WO1999052466A1

WO1999052466A1 - Stepless adjustment of angular orientation of abutment for dental implant

Info

Publication number: WO1999052466A1
Application number: PCT/US1999/007982
Authority: WO
Inventors: Dan P. Rogers; Stephan S. Porter; Glenn L. Criser
Original assignee: Implant Innovations, Inc.
Priority date: 1998-04-13
Filing date: 1999-04-12
Publication date: 1999-10-21
Also published as: AU3555299A

Abstract

Orientation of an abutment (20) relative to a dental implant (10) is made infinite by providing locking tapering surfaces (23) on a two part abutment, the first part (22) of which is secured in a fixed position on the implant (10), and the second part (24) is infinitely adjustable relative to the first part (22).

Description

1

STEPLESS ADJUSTMENT OF ANGULAR ORIENTATION OF ABUTMENT FOR DENTAL IMPLANT

FIELD OF THE INVENTION

The present invention relates generally to dental implant systems and, more particularly, to a dental implant abutment system in which the abutment is angled and can be adjusted to any desired azimuthal position around the axis of the implant. BACKGROUND OF THE INVENTION

Dental abutments are important components used to restore dentition supported on artificial roots implanted in living jawbone at an edentulous site. An artificial tooth is fixed to an abutment which, in turn, is fixed to the implanted root (commonly called an "implant"). Implants and abutments exist in a variety of designs; for each implant design there is need for an abutment that will be attachable to the implant with strength adequate to support an artificial tooth in normal use and, if need be, to restrain that tooth against twisting or rotating around the implant. One implant design that is in widespread use has a generally flat platform surface on which to support an abutment and on this surface a non-round projection (most often a polygonal projection which is frequently, but not always, of hexagonal cross-section) for restraining the abutment against twisting or rotating around the implant. Abutments made for use with that design have a non-round socket which encloses the implant projection as tightly as is practical for ease of assembly and disassembly of the two parts. These abutments are attached to these implants with a retaining screw that fits into a threaded bore in the implant which opens through the non-round projection. Implants and abutments using this design are used to make screw-retained dental prostheses which are attached to one or more implants with such screws, and which can be "unscrewed" from the supporting implant or implants to permit repair or for reasons of hygiene.

For the most part, screw-retained dental prostheses of the type described have enjoyed widespread use and success. Improvements in the size and shape of the implant platform and the anti-rotation interlock and better understanding of the physical requirements placed on the retaining screw have combined to greatly improve reliability of the system. One problem, however, has remained for many years with, at most, only a 2

partial solution. The anti-rotation interlock is based on a projection of polygonal cross- section and a mating socket which envelops the projection when the abutment is assembled to the implant. If the polygon is a hexagon, the parts can be locked in only one of six specified angular orientation positions spaced 60° apart, one relative to the other. An interlock employing eight-sided polygons will afford eight angular orientation positions spaced 45° apart, and an interlock employing twelve-sided polygons will afford twelve orientation positions spaced 30° apart. This is about the practical limit of angular adjustability that can be achieved using interlocking elements having polygonal cross- sectional shapes, owing to the small sizes of the parts used in implant dentistry. For example, in the hexagonal configuration, which consists essentially of three pairs of flat parallel surfaces, the distance between the flat surfaces of any one pair is typically about 0.1060-0.1065 inch (2.69-2.71 mm). Increasing the number of flat sides to more than twelve would reduce the size of each side so as to be too small to function effectively as an interlock. Other interlock configurations, such as, for example, castellated interlocks, suffer similar constraints.

Many frustrating situations confront the prosthodontist constructing a dental prosthesis which require greater freedom to orient a particular tooth relative to an underlying implant than is afforded by the constraints of existing interlock structures. Underlying most of these situations is the fact that the patient's jawbone is not everywhere equally suited to receive a dental implant, and often the best quality bone in which to place an implant is not the best location for the restored tooth. One result may be that the implant is not aligned with adjacent dentition, and use of an abutment that extends from the implant at an angle relative to the axis of the implant (an "angled abutment") may be indicated in order to support an artificial tooth that is aligned with the adjacent dentition. In such a case, it is of utmost importance that the abutment be freely orientable around the axis of the implant. In the case of a single tooth restoration, especially an anterior (front) tooth which naturally has an almost flat surface exposed to view, it is again of utmost importance that the supporting abutment be freely orientable around the axis of the implant. Some dental surgeons skilled in installing dental implants try to place the implants with orientation in the jawbone preselected to provide the desired orientation of the finished prosthesis, but this is an arduous task requiring special tools and great skills and of doubtful value in cases requiring use of angled abutments. SUMMARY OF THE INVENTION

This invention provides a mounting structure for attaching an abutment to an implant with freedom to adjust and fix the orientation of the abutment around the implant axis in a stepless infinity of angular positions relative to that axis. The gingival end of the implant, which is accessible at or near the surface of the jawbone in which the implant is fixed, is provided with a two-part abutment including a first part having a cone-shaped surface that tapers on a small angle suitable for use in a locking taper as it extends from the jawbone through the overlying gum tissue. The second part of the abutment is adapted for fixation to the first part and has a conical surface tapering on the same angle for mating with the first part. The first part is an initially separate member attached to an implant using, if desired, an available anti-rotation interlock means of that particular implant. The invention includes means to fasten together the two components having the conical locking tapers once their relative angular orientation has been selected. The process of the invention includes the steps of bringing these two components together, setting the desired relative angular orientation between them, and fastening them together. Selection of the relative angular orientation is stepless, and the angular positions that can be chosen are infinite in number. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially-sectioned longitudinal side view of a first embodiment of an implant abutment assembly embodying the invention.

FIG. 2 is a partially-sectioned longitudinal side view of a second embodiment of an implant abutment assembly embodying the invention. FIG. 3 is a partially-sectioned longitudinal side view of a third embodiment of an implant abutment assembly embodying the invention.

FIG. 4 is a partially-sectioned longitudinal side view of a fourth embodiment of an implant abutment assembly embodying the invention.

FIG. 5 is a partially-sectioned longitudinal side view of a fifth embodiment of an implant abutment assembly embodying the invention. 4

FIG. 6 is an exploded side elevation of the abutment of FIG. 5, with the first part of the abutment shown in section.

FIGS. 7a and 7b are a partially-sectioned longitudinal side view of a sixth embodiment of an implant abutment assembly embodying the invention and a plan view of the abutment.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In FIG. 1, a dental implant 10 of well-known form has on its gingival surface 12 a non-rotational connection fitting in the form of a projecting boss 14 of hexagonal cross- section. An angled abutment 20 of the invention has first and second parts 22 and 24, interconnected via locking tapered surfaces 21 and 23, respectively. When these two parts are interconnected, the first part 22 is within the second part 24 and, by virtue of the locking taper connection, they function in use as a single piece abutment. The first part 22 has an internal socket 22a which may take any known form (not shown) which mates non-rotationally with the boss 14 when the abutment is mounted on the implant. A connecting bolt 16 fastens the abutment 20 to the implant 10. This bolt has a socket 18 in its head suitable for engaging a wrench, such as an Allen wrench, for turning the bolt into a threaded bore 10 of known form in the implant. When the bolt 16 is tightened, it forces the locking taper surfaces 21 and 23 together.

In use, the first part 22 is placed on the implant, and the second part 24 is placed over the first part while being oriented to a desired orientation position around the implant axis, and then the two parts are forced together to lock the taper. Thereafter, the abutment can be removed from the implant as a single body comprising both pieces, and can be put back on the implant using the boss 14 to locate the abutment with the same orientation position. It is recognized that the first part 22 of the abutment could be made integral with the implant 10, eliminating the need for the boss 14, in which case a portion of the tapered surface 21 could be given a cross-sectional shape that would be useful to engage a wrench for driving the implant into a bore in living bone. Alternatively, the wrench could engage the interior of the implant. With an implant so modified, the abutment would consist of only the second part 24. Removal of the abutment from the implant 5

would then require breaking apart the tapered surfaces 21 and 23, and memory of the orientation position of the abutment relative to the implant axis, which is provided by the boss 14, would be lost. The embodiments of the invention that are illustrated in the drawings preserve memory of the orientation position of the abutment relative to the implant axis when the abutment is removed from the implant.

In FIG. 2, a different abutment 40 is mounted on the implant 10. This abutment comprises a first part 42 fitted internally with a shoulder 45 that is engaged under the head 47 of the attaching bolt 46. The bolt 46 is shorter than the bolt 16 in FIG. 1 ; the bolt 46 and its head 47 are otherwise similar to the bolt 16 and its head 18. In FIG. 2, the bolt 46 serves to fasten the first part 42 of the abutment 40 to the implant. The second part 44 of this abutment is connected to the first part only through the locking taper surfaces 41 and 43. When these two parts are assembled in the desired orientation position around the implant axis, the head 47 of the bolt is spread into a reverse-tapered surface 48 within the abutment, to lock the two parts together. To spread the head 47, an anvil member 50 is located within the abutment at the bottom of a bore 52 and resting on the head 47 and partly within its hollow wrench socket. A long tool (not shown) is placed within the bore 52 and impacted with a suitable hammer. Internal threads 54 within the bore 52 near its opening are useful to receive a bolt (not shown) for retrievably attaching a dental prosthesis to the abutment. FIG. 3 is similar to FIG. 2 except that in FIG. 3 a sphere 50' is substituted for the anvil 50 in FIG. 2, and the second abutment part 44 is modified internally to receive the sphere.

The embodiment shown in FIG. 4 provides an abutment 80 with an internally threaded bore 82 suitable for retrievably attaching a dental prosthesis, as in FIGS. 2 and 3, and which can be removed from the implant 10 if desired. The first part 84 of this abutment is held to the implant 10 with an attaching screw 86, as in FIGS. 2 and 3, except that the screw head 88 rests on the top of the part 84 rather than on an internal shoulder. The second part 90 of this abutment fits over the screw head 88, and a pair of locking taper surfaces 92 and 94 engage. 6

The embodiment shown in FIGS. 5 and 6 locates the locking taper surfaces in a bore 100 in the first part 102 of the abutment, and on the outer surface of the lower portion 103 of the second part 104 of the abutment. A locking screw 105 extends down through a hole 106 extending through both parts of the abutment and threads into a threaded bore in the implant, with the head of the screw 105 resting on a shoulder 107 within the hole 106 in the second abutment part 104. As in the other embodiments, tightening the screw 105 draws the two tapered surfaces together for locking engagement.

FIGS. 7a and 7b illustrate an embodiment in which the outer surface of the abutment is not round. Although the embodiments of FIGS. 1-6 are not necessarily limited to round exterior shapes, FIG. 7 shows that they may be made to suit the shape of the final prosthesis, which reproduces a natural tooth. The shape shown in FIG. 7b may be used to mount a prosthesis which replaces a natural molar. FIG. 7 is similar to FIG. 1 in its design. The first part 22 of the abutment 20 fits over boss 14 of implant 10. The second part 24 of the abutment 20 fits over first part 22 and the locking tapers 21 and 23 engage in the desired position of second part 24. Bolt 16 is inserted through abutment 20 and engages the interior threads (not shown) of implant 10. The head of bolt 16 seats on a shelf in the second part 24. The socket 18 receives a driver used to secure the bolt 16 in the implant 10. Surface 1 1 provides a base for mounting the prosthesis. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention. Each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the claimed invention, which is set forth in the following claims.

Claims

7WHAT IS CLAIMED IS:

1. A dental implant abutment system comprising the combination of a dental implant having a threaded bore therein and a non-round projection on the gingival end thereof; a two part abutment including a first part forming a non-round socket for fitting over said projection on said implant for preventing relative rotation between said implant and said first part, and a second part having a socket for receiving at least a portion of said first part, with opposed surfaces of said first and second parts forming cooperating locking tapers for locking said first and second parts together when said opposed surfaces are drawn against each other; and a locking screw having a threaded stem for making threaded engagement with said threaded bore in said implant for attaching said abutment to said implant, said screw having a head engaging said second part of said abutment for drawing said opposed tapered surfaces of said first and second parts together for locking engagement.

2. A dental implant abutment system comprising the combination of a dental implant having a threaded bore therein and a non-round projection on the gingival end thereof; a two part abutment including a first part forming a non-round socket for fitting over said projection on said implant for preventing relative rotation between said implant and said first part, and a second part having a socket for receiving at least a portion of said first part, with opposed surfaces of said first and second parts forming cooperating locking tapers for locking said first and second parts together when said opposed surfaces are drawn against each other; and a locking screw having a threaded stem for making threaded engagement with said threaded bore in said implant for attaching said abutment to said implant, said screw having a head engaging said first part of said abutment for securing said first part to said implant.

3. A dental implant abutment system of Claim 2, further comprising an anvil member for securing said second part to said first part by engaging and spreading the head of said locking screw. 8

4. A dental implant abutment system comprising the combination of a dental implant having a threaded bore therein and a non-round projection on the gingival end thereof; a two part abutment including a first part forming a non-round socket in the distal end thereof for fitting over said projection on said implant for preventing relative rotation between said implant and said first part, and a tapered bore in the proximal end thereof; a second part having a tapered post on the distal end thereof for mating with said tapered bore in said first part, with opposed tapered surfaces of said first and second parts forming cooperating locking tapers for locking said first and second parts together when said opposed surfaces are drawn against each other; and a locking screw having a threaded stem for making threaded engagement with said threaded bore in said implant for attaching said abutment to said implant, said screw having a head engaging said second part of said abutment for drawing said opposed tapered surfaces of said first and second parts together for locking engagement.

5. A dental implant abutment system of Claims 1, 2, 3 or 4 wherein the exterior surface of said second part adjacent to said locking taper has a shape adapted to the shape of a prosthesis reproducing a natural tooth.