement of an individual creates a movement of the entire denture mass. If the intermaxillary plane of contact is not substantially parallel-to the transverse axis passing through the condyles, the upper denture occlusion actsas one large cusp incline. For example, if the intermaxillary plane of contact were'not parallel to. the transverse axis, passing through the condyles, a lateral shift of the'mandible would cause it to move up or down, depending on the direction of transverse inclination of intermaxillary plane, and transverse denture-unseating forces would develop as the dentures move on the ridges. This change in the vertical -p'osition of planar contact would act as a cusp rise because it would change the vertical distance between the upper and lower jaws. It does not make any difference whether this change is caused-by cusp rise on individual teeth in the dentures, or by the denture mass itself. In either instance, transverse forces are created which cause denture base movement. This would stimulate the proprioceptive nervous system ,to protect the tissue from the resulting traumatic movement of-the denture bases, and would, thus, reinstate the -classic pattern of condyle movements required when the teeth contact in different planes (asin prior art dentures) to achieve balanced occlusion. The properly oriented flat intermaxillary plane of contact provided by these dentures provides the necessary environment for simplified action of the condyles in their fossae.

The dentures of this invention are particularly useful in overcoming one of the major difficulties which has consistently interfered with denture base stability when the patient slides his mandible intoaprotrusive position such as that shown in FIG. 3. In the protrusive position, the condyles 70...

move out of the fossae 72 in a transitional movement, forward and downward on the eminencae in front of the glenoid fossae. As the condyles move forward and downward, the mandible on which the lower denture rests drops in its posterior region and usually separates the teeth in the posterior part of the denture so that the forces of contact are transmitted immediately to the front teeth. In artificial dentures the front teeth are traditionally placed ahead of the anterior portions of the maxillary and mandibular ridges and, therefore, when the front teeth make contact, the interior portions of the ridges act as fulcrums. The anterior teeth become the force, an the denture bases behind the anterior ridges are levered toward each other and dislodged in back. Dentures prior to this invention have tried to compensate for this effect, but the resultant curves and cusp rise in the occlusion has always produced transverse unseating forces instead of stabilizing seating forces produced by the dentures of this invention.

The unseating forces produced by dentures prior to this invention not only act as stimuli to proprioceptive activity involving environmental compensating adjustment of the condyles, but also produce traumatic movements and pressures of the denture bases against the sensitive gum tissues. The interdenture contact provided by this invention establishes vertical seating forces within the dental arch rather than the transverse unseating forces outside the dental arch in protrusive 'movement. The seating forces are established with the dentures of this invention in the upper first or second bicuspids by creating a fulcrum (the transverse ridges 62 on the bicuspids) for the biting edge of the blade of the lower denture to ride on in As the biting edges 30 of the lower posterior teeth slide forward in the mouth in a protrusive movement, they ride on the bilateral fulcrums of stability (the transverse ridges 62 on the bicuspids), which provide the only contact between the denture masses. The mandible 52, therefore, rotates about a transverse horizontal axis on these fulcrums, providing denture seating forces behind the anterior ridges of the maxilla and mandible. This pressure behind the anterior arch provides a vertical stabilizing or seating force (FIG. 3) instead of unseating force, as experienced in previous dentures.

With the dentures of this invention, the lower anterior teeth rise in a protrusive movement ahead of the fulcrum as the lower posterior teeth drop behind the fulcrum. Thus, it can be seen why, to create noninterceptive inter-maxillary contact during mandibular movements in the protrusive, the lower anterior teeth are positioned below the intermaxillary plane of contact in the prefabricated block of teeth.

Preferably, the biting edges of the first and second bicuspids in the lower denture are continuous, and do not contain any interruptions or notches between these teeth which would tend to engage the fulcrums, causing a bump in the protrusive slide. This bumping would not only increase proprioceptive activity, but could traumatize the gum tissue underneath the denture by creating transverse forces at the moment of the contact of the notches with the fulcrum. The continuous blade on the lower bicuspids permits the lower denture to slide uninterruptedly along the fulcrum. Consequently, the biting edge of the ridge or blade on the lower first and second bicuspids is preferably continuous. Thus, in a protrusive movement of the mandible, the lower denture is seated bilaterally and evenly in the mouth by the fulcrums on the two upper bicuspids in a continuous, smooth, noninterceptive manner.

The artificial teeth used in the dentures of this invention can be manufactured to include all of the teeth or just the posterior teeth. They can be a one-piece plastic mold, or a combination of plastic and porcelain teeth, or made up totally of porcelain teeth attached to each other by any suitable means which insures that the flat surfaces of the upper posterior teeth are in the same common plane and that the biting edges of the upper central incisors are in the same common plane and that the lateral incisors and cuspids are above this same plane. The bilateral fulcrum of stability may be manufactured in either the first or the second bicuspids. The bilateral fulcrum is preferably placed in the second bicuspids. This moves the horizontal axis of rotation of the mandible in a protrusive movement more to the center of that part of the upper ridge which runs antero-posteriorly. The first bicuspids are then placed above the intermaxillary plane of contact in the manufacture of the teeth. In doing so, every means can be used to create the best aesthetic form of the first bicuspids since their functional roll is removed.

A lower prefabricated arch of teeth is correlated to each upper prefabricated arch. In the preferred form of the invention, the upper posterior teeth have the flat surfaces, and the lower posterior teeth carry the biting edges which bear against the flat surfaces of the upper posteriors. However, the positions of the flat surfaces and biting edges can be reversed in the upper and lower dentures as long as the occlusal surfaces of the dentures meet in a common intermaxillary plane as defined above.

The biting edges and the flat surfaces can be reversed from the preferred arrangement to provide a cross-bite for certain anomalous cases, e.g., a class III prognathic relationship. How ever, it is desirable for the upper posterior teeth to have the fiat surface, and the biting edge to be at the buccal side of the lower teeth as shown in FIG. 2. With this arrangement, the upper teeth hold the cheeks of the patient away from contact between the upper and lower posteriors, and thus reduce the tendency for the patient to bite his cheek. Moreover, with the biting edge at the buccal side of the posterior lower teeth, the cut portions of food being chewed tend to move toward the patients tongue rather than being caught between the patients cheek and teeth. The movement of the out food toward the patients tongue also facilitates further mastication between the lingual side of the flat surfaces and the concave portions of the posterior teeth below the plane of contact. Finally, the location of the flat surfaces on the upper posteriors permit them to be arranged in the position shown in FIG. 2 to encourage bits of food to move inwardly rather than toward the cheeks. The arrangement of FIG. 2 also has the advantage that it more nearly simulates the appearance and arrangement of natural teeth, and thus is aesthetically preferable.

With the upper and lower denture teeth prefabricated and mounted as described above, the aesthetics are excellent. A unique relationship of the dentures of this invention in the centric position is that the incisal edges of the upper central incisor teeth are in the itermaxillary plane of contact, while the incisal edges of all the lower anterior teeth are located below the plane of contact. The opposite has been traditional with dentures prior to this invention. That is, the anterior teeth usually overlap, and this is generally called an overbite." The dentures of this invention permit the teeth to be mounted as shown in FIG. 1 and described above, and, Le, there is an underbite of the anterior teeth, and it is prefabricated in the manufacture of the denture teeth.

THe various structures of artificial denture teeth described herein permit a prefabricated assembly of upper and lower dental arches in various aesthetic tooth forms and sizes which accelerate the production of dentures in the laboratory. The traditional methods used prior to this invention required assembling each tooth individually in wax rims, positioning one tooth next to the other, and then, in functional relationship with the teeth of the opposite arch set in a similar way. This invention precludes the necessity of handling teeth individually and allows a unit assembly of each dental arch between the casts on a single plane of contact. This plane of contact is related consistently and accurately to the patients anatomic landmarks which provide noninterceptive movements of the dentures.

What is claimed is:

l. A prosthodontic masticatory system for an edentulous patient, the system comprising a lower denture base adapted to rest on the gum tissue overlying the mandible of the patient, and an upper denture base adapted to bear against the gum tissue covering the maxilla of the patient, one of the denture bases inclu;ing at least one elongated portion having a flat surface facing the other denture and extending over an area substantially corresponding to that previously covered by at least the first and second natural molars, the other denture base including an elongated ridge extending for a distance at least equal to that previously covered by the span between the mesial edge of the first molar and the distal edge of the second molar, the ridge projecting toward the said flat surface to form a biting edge which lies in substantially the same plane as the flat surface when the denture bases are held in centric contact.

2. A system according to claim 1 which includes a first flat surface on one side of one of the denture bases, and a second flat surface on the opposite side of the denture facing the other denture, the first and second fiat surfaces lying in a common flat plane, and a transverse ridge adjacent to each of the fiat surfaces and extending toward the other denture base, each transverse ridge lying within the space previously occupied by the natural bicuspid teeth of the patient, and laterally spaced elongated ridges on the said other denture each projected toward a respective flat surface to form biting edges which lie in substantially the same plane as the flat surface when the denture bases are held in centric contact.

3. A system according to claim 2 in which the two flat surfaces are on the upper denture, and the biting edges are on the lower denture.

4. A prosthodontic masticatory system for an edentulous patient, the system comprising a lower denture base adapted to rest on the gum tissue overlying the mandible of the patient, and an upper denture base adapted to bear against the gum tissue overlying the maxilla of the patient, one of the denture bases including a pair of elongated, laterally spaced substantially continuous flat surfaces lying in a common plane facing the other denture base, each flat surface being disposed over an area substantially corresponding to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient, the other denture base including a pair of substantially continuous elongated laterally.

spaced. flat ridges lying substantially in the common plane, each ridge extending for a distance substantially equal to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient.

5. A system according to claim 4 in which the common plane is substantially parallel to a transverse axis passing through the temperomandibular joint of the patient.

6: A system according to claim 5 in which the common plane passes substantially through the incisal edge of the upper central incisor teeth of the upper denture.

7. A system according to claim 5 in which the common plane passes through the upper portion of the retromolar pads of the patient.

8. A system according to claim 6 in which the common plane passes through the upper portion of the retromolar pads.

9. A system according to claim 4 in which the denture base with the flat surfaces includes a downwardly facing transverse fulcrum on each side of the said denture, each fulcrum being located within the space previously occupied by the bicuspid teeth of the patient.

10. A system according to claim 4 in which the incisal edges of the lower central incisors are spaced below the common plane.

11. A system according to claim 10 in which the lower central incisors are behind the upper central incisors to form an underbite.

12. The system according to claim 4 in which each ridge also extends for a distance substantially equal to that previously occupied by the bicuspid teeth of the patient.

13. A prosthodontic masticatory system for an edentulous patient, the system comprising a lower denture base adapted to rest on the gum tissue overlying the mandible of the patient, and an upper denture base adapted to bear against the gum tissue overlying the maxilla of the patient, one of the denture bases including a pair of elongated, laterally spaced flat surfaces lying in a common plane facing the other denture base, each flat surface being disposed over an area substantially corresponding to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient, said one denture base including a downwardly facing transverse fulcrum on each side of said denture base, each fulcrum being located within the space previously occupied by the bicuspid teeth of the patient, the other denture base including a pair of elongated laterally spaced ridges lying substantially in the common plane, each ridge extending for a distance substantially equal to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient, each ridge also being continuous for a distance extending from one side to the other of such fulcrum.

14. A prosthodontic masticatory system for an edentulous patient, the system comprising a lower denture base adapted to rest on the gum tissue overlying the mandible of the patient, and an upper denture base adapted to bear against the gum tissue overlying the maxilla of the patient, one of the denture bases including a pair of elongated, laterally spaced flat surfaces lying in a common plane facing the other denture base, each flat surface being disposed over an area substantially corresponding to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient, said one denture base including a downwardly facing transverse fulcrum on each side of said denture base, the fulcrums being parallel and each fulcrum being located within the space previously occupied by the bicuspid teeth of the patient the other denture base including a pair of elongated laterally spaced ridges lying substantially in the common plane, each rid e extending for a distance substantially equal to that previous y covered by at least the first and second natural molars on a respective side of the mouth of the patient.

15. A prosthodontic masticatory system for an edentulous patient, the system comprising a lower denture base adapted to rest on the gum tissue overlying the mandible of the patient, and an upper denture adapted to bear against the gum tissue overlying the maxilla of the patient, one of the denture bases including a pair of elongated, laterally spaced flat surfaces lying in a common plane facing the other denture base, each flat surface being disposed over an area substantially corresponding to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient, the other denture base including a pair of elongated laterally spaced ridges lying substantially in the common plane, each ridge extending for a distance substantially equal to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient, the biting edges of the upper lateral incisors and upper cuspids of one of the denture bases being spaced above the common plane to prevent protrusive contact.

16. A prosthodontic masticatory system for an edentulous patient, the system comprising a lower denture base adapted to rest on the gum tissue overlying the mandible of the patient, and an upper denture base adapted to bear against the gum tissue overlying the maxilla of the patient, one of the denture bases including a pair of elongated, laterally spaced flat surfaces lying in a common plane facing the other denture base, each flat surface being disposed over an area substantially corresponding to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient, the other denture base including a pair of elongated laterally spaced ridges lying substantially in the common plane, each ridge extending for a distance substantially equal to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient, the lower anterior teeth on one of said denture bases being disposed below the common plane.

"H050 UNITED STATES PATENT OFFICE CERTIFIQAE 9F (:ORRECTIQN Patent 3,638,309 Dated February 1, 11972 Inventor( s) John Po Frush It is certified that error'appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col, 2 line 5, "becomes" should read -become--. Col, 2 line ,5 7, "form plastie" should read "from plastic--. Col, 5, line 15, "intercept should read --intercepts--.

C010 5, line 34, "he dehtisiz' should read --the dentist--.

Col 6, line 45 "interior portions" should read --anterior portions- Col, 6, line 46, "an' the" should read -and the--. Col, 7, line 42 the lateral" should read -the upper lateral". Col, 8, line 14, "itermaxillry" should read --'-ihtermaxillary--.

Col, 9, line 56 (Claim 13) "such" should read =--=each--.

Col. 10, line 24 (Claim 15) "denture adapted" should read denture base adapted.

Signed and sealed this 27th day of June 1 972 (SEAL) Attest:

- EDWARD M.FLETGHER,JR, ROBERT GOTTSGHALK Attesting Officer Commissioner of Patents

Claims

1. A prosthodontic masticatory system for an edentulous patient, the system comprising a lower denture base adapted to rest on the gum tissue overlying the mandible of the patient, and an upper denture base adapted to bear against the gum tissue covering the maxilla of the patient, one of the denture bases including at least one elongated portion having a flat surface facing the other denture and extending over an area substantially corresponding to that previously covered by at least the first and second natural molars, the other denture base including an elongated ridge extending for a distance at least equal to that previously covered by the span between the mesial edge of the first molar and the distal edge of the second molar, the ridge projecting toward the said flat surface to form a biting edge which lies in substantially the same plane as the flat surface when the denture bases are held in centric contact.

2. A system according to claim 1 which includes a first flat surface on one side of one of the denture bases, and a second flat surface on the opposite side of the denture facing the other denture, the first and second flat surfaces lying in a common flat plane, and a transverse ridge adjacent to each of the flat surfaces and extending toward the other denture base, each transverse ridge lying within the space previously occupied by the natural bicuspid teeth of the patient, and laterally spaced elongated ridges on the said other denture each projected toward a respective flat surface to form biting edges which lie in substantially the same plane as the flat surface when the denture bases are held in centric contact.

4. A prosthodontic masticatory system for an edentulous patient, the system comprising a lower denture base adapted to rest on the gum tissue overlying the mandible of the patient, and an upper denture base adapted to bear against the gum tissue overlying the maxilla of the patient, one of the denture bases including a pair of elongated, laterally spaced substantially continuous flat surfaces lying in a common plane facing the other denture base, each flat surface being disposed over an area substantially corresponding to that previously covered by at least the first and second natural molars on a respective side of the moutH of the patient, the other denture base including a pair of substantially continuous elongated laterally spaced flat ridges lying substantially in the common plane, each ridge extending for a distance substantially equal to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient.

6. A system according to claim 5 in which the common plane passes substantially through the incisal edge of the upper central incisor teeth of the upper denture.

14. A prosthodontic masticatory system for an edentulous patient, the system comprising a lower denture base adapted to rest on the gum tissue overlying the mandible of the patient, and an upper denture base adapted to bear against the gum tissue overlying the maxilla of the patient, one of the denture bases including a pair of elongated, laterally spaced flat surfaces lying in a common plane facing the other denture base, each flat surface being disposed over an area substantially corresponding to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient, said one denture base including a downwardly facing transverse fulcrum on each side of said denture base, the fulcrums being parallel and each fulcrum being located within the space previously occupied by the bicuspid teeth of the patient the other denture base including a pair of elongated laterally spaced ridges lying substantially in the common plane, each ridge extending for a distance substantially equal to that previously covered by at least the first and second natural molars on a respective side of the mouth of the patient.