US3908271A

US3908271A - Dental articulator

Info

Publication number: US3908271A
Application number: US371702A
Authority: US
Inventors: Harry J Derda; Charles H Gibbs
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-06-20
Filing date: 1973-06-20
Publication date: 1975-09-30
Anticipated expiration: 1992-09-30

Abstract

A dental articulator that simulates jaw movements in the same directions as the natural jaw. A lower jaw element is suspended from a fixed base by two pivots movable relative to the frame along restricted paths. An upper jaw element is pivotally supported by the base about a fixed axis coincident with one position of the movable pivots. Each jaw element forms a support for a dental arch cast. Each pivot can be individually locked in a fixed location and the lower jaw element can be released from the pivots for limited relative translational and rotational movement and adjusted to a new relationship with the pivots. Adjustable cam surfaces on the frame control lateral movement of the lower jaw element. A rigid link pivotally and releasably connected between the frame and lower jaw element restrains movement and establishes a chewing-type pivoted action. A plate on the lower jaw element is movable rectilinearly so that the anterior-posterior closed position of the teeth can be adjusted without changing the pivot axis. Plates with peripheral spongelike wall portions forming enclosures for plaster are adapted to be secured to the supporting jaw elements. The wall of each plate serves to support a dental arch cast and acts both as a plaster dam and as a compressive spring when opposed plates and dental arch casts are pressed in opposition on a bite registration to secure the cast to the articulator. An adjustable stop is secured to one support element for contact with the other support element to limit proximity of the jaw elements and is removable without changing its effective length.

Description

United States Patent Derda et al.

[451 Sept. 30, 1975 154] DENTAL ARTICULATOR {76} Inventors: Harry J. Derda, 81 Powers Rd..

Bedford, Ohio 44146; Charles H. Gibbs. 1918 Southwest 48th Ave., Gainesville, Fla. 32608 1221 Filed: June 20. 1973 [21] Appl. No.: 371,702

[52] US. Cl. 32/32 [51] Int. Cl. A61C ll/00 [58] Field of Search 32/12. 22, 32

[56] References Cited UNITED STATES PATENTS 2.097.701 11/1937 Pfeiffer 32/32 2.204.809 6/1940 Miller et a1. 32/32 2.428.808 10/1947 Miller 32/32 2.608.761 9/1952 Scott 32/32 2.748.481 6/1956 Glueck 32/32 3.343.264 9/1967 Guichet 32/32 3.359.639 12/1967 Guichet 32/32 3.387.369 6/1968 Swanson 32/32 3.409.986 11/1968 Freeman 3 /32 3.590.487 7/1971 Guichet 3.772.788 11/1973 Gerber Primary Examiner-Robert Peshock Attorney. Agent, or FirmWatts. Hoffmann. Fisher & Heinke Co.

[57] ABSTRACT A dental articulator that simulates jaw movements in the same directions as the natural jaw. A lower jaw element is suspended from a fixed base by two pivots movable relative to the frame along restricted paths. An upper jaw element is pivotally supported by the base about a fixed axis coincident with one position of the movable pivots. Each jaw element forms a support for a dental arch cast. Each pivot can be individually locked in a fixed location and the lower jaw element can be released from the pivots for limited relative translational and rotational movement and adjusted to a new relationship with the pivots. Adjustable cam surfaces on the frame control lateral movement of the lower jaw element. A rigid link pivotally and releasably connected between the frame and lower jaw element restrains movement and establishes a chewingtype pivoted action. A plate on the lower jaw element is movable rectilinearly so that the anterior-posterior closed position of the teeth can be adjusted without changing the pivot axis. Plates with peripheral spongelike wall portions forming enclosures for plaster are adapted to be secured to the supporting jaw elements. The wall of each plate serves to support a dental arch cast and acts both as a plaster dam and as a compressive spring when opposed plates and dental arch casts are pressed in opposition on a bite registration to secure the east to the articulator. An adjustable stop is secured to one support element for contact with the other support element to limit proximity of the jaw elements and is removable without changing its effective length.

52 Claims, 14 Drawing Figures U.S. Patent Sept. 30,1975 Sheet 2 of6 3,908,271

US. Patent Sept. 30,1975 Sheet 3 of 6 3,908,271

US. Patent Sept. 30,1975 Sheet 5 of6 US. Patent Sept. 30,1975 Sheet 6 0f6 3,908,271

DENTAL ARTICULATOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to dental articulators.

2. Prior art The general purpose of an articulator mechanism is to move cast replicas of dental arches relative to one another through the intercuspal range and to their closed position. The movements and closed positions attainable on an articulator are important in attaining a functional restoration of teeth. An articulator, along with a compatible face bow system, aids a dentist in diagnosing the articulation and occlusion of a particular patient and aids him in constructing restorations outside of the mouth.

Good articulation and occlusion are important for oral health, comfort and aesthetics, and in the case of denture wearers, are important to maintain the periodontal structures, denture stability, chewing efficiency, and comfort. In cases of improper tooth arrangement and contour, forces can be generated during articulation and occlusion that traumatize the toothsupporting structures, thereby weakening tooth support, increasing tooth mobility and increasing the likelihood of periodontal infection. In some instances improper tooth-to-tooth contact causes forces at the temporomandibular joints that result in a muscle spasm pain syndrome.

The process of dental restoration is long and involved. An articulator, when used with a face bow, in effect puts the patients head on the workbench where lengthy construction procedures can be made without discomfort or hazard to the patient. Moreover, functional jaw movements required to design and evaluate restorations are difficult to generate consciously in the mouth. In practice, mechanically reproducible movements based on preconscious functional recordings of jaw movements are preferable.

The articulator is typically used with a face bow measuring system that relates the particular patients temporomandibular joints to his dental arches, and a bite registration to relate the dental arches, one to the other, so that the dental arches can be properly positioned on the articulator.

The face bow insures the accuracy of the bite registration by indicating with pointers that the jaw is in the desired position while the impressionable material on the bite registration records the imprints of the cusp tips. Among other functions it also serves to approximately locate the particular patients temporomandibularjoints with respect to his dental arches. The bite registration is preferably thin and typically includes an impressionable material. When affixed to the face bow and clamped between the teeth of the patient, it records a relationship between the teeth and the temporomandibular joint, that can be transferred to the articulator.

The complex movements of the jaw have been recognized for some time. See, for example, the article published in 1908 by NC. Bennett entitled A Contribution to the Study of the Movement of the Mandible [Proceedings of the Royal Society of Medicine (Odont. Sect.) Vol. I (3)]. A great many articulators have been designed for dental use. According to a thesis by James E. House (The Design and Use of Dental Articulators in the United States from 1840 to 1970 Masters Thesis, School of Dentistry, Indiana University, 1970) 235 dental articulators were patented in the United States during the period 1840 to 1970. Typically, early articulators were of the so-called hinge type in which two superpose'd'support plates were used, one fixed and one supported for simple pivotal movement toward and away from the other. Also, see US. Pat. No. 1,574 issued Apr. 30, 1940 and purportedly the first patent to be issued on an articulator. More sophisticated articulators hinge the upper plate for translational and rotational movement, sometimes through the use of adjustable shafts, to simulate the temporomandibular joint. Movement of the hinged plate is controlled by the joint construction, which may include condylar elements in condylar guide housings. Typically, a pin would be provided on the pivoted jaw member and an incisal guidance table provided on the fixed frame to guide the movable jaw in chewing movement. In contrast, an articulator using only a hinge movement lacks chewing closure movement.

Articulation with pivoted upper plates have resulted in a reversal of movements from that of the normal jaw. Also, attempts to provide the variety of necessary movements and adjustments to accommodate differences in measurements for patients has resulted in complex arrangements that have practical limitations and are difficult to use. Yet, for the modern practitioner, the dental articulator must provide many different jaw positions and perform many movements through different mechanisms. The ease and simplicity with which an articulator can be adjusted to provide the needed positions and perform the needed movements accurately and precisely, largely determine its usefulness.

SUMMARY OF THE INVENTION The present invention provides a dental articulator that incorporates the necessary adjustments and movements to produce the necessary flexibility and motions to attain the needed positions and movements for diagnosing articulation and occlusion and to aid in constructing restorations. At the same time, the articulator embodying the present invention is of simplified construction readily adjustable without the need for tools, and will perform the different movements required accurately and precisely. It has the particular advantage of simulating the natural movements of a lower jaw in the normal relationship to the upper jaw by utilizing a jaw element connected to a frame in an orientation analogous to the natural position of the jaw in the skull.

Most desirably, an articulator must be capable of closely duplicating jaw chewing movement; i.e., the socalled working condyle of the articulator, corresponding to the condyle on the pressure applying side of an actual jaw, should move medially or sideways while the non-working condyle moves along a constraining path analogous to the temporo-mandibular fossa and controls the extent of the medial movement of the working condyle. The movement of the front, i.e., tooth area, of the movable articulator jaw must also,be suitably constrained along a desired approach angle to the fixed jaw. The articulator embodying the present invention attains this capability through a minimum of adjustments and constraints to assure the necessary flexibility and movements without undue mechanical complexity. An instantaneous screw axis analysis of actual jaw movement and of the present articulator movement shows that the movable articulator jaw moves through essentially the same instant axes as an aactual jaw, during typical chewing movement.

Basically, the present invention is comprised of two relatively movable jaw elements for supporting dental arch casts, and specific adjustments and constraints for the jaw elements. A lower jaw element is adjustably supported, e.g. by a support frame, for complex translational and rotational movement, to simulate chewing jaw movement and to facilitate tooth gliding. The upper jaw element is supported, as by the same frame, for simple pivoting about a single axis to provide access to the dental arch casts and for establishing maximum intercuspal position, i.e., closed position. The device is constructed to locate dental arch casts supported by the jaw elements in a forward location relative to the supporting portions of the apparatus frame, accessible for work and view without interference from the frame, pivot structure or constraints associated with the pivoted jaw member.

Movement of the lower jaw element is controlled by two joint constraints above a dental arch cast support portion and a prime link constraint between the jaw element and frame. The link constrains one degree of freedom of the jaw element movement, helps define the approach of the lowerjaw element relative to the upper element, and in addition establishes functional chewing movement. The link is adjustable in its effective length and angle between the support frame and jaw element to vary the angle and range of movement of the jaw element. It is also releasable to permit hinge type pivoting and tooth gliding movement of the lower element, or the use of an incisal table for controlling jaw element movement. Pivot mechanisms include a number of adjustments for releasing the repositioning the lower jaw element and for permitting sideward movement and guided sliding movement, analogous to that of the condyles of the jaw on the fossae of the skull. The pivot mechanisms are adjustable for different dimensions that may be required when working on dental casts for different individuals. The adjustments are useful to indicate the difference between a position determined from a bite registration mounting and the existing (ac' quired) closed position as determined by the teeth and further permit the quick remounting of dental casts to any bite registration or the comparison of a number of bite registrations with the cementing position of the dental arch casts to thereby compare the bite registrations one with another. In this manner, the device serves the same function as the known split-cast technique, but provides greater speed and indicates the amount of any discrepancy. The adjustments include, in particular, the independent setting of the slope of the structures analogous to the fossae and the setting of a desired intercondylar distance. A side shift of the pivots is provided to increase the effective lateral movement which is useful for developing clearances of posterior teeth and lateral movements as well as to develop a sideward freedom of movement at the closed position.

Each pivot mechanism provides a first lock for adjustably positioning the angle of the condyle-guiding structure analogous to the fossa slope, and a second lock for separately and selectively restraining or releasing each condyle pivot of the lower jaw to prevent or allow movement of either or both along the guiding fossae slopes. When both condyle pivots are restrained by the second lock, the lower jaw pivots about a single fixed axis. As a further feature of the pivot mechanisms, each condyle pivot can be released relative to the lowerjaw and the jaw freely moved and/or adjusted with respect to the condyle elements in two degrees of 5 freedom.

Adjustable spring tension mechanisms are provided for the lower jaw mechanism to adjust the closing force of the lowerjaw to the desired feel, or to completely release spring tension as when the condyle pivots of the jaw are released relative to the jaw in determining the existing or acquired closed position applicable to the supported dental arch casts.

A mechanism comprising a rectilinearly adjustable slide surface is carried by the lower jaw to accurately correct for overretrusion of the jaw by bringing the jaw straightforward from a retruded position rather than down the fossae slopes, and to develop anteriorposterior clearance between the dental arch casts.

The upper jaw hinge movement is selectively controlled by a lock mechanism that is positive in action and cam controlled, to selectively permit pivoting movement. The upper jaw mechanism carries an anterior stop and incisal pin constructed so that the pin can be removed without changing its setting. The pin controls the distance between the upper and lower jaw elements and can be adjusted to open the bite to compensate for thickness of articulating papers and to change the freeway space. It can also be used as a cam follower on an incisal table and can be used to make jaw movement tracings.

A novel mounting plate is provided for use with each jaw element to facilitate support of the dental arch casts. Each mounting plate includes a rigid back member and a peripheral sponge-like wall portion forming a peripheral surface against which the back surface of the dental arch cast rests and further forming an enclosure for plaster. By virtue of the sponge-like construction of the peripheral wall, a nearly constant and uniform holding pressure can be exerted against opposed casts, to maintain the casts in a desired relationship as plaster is poured between the casts and supporting plate, and within the peripheral wall. With this arrangement, both casts can be mounted concurrently and the plaster is to t the area desired. The construction of the support frame facilitates orienting the jaw elements vertically so that plaster can be easily supplied to the zones defined by the peripheral sponge walls.

It will be apparent from the above that a general object of this invention is to provide an improved dental articulator that supports dental arch casts in a natural relationship and in a position relative to the frame that facilitates working and viewing without obstruction, that mechanically reproduces jaw movement and jaw position as they occur functionally in the mouth, and that can be conveniently and easily adjusted to relate the dental arch casts to a particular patients temporomandibular joints. More specific objects as well as other features and advantages of the invention will become apparent from the detailed description that follows, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of an articulator embodying the present invention;

FIG. 2 is a top plan view of the articulator of FIG. 1;

FIG. 3 is a front elevational view of the articulator of FIG. 1;

FIG. 4 is a partial sectional view taken along the line 4-4 of FIG. 1;

FIG. 5 is a partial sectional view taken along the line 5-5 of FIG. 1;

FIG. 6 is a partial sectional view taken along the line 6-6 of FIG. 1;

FIG. 7 is a partial sectional view taken along the line 77 of FIG. 1;

FIG. 8 is a partial sectional view taken along the line 8-8 of FIG. 1;

FIG. 9 is an exploded perspective view of the shaft and one condyle pivot assembly of FIG. 4;

FIG. 9A is a perspective view of a modified embodiment of one part of the condylepivot assembly of FIG.

FIG. 10 is a partial side elevational view of the apparatus of FIG. 1 oriented with the jaw elements vertical to facilitate cementing of the dental arch casts to the articulator;

FIG. 11 is a perspective view, with parts broken away and parts in section, of the incisal pin that forms a part of the articulator;

FIG. 12 is an elevational view with parts in section of a link pin that forms a part of the articulator; and

FIG. 13 is an exploded perspective view of a mounting plate and sponge wall used to support a dental arch cast in accordance with a preferred embodiment.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT A dental articulator embodying the present invention is indicated generally by reference number in the drawings, and basically comprises a stand 22, a maxi]- lary or upper jaw member 24, and a mandibular or lower jaw member 26, which members are constructed to hold upper and lower dental arch casts DU and DL in a natural, opposed relationship, as illustrated in phantom in FIG. 1. The stand is constructed to orient the jaw members in two directions, one in which they extend substantially horizontally as shown in FIG. 1, and a second position in which the stand is placed on its back, with the jaw members in a substantially vertical direction as shown in FIG. 10, especially useful for initially mounting the dental arches. Both

jaw members

24, 26 are pivoted to the stand 22 to facilitate access to the dental arches and to permit articulation of the lower jaw, for chewing and gliding movements, relative to the upper jaw member.

The stand 22 is constructed to support the articulator on a flat horizontal surface, and for that purpose is provided with a U-shaped base 28, from which an L- shaped upright member extends, one leg 30a of which extends vertically from the back of the base and another leg 30b of which extends forwardly over the base to support the

jaw members

24, 26 in cantilever fashion. In the embodiment shown, the leg 30b is received in a slot of the base 28 and is secured by a screw 32. A through bore 34 (FIG. 4) is formed in the distal end portion of the leg 30b to receive a cylindrical shank 36 that extends transversely of the leg 30a and parallel to the plane of the U-shaped base 28. Two joint area socket-like pivot structures indicated generally at 38 and 39 are carried by the shaft 36, one at each end, and cooperate with ball-like pivot structures of the lower jaw element to articulate the lower jaw element relative to the stand in a manner generally analogous to the manner in which the fossae and condyles of the temporomandibular joint pivot the human jaw.

The upperjaw member 24 is comprised of a plate 42 with a hinge structure 43 at the back end, that receives the end of the leg 30b that journals the shaft 36. A transverse surface 44 of the hinge structure 43 (see FIG. 3) abuts the lower surface of the leg 30b, to pre vent the plate 42 from pivoting toward the lower jaw element beyond a horizontal position parallel to the base of the stand. Upward pivoting of the plate 42 to a position slightly beyond or behind a vertical position is permitted by the hinge structure. When the plate 42 is in a horizontal position, as shown in FIG. 1, a latch 46 pivotally carried by pin 48 on the leg 30b can be engaged through a lever 49 with a notch 47 of the hinge structure 43 to retain the plate in a lowered or horizontal position. A compression spring 51 biases the latching lever 46 toward a non-latching position. A central aperture 54 is provided in ,the plate for receiving a screw 56 having a knurled knob 57 above the plate, for attaching a dental arch cast. Depending locating pins 58, 59, are located on diametrically opposite sides from the aperture 54, to locate and prevent rotational movement of a dental arch cast. A front slot 60 (FIG. 2) is provided in the plate 42, perpendicular to the hinge access, for receiving an incisal guide pin 62.

The lower jaw element 26 is comprised of two parallel support arms 64, 66 (see FIGS. 1 and 3) that pivota bly depend from the

pivot structures

38, 39 through

condyle pivot assemblies

68, 69, at upper ends of the support arms, which are in part received in the

pivot structures

38, 39. A crosspiece 70 connects lower ends of the two

arms

64, 66, through a tongue and groove junction that provides for adjustment of the distance between the two

arms

64, 66. The position of each arm is secured by a

knurled nut

72, 73, on a threaded

post

74, 75, that extends from each arm through a longitudinal slot in the cross piece 70. Calibrations 76 are provided for each arm to facilitate centering or otherwise positioning the cross piece and indicate the distance between the arms.

A mandibular plate 78 extends forwardly from the cross piece 70, supported on a tongue 80 that is partially recessed into a lower groove 81 of the plate. The plate is secured to the tongue by a screw 82 that is threaded in an aperture of the plate and that extends through a slot 83 of the tongue. A spring washer 84 beneath the tongue yieldably biases the plate to the tongue for relative sliding movement. The plate is also secured to the tongue by an adjustment screw 85 rotatably secured to the plate 78 at a fixed location by a yoke 86. A fixed projection 87 receives the screw 85 in a threaded bore, so that rotation of the screw slides the plate 78 rectilinearly toward and away from the cross piece 70, relative to the tongue 80. Locating pins, 88, 89 and a knob 91 similar to the knob 57 locate and secure a dental arch cast to the plate 78.

For purposes of providing a restraint to motion of the lower jaw element 26, a curved finger 90 extends rearwardly from the cross piece 70, in an opposite direction from the tongue 80, and downwardly toward the base of the stand. The finger has a central elongated slot 92. In the preferred construction, the curvature of the finger is of approximately but not exactly a uniform radius.

A restraining linkage 94 connects the lower jaw member 26 through the finger 90 to the stand 22 to limit the freedom of movement of the lower jaw element relative to the upperjaw element in a manner that will produce a range of final closing movements of the jaw element as occur during chewing, and which is constructed to be easily released to facilitate tooth gliding and to adjust for the thickness of a bite registration. The linkage provides a degree of restraint to movement of the lower jaw member 26 by fixing the distance of a point on the jaw from a point on the stand. This linkage holds jaw movement to a desired path and, unlike an incisal pin and table, there can be no movement beyond that permitted by the link, whereas an incisal pin can be inadvertently lifted from the guide table.

The linkage 94 is comprised of a universal joint 96 movable along the slot 92 to change the angle at which the link extends relative to a plane passing through the point of connection of the link to the stand and the pivots of the lower jaw member, a universal joint 98 fixed to the stand and located generally centrally of the curvature of the finger 90, and a rigid link 100 connected to the universal joints in a manner to facilitate adjustment of the effective length of the link. Alternatively to facilitating length adjustment, the location of one of the joints 96 or 98 could be movable to facilitate a change in angle and the length of the link maintained constant.

As best shown in FIGS. 1, 3, 7 and 12 the link 100 is in the form of a pin with an integral ball 103 at one end that forms a part of the universal joint 96. The ball 103 is received in a ball housing 104 that rides in guided relationship within the slot 92 of the finger 90. A knob 106 is threadedly secured to the ball housing 104 and serves to clamp the ball housing in a fixed position along the slot 92 when the knob is tightened against the finger 90. In addition, the knob retains a compression spring 108 that spring loads a plastic bearing against the ball 103 in a direction that biases the pin outwardly of the housing.

A slotted housing 110 rotatable about a horizontal axis transverse to the link 100 supports a ball 1 12 of the universal joint 98. The housing 110 is slotted at 114, so that the ball 1 12 lies in the path of the slot. The ball 1 12 has two cylindrical apertures along radii at right angles, one of the apertures extending diametrically through the ball and receiving the link 100, and the other aperture extending at right angles thereto, communicating therewith and threaded to receive a set screw 120. The ball 112 is spring-biased against the housing 110 by a compression spring 121 and slidable bearing block 122 within a support bracket 123 in which the slotted housing is rotatable. A screw 124 retains the spring under compression against the ball.

The

pivot structures

38, 39 and

condyle pivot assemblies

68, 69 together serve to connect the ends of the parallel jaw supports 64, 66 to the stand 22 for movement with three degrees of freedom, and are constructed to (a) serve as condyle range finders to indicate the difference in mounting position at the condylar element and along the condylar axes, between the acquired and ideal positions of the jaw, (b) act as pivots that allow restrained jaw movement simulating chewing motions of the teeth, and (c) permit release and reattachment of the jaw element to ball pivots that act as condylar elements to adjust to a bite registration or to otherwise change the relationship between dental arch casts secured to the mandibular and maxillary plates without recementing the casts. Each of the

pivot structures

38, 39 and

condylar pivot assemblies

68, 69 is a mirror image of the other and therefore only the pivot structure 38 and associated condylar pivot assembly 68 will be described in detail.

A ball element 130 of the assembly 68 is carried by the upper end of the jaw arm 64 and is received in a guide slot 132 formed in a cylindrical rotatable insert 133 of the pivot structure 38. The insert 133 is carried in a cylindrical cup 134 secured to an end of the shaft 36 by a hub 135 received in a bore 137 of the shaft. The cup 134 is held in place by a screw 138 that passes through an axially elongated slot 139 in the wall of the bore 137 and threadedly received in the hub 135. The guide slot 132 is the width of a ball 130a of the ball element 130. An end surface 132a of the guide slot locates the ball with its center aligned with the center of the pivot shaft 36. A back surface 132b of the slot is inclined at about 7 from a plane perpendicular to the axis of the shaft 36, as best seen in FIG. 6, inclining inwardly from the end surface 132a toward the peripheral edge of the insert 133, through which the guide slot opens. This angle was established to produce a desired sideways movement. Rotation of the insert 133 relative to the cylindrical cup 134 changes the angle of side surfaces l32c, 132d of the guide slot with respect to the axis of the shaft 36, so that the side surfaces can be adjusted to correspond to the slope of the fossa of the temporomandibular joint, the function of which it simulates.

Adjustment of the rotatable insert 133 by rotation within the cylindrical cup 134 is made possible by a clearance fit between the two. An angular position is maintained through a clamping nut 141 on the outside of the cup 134, threaded in clamping relationship therewith upon a shaft 142 secured in the insert 133 and extending radially therefrom through a peripheral slot 144 that extends partially around the cylindrical cup.

The ball 130a can be locked in a back position, against the end surface 132a of the guide slot with a pin stop 146 (FIG. 5), controlled by a screw 147 threaded through the shaft 142. The pin stop 146 is carried within the rotatable insert 133 on the end of a cantilever spring 148 secured at one end within a cavity of the insert. The pin stop 146 is carried within the rotatable insert 133 on the end ofa cantilever spring 148 secured at one end within a cavity of the insert. The pin stop is movable on the spring lever into and out of the guide slot 132, and is biased by the spring lever to a position out of the guide slot. An inner end of the screw 147 contacts the spring lever between the point of attachment and the pin stop carried on the free end. By turning the screw 147 to advance the screw inwardly, the pin stop 146 is moved into engagement with the ball 130a. The location of the pin stop relative to the end surface 132a of the rotatable insert is such that it will retain the ball in the rearward position, while allowing the ball to rotate or pivot about its center. That is, the pin is spaced from the end surface 132a down the slot 132 a distance equal to about three-fourths the diameter of the ball.

Lateral adjustment of the

pivot structures

38, 39 so as to shift the position of the guide slots and cooperating ball elements relative to the upper jaw element, for purposes of a side shift to establish lateral freedom of jaw movement, is facilitated by axial movement of the shaft 36 relative to the L-shaped upright stand member 30. The axial position of the shaft 36 is retained in or shifted to a desired position with two adjustment screw knobs 150, 151, that are threaded in the enlarged end of the leg 30b and which abut a respective

inclined surface

154, 155 of the shaft. The

screws

150, 151 are inclined toward one another and act substantially perpendicularly to the

inclined surfaces

154, 155. Thus, the two screws, cooperating with the respective inclined surfaces, locate the shaft 36 in a fixed axially position when the two screws are in direct contact with the respective surfaces. Upon retraction of one screw and extension of the other, the shaft 36 can be shifted axially in one direction or the other. Separate lateral adjustment of each

pivot structure

38, 39 is facilitated by the associated screw 138 and the elongated slot 139. Any separate adjustment outward requires adjustment of the distance between the

support arms

64, 66 of the lower jaw element. Relative inward movement affords free sideways movement.

The ball element 130, in addition to having a ball 130a has a shaft 130b extending outwardly from the ball, with threads 1300 on the outer end. In addition, an integral flange 130d is carried by the shaft, spaced outwardly from the ball a distance sufficient to permit the ball to pivot within the guide slot 132. The flange 130d serves as a clamping surface for the upper end of the support arm 64. A clamping nut 158 is received on the threads 130c and has a counter bore 159 that faces the flange 130d. Two diametrically opposite

axial slots

161, 162 are formed at the end of the clamping nut, in the wall of the counter bore. An annular centering guide 164 is slidable within the counter bore 159 and on the shaft l30b. Two diametrically

opposite pins

165, 166 extend from the centering guide and are receivable within the

slots

161, 162. The length of the pins extends beyond the periphery of the clamping nut and are receivedin apertures 167 of a knurled sleeve 168 that slidably surrounds the clamping nut 158. The outside diameter of the centering guide 164 is closely receivable within a circular aperture 170 in the upper end of the arm 64. The depth of the counter bore 159 is substantially equal to the axial length of the centering guide 164, so that the guide can be completely retracted into the counter bore. The length of the

slots

161, 162 facilitate this movement. As a result of this construction, the centering guide can either be extended beyond the end of the clamping nut 158 so as to project into the aperture 170, thereby centering the shaft 130 relative to the aperture 170, or the centering guide can be retracted into the counter bore 159 so that the location of the shaft 130 within the aperture 170 can be adjusted or so the upper end of the arm 64 can float through an adjustable connecting relative to the shaft 130, within the limits of the aperture 170. In either event, i.e., whether the centering guide is retractedor extended, the nut 158 is rotatable through the sleeve 168 and the

pins

165, 166, to clamp the upper end of the arm 64 against the flange 130d. Rotation of the shaft 130 is restrained by a pin 172 that extends into a slot 173 in the arm 64, directly beneath the circular aperture 170 to keep the element 130 from rotating when the nut 158 is adjusted. The arrangement between the pivot assembly 68 and the arm 64 permits complete freedom of movement of the lower jaw element within a limited but adequate range so that the relationship of the lower jaw element plate can be changed relative to the pivot axis of the jaw element. The position of the lower jaw element can therefore be set to work toward an existing closed position; can be set with the centering element to work toward a closed position as determined by the mounting bite registration; or can be located in any desired relationship to the upper jaw element and locked in the relationship for pivoting and translation as controlled by the pivot structure and restraining linkage. It will be appreciated that readjustment of the ball elements relative to the

arms

64, 66 permits tilting of the lower jaw member about an axis perpendicular to the axis through the ball elements, i.e., in a manner to tilt the mandibular plate 78 and crosspiece so the left side, for example, is higher than the right side when viewed as in FIG. 3. When this adjustment is made, the shaft portions 13012 of the ball elements are no longer aligned (the ball element shaft of assembly 69 is tilted upward from the ball and the other is tilted downward) but the centers of the ball elements themselves will remain aligned with the axis of the shaft 36 as long as they are retained in a rearward position by the pin stops 146. When the stop pin is retracted, the ball is movable along the fossae slope, with the lower jaw element having a new relationship with the upper element.

A modified clamping nut 158a is shown in FIG. 9A having a threaded bore 171 for receiving threads 1300. A flat face 172 perpendicular to the axis of the bore 171 clamps against the support arm 64 when the nut is oriented as shown, to hold the arm in an adjusted position. When the nut is reversed on the shaft b, a smaller diameter portion 173 is closely received in the aperture of the arm 64 and centers the shaft 130 relative to the aperture 170.

The lower jaw member 26 is yieldably biased toward the upper jaw member by tension springs 174, 176. Each spring is attached at its lower end to a screw adjacent the base of each

support arm

64, 66, one screw being shown at 178 in FIG. 1. The upper end of each spring is secured to a

tension wheel

180, 182 rotatably supported on the shaft 36, directly adjacent the

pivot structures

38, 39, respectively. The tension wheel is shown in detail in FIG. 9 and, as shown therein, the upper end of the tension spring 174 is received in a peripheral groove 184 that extends approximately halfway around the wheel. The end of the spring is secured to a cross pin 185 within the adjacent one end of the groove. A stop pin 188 extends radially through the wheel 180 and is secured for relative sliding movement in a radial direction by a screw 189 that intersects the radial aperture 190 in which the stop pin is located. The screw 189 is received in a recess 191 of the stop pin, which recess is axially elongated to permit movement of the pin in the radial direction an amount equal to approximately the length of an end portion 188a of somewhat reduced diameter. The end portion 188a is receivable in one of a plurality of peripherally spaced apertures 195 in the shaft 36. By rotating the wheel about the shaft, and locating the end 188a of the stop pin 188 in a selected aperture 195, the tension on the spring on the lower jaw member can be varied.

The incisal guide pin 62 carried by the maxillary plate 42 serves as an anterior stop for the lower jaw member to limit its upward movement. The guide pin, as shown in FIG. 1 l, is an assembly that includes a stop pin 198 with a threaded portion 198a that is threaded into a holder portion 199. An integral collar 201 on the holder portion has two a lower flange 202 and a central portion 204 with flat sides that cooperate with the slot 60 in the maxillary plate, to support and locate the pin. A threaded end 206 of the holder portion 199 extends upwardly above the collar 201 through the maxillary plate and receives a knurled clamping nut 208 that clamps the maxillary plate against the collar 201. The upper end of the stop pin 198 extends above the threaded portion 206 and has a knurled knob 209 that can be turned to extend the stop pin 198 or retract the stop pin relative to the holder portion 199. The holder portion 199 is split at its lower end as shown at 210 and tensioned inwardly to load the stop pin and eliminate any looseness or play. With this arrangement, the incisal guide pin assembly can be removed without changing its setting relative to the maxillary plate and is rigid for use of a cam follower on an incisal table that can be carried by the lower jaw member. By adjustment of the knob 209, the pin can be extended to open the bite to compensate for the thickness of articulating papers and to change the freeway space between dental arch casts. The pin can also be used to make jaw movement tracmgs.

Upper and lower dental arch casts DU and DL (FIG. and also in phantom in FIG. 1) illustrate the manner in which the casts are secured to the articulator by upper and lower mounting

plates

212, 213 and associated

sponge walls

214, 215 against which the dental arch casts are positioned. The structure is shown in more detail in FIG. 13. The mounting plates and sponge walls are mirror images, and only the plate 213 and wall 215 will be described in detail. The plate includes a central threaded aperture 217 for receiving a threaded shaft portion of the knob 91 that is received within a slot 221 of the tongue 80, to secure the mounting plate to the movable mandibular plate 78 without interfering with the movement of the plate relative to the tongue. Two additional locating

apertures

223, 224 are formed in the lower surface of the mounting plate 213 for receiving the locating pins 88, 89 of the mandibular plate. The wall 215 is of cellular or sponge-like material and is resilient. It extends about the periphery of the mounting plate 213 and has a peripheral opening 229 at a location that faces forward or outwardly of the articulator. The general shape of the mounting plate 213 and peripheral wall 215 is compatible with the shape of the dental arch.

Because of the resilience of the sponge-like cellular wall 215, the dental arch cast DL, adapted to rest against an edge 215a of the wall, conforms the wall to the contour of the opposed surface of the cast. Thus, the wall affords complete peripheral support and together with the cast and mounting plates form a cavity therebetween. The resilience of the two

walls

214, 215 forces the two casts DU and DL against one another when the

jaw plates

42, 78 are parallel, thereby holding the two casts in a desired position, preparatory to affixing the costs to the mounting plates with plaster. Plaster is introduced through the opening 229 and into the cavity formed by the wall 215, the lower mounting plate 213, and the lower dental cast DI... The plaster hardens while the lower east is held by the resiliency of the wall in a desired position relative to the opposed cast and mounting plate. By virtue of the construction of the articulator and the location of the opening 229, plaster can be readily poured into the cavity formed by the wall 215 when the articulator is supported utilizing the leg 30a of the L-shaped upright portion of the stand as a base.

OPERATION In use and by way of an initial summary, the articulator adjustments are set to an initial condition to facilitate mounting upper and lower dental arch casts to a closed position determined with the aid of a bite registration and face bow. The casts are mounted and certain articulator restraints are then removed. The jaw is then located in the existing closed position, as dictated by the teeth. The condyle pivot assemblies of the articulator are used to determine the difference between the bite registration-determined and the existing toothdetermined closed positions and a selection of a position is made to which the reconstruction will be performed. Fossa slopes are then set on the articulator from measurements made on the patient with a face bow or protrusive bite registration. Relationships, principally of anterior teeth, are determined with chewing movements, and posterior tooth clearance is evaluated with lateral movements, facilitated by the articulator.

Prior to mounting the dental arch casts, the following adjustments are made to the articulator. The

condyle pivot assemblies

68, 69 are adjusted so that the centering guide 164 is positioned within the aperture 170 of each

lower jaw arm

64, 66 so that the ball element 130 is centrally located, and the clamping nut 158 is tightened against the lowerjaw arms. The side shift adjustment screws 150, 151 are adjusted and tightened to lock the upper jaw element centrally of the articulator. The mechanism -87 for moving it relative to the tongue 80, is set to a reference or zero position, as indicated by a scale (not shown) carried by the plate and tongue. The condyle ball elements are locked in the retruded hinge position by the pins 146 and screws 147. Mounting

plates

212, 213 are attached to the upper and

lower plates

42 and 78, and the jaw plates are locked in this mounting position by securing the latching lever 46 and the restraining linkage 94.

In mounting the casts with the aid of a bite registration and face bow, the determination of the closed (maximum intercuspal or centric occlusion) position of the cast is very important. The closed position determines the relative heights and positions of the teeth and is the reference point from which movements are made. The closed position for most persons with good occlusion occurs with the condyles slightly forward of their most retruded position. The retruded position or centric relation of the condyles is the most repeatable position and therefore used as a reference in determining the closed position of the casts.

In mounting the casts in the articulator, a bite registration is used to relate the lower east to the upper cast, and a face bow is used to locate the upper cast to the joint elements or

pivot structures

38, 39 of the articulator. The bite registration is made with rearward pressure on the chin of the patient so that the jaw is held in the retruded position. The dental arch casts are then placed in the indentations of the bite registration and supported between the

sponges

214, 215 of the mounting

plates

212, 213. The face bow pointers, attached to the bite registration, are then centered into the

condyle pivot structures

68, 69, a central aperture 130e at the outer end of the shaft 130b of the ball 130 facilitating this. The face bow is centered between the mounting plates 212,213, the articulator is placed on its back and ,1 piztster slurry is poured into the openings 229 in the peripheral sponge walls. After the plaster has hardened, the bite registration and face bow are removed.

Adjustment of the mandibular plate 78 is achieved by rotating the screw 85 to slide the plate 78 forward relative to the supporting tongue 80 approximately onehalf millimeter, to correct for over retrusion of the jaw which occurred while making the bite registration. This adjustment brings the jaw directly forward and not down the fossae slopes. A space between the casts, which exists with the removal of the bite registration, is closed by releasing the anterior end of the lower link pin 100, by loosening the screw 120, pivoting the lower jaw member about the hinge axis until the casts are in tooth-to-tooth contact, and then retightening the screw 120. The locking screws 147 for the condyle pin stops 146 need not be loosened for this hinge axis rotation. The casts are now located in the closed position determined by the bite registration.

An existing or acquired (habitual) closed position for patients with enough opposing teeth can be found by placing the casts in their maximum intercuspal position. This position or any position can be achieved on the articulator by loosening the nuts 158, the screw 120 that secures the anterior end of the link pin 100, and the medial lateral position screws 150, 151. The centering guides 164 are withdrawn from the apertures 170 of the

jaw arms

64, 66 and the tension springs 174, 176 are released by the

tension wheels

180, 182. This completely releases the lower jaw element from restraint within limited confines and the lower dental arch cast can be positioned into the upper cast, as the teeth dictate. With the lowerjaw thus in the existing closed position, the nuts 158, with the centering guides withdrawn are retightened so that the front surface of the nut 158 clamps each

arm

64, 66 against the flange 130d of the associated ball element 130, which is now somewhat off center of the aperture 170. The screw 120 of the lower link pin 100 is tightened, as are the adjustment screws 150, 151 to maintain the shaft 36 in the position dictated by the teeth. The difference between the bite registration and existing closed positions is observable at the ball elements 130 of the

pivot assemblies

68, 69. If the bite registration is made with the temporomandibular joints in their proper positions, then the difference between the existing and bite registration positions, as indicated by the condyle assemblies, is the measure of the harmony between the dentition and the temporomandibular joints. The construction or reconstruction of the teeth can be built to either the bite registration or the existing closed positions, or to some intermediate compromise, without remounting the casts on the upper and lower plates of the articulator. If the ideal closed position is chosen, the nuts 158 are again loosened, the centering guides 164 are moved inward into the apertures 170 to recenter the jaw element, and the medial lateral position adjustment screws 150, 151 are adjusted for jaw centrality.

The ability to release and reposition the lower cast and to indicate the change in position at the condyles is also useful for comparing bite registrations and, as a result, serves as an improved split cast technique. For example, if several bite registrations are found to position the casts in the same relationship, as measured at the condyles, the retruded position was probably recorded by the bite registrations, because protrusive jaw positions are seldom repeatable.

As the patients jaw is moved forward and back, the temporomandibular joints allow the jaw condyles to translate along a narrow path determined by the fossa of the temporal bone. In the profile view, this fossa path is inclined with respect to the plane of the upper teeth. The slope of this path may be different on each side and can be as shallow as 0 for some patients, and as great as 60 for others. Since the inclination of this path is so dependent on the particular patient and because it is very important in determining the clearance of the posterior teeth, an adjustment for the fossa inclination is provided on each side of the articulator. Measuring the patients fossa paths is commonly achieved with either a face bow or a protrusive bite registration. In the first method, a face bow is attached to a bite registration and the bite registration is cemented to the patients jaw teeth. As the patients jaw is moved forward and back, face bow pointers near the joints scribe lines on the skin or on a skull reference plate. The angle of the scribed lines is then measured with respect to the plane of the upper teeth and the angle of the surfaces 132c are set accordingly by rotating the insert 133 of each

pivot assembly

38, 39. In the second method, a protrusive bite registration is made and placed between the casts in the articulator. The surfaces 132c representing the fossa inclinations are then adjusted on the articulator so that the casts seat properly in the protrusive bite registration.

In beginning the reconstruction a desired closed position is selected based on either the existing or the bite registration occlusion, and the teeth are built thereto. The lowerjaw element is locked in a fixed position with the stop pins 146 and the restraining linkage 94, and the upperjaw element is opened and closed around the hinge axis provided by the shaft 36, as the operator requires access to the work. The adjustment provided by the adjustment screw and movable plate 78 of the lower jaw element and the medial-lateral position screws 150, 151 can be varied to produce anteriorposterior and side-to-side freedom of movement in the closed position, if desired. By loosening the pin at the screw 120, the lower jaw can be opened slightly around the hinge axis provided by the

pivot structure

38, 39, and coincident with the axis of the shaft 36, to compensate for the thickness of articulating papers that may be used.

With maximum intercuspal position established, the tension applied by the

springs

174, 176 is reapplied by rotating the

tension wheels

180, 182 and securing them in a position that tensions the springs, with the stop pins 188. The condyle ball pivot structures 130 are released by withdrawing the pin stops 146. The upper jaw plate 42 should be locked in a horizontal or lowered position by the latching lever 49 and latch 46. The relationships of principally the anterior teeth are now determined with chewing movements when the lower link 100 is securely clamped at both ends to establish a fixed length, initially with the posterior end tightened in the most upward position in the slot 92. The posterior end of the link is then incrementally moved downward, with the knob 106 being retightened each timev Because the arc of the curved finger 90 is not circular with a center at the universal joint 98, the screw must be loosened for each shift in position of the posterior end of the link so that the closed position (maximum intercuspal position) remains the same.

At each position of the lower link 94, the lower jaw element is moved to each side of the central position. This procedure generates a full range of chewing movements for evaluating the teeth in mastication. The posterior knob 106 of the lower link is finally adjusted downward until the flattest desired angle of approach of the lower jaw teeth relative to the upper (viewed frontally) is achieved. Although the lower jaw element is movable when the lower link 94 is released and adjusted, the inter-dentated casts maintain the jaw in the same, desired closed position until the link is retightened.

Tooth gliding movements can be performed with the articulator by loosening the screw 120 at the lower end of the link 100 to eliminate the link constraint. Tooth gliding movements are important for evaluating posterior tooth clearance in the natural dentition and posterior tooth balance in the denture occlusion, during lateral and protrusive movements. The lower cast is articulated against the fixed upper case during the tooth gliding.

Although one specific construction has been shown and described in detail, modifications thereof are contemplated, which retain certain but not all of the novel and advantageous features. For example, the movement of the pivots of the lower jaw member, analogous to the condyles of the jaw along a cam surface to provide movement analogous to that of the condyl along the fossa of the temporomandibular joint, can be restrained with different structure than that shown, as by separate pivoted links secured at a lower end to the stand and which carry the condyle pivots at the upper ends, and which ride along cam surfaces. Also, the lower restraint of the lower jaw movement can be achieved by two links rather than one. For example, one link can be provided on each side of the lower jaw plate, secured at a forward location to the stand through a universal joint, and the rearward or posterior end can be adjustably located in curved slots of the lower jaw mechanism to control chewing motions and to adjust the angle of approach of the lower jaw to the upper in articulation.

From the foregoing description it will be understood that an articulator has been provided that, in its concepts, utilizes a prime link constraint in combination with joint area constraints that include cams, a posterior stop, and condyle path grooves or condyle links. Various combinations of the prime link and joint con straints are utilized to duplicate such jaw positions and motions as (l) the cementing or bite registration position, (2) any other bite registration position, (3) the existing or acquired closed position, (4) a full range of chewing closure motions, both toward left side and toward right side, (5) hinge access movement, (6) protrusive movement, and (7) tooth gliding movements.

Modifications and alterations of the articulator described herein may be made without departing from the spirit and scope of the invention defined in the appended claims.

What is claimed is:

l. A dental articulator comprising a support, two generally opposed jaw-like first and second connections between one said member and the support that permit complex movement of said one member relative to the other, and means, including a rigid link functionally constant in length between said one member and the support pivotally connected to both, to constrain said movement of said one member relative to said support to simulate chewing movement.

2. An articulator as set forth in claim 1 wherein said first and second connections comprise movable pivots. 3. An articulator as set forth in claim 1 including means to change the location of at least one of said link connections to adjust its angular relationship with respect to said support and said one member to change the range of movement of said one member relative to said support.

4. A dental articulator comprising first and second structures, each adapted to support a dental arch cast in opposing relationship to the other; means at two 10- cations of said first structure interengaged with said second structure at two locations to allow said first structure to move relative to said second structure with more than one degree of freedom; and means, including a rigid link functionally constant in length connected for universal pivoting at two locations, one location fixed with respect to the first structure and the other fixed with respect to the second structure, for providing one constraint for the movement of said first structure relative to said second structure.

5. A dental articulator as set forth in claim 4 wherein said second structure includes a support, a plate for supporting a dental arch and means defining a fixed axis about which said plate is selectively pivotable.

6. A dental articulator as set forth in claim 4 wherein said rigid link is adjustable in length.

7. A dental articulator as set forth in claim '4 including means for changing one of said two locations at which the link is connected. I

8. A dental articulator as set forth in claim 1 including means to release said link at one of said locations to eliminate its restraint of movement of said first structure, and means to establish a fixed pivot axis at said interengaged means between said first and second structures.

9. A dental articulator as set forth in claim 4 wherein said first structure includes a first plate for supporting a dental arch cast and said second structure includes a stand and a second plate for supporting a dental arch cast, said second plate is located vertically above the first plate, and including means to secure said second plate in a fixed position relative to the stand analogous to a maxilla, and means securing said first plate to said first structure for articulation relative to the stand in an analogous manner to a mandible.

10. A dental articulator comprising a stationary support and a movable jaw member, means, including two portions of said jaw member interconnected with said support, for providing relative movement between the support and jaw member with a plurality of degrees of freedom that permit lateral movement of the jaw member to the left and right of a central position relative to said support, and single rigid link means functionally constant in length connected between a third portion of the jaw member that is displaced from an axis through said two portions and a point on the support, to maintain said third portion a constant distance from said point on the support and to constrain movement of said jaw member in directions both left and right of the central position.

11. A dental articulator comprising a support, a maxillary member pivotably connected to said support and adapted to support a dental arch cast, a manibular member movable relative to said support, said mandibular member including a plate adapted to support a dental arch cast and also including two means located to one side of a plane defined by said mandibular plate for interconnecting the mandibular member with said support for relative translational and pivotal movement, and a rigid link on an opposite side of said plane from said two portions, connected between a third portion of said mandibular member and a point on said support, a universal pivot at each connection of said link, and means permitting adjustment of at least one of the locations of connection for the link to increase or decrease an angular relationship between the link and an imaginary plane defined by said point on the support and said two portions of the mandibular member.

12. A dental articulator as set forth in claim 11 wherein said means permitting adjustment of the location at which said link is connected includes a curved member providing different locations for connection of said link on one of said jaw member and support.

13. A dental articulator as set forth in claim 11 including means to change the length of the link between said two locations of connection to pivot the mandibular member relative to said maxillary member and thereby change the distance between the plates thereof.

14. A dental articulator comprising a support, a maxillary plate carried by said support, means hinging said maxillary plate to the support for rotational movement about a single axis, a mandibular plate, means connecting said mandibular plate to said support at two locations for rotational movement about plural axes, one of said plural axes being coincident with said single axis.

15. A dentalarticulator as set forth in claim 14 including means to lock the maxillary plate in fixed relationship to the support.

16. A dental articulator as set forth in claim 14 including means to restrict pivoting of said mandibular plate to universal pivoting about only one of said two locations.

17. A dental articulator as set forth in claim 14 including a rigid link extending between said mandibular plate and said support and pivotally connected to both.

18. A dental articulator as set forth in claim 17 including adjustment means connected with said link for changing the position of the mandibular plate relative to the maxillary plate.

19. A dental articulator comprising a support stand, a first member adapted to support a dental arch cast and carried by said stand, means securing said first member to said stand for rotational movement about a single fixed axis; a second member adapted to support a dental arch cast in generally opposed relationship to said first member and carried by said stand, and means securing said second member to said stand for rotational movement about a plurality of axes, including an axis coincident with said single fixed axis.

20. A dental articulator as set forth in claim 19 including a rigid linking means pivotally connected to and extending between said second member and said stand for permitting movement of said second member relative to said stand when said second member pivots about axes not coincident with said single fixed axis and which prevents movement of said second member relative to said stand about an axis coincident with said single fixed axis, and means for releasing the connection between said rigid linking means and one of said stand and second member.

21. A dental articulator comprising a stand, two supports for dental arch casts carried by said stand, two pivots on one of said supports with a common axis, two spaced pivot supports on said stand for receiving said pivots, said pivot supports each providing an elongated path of restrictive movement for said pivots, means securing said pivot supports to said stand for angular adjustment of said paths about a common axis, and means on said stand providing a fixed pivot axis for the other of said supports coincident with said last-mentioned common axis.

22. An articulator as set forth in claim 21 wherein said pivot supports are each in the form of a guide with a groove that receives the end of one of said pivots.

23. An articulator as set forth in claim 22 wherein each of said pivots terminates in a spherical surface and each of said grooves has a back surface that is inclined relative to a plane perpendicular to said common axis of the guides.

24. An articulator as set forth in claim 22 wherein the common axis of angular adjustment through said pivot guides is adjacent one end of each of said grooves so that the center of said pivots coincides with the common axis when the pivots are at said one end of the grooves.

25. A dental articulator comprising a stand, two supports for dental arch casts carried by said stand, two pivots on one of said supports with a common axis, two spaced pivot supports each providing an elongated path of restrictive movement for said pivots and each in the form of a guide with a groove that receives an end of one of said pivots, and means securing said pivot supports to said stand for angular adjustment of said paths about a common axis adjacent one end of each of said grooves so that the center of said pivots coincides with the common axis when the pivots are at said one end of the grooves, each said groove having a back surface that converges toward that of the other in a direction along the length of the groove from said common axis of adjustment.

26. A dental articulator comprising a support frame, two members with dental arch support portions in generally opposed relationship carried by said frame, one having two pivot parts movable relative to the frame to provide translational and rotational movement of said one member relative to the frame, rigid link means functionally constant in length pivotally connected between the frame and said one member to constrain movement of said one member relative to the frame, two cam surfaces one adjacent each of said two pivot parts to control movement of said one member in a direction along an axis defined by said pivot parts, and means carried by said frame for receiving said pivot parts and limiting movement thereof to elongated paths.

27. A dental articulator comprising a support frame, two supports carried by said frame representative of upper and lower jaws, one of said supports having two oppositely projecting pivot members, two grooves on said frame, each receiving one of said pivot members and constraining the received members to movement along the grooves, two cam surfaces carried by said frame and converging toward one another for constraining movement of each of said pivot members in its projecting direction, and a single rigid link functionally constant in length pivotally connected to both said one support and said frame.

28. An articulator comprising a support, a member carried by said support, cooperating connecting means on said member and the support at two locations to permit articulation between the member and the support, means to selectively establish a fixed pivot axis location between cooperating connecting means. and a position adjustment connection between the member and the connecting means thereon to permit selectively changing the location of the connecting means on the member.

29. Apparatus as set forth in claim 28 wherein said position adjustment connection includes means to selectively reestablish one particular location between the member and the connecting means.

30. An articulator as set forth in claim 28 wherein said connecting means at each of said two locations is comprised of an elongated guide slot on said support and a ball connected to said member and engaged with said guide slot and said means to selectively establish a fixed pivot axis includes means to prevent movement of said ball along said slot while permitting rotational movement thereof.

31. In a dental articulator, structure for interconnecting a dental arch support to a stand for relative translation and rotation, said structure including two spaced members on said support, two spaced receptacles on said stand located to concurrently receive said members for relative rotational and translational movement, and means to selectively change the locations of said spaced members on the support to change the relationship of the support relative to the stand.

32. Apparatus as set forth in claim 31 including means to selectively establish one particular location of each said spaced member relative to said support.

33. Apparatus as set forth in claim 32 wherein said means to selectively establish one particular location of said spaced member relative to the support includes a clamping nut with a counterbore, a circular aperture in the support, an annular centering guide movable in an axial direction within the counterbore of the clamping nut such that when the annular centering guide is extended axially beyond the clamping nut, its outside diameter is closely received within the circular aperture in the support and when the centering guide is retracted within the clamping nut, no effective restraint exists between the centering guide and the support.

34. Apparatus as connected forth in claim 33 wherein said centering guide is connencted by pins, which project through axial slots in the clamping nut, to a sleeve surrounding the clamping nut, such that rotation of the sleeve produces rotation of the clamping nut and centering guide, and sliding movement of the sleeve produces a sliding movement of the centering guide relative to the nut.

35. Apparatus as set forth in claim 32 wherein said means to selectively establish one particular location of said spaced member relative to said support includes a knob with a threaded bore, one end of the knob being flat and perpendicular to the axis of the threaded bore for clamping the member in a range of positions relative to the support, and with the other end shaped for positive seating of the member at one particular location relative to the support.

36. Apparatus as set forth in claim 31 wherein each said spaced member includes a pin offset from the central axis of the spaced member, which is received by an elongated slot in the said support such that rotational movement of the spaced member relative to the support is limited.

37. Apparatus as set forth in claim 31 wherein said support has two arms, said two spaced members are each adjustably secured to a different one of said anns, and each receptacle includes an elongated aperture that receives and guides movement of one of said spaced members.

38. Apparatus as set forth in claim 37 wherein said spaced members are ball pivots, and said apertures are located with one portion of each defining a pivot axis for rotational movement of said support relative to said stand, each aperture extending from said axis in a generally common direction with the other aperture, and said structure further including means to retain said ball pivots at said pivot axis.

39. Apparatus as set forth in claim 38 wherein said receptacles are movable relative to said stand to change the direction at which said apertures extend from the axis.

40. A dental articulator comprising a stand, two supports for dental casts carried by said stand in generally opposed relationship, means connecting at least one of said supports to the stand for relative pivotal movement, a stop member extending between said two supports to limit the proximity of the supports to one another, said stop member including means to adjust the effective length of the stop member between the two supports, means to releasably secure the stop members to one of said supports for removal without changing the effective length, two concentric relatively movable parts one of which is pin-like and movable longitudinally relatively to the other, and spring pretension means yieldably retaining said movable parts in longitudinally adjusted positions.

41. A dental articulator comprising a stand having a primary base portion and a frame portion extending therefrom, said frame portion forming a secondary base portion with said primary base portion oriented at approximately to the primary base portion, two dental arch cast support elements secured to said frame portion in generally opposed relationship, at least one of which is pivotally secured to said frame portion, said elements being positionable horizontally when said stand is supported with its primary base portion horizontal and vertically when said stand is supported with its secondary base portion horizontal, a receptacle secured to each of said support elements in opposed relationship for use in securing dental arch casts to said elements, said receptacles each including a side portion extending in a direction from the associated support element toward the other and forming a peripheral receiving surface for a dental arch cast, and an opening in the side portion located to face upward when said secondary base portion is horizontal.

42. A dental articulator as set forth in claim 41 wherein said side portion is deformable.

43. A dental articulator as set forth in claim 42 wherein said side portion is resilient.

44. A dental articulator as set forth in claim 41 wherein said side portion is a foamed sponge-like resilient material.

45. A device for securing a dental arch cast to a support member of an articulator, comprising a base and a readily deformable wall secured to said base, extending therefrom along a path defining a concave shape and with a distal surface adapted to receive a dental arch cast.

46. A device as set forth in claim 45 wherein said wall is resilient.

47. A device for yieldably supporting a dental arch cast and constraining a hardenable material in contact with the arch cast, comprising a compressibly yieldable and resilient barrier means capable of temporarily supporting a dental arch cast and retaining a flowable hardenable material, shaped to form a receptacle for flowable hardenable material and having an opening in the barrier means through which said material can be introduced.

48. A device as set forth in claim 47 wherein said barrier means is formed of sponge-like material.

49. ln combination, a dental articulator with two dental arch support members in generally opposed relatively pivotable, relationship and soft, resilient, positioning members carried by said support members for supporting and resiliently urging dental arches into opposed interengagement during mounting.

S0. A dental articulator comprising a base, two supports carried by said base, each adapted to support a dental arch cast, means securing one of said supports to the base for relative pivotal movement, a plate carried by one of said supports, means securing the plate to the carrying support for relative movement in the plane of said plate, guide means to limit the movement in said plane to a straight path in a direction perpendicular to a plane containing the pivot axis of said pivotally secured support, positive drive means to provide controlled movement of said plate along said path, and a spring bias acting perpendicularly to and between said plate and carrying support to yieldably maintain position of said plate relative to said support.

51. An articulator comprising a support, a member carried by said support, cooperative connecting means on said member and the support at two locations to permit articulation between the member and the support, and adjustable biasing means to urge the member and support in the direction of articulated movement, said adjustable biasing means including a tension wheel rotatably supported on a shaft of the support, a tension spring secured between the tension wheel and the member, and a stop pin extending radially through the wheel and movable to selectively engage in one of a number of apertures in the shaft to control the rotational position of the wheel and hence the tension of the spring.

52. An articulator comprising a support, a member carried by said support, a shaft on the support movable axially, cooperative connective means on said member and the support carried at two locations on the shaft and constructed to permit articulation between the member and the support, and means to laterally shift the shaft relative to the support, including two screws movable in threaded bores, of the support inclined toward one another and acting on and substantially perpendicularly to generally opposed surfaces on said shaft.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3908271 DATED September 30, 1975 INVENTOMS): Harry J. Derda and Charles H. Gibbs fimcmmmdmmamrwmmsmmewWeJMMWwpMWtmdmmsmdLflmwPmwt amhwdwcmmdwasdmwnmmw Column 3, line 2, "aactual" should be actual Column 4, line 45, after "is" confined was omitted;

line 45, erase "t";

Column 9, line 54, "connecting" should be connection Column 11, line 1, cancel "two".

In the C laims:

Claim 8 (Column 16, line 33) change "1" to 4 Signed and Scalcd this sixteenth D ay Of December 1 9 75 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer 7 Commissioner oflarents and Trademarks

Claims

1. A dental articulator comprising a support, two generally opposed jaw-like first and second connections between one said member and the support that permit complex movement of said one member relative to the other, and means, including a rigid link functionally constant in length between said one member and the support pivotally connected to both, to constrain said movement of said one member relative to said support to simulate chewing movement.

2. An articulator as set forth in claim 1 wherein said first and second connections comprise movable pivots.

3. An articulator as set forth in claim 1 including means to change the location of at least one of said link connections to adjust its angular relationship with respect to said support and said one member to change the range of movement of said one member relative to said support.

4. A dental articulator comprising first and second structures, each adapted to support a dental arch cast in opposing relationship to the other; means at two locations of said first structure interengaged with said second structure at two locations to allow said first structure to move relative to said second structure with more than one degree of freedom; and means, including a rigid link functionally constant in length connected for universal pivoting at two locations, one location fixed with respect to the first structure and the other fixed with respect to the second structure, for providing one constraint for the movement of said first structure relative to said second structure.

7. A dental articulator as set forth in claim 4 including means for changing one of said two locations at which the link is connected.

15. A dental articulator as set forth in claim 14 including means to lock the maxillary plate in fixed relationship to the support.

28. An articulator comprising a support, a member carried by said support, cooperating connecting means on said member and the support at two locations to permit articulation between the member and the support, means to selectively establish a fixed pivot axis location between cooperating connecting means, and a position adjustment connection between the member and the connecting means thereon to permit selectively changing the location of the connecting means on the member.

37. Apparatus as set forth in claim 31 wherein said support has two arms, said two spaced members are each adjustably secured to a different one of said arms, and each receptacle includes an elongated aperture that receives and guides movement of one of said spaced members.

41. A dental articulator comprising a stand having a primary base portion and a frame portion extending therefrom, said frame portion forming a secondary base portion with said primary base portion oriented at approximately 90* to the primary base portion, two dental arch cast support elements secured to said frame portion in generally opposed relationship, at least one of which is pivotally secured to said frame portion, said elements being positionable horizontally when said stand is supported with its primary base portion horizontal and vertically when said stand is supported with its secondary base portion horizontal, a receptacle secured to each of said support elements in opposed relationship for use in securing dental arch casts to said elements, said receptacles each including a side portion extending in a direction from the associated support element toward the other and forming a peripheral receiving surface for a dental arch cast, and an opening in the side portion located to face upward when said secondary base portion is horizontal.

46. A device as set forth in claim 45 wherein said wall is resilient.

49. In combination, a dental articulator with two dental arch support members in generally opposed relatively pivotable, relationship and soft, resilient, positioning members carried by said support members for supporting and resiliently urging dental arches into opposed interengagement during mounting.

50. A dental articulator comprising a base, two supports carried by said base, each adapted to support a dental arch cast, means securing one of said supports to the base for relative pivotal movement, a plate carried by one of said supports, means securing the plate to the carrying support for relative movement in the plane of said plate, guide means to limit the movement in said plane to a straight path in a direction perpendicular to a plane containing the pivot axis of said pivotally secured support, positive drive means to provide controlled movement of said plate along said path, and a spring bias acting perpendicularly to and between said plate and carrying support to yieldably maintain position of said plate relative to said support.