US2070025A - Dental instrument - Google Patents

Description

Feb. 9, 1937. G. P. PHILLIPS DENTAL INSTRUMENT 2 Sheets-Sheet 1 Filed June 7, 1934 Feb. 9, 1937. G. P. PHILLIPS DENTAL INS TRUMENT 2 Sheets-Sheet 2 Filed June 7, 1954 Patented Feb. 9, 1937 UNlTED STATES PATENT OFFICE 12 Claims.

This invention relates to scientific instruments designed for use in the study of the physiology of the human jaws and teeth and their relation to each other.

Full chewing efficiency results from the coordination of the curved occlusal tooth planes in correct relation to the forces exerted by the functicning muscles of mastication, and consequently many of the problems with which the dentist must deal have to do with abnormalities in the anatomy or functions of the jaws and teeth. Mechanically considered, the human masticatory apparatus, when in function, moves in three dimensions describing arcs within these dimensions from a multiplicity of centers of rotation. This invention aims to devise an instrument with the aid of which these arcs or paths of movement may be determined and reproduced and which will facilitate the correction of functional and anatomic abnormalities of the jaws.

The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawings, and the novel features will be particularly pointed out in the appended claims.

In the drawings,

Figure 1 is a plan view of an instrument constructed in accordance with this invention;

Fig. 2 is a side elevation of the instrument shown in Fig. 1;

Fig. 3 is a sectional view through a portion of the instrument;

Figs. l and 5 are plan and sectional views illustrating a modification;

Figs. 6 and 7 are sectional views approximately on the lines 0 and 1-1, respectively, Fig. 1;

Fig. 8 is a front elevation of the parts shown in Fig. 3; and

Figs. 9 and 10 are horizontal and vertical sectional views, respectively, of the universal joint.

The instrument shown in the drawings comprises a stand 2 designed to rest on a table or other suitable support. It includes a forwardly projecting arm which terminates in a clamp 3 designed to hold the lower jaw cast. Mounted on the stand 2 is a carriage 4 provided with a forwardly extending arm 5 which carries an upper clamp B for holding the upper jaw cast. The carriage is mounted for floating or bodily movement in a horizontal plane and also for limited movement transversely to said plane.

As above indicated, an important function of instruments of this type is to reproduce the relative movements of the jaws. These movements involve not only forward, backward and lateral components, but also additional components in diagonal planes, and the extent and direction of such movements necessarily vary with different individuals. Consequently, to reproduce such movements accurately and in the ranges necessary to accommodate the great variety of conditions found in patients, is an important functicn of this instrument. This requirement introduces unusual problems in the relative guiding of the jaw casts.

The guiding mechanism for the carriage 4 comprises two upright pins indicated, respectively, at l and 7, both secured rigidly to the upper horizontal arm of the carriage, and equally spaced laterally from the longitudinal median plane of the instrument. Both pins rest on rocking planes, each of which may be tipped forward, backward, or laterally, theoretically into an infinite number of vertical planes, all intersecting the axis of its respective pin. Since the rocking planes for the two pins are duplicates one of the other, a description of one only need be given. Referring more especially to Figs. 2 and 3, it will be seen that the rocking plane 8 for the pin 7 consists of a section of a sphere having an approximately fiat upper surface on which the ball end of the point of the pin 1 rests. While said upper surface can be a plane, it is preferable to make it very slightly concaved, the degree of concavity being somewhat exaggerated in the drawings. For practical purposes this entire guiding surface may be regarded as located approximately in a plane bisecting the sphere, the center of the sphere normally lying in the axis of the pin 1. This hemispherical member 8, which usually is referred to as a rocking plane, or as the horizontal rocking plane, is mounted in a tapered socket 9 formed in a portion of the stand 2, or more conveniently in a bushing ll threaded into the arm a of the stand 2, the socket being of frusto-conical form.

For the purpose of adjusting the rocking member 8 and holding it in any position to which it may be adjusted, a stem 10 is secured rigidly in it and projects downward radially therefrom through av slide or plate l2 with Which the stem has a sliding fit. The connection between the stem and the slide preferably includes a ball I3 through which the stem slides, the ball having a rotary fit with the slide 12 but being held against it by a spring I5 which encircles the stem l0 and bears at its upper end against the ball and at its lower end against a handle l6 threaded on the lower end of the stem. The slide I2 is mounted to run in guideways formed in a second slide I! which is mounted to slide in a direction transverse to the direction of the sliding movement of the part l2, the slide l1, however, carrying the slide i2. By moving the handle l6, therefore, the plane 8 may be rocked in its socket into any one of a multitude of vertical planes, each intersecting the center of the member 8. It can also be swung into any one of a great variety of angular positions in any selected one of said vertical planes. During such movements the spring I5 holds the member 8 bottomed in its socket. The two slides I2 and I? serve to resolve the movements of the rocking member into its two horizontal components. Consequently, by suitably graduating these slides or parts adjacent to them, and associating pointers with them, an accurate designation of any adjustment of the member 8 may be made. As shown in'Fig. 2, the edge of the slide I1 is graduatedin degrees and a pointer l8, Fig. 8, secured to the slide I2 is arranged to run along the lower edge of said graduations as the slide is moved. Another scale, similarly graduated, is secured to the front face of the slide I I, as shown in Fig. 8, and cooperates with a center mark on a stationary part of the instrument to designate the adjustment of the slide I! in either direction away from its central position. A thumb screw I9, Figs. 1, 3 and 8, is threaded through a portion of the slide I! and is arranged to bear against a stationary part of the instrument to lock this slide in its adjusted position, while another thumb screw 28 is threaded through the slide I! and is arranged to engage the edge ofthe plate I2 to lock the latter in its adjusted location.

Parts corresponding to those cooperating with the pin I are provided to cooperate with the other pin 1' at the opposite side of the instrument,and these parts have been designated by corresponding, but primed, numerals. With this arrangement, therefore, it is a simple matter for the user of the instrument to adjust the planes into the positions necessary to suit the requirements of any individual case, to make a record of those positions, and thereafter to reproduce the same adjustment with a high degree of accuracy.

The planes 8 and 8' determine the plane of the path of movement of the carriage, or, in other words, the angular relationship of said path to a horizontal plane. In order to guide the carriage along the desired path or paths in a horizontal plane or in any plane of inclination determined by the members 88', a pair of circular plates, each provided with a knife edge, is arranged to engage the stem I immediately above the plane 8. As shown in Figs. 1 and '7, these two plates 2| and 22, respectively, are mounted one above the other in a circular holder 23 which is set into the arm b integral with the stand 2. Two small bolts 24, 25, Fig. 7, secure the holder in a fixed, stationary position and hold the plates in the part 23. Both of the circular plates 2| and '22, however, are free to be rotated within the holder 23 and they may be selectively locked in their adjusted positions by thumb screws 24 and 25, respectively. These two plates thus may be adjusted so that their knife edges, which engage the stem 1, will define any one of a great variety of angular paths in which the stem can be guided while its lower end rides over the surface of the rocking plane 8. A scale 26, Fig. 1, engraved on the edge of the holder 23, cooperates with pointers 21 and 28, Fig. 7, on the respective plates, to designate the angular positions of the plates for convenience in making a record of the setting required for any individual case. The various parts above described which cooperate with the pin I are duplicated at the other side of the machine to co-a-ct in the same manner with the pin 7.

It is of advantage to be able to rotate the member 8 around the axis of the spindle, together with the slides I2 and I1, while maintaining the relationship of the member 8 to the slides undisturbed. An arrangement suitable for this purpose is illustrated in Figs. 2, 3 and 8 in which an intermediate member 29 is secured to the lower face of the arm a by the socket member a II. This socket member is made of circular outline and is flanged to receive and hold the part 29, while the latter is grooved to support the slide IT. The second slide I2 is carried by the first slide as above described. This arrangement, however, permits the rotation of the part 29, with the slides mounted on it, about the axis of the pin 7 without disturbing the adjustment of the member 8. Normally the member 29 is locked in a stationary position by means of a thumb screw 38, Figs. 2 and 8, threaded through the arm a and bearing against the upper surface of the member 29. A scale 3I-, Figs. 2 and 8, secured to the forward curved end of the arm a cooperates with a center mark 32, Fig. 8, on the intermediate member 29 to designate the degree of angular adjustment of the latter member.

In some instruments which do not require the refinements of the instrument shown in Figs. 2 and 3, a simpler arrangement for supporting the rocking planes may be used. One such construction is illustrated in Figs. 4 and 5-and comprises a rocking plane 34, similar to the member 8, supported in a hemispherical socket formed in the upper surface of a socket member 35 which is mounted on a suitable stand 36. Adjustment of the member 34 into any desired angular position may be made by suitably manipulating screws 31. 38 and 39 located apart around the margin of the rocking member 34. As shown in Fig. 5, the screw 31 is held against vertical movement and is threaded through a slide 40 which runs in a vertical guideway and carries a finger 4| arranged to bear against the edge of the rocking member 34. Each of the other screws 38 and 39 are likewise connected with similar fingers 42 and 43, so that by properly manipulating the three screws the member 34 may be adjusted into any angular position within the limits of this construction. The degree of adjustment so produced can be measured by suitable graduations on the edges of the guides for the slides, or, by making two semicircular rows of graduations, each on great circles of the hemispherical socket in which the member 34 rocks, these two circular lines of graduations being at right angles to each other.

For the purpose of reproducing relative retrusive and protrusive movements and opening and closing movements of the jaws without the loss of normal relations, a post 45, Figs. 1, 2 and 6, is fixed rigidly in the. frame or stand 2 and a ball 46 is slidably mounted on it, this ball being received in a tubular extension 41 projecting rearwardly from the carriage 4. Preferably this extension is a separate piece from the carriage and is provided at its forward end with a horizontally flattened end face to fit against a similar face of the carriage. These parts are secured together by a pivot screw 58, thus providing a joint which permits relative lateral movement between the main part of the carriage and the extension 41. A thumb screw 5I, threaded on the screw 50 looks both of these parts rigidly together, when desired.

The extension 41 can slide freely backward and forward on the ball 46, and the ball can be moved with the extension up and down on the post 45, the upper limit of this movement being predetermined, when desired, by means of a thumb nut 53 threaded on to the post.

This ball may also be used conveniently as a stop in producing the relative protrusive and retrusive movements of the dentures. As shown in Fig. 6, a spring 52 is enclosed in the tubular extension 4'! and abuts at one end against a plate 56, slidable in said extension, and at its opposite end against the end of the bore in said extension. Consequently, this spring tends to force the ball and the carriage apart, and thus to maintain the inner end of the screw 57 against the ball. The screw itself does not directly engage the ball but it carries an internal screw 58 which does bear against the ball. However, this inner screw 58 is used only in making the initial adjustment and thereafter turns with the screw 51 so that so far as the normal functional movements of the screw 51 are concerned, the member 58 is a part of it. It will be evident from an inspection of Figs. 2 and 6 that if the screw 57 is turned inwardly it will act against the ball 46 as a stop to draw the entire carriage and the upper jaw cast backwardly, thus producing a relative protrusive movement of the lower jaw. If a scale. such as that illustrated at 6| in Fig. 1 is operatively associated with this screw, the extent of the said protrusive movement may be measured. It will also be evident that if the screw 51 is backed up, it will permit the entire carriage and the upper denture to slide forwardly and such a sliding movement will be produced by the spring 52 whichserves to hold the plate 56 constantly against the ball 46. The extent of this movement can also be measured on such a'scale as that shown at 6|, Fig. 1.

Frequently it is important in making these movements to be able to come back quickly to a zero position. This position may conveniently be fixed by means of a spring pressed pin 62, Fig. 6, slidable freely in a portion of the extension 41, the lower end of this pin being adapted to enter a hole drilled radially in a smooth or non-threaded part of the screw 51. The initial zero adjustment is made with the pin 62 looking the screw 51 against rotation, as shown in Fig. 6, and then turning the inner screw 58 inward or outward, as desired, until the carriage is brought into its central or zero relationship to the stationary parts of the instrument. This screw 5'! then is locked in its adjusted position by means of a set screw.

: Thereafter the screw 51 may be freed from the locking pin whenever desired by lifting the latter and the end of this pin will simply ride on the smooth unthreaded portion of the screw until the latter is brought back again to its zero position.

When it is desired to make the movements of the carriage as free as possible, the plate 56 may be moved forward to compress the spring 52, after which its ends, which are relatively narrow and flat, are forced into notches 63, which look the plate and thus hold the spring in a compressed condition. Several pairs of these notches provide for the locking of this plate in different positions.

It will be observed that in this instrument the movements of the carriage, and consequently of the upper jaw cast, are guided by the engagement of the lower ends of the pins 1 and l with the horizontal planes 8 and 8. Since these rocking planes can be adjusted into a horizontal plane or any angle of inclination (within the limits of the instrument) with reference to such a plane, an almost infinite variety of angular paths of movement may be produced. The direction of any desired path may also be predetermined by properly adjusting the knife edges 2| and 22 and 2| and 22', all of which can be moved through a range of 360. Consequently, the relative movements in three dimensions made by the jaw can be reproduced with a high degree of accuracy. In addition, the protrusive and retrusive movements can be closely simulated. In opening the bite the tipping movement of the carriage is guided partly by the movement of the ball 46 on the post 45 and partly also by the contact of the lower ends of the pins 1 and I with the rocking planes 8 and 8. Also, the carriage can be freed from any substantial drag of the extension 47, when desired, by compressing and locking the spring 52 and loosening the thumb nut 5|. The wide range of movement thus provided in this instrument greatly facilitates the study of anatomic and functional abnormalities of the jaws and teeth and enables the dentist to reproduce faithfully the conditions peculiar to individual cases.

Preferably the upper arm 5 is hinged to the carriage 4 by the thumb screw 65 so that it can be swung upwardly, whenever desired, relatively to the carriage or may be locked rigidly to the latter.

A novel form of clamp for securing the jaw casts in position is provided, that for the upper cast comprising three threaded rods 66, 61 and 68, all pivoted independently between the collars 68 of the upper clamp 6 to swing around the axis of the clamp. On each rod is a slide 10 carrying two pins which project downwardly therefrom and serve to engage the sides of the cast and each slide is backed up by a screw H which serves to force it inwardly against the cast or to release it to permit the removal of the cast. The lower clamp is of essentially the same construction.

Preferably the upper clamp 6 is secured to the arm 5 by a universal joint which permits adjustment of the upper clamp in any direction in a horizontal plane relatively to the arm as well as rocking or angular adjustments. This joint construction is best shown in Figs. 2, 9 and 10. As

there illustrated, the clamp is mounted on the lower end of a vertical rod H which passes through a split ball 12. This ball is held between upper and lower socket members 13 and 14, respectively, having spherical surfaces to engage the ball, and these socket members, in turn, are mounted in a holder which includes a cylindrical extension [5 integral with and projecting downwardly from the arm 5 and a collar 16 threaded on said extension. It will be observed that the holes in the arm 5 and collar 16 through which the rod or stem H projects are relatively large so that they permit a considerable movement of the stem relatively to the arm in any direction in a horizontal plane and also provide for a considerable rocking movement of the stem about the center of the ball 12. The upper clamp 6 is rigidly secured to the stem and consequently moves with it. This arrangement, therefore, provides for the movement of the upper clamp and the jaw cast secured in it into various relationships to the lower east. When it has been moved into its adjusted position it can be clamped by turning up the threaded collar 16. In addition, a nut 11 is threaded onto the upper end of the stem H and provides for the vertical adjustment of the clamp 6 and the upper jaw cast relatively to the arm 5.

While I have herein shown and described a preferred embodiment of my invention, it will be understood that the invention may be embodied in other forms without departing from the spirit or scope thereof.

Having thus described my invention, what I desire to claim as new is:

1. In an instrument of the character described, the combination of a stand, a carriage mounted on said stand for floating movement in substantially any direction in a horizontal plane and for additional movement away from said plane, means for fastening a cast to said carriage, means for guiding said carriage comprising two pins secured to said carriage and spaced apart, two rocking hemispherical members each provided with a substantially fiat upper surface for supporting said pins, respectively, for movement on said surfaces, means provided with sockets supporting each of said members for tipping adjustment in any vertical plane intersecting said surfaces of the respective rocking members, and additional means cooperating with said rocking members to engage and guide said pins in the desired paths as said pins are moved on the surfaces of said rocking members, said additional means being adjustable to vary the direction of said paths, as desired.

2. An instrument according to preceding claim 1, characterized by the fact that said additional means for guiding each pin comprises a pair of straight edged plates, and means for supporting said plates for adjustment about approximately the axis of the pin which they guide to form an angle along the edges of which the pin can. move.

3. An instrument according to preceding claim 1, characterized by the fact that said additional means for guiding each pin comprises a pair of straight edged plates, means mounted on said stand for supporting said plates for adjustment around the axis of said pin into any angular position within a range of substantially 360, and scales associated with said plates for designating their angular positions.

4. An instrument according to preceding claim 1, comprising a stationary post mounted on said stand at the rear of the vertical plane connecting said pins and approximately midway between said rocking planes, an extension projecting rearwardly from said carriage and cooperating with said post to guide the carriage, a joint connecting said carriage with said extension and permitting relative lateral movement between said carriage and said extension, and means for lock ing said extension rigidly to said carriage when desired.

5. An instrument according to preceding claim 1, comprising a stationary post mounted on said stand at the rear of the vertical plane connecting said pins and approximately midway between said rocking planes, a tubular extension projecting rearwardly from said carriage, a ball slidable on said post and positioned in said extension, a spring located in said extension and tending to force said carriage and ball away from each other, and screw threaded adjusting means for engaging the side of said ball opposite to said spring and cooperating'with said ball to adjust the position of said carriage in the desired forward and backward relationship.

6. In a dental articulator, the combination with a stand, a carriage mounted on saidstand for bodily movement in substantially any direction in' a horizontal plane and for limited movement transversely to said plane, and means for fastening a cast to said carriage, of means for controlling the movements of said carriage comprising a rocking member having a shape substantially like that of a section of a sphere and provided with an approximately fiat upper surface, a support having a socket in which said member is mounted for substantially universal tipping movement around the center of said sphere, and means operable to adjust said member into any of its various angular positions.

'7. In a dental articulator, the combination with a stand, a carriage mounted on said stand for bodily movement in substantially any direction in a horizontal plane and for limited movement transversely to said plane, and means for fastening a cast to said carriage, of means for controlling the movementsof said carriage comprising a rocking member having a shape approximately like that of a section of a sphere and provided with an approximately fiat upper surface, a support having a socket in which said member is mounted for substantially universal tipping movement about the center of said' sphere, and two horizontal slides operatively connected with said member and movable transversely to each other for indicating variations in the positions of adjustment of said member about said center.

8. An instrument according to preceding claim 6, characterized by the fact that the socket in' which said member is mounted is tapered about an axis passing substantially through the center of said member.

9. An instrument according to preceding claim 6, in which said adjusting means comprises a stem extending radially from said rocking mem ber, a slide through which said stem projects, and a ball guide for said stem mounted in and movable with said slide.

10. An instrument according to preceding claim 6, in which said adjusting means comprises a stem extending radially from said rocking member, a slide through which said stem projects and with which it has a sliding fit, whereby said member may be angularly adjusted by moving said slide, and means cooperatively associated with said slide to indicate the angular positions of said member.

11. An instrument according to preceding claim 6, in which said adjusting means comprises a stem extending radially from said rocking member, a slide through which said stem projects and with Which it has a sliding fit, whereby said member may be angularly adjusted by moving said slide, a second slide mounted on said stand for movement transversely to the direction of sliding movement of the first slide, the first slide being carried by said second slide, the upper surface of the first slide being graduated, and a pointer associated with said graduations to indicate the angular positions of said rocking member.

12. An instrument according to preceding claim 6, in which said adjusting means comprises a stem extending radially from said rocking member, a slide through which said stem projects and with which it has a sliding fit, whereby said member may be angularly adjusted by moving said slide, a second slide mounted on said stand for movement transversely to the direction of sliding movement of the first slide, the first slide being carried by said second slide, and means for supporting both of said slides on said stand for rotary adjustment around the center of said rocking member.

GEORGE P. PHILLIPS.

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