WO1999039653A1

WO1999039653A1 - Endo-osseal dental implant with a self-cutting screw

Info

Publication number: WO1999039653A1
Application number: PCT/CH1999/000038
Authority: WO
Inventors: Martin Vogt; Alex SCHÄR
Original assignee: Institut Straumann Ag
Priority date: 1998-02-05
Filing date: 1999-01-29
Publication date: 1999-08-12
Also published as: AU2043799A

Abstract

The inventive endo-osseal implant (1) has a top head (10), a central, downwardly extending shaft (20) and a bottom tip (30) which points towards the apex. Self-cutting threading edges (27) which are known per se are provided inside an externally threaded section (22) and the tip (30) has at least one self-boring bit (34). The bits (34) and the threading edges (27) can be arranged in the same direction or in opposite directions, in which case in one direction of rotation of the implant (1), either the bits (34) or the threading edges (27) only perform their cutting function. The main advantage of the implant (1) is that the task of creating the implantation bed is made simpler, both in surgical terms and in terms of the instruments required. There are less possible sources of error and the bed is prevented from being apically too deep. An implanted implant (1) also benefits from greater post-operative primary stability when it is optimally embedded, and as a result, it is possible to take impressions and provide prosthetic care at an earlier stage.

Description

Endosseous dental implant with self-tapping thread

Field of application of the invention

The present invention relates to an endosseous dental implant with a self-tapping thread, so that the implant can be implanted in the jawbone without first producing an internal thread: The implant consists of an apically oriented tip, a middle part designed as a shaft and an implant head. The implant preferably consists of titanium with a surface structure that promotes its osseointegration. All indications are considered for the implant, provided that the anatomical conditions with the special local bone supply and the prosthetic situation allow.

State of the art

A distinction is made between threadless implants and screw implants. For both types, the implant site must be prepared in a relatively complex procedure. If the totality of the conditions permits, screw implants are usually preferred because they guarantee increased primary stability and a more favorable application of force under the thread flanks, with rounded threads avoiding local stress peaks (see Hartmann, Hans-Jürgen, publisher: Current status of the dentists Implantology. Spitta Verlag GmbH, Baiingen, DE, loose-leaf edition,

Scand November 1997, part 4, chapter B4, picture page 2). The present invention is concerned with screw implants. The preparation of the implant site for receiving a screw implant usually comprises the following steps (see monograph by SCHROEDER / SUTTER / BUSER / KREKELER: Oral Implantology, Georg Thieme Verlag Stuttgart and New York, 2nd edition, 1996, p. 181f.):

a) Mark the intended implantation site with a ball end mill; usually several such milling cutters are used with increasing diameters; b) creating the drilling tunnel with several twist drills of increasing diameter; c) rinsing the drilling tunnel to remove bone chips; d) measuring the depth of the drilling tunnel with a depth gauge; e) Depending on the shape of the implant, drilling a countersink or a conical neck area at the exit of the drilling gallery with a special drill; f) Pre-cutting the thread with a tap to the determined depth.

These numerous procedural steps require extensive instruments, cause considerable workload, strain the patient and also represent an increased source of error.

In order to reduce the effort required to prepare the implant site and thus to simplify the implantation overall, self-tapping implants have been developed that are inserted into the prepared implant site without first having a thread in the bone must be cut. There are different versions of such self-cutting implants.

One embodiment has threads over the entire shaft up to the apical end, with three notches provided at 120 °, which penetrate transversely into the implant body and extend over a length, e.g. about 1/3 of the shaft length, extend in the coronal direction. The notches in the cross-sections of some threads are exposed, which in this way form tapping edges, while the cavities created by the notches serve as a reservoir for the bone chips formed (see Hartmann, loc. Cit., Chapter B3, picture page 5; EP-B - 0 282 789). To reduce friction, it is known to create free areas behind the thread cutting edges (see EP-B-0 530 160). Instead of the notches, a transversely continuous opening has also been provided, which serves as a reservoir for the bone chips produced during thread cutting and at the same time for the bone to grow through for the more firm anchoring of the implant (see EP-A-0 705 574).

In another version, short chamfer grooves are present at the apical end and offset longitudinal or spiral grooves for chip absorption and for better growth, which extend over the entire length of the shaft (see Hartmann, loc. Cit., Chapter Hl, picture page 1; EP-A -0 622 058).

In a further embodiment, the external thread on the shaft of the implant is shortened and ends at a distance from the apical end. There are also chamfer grooves here to form tapping edges (see EP-B-0 263 274). With the previously known self-tapping implants, the preparatory work step of tapping in the implant bearing is no longer necessary, the entire surgical procedure is thus somewhat shortened and the necessary instruments reduced. Nevertheless, considerable preparation and instructional effort remains for the manufacture of the implant site.

Self-tapping and self-drilling bone fixation elements with tapping edges and a drilling tip are known (see D-U-86 31649, EP-A-0 657 142, WO-A-96 41573, US-A-2 388 482) ). However, the cutting edge geometry of these instruments cannot be transferred to dental implants. The cutting performance is unsatisfactory, too high a cutting pressure has to be applied, the removal of the resulting bone chips is insufficient or the instruments beat during operation.

Object of the invention

The invention is therefore based on the object of proposing a self-tapping dental implant which can be used with less surgical and instrumental outlay, so that fewer sources of error occur and at the same time the effort for sterilizing the required instruments is reduced. Furthermore, an inserted dental implant should have a high primary stability postoperatively and thus immediately allow the taking of impressions. Essence of the invention

The implant according to the invention has an external thread section on its shaft, at least some threads being self-tapping, and the apical end being designed as a self-drilling tip. The other features result from the dependent claims.

Thanks to the invention, a dental implant is now available with the following advantages:

reduced and simplified surgical and instrumental effort when creating the implant site and thus less effort to sterilize instruments; - reduction of possible sources of error; high postoperative primary stability of an inserted implant with optimal embedding of the implant and early possibility of taking impressions as well as full denture care; and - avoidance of an apical deep implant placement, thus minimally invasive surgical procedure while protecting the bone substance.

Brief description of the accompanying drawings.

Figure 1: an implant according to the invention as an overall view;

Figure 2A: the self-drilling tip of the implant according to Figure 1 as a perspective view from the apical; Figure 2B: the self-drilling tip of the implant according to Figure 2A as a front view;

Figure 3A: the self-tapping thread section of the implant fact according to Figure 1 as a perspective view of apical; Figure 3B: the self-tapping thread according to figure

3A as a front view;

FIG. 4A: an implant head with an octagon and a conical part which closes at the top as a perspective view; FIG. 4B: an implant head with an octagon and a cylindrical part closing at the top as

Perspective view;

Figure 5A: a cap-shaped support structure with octagon inside as a perspective view in partial section; and FIG. 5B: a cap-shaped support structure with a rotationally symmetrical inner contour as a perspective view in partial section.

Exemplary embodiment With reference to the accompanying drawings, the detailed description of a preferred exemplary embodiment of the dental implant according to the invention is given below. Finally, possible modifications are mentioned.

The following stipulation applies to the entire further description: if reference numerals are included in a figure for the sake of clarity in the drawing, but are not explained in the immediately associated description text, reference is made to their mention in previous or later figure descriptions. In the interest of clarity, the repeated description of components in the following figures is mostly dispensed with, provided that - 7 -

It is clearly recognizable from a technical point of view that these are "recurring" components.

FIGS. 1, 2A and 2B. The basically cylindrical implant 1 consists at the top of the head 10, the middle, downwardly extending shaft 20 and the lower, apical-pointing tip 30. At the transition between the shaft 20 and the head 10 there is a radial Circumferential, horizontal shoulder 11, over which the head 10 rises axially and here as an outer night edge 12 with eight side surfaces 13, which span parallel to the central axis M. The upper part of the shaft 20 facing the head 10 is formed by a trumpet-shaped extension 21. The blind hole-shaped internal bore, which is usually present in dental implants and which extends axially into the implant 1 from the top 14 of the head 10, is not shown. This internally threaded hole is used for the engagement of an occlusal screw to fix the healing cap or the prosthetic parts, such as e.g. an artificial tooth crown modeled over a gold cap.

Approximately in the central region of the shaft 20 there is an external thread section 22 with a plurality of thread turns 23 which project beyond the core diameter of the shaft 20. The thread start 24 of the first thread 23, which faces the tip 30, rises in a harmoniously rising manner from the surface 25 of the shaft 20 to the fully formed thread height of the subsequent threads 23. The thread end 26 of the last thread 23, which is the head 10, runs analogously facing, descending harmoniously the surface 25 of the shaft 20. The threaded end 26 lies in the area of the extension 21. The external thread section 22 is positioned on the shaft 20 in such a way that the threads 23 come to rest in the area of the hard cortical bone of the jawbone in the later inserted state.

For the known formation of thread cutting edges 27, notches 28 are provided behind the thread start 24, via the first threads 23; Three notches 28, each offset by 120 °, are customary. A notch 28 is formed by a puncture surface 280 penetrating transversely into the shaft 20 and directed onto the central axis M and a peripheral surface 281 which strikes the latter perpendicularly. The puncture surface 280 has - apart from the raised thread cutting edges 27 - the shape of a segment of a circle, so that the peripheral surface 281 is correspondingly concave. The cross-sections of some threads 23 are exposed through the notches 28; In this way, the thread cutting edges 27 are created. Those obtained with the notches 28

Cavities serve as a reservoir for the bone chips produced during thread cutting. The notches 28 will advantageously be produced by milling.

The tip located at the apical end of the implant 1

30 extends from the lowest cutting edge

31 to the upper outlet 32, 32 'of both chip spaces 33, 33'. A portion of the fully formed cylindrical shaft 20 remains between the outlet 32, 32 ′ and the thread start 24 or the inserted notches 28, so that the fixed one

Anchoring the implant inserted in the jawbone - 9 -

1 to ensure. Essential features of the tip 30 are also the two cutting edges 34, 34 'with the respectively adjacent free surface 35, 35', the notches 36, 36 'and the basic shape of a double-sided cannon drill.

The cutting edges 34, 34 'and the thread cutting edges 27 are advantageously arranged in opposite directions, i.e. The drill hole is drilled in one direction of rotation by penetrating the corticalis and the thread is then cut in the opposite direction. The greater depth of the drilled tunnel - now lying in the area of the softer cancellous bone - can be easily cut in the direction of rotation with the open spaces 35, 35 'ahead. This cutting arrangement and the working in two directions of rotation prevent the external thread section 22 from engaging with the jaw bone during drilling and the relatively large thread pitch then determining the feed. As with the arrangement of thread cutting edges 27 and drilling cutters 34, 34 'described below, it will be advantageous to produce the drill hole in the bone by turning to the left and then to cut the thread in the jawbone by turning to the right.

The tip 30 is the extension of the shaft 20, from which material has been removed on several sides, preferably by milling, in order to produce the special cutting geometry. From the underside 37 of the tip 30 rise two flats 38, 38 ′ parallel to the central axis and to one another, so that only convex side flanks 39, 39 ′ remain from the previous cylindrical surface 25. At both flats 38, 38 'there is an ascending one - 10 -

concave transition surface 40, 40 ', each of which opens into an outlet 32, 32' on the surface 25 of the shaft 20. The free volume created in this way represents the two chip spaces 33, 33 '.

In both flats 38, 38 ', an ascending, downwardly open notch 36, 36' is made from the underside 37, next to the central axis M. Both notches 36, 36 'lie opposite each other, so that on the underside 37 in the area of the central axis M, between the flats

38, 38 'the apical end of the implant is tapered. The underside 37 is also tapered in a V-shape from the side flanks 39, 39 ′. In addition, two opposing free surfaces 35, 35 'are provided on the underside 37 between the side flanks 39, 39' and the flats 38, 38 '. The free surface 35 rises from the flat 38 to the flat 38 ′, so that the cutting edge 34 is formed at the bottom of the flat 38. The free surface 35 'rises from the flattened area 38' to the flattened area 38, thus the cutting edge 34 'is formed at the bottom of the flat area 38'. For example, the free surfaces 35, 35 'have an undercut of 30 °, while there is an angle of 118 ° between the cutting edges 34, 34'.

The transverse cutting edge 31 is formed on the underside 37 in the region of the central axis M by the notches 36, 36 'and the position of the free surfaces 35, 35'. In order to facilitate the drilling process, ie to reduce the friction between the surface 25 and the inner wall of the drilling tunnel that is created, it is advantageous to move from the tip 30 to approximately - 11 -

Thread start 24, a slight conical taper - e.g. 0.5 ° - to be provided.

FIGS. 3A and 3B The thread cutting edges 27 and the drilling cutters 34, 34 'are arranged here, for example, in opposite directions so that the drilling lugs are largely driven first by turning the implant 1 in the jawbone to the left. If necessary, the two chip spaces 33, 33 'are then emptied when the implant 1 is pulled out of the drilling gallery. The direction of rotation is then reversed - now clockwise - in order to cut the thread in the drill tunnel, for which purpose the thread cutting edges 27 come into action. In the case of machine thread cutting, the speed must be reduced considerably. If you work with a newer electrically driven dental handpiece, there is a changeover switch for changing the direction of rotation and a speed controller on its drive device.

Figure 4A

In contrast to FIG. 1, the head 10 of the implant 1 can have a different shape. In Figure 4, the radially circumferential shoulder 11 lying at the transition between the shaft 20 and the head 10 is tapered towards the head 10. The head 10 rises axially over the shoulder 11. This head also has an outer octagon 12 with eight side surfaces 13 which span parallel to the central axis M. The uppermost part of the head 10 closes with an ascending conical section 15. A blind hole extends from the top 14 of the head 10. - 12 -

shaped internal threaded bore 16 axially into the implant 1.

FIG. 4B The differences from the previous variant in accordance with FIG. 4A consist in the fact that the head 10 terminates at the top with a cylindrical section 17 which is placed on the cone section 15. Furthermore, this head 10 also projects beyond a conical shoulder 11, and it has an outer octagon 12 with eight side surfaces 13 and on the upper side 14

Internal threaded bore 16. Between the shoulder 11 and outer octagon 12, a radial recess 18 can be seen, which may have arisen during the processing of the one-piece implant 1 or is intended to demonstrate that the head 10 is inserted as a separate abutment into the then two-piece implant 1. The cylindrical section 17 together with the shoulder 11 gives the prosthetic parts, e.g. a gold cap, an improved side support. The edges 19 of the outer edge 12 are chamfered.

Figure 5A

The shown, in principle bell-shaped, cap-like support structure 50 - mostly referred to as a gold cap - has a conical attachment shoulder 51 at the bottom, complementary to the shoulder 11 of the implant 1. This support structure 50 is suitable for the configuration of the head 10 according to FIG. 4A. An internal octagon 53 which can be plugged onto the outer octagon 12 of the head 10 is provided above an undercut 52 used to compensate for height tolerances. Above the inner octagon 53 is a cone section 54 and at the top a screw seat 55 for receiving the head of an occlusal screw, the thread - 13 -

shaft engages in the internal threaded bore 16 in the head 10. The placement shoulder 51 should interact with the shoulder 11 as free of gaps as possible; therefore, play is provided between the cone section 15 of the head 10 and the cone section 54 of the supporting frame 50. Typically, the support structure 50 is made of gold, titanium or burn-out plastic.

Figure 5B

The modified supporting structure 50 differs only in its inner contour; instead of the inner octagon 53, a cylinder section 56 is provided. The support structure 50 shown here is also used in connection with the head 10 according to FIG. 4A. This support structure 50 will be used for bridge or web constructions where radial positioning by means of a polygon is not necessary or even troublesome.

Further design variations can be implemented for the devices described above. It should be explicitly mentioned here:

- The radially circumferential shoulder surface 11 according to Figure 1 could instead of horizontal, e.g. also an angle of

Take 45 °.

- The implant 1 is preferably in one piece. If two-part implants 1 are used, a very rigid connection between the insertion tool and the implant 1 must be ensured with regard to the torques that occur when the implant 1 is placed.

- To promote osseointegration one becomes the surface - 14 -

25 of the shaft 20 impart a known specific roughness by applying material as a coating or by removing material by mechanical / chemical treatment.

- The trumpet-shaped extension 21 is not mandatory, but is advantageous for later anchoring of the implant 1 in the jawbone. So the shaft 20 could also continue cylindrically up to the head 10. The extension 21 or the adequate cylindrical portion on the surface 25 is preferably smooth.

- If you want to reverse the directions of rotation when drilling with the cutting edges 34 and when threading with the cutting edges 27 contrary to the exemplary embodiment - i.e. Drilling clockwise and tapping counter-clockwise - it would be necessary to lay the plunge and peripheral surfaces 280,281 and the cutting edges 34 in the same way.

In such a case, the thread 22, 23 is left-handed.

- Instead of the outer night edge 12 on the head 10, other outer, non-rotationally symmetrical geometries are also conceivable, e.g. another polygon. Finally, the attack contour for the insertion tool could not be an outer, non-rotationally symmetrical contour, but could lie internally in the uppermost region of the implant 1. Such an inner contour would be e.g. a hexagon socket.

- With special care, drilling and tapping can be done in the same direction of rotation to avoid that the external thread section 22 with the higher speed does not penetrate the drill holes during drilling and thus damage the implant bearing in the thread section. The GE- - 15 -

Wind cutting must be carried out at a significantly reduced speed. A covering of the external thread section 22 is conceivable as a safety precaution during drilling. For this, e.g. a sleeve that can be plugged onto the implant 1.

A support frame 50 complementary to the configuration of the head 10 according to FIG. 4B would have a further cylinder section above the cone section 54, which is suitable for the cylindrical section 17.

Claims

lδ patent claims

1. Endosseous dental implant (1) with a theoretical axial central axis (M) consisting of: a) an upper head (10), b) a central, downwardly extending shaft (20) and c) a lower, apically pointing tip ( 30), wherein d) the implant (1) has an external thread section (22) within which known self-tapping thread cutting edges (27) are provided, characterized in that. that e) the tip (30) has at least one self-drilling cutting edge (34, 34 ').

2. Dental implant according to claim 1, characterized in that the external thread section (22) a) is arranged on a part of the shaft (20) and inserted into the jawbone comes to lie within the corticalis; b) consists of several threads (23) which protrude beyond the core diameter of the shaft (20); c) has a thread start (24) within the first, lowest thread (23) and a thread end (26) within the last, uppermost thread (23); d) notches (28) are provided to form the thread cutting edges (27) behind the thread start (24) and extend transversely into the shaft (20) over the first threads (23); and - 17 -

e) between the tip (30) and the beginning of the thread (24) with the notches (28), a completely preserved section of the shaft (20), without recesses in the surface (25), is present.

3. Dental implant according to claim 1 or 2, characterized in that the tip (30) represents the extension of the shaft (20) and is formed from: a) two from the underside (37) of the tip (30) rising on both sides to the central axis (M) and flats (38, 38 ') which are at least substantially parallel to one another, as a result of which only two convex, diametrically opposite side flanks (39, 39') arise from the surface (25); b) the flats (38, 38 ') adjoining transition surfaces (40, 40'), each opening in an outlet (32, 32 ') on the surface (25) of the shaft (20); c) in both flattenings (38, 38 ') from the underside (37), next to the central axis (M), a notch (36, 36') which is open at the bottom, the notches (36, 36 ') being opposite one another , so that on the underside (37) in the area of the central axis (37) between the flats (38, 38 ') there is a taper; d) a V-shaped tapering of the underside (37) from the side flanks (39, 39 '); and e) two on the underside (37), between the side flanks (39,39 ') and the flats (38,38'), opposing free surfaces (35,35 '), so that f) on the underside (37 ), in the area of the central axis (M), a chisel edge (31) and at the bottom of the flats

(38,38 ') two drilling cutting edges (34,34') arise. 18th

4. Dental implant according to claim 3, characterized in that the free volume created by the flattened portions (38, 38 ') and the transition surfaces (40, 40') creates spaces (33, 33 ').

5. Dental implant according to claim 3, characterized in that a) the free surface (35) from the flattening (38) to the flattening (38 ') is ascending, whereby the bottom

Flattening (38) the cutting edge (34) is formed; and b) the free surface (35 ') rises from the flattened area (38') to the flattened area (38), as a result of which the cutting edge (34 ') is formed at the bottom of the flattened area (38').

6. Dental implant according to claim 3, characterized in that from the tip (30) to approximately the beginning of the thread (24) a conical taper, e.g. 0.5 °, is provided.

7. Dental implant according to claim 1, characterized in that the drilling cutting edges (34, 34 ') and the thread cutting edges (27) are arranged in opposite directions, whereby in a direction of rotation of the implant (1) only the drilling cutting edges (34, 34') or the thread cutting edges (27) come into effect in their cutting function.

8. Dental implant according to claim 7, characterized in that the cutting edges (34, 34 ') only when the implant (1) rotates to the left and the thread cutting edges (27) only when the implant (1) rotates to the right in their cutting - 19 -

end function come into effect.

9. Dental implant according to claim 1, characterized in that a) the upper part of the shaft facing the head (10)

(20) is formed by a trumpeter-shaped extension (21) which ends at the top with: a horizontal or conical shoulder (11); b) the head (10) extends on the central axis (M) and projects above the shoulder (11); and c) the head (10) has an external polygon (12).

10. Dental implant according to claim 9, characterized in that a) a cone section (15) is arranged above the outer polygon (12); and b) a cylindrical section (17) can be provided over the cone section (15).

11. Dental implant; according to claim 9 or 10, characterized in that on the shoulder (11) and the head (10) covering a cap is provided, which consists of: a) a lower placement shoulder (51) which is complementary to the shoulder ( 11) is; b) a horizontal, radially circumferential undercut (52) which is internal to the mounting shoulder (51); c) a cylinder section (56) arranged above the undercut (52), which can be replaced by an internal polygon (53) complementary to the external polygon (12) of the head (10); - 20 -

d) a cone section (54) present above the cylinder section (56) or the internal polygon (53), which can be followed by a further cylinder section - complementary to the cylindrical section (17) on the head (10); and e) an uppermost screw seat (55) for receiving the head of an occlusal screw.