CH705687A2 - Screw implant for a jaw bone with coronal compression thread and apical self-tapping thread. - Google Patents

Abstract

The invention relates to a screw implant (1) with coronal compression thread (4) having thread helices (11a-11j) and apical self-tapping thread (6) with thread helices (16a, 16b) whose thread pitches are approximately equal to one another to a coronal implant head (2), which may also constitute a second, separable implant part, apically connects the compression thread (4) to the end position at least in the cancellous bone substance, followed apically by the cutting thread (6) to the end position in the apical cortical bone substance, both the core diameter and Also, the outer diameter of the compression thread (4) and optionally also of the cutting thread (6) taper conically at least in its apical region from coronal to apical, characterized in that the axial length of the compression thread (4) about 2 to 15 times + / - corresponds to 25% of the axial length of the cutting thread (6) and that of the maxim outer diameter of the compression thread (4) is greater than or less than and of the cutting thread (6), preferably approximately equal to 1.2 to 2-fold + / - 10%, and that the radial thread depth of the cutting thread is greater than that radial thread depth of the compression thread (4), preferably 1.5x + / - 25%, and that the wedge angle of the thread helices (11a-11j) of the compression thread (4) is greater than the wedge angle of the thread helices (16a, 16b) of the cutting thread (6), preferably 1.5 times + / -. 25%. Advantage is that the screwing forces are reduced, that both the time to load the implant immediately after implantation can be extended by the high primary stability of the implant, and after the healing time, the retention and stability is increased, and that the implant in Immediate load logs can be used.

Description

The invention relates to a screw implant for a jawbone with coronal compression thread and apical self-tapping thread according to the preamble of independent claim 1.

[0002] DE 3 918 309 C2 and EP 0 320 740 B1 to Bauer (Bauer KSI) discloses a screw implant for a jaw bone having a compression thread whose core and sheath taper conically from the coronal to the apical end and the core is concave between the threads is trained. Due to the concave threads also remains between these bone substance. This is mainly a fixing of the implant in cancellous bone achieved by continuous radial compression of the bone substance during screwing of the conical screw implant, the implant is relatively good load immediately after implantation, without having to wait for its healing. It is additionally disclosed in DE 3 918 309 C2 that the ratio of the cone angles of the outer jacket cone and the core cone lies between 1.177 and 1.666.

Biomed's DE 20 2011 001 474 U1 discloses a screw implant for a jawbone which has one or two self-tapping threads which, after screwing in the implant, come to lie in the distal and possibly proximal cortical bone. Due to the radial relatively deep threads mainly a fixing of the implant in the cortical bone is achieved by axial positive engagement. Here, before a heavy load, a healing phase has to be awaited, after which, however, the implant is more resilient than in the previously mentioned Bauer implant.

The DE 10 251 469 A1 Brasseler GmbH discloses a screw implant for a jaw bone with three different threaded sections in the enossal area, wherein the apical threaded portion has a high thread depth with steep edges, the central threaded portion has a conical core and cylindrical mantle curve and the coronal threaded section is a trapezoidal thread with low thread depth. The three threaded sections are about the same length.

DE 20 2007 004 943 U1 of Champions-Implants GmbH discloses a screw implant for a jawbone with two different threaded sections in the enossal area, wherein the apical threaded section is a self-tapping conical compression thread, and the coronal threaded section is a conical micro-thread, wherein both cones taper to the apical end.

US 5 588 838 to Avon Hansson and Holmen discloses a screw implant for a jawbone with two different threaded sections in the enossal region, the apical threaded section being a self-tapping cylindrical cutting thread, and the coronal threaded section being a conical microthread extending to the apical end rejuvenated.

DE 69 017 349 T2 (= EP 0 424 734 B1) of Vrespa discloses a screw implant for a jawbone with two or three different threaded sections in the enossal area, wherein the apical threaded section is a self-tapping conical triangular cutting thread, the central threaded section a core conical outer diameter but cylindrical trapezoidal thread is, and the coronal threaded portion is again a self-tapping cylindrical cortical thread.

DE 10 356 920 B4 to Lippe discloses a screw implant for a jawbone having three different threaded portions in the enossal region, the apical threaded portion being a self-tapping cylindrical cutting thread, the middle threaded portion being a non-cutting cylindrical compression thread, and the coronal thread portion is a self-tapping cylindrical cortical thread with a diameter gradation between the cortical thread and the compression thread, as well as between the compression thread and the apical cutting thread.

EP 1 527 749 A2 to Lippe discloses a screw implant very similar to DE 10 356 920 B4, but no steps are provided between the threaded sections. The core and outer diameter of the cutting thread and the compression thread may also be tapered towards the tip.

All screw implants mentioned above offer immediately after implantation so even after a healing time more or less good grip in the jawbone, but it always happens that overloading occur and the screw implant loosens or even breaks out. In addition, especially with cylindrical or slightly conical compression threads the screwing forces are relatively high, so there is a risk of breakage in the region of the weakest diameter, so for example. in the area of the neck between the coronal area and the first threaded portion, or just in front of the apical threaded portion.

The object of the present invention is to avoid these disadvantages and to develop a generic screw implant starting from the above-mentioned prior art EP1 527 749 A2 so on that the Einschraubkräfte are reduced, reverse rotation probability is reduced, that both the load directly after implantation, as well as after the healing time is increased, and that the healing time is shortened.

To solve the features of the independent claim 1, wherein advantageous developments are the subject of further claims.

It is essential that the axial length of the compression thread at least twice the +/- 25% of the axial length of the cutting thread corresponds and that the maximum outer diameter of the compression thread and the cutting thread are approximately equal to +/- 10% and that the radial thread depth of the cutting thread is greater than the radial thread depth of the compression thread (4), preferably 1.5 times +/- 25%, and that the wedge angle of the thread helices of the compression thread is greater than the wedge angle of the thread helices of the cutting thread, preferably 1, 5x +/- 25%.

As a result, the advantage is achieved that both known anchoring forms of screw implants are used, on the one hand via non-positive compression of cancellous bone substance by the compression thread and on the other by positive cutting into the cortical bone substance by the self-tapping cutting thread. The bone substance to be compressed by the compression thread is therefore first cut open by the cutting thread, and then compressed. This results in improved compression combined with reduced insertion force. After penetrating the cancellous bone substance, the cutting thread comes to lie in the opposite cortical bone. There, the simple anchoring succeeds thanks to the good cutting properties of the apical cutting thread.

Advantage of the feature that the axial length of the compression thread is about twice the +/- 25% of the axial length of the cutting thread corresponds, that the compression thread completely in the cancellous bone substance and the cutting thread is completely absorbed in the cortical bone substance, whereby a optimal combination between force and positive connection in the cancellous bone and the cortical bone substance is ensured. As a result, the implant becomes extremely stable immediately after implantation resilient.

Advantage of the feature that the maximum outer diameter of the compression thread is smaller than that of the cutting thread, preferably 1.2 to 2 times about equal to +/- 10%, that the cutting thread cuts the bone during insertion and subsequently in the cortical bone is supported. The cut through the cutting thread, but still together hanging bone substance is then compressed again by the compression thread and stabilized and compacted. It is thus easier to compress the bone substance, so that a smaller hand force when screwing the implant must be spent. At least the cutting thread must be larger in diameter than the compression thread in the lower apical region. This difference in the thread diameters reduces the probability of reverse rotation.

Advantage of the feature that the maximum outer diameter of the compression thread is greater than that and the cutting thread preferably about 1.2 to 2-fold +/- 10% is that the insertion of the implant is greatly facilitated, without causing large lesions, resulting in a reduction in healing time. In addition, the cut through the cutting thread, but still hanging together by the periphery of the bone, bone substance is then compressed by the compression thread and stabilized. The bone close to the implant is therefore structurally damaged by this implant several times, which (surprisingly) has a positive effect on the durability of the implant in that, for a long time, no initial remodeling close to the implant is possible. Thus, the implant remains anchored for a longer time with primary stability, i. the time until the prosthetic splint (through the bridge) is considerably prolonged. This represents a huge advantage, as sometimes the prosthetic restoration can not be provided in time by the dental laboratory, thus increasing the risks for implant loosening.

Advantage of the feature that the radial thread depth of the cutting thread is greater than the radial thread depth of the compression thread (4), preferably 1.5 times +/- 25%, that thereby already during the insertion of the implant a radial and vertical precompression of Spongiosaknochensubstanz takes place through the surface-smooth cutting thread, so that much less cancellous bone must be compressed by the surface rough compression thread, resulting in a much easier insertion of the implant.

Advantage of the feature that the wedge angle of the thread helices of the compression thread is greater than the wedge angle of the thread helices of the cutting thread, preferably 1.5 times +/- 25%, is that so that the cutting thread axial bone cancellous bone substance can stand, which then displaces the compression thread, creating a very large axial positive engagement.

Preferably, between the threads of the compression thread, the material of the implant is circular-concave hollowed out, so that thus an optimal radial compression of Spongiosaknochensubstanz is achieved. But it can also be provided other concave shapes between the threads of the compression thread.

Preferably, the compression thread is coated and / or treated with a surface enlarging and roughening agent, whereby the static friction is increased and the adhesion of blood is improved. For reasons of hygiene, however, the cutting thread is free of this surface roughening and preferably smoothed on the surface, in particular polished. This feature is particularly advantageous because the implant according to the invention is usually selected so that the cutting thread comes to lie in the counter-cortex or protrudes slightly out of this cortical bone, e.g. into the antrum or nasal cavity.

Preferably, after implantation, the coronal area of the compression thread is located in the coronal cortical bone substance, whereby a certain, albeit small, radial compression can take place in the coronal cortical bone substance and thus the attachment is improved. However, the entire compression thread can come to lie exclusively in the cancellous bone substance even after implantation, so that the implant neck is relatively unguided in the coronal cortical bone substance, since the main attachment is made by the compression thread in the cancellous bone substance and the cutting thread in the apical cortical bone substance. Of course, between the implant neck and the compression thread, another coronal cutting thread, e.g. be provided identically to the apical cutting thread to produce an additional positive fit in the coronal cortical bone substance.

Preferably, a threadless area is provided between the compression thread and the cutting thread, which is cylindrical or conical and has the same diameter and or the same conicity as the areas before and after. This threadless area serves only to improve the production of the implant, since hereby the two threaded areas are clearly delimited and thus separate production steps, in particular a surface treatment, can take place. The compression thread should be as rough as possible in the surface, the cutting thread as smooth as possible.

In summary, it can be stated:

The implant has in the area in which it passes in the jawbone via a compression thread, and which adjoins a self-tapping sharp thread, which is inserted into the opposite cortical region. This sharp thread must not have any surface enlargements because it is possible (the surgeon can not control this) that the thread extends beyond the countercortical bone, e.g. in the nose or the maxillary sinus is screwed. There it would be disadvantageous if the thread is rough, because these regions are filthy / non-sterile. Rough implant parts would sustain infections there.

Rough parts in the bone lead to good bone attachment.

Thus, this implant has two very different anchoring forms: in the conical region lateral bone compression (which is known) takes place, while in the cortical region there is a cortical anchoring. The advantage is the extremely high primary stability, and that both forms of anchoring are exploited.

The implant shown here is made in one piece with the head. However, the invention is not limited to one-piece implants, even conventional two-part implants can be designed in the enossal area.

Surprisingly, a diameter of 1.8-2.2 mm is sufficient at the thin point between the threads to prevent the implant from breaking off, e.g. it could break off during insertion.

In a particularly advantageous subform, the cutting thread is offset from the compression thread (and interconnected only by a comparatively thin spot) and threads of the cutting thread have increasing diameters on both sides (top and bottom). The maximum diameter of the cutting thread lies in the middle of the thread. This embodiment has the particular advantage that a reverse rotation of the implant is prevented. Because the cortex is displaced when screwing in the thread. It recovers elastically as soon as the threads have penetrated deeper and smaller thread diameters or the thin connecting point come to rest in the cortical bone.

In the following the invention will be explained in more detail by way of example with reference to drawings, from which further features emerge.

It shows: <Tb> FIG. 1: <sep> Radial view of the screw implant according to the invention; <Tb> FIG. 2: <sep> Schematized representation of Fig. 1; <Tb> FIG. 3: <sep> Axial view of Fig. 2 from apical direction; <Tb> FIG. 4: <sep> Axial view of Fig. 2 from coronal direction; <Tb> FIG. 5: <sep> Enlarged view of FIG. 1 in the region of the compression thread; <Tb> FIG. 6: <sep> Enlarged view of FIG. 1 in the area of the cutting thread.

1 and 2 show the inventive screw implant 1, once in the actual radial overall view (FIG. 1) and once in a schematic representation (FIG. 2) with schematically drawn threads 4 and 6 with their invisible and outer envelope lines. Also in the implant head 2 invisible lines are located.

The implant neck 3 adjoins the coronal implant head 2, to which the compression thread 4 adjoins, followed by a transition region 5, which opens into the cutting thread 6, which ends in an implant tip 7.

The conically tapered in coronal direction implant head 2 has according to FIG. 4drei each 120 ° to each other over the jacket offset notches 8 for fixing a dental prosthesis, not shown, or substructure thereof. The implant head 2 here has an axial length of 7.2 mm and a cone of about 10 ° between an outer diameter of 2.65 mm to 3.91 mm.

From the implant neck 3 in the apical direction, the screw implant 1 has a conical core which is approximately rotationally symmetrical with respect to the longitudinal axis A.

The following in the apical direction implant neck 3 forms a constriction between the implant head 2 and the compression thread 4, here is 3 mm long and goes from a diameter of 3.91 mm at the implant head 2 to 2.3 mm back in the middle of the Implant neck 3 and back to 3.7 mm on the compression thread 4 up, the transitions are rounded.

The compression thread 4 following in the apical direction has an axial length of 15.2 mm and extends apically tapered conical from an outer diameter of 3.7 mm to 2.5 mm, resulting in a cone angle of about 4.920. The core diameter of the compression thread 4 is equivalent to the outer diameter and has a thread depth 9 of about 0.52 mm, wherein the thread pitch 10 is 1.5 mm (Fig. 5). Between the adjacent triangular threads 11a-11j (FIG. 1), a circular concave recess 12 with a radial depth of 0.75 mm (measured from outside diameter) is provided on the core diameter, which extends up to the tips 18a, 18b pulls, with a mean wedge angle of β = about 60 °. This significantly improves in particular the axial compression of cancellous bone substance. The tips 13a, 13b (Figure 5) on the outer surface of the threads are rounded to 0.05 mm.

The threadless region 5 following in the apical direction is again 1.5 mm long and is rounded off from an external diameter of 2.5 mm at the compression thread 4 to 1.5 mm.

The cutting thread 6 following in the apical direction is 3 mm long and rises from an outside diameter of 1.5 mm to 3.55 mm and then drops over a length of 1.3 mm to 3.4 mm and then back on an outer diameter of 1.5 mm. The cutting thread 6 has a cone angle in the apical direction tapering from about 3.58 °, which makes due to its small length only in a diameter difference of 0.15 mm noticeable. The core diameter of the cutting thread 6 is equivalent to the outer diameter and has a thread depth 14 of about 0.875 mm, wherein the thread pitch 15 is 1.5 mm (Fig. 6). Between the two adjacent triangular threads 16a and 16b (FIG. 1), a circular concave recess 17 having a radial depth of 1.75 mm (measured from outside diameter) is provided on the core diameter, but the flanks of threads 16a and 16b themselves are straight are formed and between them form a wedge angle of α = about 40 °. This significantly improves in particular the axial compression of cancellous bone substance. The tips 18a, 18b (Fig. 6) on the outer surface of the threads are not rounded, but razor sharp with an axial width of about 0.03 mm.

The implant tip 7 following in the apical direction has a length of 1.5 mm, an outer diameter of 1.4 mm and an apical chamfering to 0.68 mm.

The shape of the thread turns 11a-11j of the compression thread 4 is approximately equal to the shape of the thread turns 16a, 16b of the cutting thread 6, namely triangular. The difference, however, is that the thread turns 16a, 16b of the cutting thread 6 are axially steeper (wedge angle α = about 40 °) and radially deeper (about 1.5 times deeper) than the axially flatter (mean wedge angle of β = approx 60 °) and radially less deep thread turns 11a-11j of the compression thread 4. This allows easier insertion of the implant 1 and a compression of the cancellous bone substance also in the axial direction, which was previously unknown in the prior art.

With regard to the height of the cutting thread, the following can also be carried out:

The thread height (axial length) of the cutting thread 6 is always the same (ie, regardless of how large the bone length in the implant 1 is), - preferably the cutting thread height of the cutting thread 6 at 1.5-4 mm, while the endosseous compression portion of the compression thread 4 can be between 4 and 20 mm long.

The reason is that this thread portion of the cutting thread 6 only needs to reach and penetrate the countercortical, this cortical bone is about always the same thickness, regardless of how high the alveolar process is, in which the compression screw portion 4 of the implant 1 then is used.

In principle, it is sufficient if this cutting thread 6 is anchored between 0.5-1 mm in the Gegenkortikalis. However, since the rough compression thread always has to be completely buried in the bone (rough parts would come to rest in the mucosa area or even in the mouth, bacteria would then attach to it and it would come to an inflammation), and because the exact length of the implant 1 is often not can be well planned, a thread length of the cutting thread 6 of 1.5-4 mm is desirable so that the surgeon has a certain variance and the implant can optimally use or can compensate for planning errors.

The thread widths can be performed as follows:

In a particularly advantageous embodiment, the cutting thread 6 is wider than the widest point of the compression thread 4: For example, the cutting thread 6 between 5.5-7 mm wide, - for use in the back upper and lower jaw- while the compression thread 4 a maximum diameter of 4-4.5 mm. In this way, the following happens: the cutting thread 6 cuts the bone during insertion and subsequently rests in the cortical bone. The cut by the cutting thread 6 (but but still hanging together bone substance) is then compressed by the compression thread 4 again and stabilized and compacted. It should be remembered that the core bore for such an implant is e.g. is made with 2.0 mm, then the cutting thread 6 with e.g. 5-7 mm and the core of the compression thread (nominal diameter 4.1 mm max) is e.g. 3.6 mm thick. The process is similar to sandblasting: there, not only is it removed, but the surface is also compacted.

If the crestale cortical bone is highly mineralized, it may be advantageous if the crestalen threads are replaced in the inventive implant by per se known micro threads or microgrooves. These structures may be smooth to me advantage in the upper (abutment-proximate) portion to avoid bacterial colonization.

Particularly advantageous over the prior art is in this implant 1 that the rough compression thread 4 in conjunction with the tapered in both directions cutting thread avoids the back and further screwing the implant 1 very safe. It was found, surprisingly, that the implant according to the invention requires very high insertion forces even with very short thread portions, which indicates a high primary stability. This stability is higher than the two partial stabilities of the threads, which could be proved by an experiment:

Insertion force for an identical compression screw (13 mm endosteal length) without apical cutting thread: 50 Ncm.

Insertion force for a cortex screw (apical cutting thread only, 3mmh): 30 Ncm.

Insertion force of a screw according to the invention with compression and cutting threads (13 mm endosteal length, plus 3 mmh): 140 Ncm.

The inventive implant design is not limited to one-piece implants: so multi-part implants, which consist of the endosseous implant body and an abutment connected thereto, have the two different threads and are advantageously used.

drawing Legend

[0055] <Tb> 1 <sep> screw implant <Tb> <sep> second implant head <Tb> 3 <sep> implant neck <Tb> 4 <sep> Compression thread <tb> 5. <sep> threadless area <Tb> 6 <sep> cutting thread <Tb> 7 <sep> implant tip <Tb> 8 <sep> notches <tb> 9. <sep> radial thread depth of 4 <tb> 10. <sep> thread pitch of 4 <tb> 11. <sep> thread helices 11a-11j of 4 <tb> 12. <sep> Circular recess between 11 <tb> 13. <sep> Tips 13a-13j on 11 <tb> 14. <sep> radial thread depth of 6 <tb> 15. <sep> thread pitch of 6 <tb> 16. <sep> Thread helices 16a and 16b of FIG <tb> 17. <sep> Circular recess between 16 <tb> 18. <sep> peaks 13a and 13b on 16 <tb> A: <sep> Center-long symmetry axis for imaginary inner cone <tb> α = <sep> wedge angle of 16 <tb> β = <sep> wedge angle of 11

Claims (18)

A screw implant (1) for a jaw bone with coronal compression thread (4) with thread helices (11a-11j) and apical self-tapping thread (6) with thread helices (16a, 16b) whose thread pitches (10, 15) are approximately equal to each other a coronal implant head (2) apically connects the compression thread (4) to the end position at least in the cancellous bone substance, followed apically by the cutting thread (6) to the end position in the apical cortical bone substance, wherein both the core diameter and the external diameter of the compression thread (4 ) and also of the cutting thread (6) taper conically at least in its apical region from coronal to apical, characterized in that the axial length of the compression thread (4) is approximately 2 to 15 times +/- 25% of the axial length of the Cutting thread (6) corresponds, and that the maximum outer diameter of the compression thread (4) and the cutting thread (6) is approximately equal to +/- 10% si nd, and that the radial thread depth (14) of the cutting thread is greater than the radial thread depth (9) of the compression thread in the apical portion (4), preferably 1.5 times +/- 25%, and that the wedge angle (β) of Thread helices (11a-11j) of the compression thread (4) is greater than the wedge angle (α) of the thread helices (16a, 16b) of the cutting thread (6), preferably 1.5 times +/- 25%. 2. screw implant (1) according to claim 1, characterized in that the maximum outer diameter of the compression thread (4) is equal to or smaller than that of the cutting thread (6), preferably 1.2 to 2-fold +/- 10%. 3. screw implant (1) according to claim 1, characterized in that the maximum outer diameter of the compression thread in the crestalen portion (4) is greater than that of the cutting thread (6), preferably 1.2 to 2-fold +/- 10%. 4. screw implant (1) according to one of claims 1 to 3, characterized in that the core diameter and / or the outer diameter of the cutting thread (6) tapers conically at least in its apical region from coronal to apical. 5. screw implant (1) according to one of claims 1 to 3, characterized in that the core diameter and / or the outer diameter of the cutting thread (6) in its coronal region is tapered conically from apical to coronal. 6. screw implant (1) according to one of claims 1 to 3, characterized in that the core diameter and / or the outer diameter of the cutting thread (6) extends conically in its apical region from coronal to apical tapering. 7. screw implant (1) according to one of claims 1 to 6, characterized in that the minimum core diameter of the compression thread (4) is approximately equal to +/- 10% of the maximum core diameter of the cutting thread (6). 8. screw implant (1) according to any one of claims 1 or2 to 7, characterized in that the cone angles of the core diameter and the outer diameter of the compression thread (4) and the cutting thread (6) are the same and in particular between about 3.5 ° and 5 ° +/- 10% lie. 9. screw implant (1) according to one of claims 1 or 2 to 7, characterized in that the cone angles of the core diameter and the outer diameter of the compression thread (4) are the same, and in particular at about 5 ° +/- 25% and that the Cone angle of the core diameter and the outer diameter of the cutting thread (6) are the same, and in particular at about 3.5 ° +/- 25%. 10. screw implant (1) according to one of claims 1 to 49, characterized in that between the threads (11 a-11 j) of the compression thread (4) has a circular-concave recess (12) with a diameter of 0.75 mm + / - 25% is available. 11. .Schraubenimplantat (1) according to one of claims 1 to 510, characterized in that between the threads (16a, 16b) of the cutting thread (6) has a circular-concave recess (17) with a diameter of 1.75 mm +/- 25% is available. 12. screw implant (1) according to one of claims 1 to 611, characterized in that the surface of the compression thread (4) is roughened, but the surface of the cutting thread (6) is smoothed. 13. screw implant (1) according to one of claims 1 to 712, characterized in that after implantation of the coronal portion of the compression thread (4) comes to rest in the spongious cortical bone substance or in the crestalen bone substance. Screw implant (1) according to one of Claims 1 to 813, characterized in that between the implant neck (3) and the compression thread (4) there is another coronal cutting thread, e.g. identical to the apical cutting thread (6) is provided, which comes to rest after implantation in the coronal cortical bone substance. 15. screw implant (1) according to one of claims 1 to 914, characterized in that between the compression thread (4) and the cutting thread (6) a threadless area is provided, which is cylindrical or conical and the same diameter and or the same Has cone angle, as the areas immediately before and thereafter set of screw implants (1) according to one of claims 1 to 15, characterized in that the axial lengths of the cutting thread (6) in all screw implants (1) of the set are always about the same and in a range between about 1.5 mm-4 mm, and that the axial lengths of the compression thread (4) in all screw implants (1) of the set differ stepwise by at least 2 mm and in a range between about 4 mm and 20 mm , 16. Screw implants according to one of the preceding claims, characterized in that in the upper part of the compression thread, the thread is formed as a micro-thread or has circular micro-grooves. 17. Screw implant according to claim 17, characterized in that at least a part of the micro-thread or the micro-grooves has no surface enlargement. 18. Screw implant according to one of the preceding claims, characterized in that the endosseous implant body and the abutment consist of two different parts, and that these parts can be screwed or glued together.