US3518761A - Pin and sleeve combination to support dies in dentistry - Google Patents

Description

July 7, 1970 H. SUSMAN EI'AL 3,518,761

PIN AND SLEEVE COMBINATION TO SUPPORT DIES IN DENTISTRY Filed Sept. 28, 1967 INVENTORS HARRY SUSMAN JON E. SUSMAN ATTORNEY United States Patent 3,518,761 PIN AND SLEEVE COMBINATION TO SUPPORT DIES IN DENTISTRY Harry Susman and Jon E. Susman, both of 6439 Prestonshire, Dallas, Tex. 75225 Filed Sept. 28, 1967, Ser. No. 671,450 Int. Cl. A61c 13/00 US. CI. 32-11 12 Claims ABSTRACT OF THE DISCLOSURE A pin and a sleeve that only partially surrounds it in supporting engagement are used in conjunction with a stone die and model. The pin has a rod portion which extends into the die, with the pin base or shank extending outwardly from the die. The sleeve is set in the stone base of the model and is adapted to receive the shank of the pin in order to support the removable die. The sleeve is well supported in the stone since it has portions disposed to resist axial displacement with respect to the stone.

FIELD OF THE INVENTION This invention relates to dentistry, and, more particularly, to the fabrication of inlays and crown and bridge prosthesis. The pin-sleeve combination of the present invention is utilized to support removable castings of the preparations, i.e., dies, on a stone model. The support so, provided is highly stable and maintains the relative spatial relationships of the dies one to the other, and to the model, even though the dies be removed and reimplaced numerous times.

BACKGROUND OF THE INVENTION It is well known in the art to utilize an impression, followed by a casting in stone, to provide a model of a patients teeth and surrounding gum structure. As an example, if a single missing tooth is to be replaced by a prosthesis, typically a so-called 3-unit bridge would be utilized. The immediately adjacent teeth on either side of the missing one are prepared to receive and support the ends of the bridge structure. At this point an impression is taken, as by hydrocoiloid, rubber base, silicones, etc., and from the impression, the shape of the teeth and the gum structure of the patient is cast in die stone. The integrity of the shape and the relative spatial relationships of the castings of the preparations which support the bridge structure are most important if the prosthesis is to fit properly. Moreover, it is necessary that the preparation castings be individually removable or separable from the body of the stone casting in order to make the subsequent prosthesis possible. For this reason, the stone model ridge approximating the preparation casting is cut or sawed along an even line to provide for removing and replacing the preparation castings as required. These resulting removable preparation castings are known in the art as dies, and they will be hereinafter so designated.

The stone casting, including the dies, is mounted upon a stone base or substrate region of stone. This provides a working model of the prepared teeth and gum structure of the patient. Then this model is articulated with a stone casting of the opposing teeth. The bite of the patient is set up by this procedure. In such an articulated structure, the dies need to be removable, and yet it is important that they be replaceable in precisely their original position. A popular prior art method of providing such removability is to insert a die pin member into the central base region of the preparation casting before the stone has hardened. The shank of the pin extends outward from the base of the die. Thereafter, a stone base is formed as a support for the die and the shank of the die pin extends into this base. The

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die may be removed by simply withdrawing the die pin from the mating recess in the stone base. Replacement is accomplished by inserting the die pin again into position in the stone base.

While the procedure described above has the advantage of simplicity, it possesses a marked disadvantage. The removal and reinsertion of the die pin into the mating recess in the stone invariably wears the stone material that defines the recess. This occurs even when great caution is exercised. The results are most unfortunate. The die no longer is supportable in its precise original position, and as a result, the spatial relationship of the dies to each other, indeed to the balance of the model, is no longer accurate. This loss of accurate relative spatial positioning results in inaccuracy in the prosthesis made from the model.

The present invention is directed to overcoming the problem just described. It involves the provision of a sleeve member which only partially surrounds and encases the pin shank to provide support for it. The sleeve and pin as a unit are cast in the stone base, and the sleeve remains in the stone base as a stable support for the pin. When the pin is removed, or replaced, the rubbing or sliding contact is with the relatively tough sleeve, which remains in an integral relationship with the stone.

It appears that a sleeve and pin combination has had limited use in the past. In such combination, the sleeve served as a full scabbard for the pin and entirely surrounded it. The tolerance problems inherently present in such an arrangement have caused the combination to be unsatisfactory since the pin, in most instances, moves laterally with respect to the scabbard. Moreover, the full scabbard member of the prior art itself was susceptible to being axially unstable in the stone. Accordingly, the pin and full scabbard prior art combination was prone to cause both lateral and axial movement. The present invention overcomes these problems with an inexpensive structure which is simple to fabricate.

THE DRAWINGS FIG. 1 is a pictorial view of the pin-sleeve combination of the present invention, the pin and sleeve being shown in disengaged position;

FIG. 1A is a section taken along the longitudinal axis of the pin-sleeve combination of FIG. 1, the pin and sleeve being in engagement in this view;

FIG. 2 is a pictorial illustration of an impression tray carrying die stone in which two pin-sleeve members of the present invention are mounted;

FIG. 3 is a section taken along 33 of FIG. 2;

FIG. 4 is a pictorial view schematically illustrating a stone model utilizing two of the die-pin members of the present invention;

FIG. 5 is a sectional view through a die and stone base and showing their engagement by means of the pin-sleeve combination of the present invention;

FIG. 6 shows the same subject matter as FIG. 5, except the stone base and sleeve are shown alone, with the die pin and die removed; and

FIG. 7 is a pictorial illustration of a preferred embodiment of sleeve which is adapted to be adjustable to eliminate tolerance problems.

DESCRIPTION OF A PREFERRED EMBODIMENT FIGS. 1 and 1A illustrate a die pin 11 and die sleeve 13. The pin comprises a pin shank 15 which is shaped generally as the frustrum of a four sided pyramid. Integrally from the base of the shank concentrically extends a knurled support rod 17 which is adapted to seat within a die, as subsequently will be explained.

The sleeve 13 includes a pair of spaced apart generally rectangular frames 19 and 21. The frame 19 is larger than the frame 21, and both are constructed so that the inner frame faces are at an angle corresponding to the angle of the faces of the pin shank 15. An integral strap 22 connects and coaxially supports frames 19 and 21 in spaced relationship. Note that sleeve 13 is adapted to receive the pin 11, with frames 19 and 21 in mating and supporting relationship with pin shank 15 (see FIG. 1A).

It is preferred that outer frame 19 have a reverse taper, compared to the sense of the taper of pin shank 15 (FIG. 1A). The importance of this reverse taper will be explained at a later point herein.

The die pin 11 may be made of a variety of materials, since any material may be used that has good structural integrity and that is abrasion resistant, as contrasted to stone. The sleeve 13 is made of a material with similar properties. Exemplary of suitable construction materials for the pin and sleeve are stainless steel, aluminum, brass, copper and metal alloys. In general, the material of construction will be a metal; however, other comparatively strong and abrasion resistant materials may be utilized.

FIGS. 2 through 6 illustrate the utilization of the die pin and sleeve combination of the present invention. In FIG. 2, impression tray 30, carrying impression 31, is filled with stone 32. Note that impression tray 30 is marked with indica 33 to provide a way to locate the cast dies.

Die pins 11 extend upwardly from the central regions defining the base of each die. The pins and mating sleeves 13 are placed in position as a unit after the stone is vibrated in the impression tray but before the stone hardens. Such emplacement is accomplished by inserting the knurled rod 17 of each pin and the upper portion of frame 19 into the die stone. Note that after insertion the frame 19 is partially embedded in the stone die, e.g. with about half the frame within the stone die and the other half extending above it.

The appearance of each die at the stage of FIG. 2 is schematically illustrated in FIG. 3, which is a schematic section applicable to either one of the dies being cast in FIG. 2. Note that knurled rod 17 and the upper portion of frame 19 extend into the central base portion of the stone die 35, which is surrounded by the impression 31, carried in support tray 30.

After the step of FIGS. 2 and 3, the stone is permitted to harden. A conventional release agent is applied over the die area and additional stone is then poured over the casting carried by the impression tray 30. The wet stone is vibrated and then permitted to harden. This provides a model stone base 39 (FIG. as is well known in the art. The sleeve 13, carrying the pin shank 15, of each die 35 is covered by the moist stone preparation, and on setting, the sleeve 13 becomes embedded in the hardened stone base. Thereafter, the tray and rubber base impression are removed and cuts, as by a saw, are made on either side of the dies in the locations defined by indicia 33, and the dies are then separable from the model. The separation of the die from the model is facilitated by the reverse taper of the frame 19, which permits the die to be easily removed from the frame.

The appearance of the resulting model is pictorially illustrated in FIG. 4, wherein the removable dies 35 are carried by stone base 39 of the model 41. The sleeves 13, with the exception of the end of frames 19, are embedded in and supported by the stone base 39. (FIGS. 4, 5 and 6). Each pin shank 15 is removable from its sleeve to define a mating cavity in the stone base (see FIG. 6). Moreover, since the sleeve only partially encases the pin, a large portion of the pins surface is encased with and supported directly by the stone base. Indeed, over half the supporting and encasing area for the pin is provided by direct contact with stone in the embodiment being described since the frames are spaced rather far apart, compared to their axial dimensions, and since the planar interconnecting strap 22 for the frames lies along only one side of the pin.

Removal and replacement of the pin shank does not disturb the sleeve, which remains anchored in the stone base. The reverse taper of frame 19 assists in assuring that the sleeve remains anchored, as do the embedded end edges of frame 19 and frame 21.

It will then be apparent that the pin shank may be reinserted into the stone supported sleeve, and removed, as desired, without disturbing the relative positions of the dies to the model.

It should be noted that the reverse tapered frame 19 provides direct support for the die since a part of the frame extends into the die when the die is emplaced on the model. This extension of the frame into the die has another advantage. It makes it possible to vibrate the material from which the stone base is being formed (before hardening of this material) without dislocating the proper position of the sleeve 13.

It is preferred that the tip of pin shank 15 stick out of the bottom of stone base 39 (FIG. 5). This is helpful in removing a die 35 since a push on the pin tip will loosen the die. This extension of the tip may be obtained by removing stone from the bottom of the stone base after it is cast.

In some instances, despite reasonable care in manufacture, tolerances of the frames of the sleeve 13 and the pin v11 will not be compatible to provide support against all lateral movement of the pin relative to the sleeve. The embodiment of sleeve member illustrated in FIG. 7 provides means to solve this problem. The frames 19a and 21a of sleeves 13a are separated by slits at 109 and 111, respectively, in their sides opposite the interconnecting strap 22a. Such slits make it possible to mash the frames together, as required, to closely engage and support a pin positioned within the sleeve. By utilization of this embodiment, tolerance problems are eliminated.

In summary, the present invention overcomes numerous problems of the prior art. High quality crown and bridge prosthesis is an exacting science demanding the absolute maintenance of spatial relationships. The present invention meets this demand. The unique design of the pin and partial sleeve firmly locks the sleeve in the stone base thus completely eliminating any lateral or axial movement. Slits in the frames may be utilized to provide means to adjust for occasional manufacturing deficiencies. The reverse taper of the larger sleeve frame has many unique advantages. This frame not only helps lock the sleeve securely in the stone base, but also facilitates the easy removal of the die pin. In addition, the upper edge of this frame is, in effect, a part of the base of the die unit itself when the die is in position on the model. This feature imparts great strength to the die (crown portion) making breakage of the die from its rod supports virtually impossible.

What is claimed is:

1. A dental pin-sleeve combination comprising:

(1) a pin having a tapered shank portion with anchor means extending from one extremity thereof; and

(2) a partial sleeve adapted to receive said pin, comprising a pair of spaced apart frames, interconnected by a strap portion, said frames having inner tapered surfaces generally parallel to the taper on said pin to provide close engagement of the tapered surfaces of the pin and frames when said sleeve receives said pin, and at least one of said frames having a reverse taper on its outer surfaces with reference to the tapef of said shank. I"

2. The combination of claim 1 wherein one of said frames is larger than the other of said frames, and wherein the larger frame has a reverse taper on its outer surfaces.

3. The combination of claim 1 wherein said pin shank is generally shaped as the frustru-m of a four sided pyramid and said one frame having the reverse taper on its outer surface, and being adapted to receive and support the surface of said pin adjacent the base portion of said frustrum.

4. The combination of claim 3 wherein each of said frames is configured to provide a generally axial slit therein.

5. The combination of claim 1 wherein each of said frames is configured to provide a generally axail slit therein.

6. A dental pin-sleeve combination comprising:

(1) a pin having a shank portion with anchor means extending from one extremity thereof; and

(2) a partial sleeve adapted to receive said pin comprising a pair of spaced apart frames, interconnected by a strap portion, each said frame carrying surfaces that are adapted to mate with surfaces of the shank portion of said pin and provide lateral support thereof, and wherein each of said frames includes means to adjust its transverse dimensions to permit tightening said frame to better laterally support said pin.

7. The combination of claim 6 wherein each of said frames is configured to provide a generally axial slit therein.

8. A dental pin-sleeve combination comprising:

(1) a pin having an elongated tapered shank and anchor means extending from an end of said shank; and

(2) a sleeve adapted to receive said pin, said sleeve including an inner surface portion adapted to mate with said pin adjacent the said end of the shank, said sleeve further including an outer surface portion having a reverse taper with reference to the taper of said shank.

9. A dental pin-sleeve combination comprising:

(1) a pin having a tapered shank portion with anchor means for supporting a die extending from one extremity thereof; and

(2) a partial sleeve adapted to receive said pin and only partially enclose the shank portion thereof comprising a pair of spaced apart frames interconnected by a strap portion, one of said frames being adapted to extend partially within said die when receiving said pin.

10. The combination of claim 9 wherein one of said frames is larger than the other of said frames, and Wherein the larger frame has a reverse taper on its outer surfaces.

11. The combination of claim 10 wherein said pin shank is generally shaped as the frustrum of a four-sided pyramid, and wherein said larger frame is adapted to receive and support the surface of said pin adjacent the base portion of said frustrum.

12. The combination of claim 11 wherein each of said frames is configured to provide a generally axial slit therein.

References Cited UNITED STATES PATENTS 1,867,300 7/1932 Bailey 3240 3,286,350 11/1966 Cooper 324O ROBERT PESHOCK, Primary Examiner

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