WO1993012733A1

WO1993012733A1 - Peg for fixing, at a selected level, a prosthetic tooth socket to a cylindrical dental implant

Info

Publication number: WO1993012733A1
Application number: PCT/FR1992/001220
Authority: WO
Inventors: Jean-Claude Yeung
Original assignee: Yeung Jean Claude
Priority date: 1991-12-26
Filing date: 1992-12-21
Publication date: 1993-07-08
Also published as: FR2685626B1; FR2685626A1

Abstract

The peg (1) as a whole is designed to secure, with fixed spacing, the socket (31) of a prosthetic tooth (3) to an implant (2). The implant (2) includes an impression (21) of polygonal section (21), axially extended by a central canal (22). The peg (1) comprises on each side a neck (10), the length of which determines the fixed spacing, a head of hexagonal section and a stem consisting of a root (14), which is complementary to the impression (21), and a rod (13) capable of being inserted into the central canal (2). The peg (1) is anchored into the implant. The head (11) is pierced with an axial tapped canal (12) which extends into the root of the stem (14). The prosthetic tooth crown receives the socket (31) in which is formed a cavity (32) that is complementary to the head (11). A screw (4) locks the socket onto the peg. The presence of the root (24) reduces the minimum length of the neck (10).

Description

Abutment for connecting, at a selected level, a prosthetic tooth reinforcement to a cylindrical dental implant

The invention relates to a pillar for connecting to a cylindrical dental implant having a threaded central channel and inserted into a maxilla of a subject a prosthetic tooth frame with a fixed gap, the pillar comprising, on either side of '' a cylindrical collar whose length defines the fixed distance, a head and a tail, the latter ending in an axial rod able to penetrate the threaded implant channel, while the head is in the form of a complementary right prism d 'A cavity formed in the prosthetic tooth frame and having a threaded axial channel.

Cylindrical implants are known, which are inserted into a cylindrical cavity drilled in the maxilla, either by screwing when their outer surface is threaded with a self-tapping entry, or by impaction, when their outer surface is made porous to promote a connection with the newly formed bone, commonly called rehabitation. Normally the implants are inserted into the maxilla up to their accessible end edge. They are also provided with a threaded axial channel, to allow connection with parts forming a prosthetic tooth frame.

However, for reasons that are both aesthetic and practical, the crown that simulates the tooth is of limited height, and its base must be at a distance from the maxilla which can reach several millimeters. It is certainly possible to provide for the prosthetic tooth reinforcement to be in one piece, with a projecting collar ending in a rod which is fixed in the axial implant channel. But then the prosthetic tooth frame must be machined to the exact desired dimension, without it being possible to adjust the distance between the base of the prosthetic tooth and the maxilla. In general we prefer to insert between the prosthetic tooth and the implant cylindrical, a pillar designed to determine the desired gap between prosthetic tooth and implant.

In this case, the prosthetic tooth frame is constituted by a part of revolution sealed in the crown, a cavity being formed in the base corresponding to the crown base, with a shape complementary to a pillar head. Often an orifice, which will be closed when the prosthesis is in place, is provided in the crown to let pass a screw which will be engaged in a tapping of the abutment head.

The abutment, for its part, has a cylindrical collar, the length of which corresponds to the distance fixed between the prosthetic tooth and the implant, with flat sections which form bearing surfaces. From a slice protrudes a head in the form of a straight prism, with a threaded axial channel, the prismatic head being complementary to the prosthetic tooth frame cavity, and the axial channel receiving the fixing screw. On the other edge, a tail protrudes, terminating in an axial rod capable of penetrating the threaded implant channel.

In the conventional arrangements of implants for the use of abutments, the implant channel opens into the accessible edge and the tail is reduced to the end rod, threaded or possibly to be sealed; either this tail has a diameter significantly greater than that of the axial head channel, which implies a relatively large and frequently unacceptable implant outside diameter; either the implant axial channel has a diameter of the same order as that of the axial channel in the head, and the latter cannot extend beyond the collar, under penalty of cutting the stem at its origin, which implies that the minimum collar length cannot be small. This is a serious drawback when the repair of the teeth involves several teeth joined to a jaw which has irregularities of significant levels, the mounting of the prosthetic teeth on pillars may be impossible at the positions of maximum projection of the jaw. To overcome these drawbacks, the invention proposes a pillar for connecting to a cylindrical dental implant having a tapped central channel and inserted into the jawbone of a subject, a prosthetic tooth frame with a fixed gap, the pillar comprising, on the one hand and on the other hand, a cylindrical collar whose length along the axis defines the fixed distance, a head and a tail, the latter ending with an axial rod intended to penetrate into the implant threaded channel and to be fixed there, while the head is shaped as a right prism complementary to a cavity formed in the prosthetic tooth frame and has a threaded axial channel, characterized in that, the implant comprising a hollow impression with constant cross section opening in the accessible slice of implant coaxially to the threaded central channel of the implant, the threaded axial channel of the head has a diameter substantially equal to that of the threaded channel of implant where it st provided that penetrates the rod, while the tail of the abutment comprises, between the collar and the rod, a root capable of being housed, substantially without radial clearance, in the implant imprint.

Are known, in particular for the mounting of prosthetic teeth with framework obtained by replication of a burnable model, cylindrical implants which have a hollow imprint, in particular in hexagonal prism, extended by a tapped axial channel; this type of implant, in a screw or impact embodiment, can be used according to the present invention, the tail of the abutment comprising, between collar and rod, a root which is housed in the hollow impression of the implant. The axial channel formed in the abutment head can then extend into the root of the tail, so that the collar can be reduced to a thin washer.

In one embodiment, the cross section of the implant impression comprising at least two parallel straight segments, the tail root is complementary to the implant impression, and the rod passes through the canal. central and has peripheral grooves. The abutment is placed by sealing the tail stem in the threaded channel, and the insertion of the tail root into the impression blocks the abutment in rotation in the implant.

In another embodiment, the rod is threaded in complementarity with the central implant channel, and the root is cylindrical with a cross section inscribed in the corresponding section of implant impression. The abutment is inserted by screwing, the root ensuring the centering of the abutment relative to the implant.

Preferably the collar, at the intersection of its transverse surface, from which protrudes the tail and its peripheral surface, has a chamfer.

This chamfer prevents scar tissue around the accessible edge of the implant from being injured by a sharp edge.

Preferably the head has a cross section in regular hexagon to accommodate conventional reinforcements.

Preferably then, in the embodiment to be sealed, one of the sides of the hexagon is parallel to a section of the root, complementary to a straight segment of the cross section of the implant impression.

In a preferred arrangement, the pillars will be executed in series of at least five, with collar chamfers occupying approximately 0.3 mm of collar height, a collar with the height of the chamfer, and the following in the series having heights representing successive whole numbers of millimeters, the head having a height of 1 mm.

It is thus possible to adjust the distance between the prosthetic tooth and the implant to within half a millimeter. Secondary characteristics and advantages of the invention will also emerge from the description which will follow by way of example, with reference to the accompanying drawings in which: Figure 1 is an exploded sectional view of the mounting of a pillar according to the invention; Figure 2 is a view along arrow II of Figure 1; Figure 3 is a section of the pillar along the plane III-III of Figure 1; Figure 4 is a view along arrow IV of Figure 1; Figures 5 and 7 to 10 show five pillars of a series with progressive heights of collars; Figure 6 is a section along the plane VI-VI of Figure 5, the abutment being shown screwed into the implant. According to the embodiment chosen and shown in Figures 1 to 4, a pillar 1 as a whole is adapted to connect to a cylindrical implant 2 as a whole inserted into a jaw 28, a prosthetic tooth as a whole. The implant 2 was introduced into a bore 28a made in the jaw 28 by impaction. It comprises a substantially cylindrical titanium barrel 20 whose peripheral surface 20a, below a smooth part

20b, was lined with a porous material consisting of an agglomeration of small beads, to facilitate rehabitation by the newly formed bone. The barrel 20 ends in a dome 25 towards the bottom of the borehole 28a. It is hollowed out, in its half on the side of the dome 25, with two grooves parallel to the axis 23, into which opens a cylindrical passage 24 at the start of the dome. The grooves and the canal are provided in a conventional manner, to allow the flow of scar serosities.

Opposite the dome 25, the barrel 20 has a slice

20ç which will be called accessible tranche. In this section opens an imprint 21 with walls parallel to the axis, the cross section of which consists of eight segments each occupying an angle of 45 ° seen from the axis. These segments are alternately an arc centered on the axis, and a cord; these rope segments are straight, of course, and parallel two by two.

At the bottom of the imprint 21 opens a tapped central channel 22, blind.

The pillar 1 comprises, on either side of a collar 10, here of reduced axial height, a head 11 with a section in regular hexagon, and a tail formed by a root 14, adjacent to the collar 10, extended by a rod 13. In the head 11 opens a tapped axial channel 12, blind, which corresponds in diameter and not to the central threaded channel 22, and which, in the representation given here, extends through the collar 10 into the root 14. The collar 10 has, at the connection of its periphery with its face from which emerges the tail 14, 13, a chamfer 10a., which occupies in the example shown, the entire height of the collar.

It will be noted that this arrangement makes it possible to provide the axial head channel 12 with a sufficient diameter so that the screw 4 which will engage there, as will be explained below, has sufficient mechanical strength, without it being necessary, either to provide a collar 10 long enough to contain the axial channel 12 over its entire length, or to increase the diameter of the rod 13 and as a corollary the outside diameter of the implant.

In the tail, the root 14, as best seen in FIG. 3, has a cross section complementary to the imprint 21 of the implant 2. Furthermore, the rod 13 has a diameter such that it can engage in the central threaded channel 22, between the thread edges. Peripheral grooves 13a are provided in the rod 13. To fix the pillar 1 in the implant 2, a small amount of sealant is introduced into the central channel 22, then the pillar is lowered axially so that the rod 13 slides into the central channel 22, and the root 14 is housed in the cavity 21, until the collar 10 rests on the accessible edge 20ç_ of the implant 2. The sealant penetrates into the threads of the channel 22, and the grooves 13a of the rod 13, so that, after hardening, the abutment is firmly fixed in the implant, with their axes combined and with a determined orientation.

It will be noted that two sides of the head section hexagon 11 are parallel to two straight segments of the root section 14, so that the head has an orientation around the axis defined relative to that of the implant.

The pillar head 11 will be capped by a framework 31 of prosthetic tooth 3. This framework is here in the form of a disc embedded in a crown 30, for example made of ceramic, which reproduces the shape of a natural tooth. The frame 31 comprises, in succession along its axis, a cavity 32 with a hexagonal section complementary to the head 11 of the pillar 1, a passage 33 at the nominal diameter of the threaded axial channel 12 of the pillar, so as to allow a screw 4 which passes will engage in the channel 12, and a bowl 34 where will take place the head 41 of the screw 4. In the crown 30 is formed a passage 36 to let pass the screw 4, passage which will be closed later.

The screw 4, which fixes the prosthetic tooth 3 on the abutment 1, has a threaded rod which corresponds to the axial channel 12 of the abutment 1, and, in fact to the central implant channel 22, a cylindrical head 41 with a hollow impression 42 for a calibrated hexagon wrench.

Figures 5 to 10 show a series of five pillars 5, 6, 7, 8, 9, of increasing collar height. All the pillars of the series have a protruding hexagonal head 55 into which opens a tapped axial channel 56, similar respectively to the head 11 and to the channel 12 in FIG. 1. The pillars 5-9 have a tail, formed by a root 57 and a rod 58, analogously to the root 14 and the rod 13 of FIG. However, the rod 58 is threaded in complementarity with the central channel 22 of implant 2, and the root 57 is cylindrical, with a diameter equal to the distance between straight segments of the implant impression 21, so that the root section 57 s ^• inscribes in the impression section 21, as best seen in FIG. 6. The collars 50, 51, 52, 53 and 54 of pillars 5, 6, 7,

8, 9 all have a chamfer 50a _. , at the connection of their periphery to their face from which protrudes the tail 57, 58. But the heights increase from pillar 5 to pillar

9. The height of the collar 50 of the pillar 5 is limited to that of the chamfer, as for the pillar 1 of FIG. 1. The heights of the collars 51 to 54 of the pillars 6 to 9 are integral multiples increasing from the head height 55 .

To give dimensions, the head 55 has a height of 1 mm, the height occupied by the chamfer 50a is 0.3 mm. The heights of the collars 51, 52, 53, 54 are respectively 1, 2, 3 and 4 mm.

Of course, the invention is not limited to the examples described, but embraces all the variant embodiments thereof, within the framework of the claims. Thus the implants 2 may be of a screw type or of an impact type. The sections of the imprints may be of any convenient shape, and in particular in the form of a circle interrupted by two parallel cords seen at the same angle from the center.

Claims

1. Abutment for connecting to a cylindrical dental implant (2) having a threaded central channel (22) and inserted into the jawbone (28) of a subject, an armature

(31) of prosthetic tooth (3) with a fixed distance, the abutment (1) comprising, on either side of a cylindrical collar (10) whose length along 1 • axis defines the fixed distance, a head (11, 55) and a tail, the latter terminated by an axial rod (13, 58) intended to penetrate and be fixed in the threaded implant channel (22), while the head is shaped in a complementary right prism of a cavity

(32) formed in the framework (31) of prosthetic tooth and has an axial channel (12) threaded, characterized in that, the implant comprising a hollow impression (21) of constant cross section opening in the edge ( 20c) accessible from the implant coaxially to the central threaded channel (22) of the implant (2), the axial threaded channel (12) of the head (11, 55) has a diameter substantially equal to that of the threaded channel (22) implant (2) where it is intended that the rod (13, 58) penetrates, while the tail of the pillar comprises, between the collar (10) and the rod (13, 58), a root (14, 57) able to be housed, substantially without radial clearance, in the implant impression (21).

2. Abutment according to claim 1, intended to be sealed in the implant, characterized in that the cross section of the impression (21) of the implant comprising at least two parallel straight segments, the tail root is complementary to the hollow implant impression (21), while the rod (13) passes through the threaded central channel (22) and is provided with peripheral grooves (13a).

3. Abutment according to claim 1, designed to be screwed into the implant, characterized in that the rod (58) is threaded in complementarity with the central channel (22) of the implant, and the root (57) is cylindrical with a cross section inscribed in the corresponding implant impression section (21).

4. abutment according to any one of claims 1 to 3, characterized in that the collar (10, 50), at the intersection of its transverse surface from which protrudes the tail and its peripheral surface, has a chamfer (10a, 50a).

5. Pillar according to claim 1, characterized in that the head (11, 55) has a cross section in regular hexagon.

6. Pillar according to claims 2 and 5 taken together, characterized in that one of the sides of the hexagon is parallel to a section of the root (14), complementary to a straight segment of the cross section of the imprint implant (21).

7. A series of pillars according to claim 3, characterized in that it comprises at least five pillars

(5-9) with chamfers (50a) of collars occupying approximately 0.3 mm in height of the collar, one collar (50) having the height of the chamfer, and the following (51-54) heights representing successive whole numbers of millimeters, the head (55) having a height of l mm.