Implant

Abstract

The present invention relates to an implant, an implant set, and a method of implanting an implant. The implant comprises an external fixture thread having a radius, thread making means at an apical end of the external fixture thread for making a bone thread in bone tissue during insertion of the implant. The thread making means having a radius, which radius is generally equal to the radius of a first portion of the external fixture thread. The radius of a second portion of said external fixture thread is further reduced in relation to said radius of said thread making means.

Description

BRIEF DESCRIPTION OF THE FIGURES

Preferred embodiments of the present invention will in the following be described in more detail with reference to the accompanying exemplary drawings, in which:

FIG. 1 shows a perspective view of a dental implant according to the invention, with a thread making means.

FIGS. 2 a-c depicts a cross-section of different ingrowth stages of bone tissue into an external fixture thread.

FIG. 3 a shows a cross-section according to A-A or A′-A′ in FIG. 3b-c.

FIGS. 3 a-b shows in perspective view a portion of a dental implant with reduced portions.

FIG. 4 shows a lengthwise cross-section view of a dental implant.

FIGS. 5-7 shows various implants with differently reduced thread profiles.

FIG. 8 shows in a perspective view an implant set according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following description, reference is made to the figures which show dental implants.

With reference to FIG. 1, there is shown a dental implant 1 provided with an external fixture thread 2 with an apical thread making means 3 having a radius r_t, further the implant is provided with a portion of said thread having a reduced radius r₁ and a portion of the thread having a radius r₂ being generally equal to the radius r_t.

The expression “radius” is here used for describing the shape of the exterior geometry of the implant 1 (or thread making means 3,3′), i.e. the radius is the distance from the centre axis of the implant 1 to the exterior surface of the thread profile, which distance is variable with the position (x) along the centre axis and the angle position (α) around the implant 1. The radius of the external fixture thread 2 is hence a variable function (f(x,α) of x and α.

The comparison, of the radius of the first (r₁) and second (r₂) portions of the external fixture thread 2 with the radius (r_t) of the thread making means, should be performed along a thread pitch curve (i.e. a curve along the implant 1 with constant thread pitch), since this thread pitch curve of the implant will be in contact or pass by the same point in the bone tissue 6 during screwing of the implant into the bone. This applies particularly for threads with more than one thread.

The initial part of such a thread pitch curve, i.e. the portion of the thread pitch curve associated with the thread making means 3, will form a bone thread by making a thread geometry in the bone 6 corresponding to the geometry of the radius r_t of the thread making means 3. Thereafter, clue to further screwing of the dental implant 1 into the hole in the bone, the following part of this thread pitch curve will pass this bone thread geometry formed by the corresponding portion of the thread pitch curve of the thread making means 3.

Since one thread pitch curve of the external fixture thread may pass through both first 5 and second 4 portions/areas, where the outer radius of the second portion is reduced. Alternatively there may be two (or more) external fixture threads of which one may constitute a thread pitch curve, and hence the (second) reduced portion of the external fixture thread may follow and constitute another thread pitch curve.

With reference to the inventive concept of the present invention both these given alternatives provides an initially made thread and an implant 1 with an external fixture thread 2 having a second portion/region 4 which is reduced and hence locally provides a distance between the implant and the bone thread. This distance is advantageous for growth of new bone since it is unloaded and make it possible for blood, growth hormone etc. to faster create new bone and avoid resorption.

Preferably the reduced second portion 4 is not only a small local reduction, but a reduction providing an area at the implant which is loading the bone with low or zero stress and further providing access for blood, and other bone growth stimulating substances to the current area, which accelerates the bone growth and will prevent resorption in the area.

Further, when the implant 1 is out of contact with the bone 6, at the reduced portion, the stress on the bone 6 in this area is of course substantially reduced.

The reduced 4 and non-reduced 5 portion/s of the external fixture thread is/are positioned such that it provides a stable contact between the thread of the implant 1 and the bone thread over time. As shown in FIG. 2a, initially the non-reduced thread 5, having generally the same radius as the thread making means, will be in stable contact with the bone tissue 6 during a first period of time. After 1-4 weeks there may occur resorption in the bone area adjacent the non-reduced thread 5, as shown in FIG. 2b, on the other hand at the same time the bone tissue 6 in the area of the reduced (second) portion 4 has now grown into contact with the implant 1 and holds the implant in stable engagement. In a third stage, after about 4-8 weeks, the bone tissue 6 has grown into contact with both the reduced 4 and non-reduced 5 portions of the implant, as shown in FIG. 2c.

This alternating engagement between the reduced 4 and non-reduced 5 portions of the implant 1 and the bone 6 may be enhanced by alternating positioning of reduced 4 and non-reduced 5 portions/areas at the implant. As shown in FIGS. 3b-3c the reduced portions 4 may be provided as sectors around the dental implant 1.

FIG. 3 a could represent both the cross-section A-A and A′-A′, which shows three uniformly, distributed portions with reduced radius in sectors around the implant periphery. The change from reduced to non-reduced radius may be performed with curved shape or as a sharp change.

When using an implant 1 according to the present invention it can be installed in a cylindrical bone hole in a conventional way. Usually the hole is pre-drilled in the bone where after the bone thread is formed either with a separate thread making means 3′ or with an integrated thread making means 3 with the implant.

However, the apical end of the implant may or may not be provided with reduced threads 4. If a separate thread making means 3′ is used, the entire length of the implant can be used for threads with reduced radius.

When using a dental implant 1 having integrated thread making means 3 it is also possible to provide portion/s with reduced radius at the thread making apical end, which will result in the thread being formed initially by the thread making means and thereafter a sometimes undesirable pressing wedge-effect will act on the bone tissue 6 from the increasing thread radius.

If the thread making apical end 3 is provided with portion/s with reduced radius, it is desirable to position these portions coronally of the thread making means with non-reduced radius in order to minimize the risk of destructive pressure on the bone tissue 6. It is of course also possible to provide a reduced radius at a portion of the thread making means, which reduced radius will continue with the thread in the direction a along the periphery, and hence there will be no risk of overloading the bone.

For the embodiments shown in the accompanying drawings it is advantageous if about 1-50% of the area of the external fixture thread 2, intended for holding/engaging the bone 6, is reduced and the resulting portion is non-reduced. More preferably the reduced area of the external fixture thread constitutes 10-20%. The reduced portion 4 may for example be provided as two 90° sectors, alternatively totally three sectors of each 60° or even more sectors. Further, with specific alternative embodiments more than 50% might be reduced.

The desired effect will also be achieved by e.g. a double thread, of which one of the threads is reduced. This is due to that the double thread will provide alternating reduced and non-reduced areas along the implant, as seen in FIGS. 2a-c.

The inventive concept according to the present invention can be applied to a number of different thread profiles. Embodiments of different thread profiles are shown in FIGS. 5-7. FIG. 5 shows non-reduced threads 5 and reduced threads 4, having crest 7, apical 8 and coronal 9 flanks reduced. Further, FIG. 7 shows a more sharp thread profile with reduced flanks 83,93 and reduced crest. FIG. 6 shows the principle for an implant thread having non-reduced thread profiles 52 and reduced thread profiles 42, where the apical and coronal flanks are reduced. It is also possible to provide a number of subsequently reduced threads, as shown in FIG. 4.

According to one aspect of the present invention, the thread making means is not necessarily positioned at the apical end of the implant, but at the apical end of an external fixture thread. An implant might for instance have a first portion with a maximum radius less than the radius of a thread making means coronally of said first portion, the thread making means making threads for a second coronal portion according to the present invention. Further, said first portion might have threads and its own thread making means, integral or not with the implant, also possibly according to the present invention such that threads on the first portion have reduced radius compared to the corresponding radius of the thread making means for the first portion.

Claims

1. An implant, comprising: an external fixture thread having a radius,thread making means at an apical end of the external thread for making a bone thread in bone tissue during insertion of the implant,

2. An implant according to claim 1, wherein portions with reduced radius are provided repeatedly at said implant for providing both initial stability and future stability between the implant and the bone due to the ingrowth process of the bone tissue with said implant.

3. An implant according to claim 1, wherein the reduced radius in relation to said radius of the thread making means is preferably 0-5%, more preferably 0-2.4% and most preferably 0.06-0.16% of the radius of the thread making means.

4. An implant according to claim 1, wherein the distance between a specific position on a reduced thread and the closest corresponding position on the thread making means is preferably 0-100 μm, more preferably 0-50 μm and most preferably 10-30 μm.

5. An implant according to claim 1, wherein a crest of said external fixture thread of said implant is reduced.

6. An implant according to claim 1, wherein an apical flank of said external fixture thread of said implant is reduced.

7. An implant according to claim 1, wherein a coronal flank of said external fixture thread of said implant is reduced.

8. An implant according to claim 1, wherein a bottom of said external fixture thread of said implant is reduced.

9. An implant according to claim 1, wherein the radius of said fixture thread is continuously reduced along said external fixture thread of said implant.

10. An implant according to claim 1, wherein the reduction of the fixture thread is uniform along the axial extension of the implant.

11. An implant according to claim 1, wherein said core of the external fixture thread is provided with a reduced radius.

12. An implant, comprising: a double external fixture thread, each of the thread profiles having a radius, andthread making means at an apical end of said double external thread for making bone threads in bone tissue during insertion of the implant, said thread making means having a radius being generally equal to at least one external fixture thread radius, wherein the radius of one of said external fixture threads is reduced in relation to the radius of said thread making means.

13. An implant according to claim 12, wherein the reduced radius in relation to the radius of the thread making means is preferably 0-5%, more preferably 0-2.4% and most preferably 0.06-0.16% of the radius of the thread making means.

14. An implant according to claim 13, wherein the distance between a specific position on a reduced thread and the closest corresponding position on the thread making means is preferably 0-100 μm, more preferably 0-50 μm and most preferably 10-30 μm.

15. An implant according to claim 12, wherein a crest of said external fixture thread is reduced.

16. An implant according to claim 12, wherein an apical flank of said external fixture thread is reduced.

17. An implant according to claim 12, wherein a coronal flank of said external fixture thread is reduced.

18. An implant according to claim 12, wherein a bottom of said external fixture thread is reduced.

19. An implant according to claim 12, wherein the radius of said fixture thread is continuously reduced along the length of the thread of said implant.

20. An implant, comprising: an external fixture thread having a radius,a reduced portion of the external thread defined by a sector of the implant cross-section of less than 360°, andthread making means at an apical end of the external fixture thread for making a bone thread in bone tissue during insertion of the implant,

21. An implant according to claim 20, wherein the reduced radius in relation to said radius of the thread making means is preferably 0-5%, more preferably 0-2.4% and most preferably 0.06-0.16% of the radius of the thread making means.

22. An implant according to claim 20, wherein the distance between a specific position on a reduced thread and the closest corresponding position on the thread making means is preferably 0-100 μm, more preferably 0-50 μm and most preferably 10-30 μm.

23. An implant according to claim 20, wherein the reduced portion has a generally straight axial extension along said implant.

24. An implant according to claim 20, wherein the reduced portion has a curved axial extension along said implant.

25. An implant according to claim 20, wherein said implant comprises two reduced portions, each reduced portion being defined by a sector of less than 180° of the cross-section of the implant.

26. An implant according to claim 25, wherein said reduced portions are positioned diametrically opposed one another.

27. An implant set, comprising: an implant,a thread making means for making a bone thread in bone tissue prior to insertion of said implant,

28. An implant set according to claim 27, wherein the reduced radius in relation to said radius of said thread making means is preferably 0-5%, more preferably 0-2.4% and most preferably 0.06-0.16% of the radius of the thread making means.

29. An implant set according to claim 27, wherein the distance between a specific position on a reduced thread and the closest corresponding position on the thread making means is preferably 0-100 μm, more preferably 0-50 μm and most preferably 10-30 μm.

30. An implant set according to claim 27, wherein a crest of said external fixture thread of said implant is reduced.

31. An implant set according to claim 27, wherein an apical flank of said external fixture thread of said implant is reduced.

32. An implant set according to claim 27, wherein a coronal flank of said external fixture thread of said implant is reduced.

33. An implant set according to claim 27, wherein a bottom of said external fixture thread of said implant is reduced.

34. An implant set according to claim 27, wherein the reduction of the fixture thread is uniform as seen along the axial extension of the implant.

35. An implant set, comprising: a dental implant having a double external fixture thread, each of the thread profiles having a radius,a thread making means for making bone threads in bone tissue prior to insertion of said implant,

36. An implant set according to claim 35, wherein the reduced radius in relation to said radius of the thread making means is preferably 0-5%, more preferably 0-2.4% and most preferably 0.06-0.16% of the radius of the thread making means.

37. An implant set according to claim 35, wherein the distance between a specific position on a reduced thread and the closest corresponding position on the thread making means is preferably 0-100 μm, more preferably 0-50 μm and most preferably 10-30 μm.

38. An implant set according to claim 35, wherein the crest of said reduced external fixture thread of said implant is reduced.

39. An implant set according to claim 35, wherein an apical flank of said reduced external fixture thread of said implant is reduced.

40. An implant set according to claim 35, wherein a coronal flank of said reduced external fixture thread of said implant is reduced.

41. An implant set according to claim 35, wherein a bottom of said reduced external fixture thread of said implant is reduced.

42. An implant set according to claim 35, wherein said reduced fixture thread is continuously reduced along the length of the thread of said implant.

43. An implant set, comprising: a dental implant,a thread making means for making a bone thread in bone tissue prior to insertion of said implant,

44. An implant set according to claim 43, wherein the reduced radius in relation to said radius of the thread making means is preferably 0-5%, more preferably 0-2.4% and most preferably 0.06-0.16% of the radius of the thread making means.

45. An implant set according to claim 43, wherein the distance between a specific position on a reduced thread and the closest corresponding position on the thread making means is preferably 0-100 μm, more preferably 0-50 μm and most preferably 10-30 μm.

46. An implant set according to claim 43, wherein said second portion has a generally straight axial extension along said implant.

47. An implant set according to claim 43, wherein said second portion has a curved axial extension along said implant.

48. An implant set according to claim 43, wherein said implant comprises two second portions, each second portion being defined by a sector of less than 180° of the cross-section of the implant.

49. An implant according to claim 1, wherein the implant is a dental implant.

50. A method of implanting an implant into bone, comprising: boring a hole in the bone; andinserting into the bored hole of the bone an implant according to any one of the preceding claims.

51. A method according to claim 50, wherein inserting the implant involves screwing the implant into the bored hole.

52. A method according to claim 50, wherein inserting the implant involves making bone threads within the bored hole in the bone prior to said insertion of the implant using thread making means.

53. A method according to claim 50, wherein the implant is a dental implant.