TOOL AND METHOD FOR FORMING A NON-CIRCULAR CAVITY IN BONE TISSUE AND KIT COMPRISING THE TOOL

Abstract

Method and system for implanting an implant (20, 130) in a bone (12) is provided. An osteotomy (10) having a first transverse cross-sectional shape is formed in a bone (12). An implant (20, 130) having a second transverse cross-sectional shape is inserted into the osteotomy (10), the transverse cross-sectional shape of the implant (20, 130) being different from the transverse cross-sectional shape of the osteotomy (10). The invention further relates to a preparation tool (100) for forming a non-circular cavity (10) in bone tissue (12). The preparation tool (100) comprises a proximal portion (102) and a distal portion (104). The distal portion (104) has a main body (106) and at least one bone removing element (108). At least apart of the at least one bone removing element (108) extends radially outward beyond an outer circumference of the main body (106). Moreover, the invention relates to a kit comprising the preparation tool (100) and an implant (130), such as a dental implant. Also, the invention relates to a kit comprising the preparation tool (100) and a tool guiding means, such as a surgical template.

Claims

1. A preparation tool (100) for forming a non-circular cavity in bone tissue, the preparation tool comprising a proximal portion; and a distal portion, wherein the distal portion has a main body and at least one bone removing element, and at least a part of the at least one bone removing element extends radially outward beyond an outer circumference of the main body.

2. The preparation tool according to claim 1, wherein the at least a part of the at least one bone removing element has an abrasive surface.

3. The preparation tool according to claim 1, wherein the at least one bone removing element is movable relative to the main body in the axial direction of the preparation tool.

4. The preparation tool according to claim 3, further comprising a shaft extending in the axial direction of the preparation tool, wherein the shaft is rotatable relative to the main body, and the shaft is connected to the at least one bone removing element so that rotation of the shaft relative to the main body causes the at least one bone removing element to move relative to the main body in the axial direction of the preparation tool.

5. The preparation tool according to claim 4, wherein the shaft is connected to the at least one bone removing element so that continuous rotation of the shaft relative to the main body causes the at least one bone removing element to reciprocate relative to the main body in the axial direction of the preparation tool.

6. The preparation tool according to claim 4, wherein the shaft has at least one recess extending in the radial direction of the shaft and in the circumferential direction of the shaft, the at least one bone removing element has at least one protrusion extending in the radial direction of the shaft, and the at least one protrusion is at least partly received within the at least one recess, or wherein the shaft has at least one protrusion extending in the radial direction of the shaft and in the circumferential direction of the shaft, the at least one bone removing element has at least one recess extending in the radial direction of the shaft, and the at least one protrusion is at least partly received within the at least one recess.

7. The preparation tool according to claim 4, wherein the shaft extends from the proximal portion to the distal portion.

8. The preparation tool according to claim 4, wherein a proximal end of the shaft is exposed to the outside of the preparation tool.

9. The preparation tool according to claim 1, wherein the main body has at least one fixation element for rotational fixation of the main body in a pilot hole formed in bone tissue so as to prevent rotation of the main body relative to the bone tissue in the circumferential direction of the main body.

10. The preparation tool according to claim 1, further comprising an intermediate portion, wherein the intermediate portion is arranged between the proximal portion and the distal portion, and at least a part of the intermediate portion has a non-circular cross-section perpendicular to the axial direction of the preparation tool.

11. (canceled)

12. The preparation tool according to claim 1, wherein a distal part of the at least one bone removing element has a radial extension in one or more directions perpendicular to the axial direction of the preparation tool, which radial extension decreases in the direction from the proximal portion towards the distal portion.

13. The preparation tool according to claim 1, wherein the distal portion has a plurality of bone removing elements.

14. The preparation tool according to claim 13, wherein the bone removing elements are arranged so as to be spaced apart from each other in the circumferential direction of the main body.

15. The preparation tool according to claim 14, wherein the bone removing elements are arranged so as to be equidistantly spaced apart from each other in the circumferential direction of the main body.

16. (canceled)

17. (canceled)

18. (canceled)

19. (canceled)

20. (canceled)

21. (canceled)

22. (canceled)

23. A method of forming one or more zones of no or lower bone stress and one or more zones of higher bone stress around a dental implant comprising, forming a hole in a patient's bone, the hole forming a first transverse cross-sectional shape; and inserting a dental implant into the hole, the dental implant having a portion positioned within the hole that has a second transverse cross-sectional shape that is different than the first transverse cross-sectional shape such that when the portion of the dental implant is inserted into the hole one or more zones of no or lower bone stress and one more zones of higher bone stress are created around the portion of the dental implant.

24. The method of claim 23, wherein the first transverse cross-sectional shape is non-round and the second transverse cross-sectional shape is round.

25. The method according to claim 23, wherein the hole in the patient is formed by drilling more than one hole in the patient with each hole having a different center axis.

26. The method according to claim 25, further comprising using a template to form the more than one hole in the patient.

27. (canceled)

28. (canceled)

29. (canceled)

30. (canceled)

31. (canceled)

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. (canceled)

38. (canceled)

39. (canceled)

40. (canceled)

41. An assembly comprising an implant and a tool for creating an osteotomy with a non-round transverse cross-section.

42. The assembly of claim 41, wherein the implant is a dental implant.

43. The assembly of claim 41 wherein the non-round osteotomy has a generally oval transverse cross-sectional shape, a generally square transverse cross-sectional shape, and/or a generally triangular transverse cross-sectional shape

44. The assembly of claim 41 wherein the tool for creating a non-round osteotomy comprises one or more of custom tooling, lasers, piezo surgical instrumentation, standard drills, and/or drill templates.

45. (canceled)

46. (canceled)

47. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0128] Throughout the drawings, reference numbers can be reused to indicate general correspondence between reference elements. The drawings are provided to illustrate example embodiments described herein and are not intended to limit the scope of the disclosure.

[0129] FIG. 1A shows a top view of an embodiment of an osteotomy.

[0130] FIG. 1B shows a top view of the osteotomy of FIG. 1A.

[0131] FIG. 1C shows a top view of the osteotomy of FIG. 1A.

[0132] FIG. 2A shows a top view of an embodiment of a non-round osteotomy.

[0133] FIG. 2B shows a top view of a round implant inserted into the non-round osteotomy of FIG. 2A.

[0134] FIG. 3A shows a top view of an embodiment of a non-round osteotomy.

[0135] FIG. 3B shows a top view of a round implant inserted into the non-round osteotomy of FIG. 3A.

[0136] FIG. 4A shows a top view of an embodiment of a non-round osteotomy.

[0137] FIG. 4B shows a top view of a round implant inserted into the non-round osteotomy of FIG. 4A.

[0138] FIG. 5 shows a top view of an embodiment of a non-round osteotomy.

[0139] FIG. 6A shows a top view of an embodiment of a non-round osteotomy.

[0140] FIG. 6B shows a top view of a round implant inserted into the non-round osteotomy of FIG. 7A.

[0141] FIG. 7A shows a top view of an embodiment of a non-round osteotomy.

[0142] FIG. 7B shows a top view of a round implant inserted into the non-round osteotomy of FIG. 6A.

[0143] FIG. 8A shows a top view of an embodiment of a non-round osteotomy.

[0144] FIG. 8B shows a top view of a round implant inserted into the non-round osteotomy of FIG. 8A.

[0145] FIG. 9 shows a preparation tool according to an embodiment of the present invention, wherein FIG. 9(a) is a perspective view of the entire preparation tool, and FIG. 9(b) is a perspective view of the preparation tool with some of the outer parts thereof removed.

[0146] FIG. 10 shows the preparation tool according to the embodiment of the present invention, wherein FIG. 10(a) is a perspective view of distal and intermediate portions of the preparation tool, and FIG. 10(b) is a side view of the distal portion of the preparation tool.

[0147] FIG. 11 shows the preparation tool according to the embodiment of the present invention, wherein FIG. 11(a) is a perspective view of bone removing elements and a portion of a shaft of the preparation tool, FIG. 11(b) is a cross-sectional view of the distal and intermediate portions of the preparation tool taken along a plane parallel to the axial direction of the preparation tool, and FIG. 11(c) is a cross-sectional view of the preparation tool along line C-C in FIG. 11(b).

[0148] FIG. 12 shows components of the preparation tool according to the embodiment of the present invention, wherein FIG. 12(a) is a perspective view of the shaft of the preparation tool, and FIG. 12(b) is a perspective view of a bone removing element of the preparation tool.

[0149] FIG. 13 shows the preparation tool according to the embodiment of the present invention and an implant, wherein FIG. 13(a) is a perspective overlay view of the entire preparation tool and the implant, and FIG. 13(b) is a perspective overlay view of the distal portion of the preparation tool.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0150] Embodiments of systems, components and methods of assembly and manufacture will now be described with reference to the accompanying figures, wherein like numerals refer to like or similar elements throughout. Although several embodiments, examples and illustrations are disclosed below, it will be understood by those of ordinary skill in the art that the inventions described herein extends beyond the specifically disclosed embodiments, examples and illustrations, and can include other uses of the inventions and obvious modifications and equivalents thereof. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive manner simply because it is being used in conjunction with a detailed description of certain specific embodiments of the inventions. In addition, embodiments of the inventions can comprise several novel features and no single feature is solely responsible for its desirable attributes or is essential to practicing the inventions herein described.

[0151] Certain terminology may be used in the following description for the purpose of reference only, and thus are not intended to be limiting. For example, terms such as above and below refer to directions in the drawings to which reference is made. Terms such as front, back, left, right, rear, and side describe the orientation and/or location of portions of the components or elements within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the components or elements under discussion. Moreover, terms such as first, second, third, and so on may be used to describe separate components. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import.

[0152] FIG. 1A depicts an osteotomy 10a and a portion of bone 12a that surrounds the osteotomy 10a. When an implant (shown in FIG. 1B) is installed into the osteotomy 10, the bone 12 surrounding the osteotomy may be subjected to high stress, high strain, high insertion torques and/or high temperatures that may result in localized bone cell damage and/or bone cell death in the vicinity of the osteotomy. The depth of the bone cell damage can be referred to as a zone of death 14 (ZOD). The size and shape of the ZOD 14 will depend on the shape of the osteotomy 10 and the shape of the implant that is installed into the osteotomy 10. The osteotomy 10 shown in FIGS. 1A-C has a generally circular or round transverse cross-sectional shape. If an implant with a circular transverse cross-sectional shape is installed into the osteotomy 10, the ZOD 14 will have a generally circular shape and be concentric with the osteotomy 10. FIG. 1B shows a ZOD 14b that is thinner than the ZOD 14c shown in FIG. 1C. Such an instance could arise if a circular implant were implanted into both osteotomies, with the implant that is installed into the osteotomy of FIG. 1B having a smaller diameter than the implant that is installed into the osteotomy of FIG. 1C.

[0153] It is believed that the ZOD 14 is largely a function of stress-strain and heat. The bone cell damage or death in the ZOD 14 can lead to bone resorption, resulting in implant loosening and then bone remodeling. Low stress can be associated with good bone healing response, while high stress can be associated with bad healing response. The smaller the ZOD 14 the better.

[0154] When a round dental implant is inserted in a round osteotomy, particularly if the osteotomy is undersized, there can be uniform high compression stresses in the bone. These high stresses can lead to bone resorption and remodeling around the implant. Because the stress mode is uniform, the resorption and remodeling process can also be substantially uniform. Hence, bone can resorb around the whole implant at the same time, which can result in implant loosening and further subsequent complications.

[0155] According to certain embodiments, the methods and devices disclosed herein allow the ZOD 14 to be reduced, managed or tailored to improve implant healing. In certain embodiments of the present disclosure, an implant has a different transverse cross-sectional shape than the osteotomy into which the implant is inserted. In certain embodiments, it would be beneficial to create a non-round osteotomy with a non-round transverse cross-sectional shape. A non-round osteotomy can provide areas of relatively higher bone compression or stress that provide primary implant stability following implantation. The non-round osteotomy can also provide areas of relatively lower or no bone compression or stress that achieve good blood supply to the region and can promote rapid osseointegration and development of secondary stability.

[0156] FIG. 2A depicts an embodiment of a non-round osteotomy 10 with a non-round transverse cross-sectional shape. The illustrated osteotomy is oval, having a first width 16 that is slightly larger than a second width 18. The osteotomy 10 can be formed by placing two holes adjacent but off center to each other. In certain embodiments, the holes can be formed by a tool that can create a non-round hole such as a milling instrument. FIG. 2B shows a round implant 20 that has been installed in the non-round osteotomy 10. As shown in FIG. 2B, the bone 12 in the vicinity of the second width 18 of the osteotomy 10 will be subjected to higher compression forces (solid arrows) while the bone in the vicinity of the first width 16 will be subjected to lower compression forces (dashed arrows). The bone 12 in the areas of higher compression forces or stress can stabilize the implant 20 (e.g., primary stability or mechanical stability) while the bone 12 in the areas of lower compression forces or stress can osseointegrate with the implant 20 (secondary stability). In this way, the higher compression zone can be referred to as a mechanical zone and the lower compression zone can be referred to as a biologic zone.

[0157] FIG. 3A depicts another embodiment of a non-round osteotomy 10 with a non-round transverse cross-sectional shape. The illustrated osteotomy 10 has round or non-round central portion 22 with one or more round or non-round minor or smaller diameter portions 24 distributed around the perimeter of the central portion 22. As shown in FIG. 3B, lower compression forces (dashed arrows) can be associated with the minor portions 24 of the osteotomy 10 while higher compression forces (solid arrows) can be associated with the regions of the central portion 22 that are interposed between the minor portions 24. The illustrated osteotomy can be created with a drill template. In certain embodiments, the central potion 22 can be formed first and then the minor portions 24 can be formed afterwards. In certain embodiments, the central portion 22 can be drilled first using a large drill, then the minor portions 24 can be drilled with a smaller drill. In some variants, the central portion 22 and minor portions 24 can be drilled using normal twist drills. In some embodiments, the central portion 22 and minor portions 24 are round, and combining the round central portion 22 and the round minor portions 24 produces an osteotomy 10 that is non-round. In certain embodiments, the central portion 22 and/or the minor portions can be non-round and combining the round central portion 22 and the round minor portions 24 produces an osteotomy 10 that is non-round. In certain embodiments, the implant 20 positioned within the osteotomy 10 can have a diameter that is close to or smaller than the diameter of the central portion 22.

[0158] FIG. 4A depicts another embodiment of a non-round osteotomy 10 that is similar to the embodiment shown in FIG. 3A except that the embodiment in FIG. 4A includes additional minor portions 24. The minor portions 24 can be substantially equal to one another in size and shape and distributed substantially uniformly circumferentially around the central portion 22. However, in certain embodiments, the minor portions 24 are not substantially equal to one another in size and/or in shape and/or are unevenly distributed circumferentially around the perimeter of the central portion 22. In certain embodiments, the implant 20 positioned within the osteotomy 10 can have a diameter that is close to or smaller than the diameter of the central portion 22.

[0159] FIG. 5 depicts another embodiment of a non-round osteotomy 10 with a non-round transverse cross-sectional shape. The illustrated osteotomy 10 can be formed by drilling three holes close together where the center of each hole forms the apex of a triangle. A round implant (not shown) can be inserted into the illustrated osteotomy 10 would have result in high compressive stresses in the bone 12 in the vicinity of R1 and low compressive stresses in the bone 12 in the vicinity of R2. The formation of the osteotomy 10 can be guided by a surgical guide or a robotic surgical arm. In a modified arrangement, the non-round osteotomy 10 can be formed by using a combination of a drill and hand-held reamers that are used to enlarge portions of the osteotomy 10. In other arrangements, the osteotomy 10 can be formed by a tool that includes separate rotating end mills configured to form a non-round opening.

[0160] FIG. 6A depicts another embodiment of a non-round osteotomy 10 with a non-round transverse cross-sectional shape. The illustrated osteotomy 10 has a generally square shape having corner portions 26. In the illustrated embodiment, each of the four corner portions 26 forms an angle that is substantially 90. However, is some embodiments, some of the corner portions 26 can form acute angles while other corner portions 26 form obtuse angles, giving the osteotomy 10 a rhombus or slanted rectangular shape. FIG. 6B shows a round implant 20 that has been inserted into the non-round osteotomy 10 of FIG. 6A. As shown in FIG. 6B, low compression forces (dashed arrows) can be associated with bone in the vicinity of the corner portions 26 of the osteotomy 10 while high compression forces (solid arrows) can be associated with the bone in the vicinity of the regions of the osteotomy 10 that are interposed between the corner portions 26. In certain embodiments, the implant 20 positioned within the osteotomy 10 can have a diameter that is greater than the length of one or more sides of the osteotomy 10.

[0161] FIG. 7A depicts another embodiment of a non-round osteotomy 10 with a non-round transverse cross-sectional shape. The illustrated osteotomy 10 has a generally triangle shape having apex portions 28. In the illustrated embodiment, each of the three apex portions 28 forms an angle that is substantially 60. In some variants, the apex portions 28 form angles that are different from one another. FIG. 7B shows a round implant 20 that has been inserted into the non-round osteotomy 10 of FIG. 7A. As shown in FIG. 7B, low compression forces (dashed arrows) can be associated with bone in the vicinity of the apex portions 28 of the osteotomy 10 while high compression forces (solid arrows) can be associated with the bone in the vicinity of the regions of the osteotomy 10 that are interposed between the apex portions 28.

[0162] FIG. 8A depicts another embodiment of a non-round osteotomy 10 with a non-round transverse cross-sectional shape. The illustrated osteotomy 10 has a first generally square shape that is rotated substantially 45 relative to a second generally square shape. In the illustrated embodiment, the first and second generally square shapes are similar in size. In some variants, the first and second generally square shapes are different from one another in size. In certain embodiments, the first generally square shape is rotated relative to the second generally square shape at an angle other than 45 (e.g., 20). FIG. 8B shows a round implant 20 that has been inserted into the non-round osteotomy 10 of FIG. 8A. As shown in FIG. 8B, low compression forces (dashed arrows) can be associated with bone in the vicinity of the corner portions 26 of the osteotomy 10 while high compression forces (solid arrows) can be associated with the bone in the vicinity of the regions of the osteotomy 10 that are interposed between the corner portions 26.

[0163] In certain embodiments, the non-round osteotomy 10 of the embodiments describe herein can be created with specialized tooling (e.g., special drills, lasers, piezo, millers, etc.). In certain embodiments, the non-round osteotomy 10 of the embodiments describe herein can be using a template and drilling plurality of round holes at different locations. As discussed, creating a non-round osteotomy can introduce areas of relatively lower or no stress (also referred to as biologic zones) and areas of relatively higher stress (also referred to as mechanical zones). The bone in the relatively higher stress zones can resorb and remodel the same as a round implant but the bone can remodel faster in the relatively lower stress zones. Since the rate of resorption and remodeling is different between the two zones, the implant will always be in contact with bone and therefore will not become loose or unstable. The non-round osteotomy 10 can be created with standard drills and/or a drill template. The non-round osteotomy 10 can be created with lasers and/or custom tooling. In some variants, the amount of non-roundness or misfit of the osteotomy 10 to the implant 20 in orientation is controlled at a micron level.

[0164] Certain embodiments can comprise forming osteotomy with a non-round cross-section and then inserting an implant with a non-round cross-section into the osteotomy with the non-round cross-section. To create the areas of relatively lower or no compression or stress and areas of relatively higher compression or stress, the implant can be orientated within the osteotomy such that the non-round cross-sections of the osteotomy and the dental implant are not aligned.

[0165] In the embodiments described herein, the non-round shape of osteotomy can be with respect to a cross-section that is generally perpendicular to or perpendicular to a longitudinal axis of the osteotomy, which is sometimes referred to as the transverse cross-sectional shape of the osteotomy herein. In a similar manner, the round or non-round shape of the implant can be with respect to a cross-section that is generally perpendicular to or perpendicular to a longitudinal axis of the implant, which is sometimes referred to as the transverse cross-sectional shape of the implant herein.

[0166] Certain embodiments can include a method of implanting an implant can comprise creating in a bone an osteotomy 10 having a first transverse cross-sectional shape; inserting into the osteotomy 10 an implant having a second transverse cross-sectional shape, wherein the transverse cross-sectional shape of the osteotomy is different from the transverse cross-sectional shape of the implant.

[0167] In certain embodiments, a dental implant system can comprise a device for creating in a bone an osteotomy having a first transverse cross-sectional shape; and an implant having a second transverse cross-sectional shape, wherein the second transverse cross-sectional shape is different from the first transverse cross-sectional shape.

[0168] FIGS. 9 to 13 show a preparation tool 100 according to an embodiment of the present invention.

[0169] The preparation tool 100 is a preparation tool for forming a non-circular or non-round cavity, osteotomy or hole in bone tissue, such as the jaw bone of a patient. The preparation tool 100 comprises a proximal portion 102 and a distal portion 104, as is shown in FIGS. 9(a) and (b). The distal portion 104 has a main body 106 and four bone removing elements 108 (see FIG. 11(c)). A part of each bone removing element 108 extends radially outward beyond an outer circumference of the main body 106 (see, for example, FIGS. 9(a), 9(b), 10(b) and 11(b)). The four bone removing elements 108 are arranged so as to be equidistantly spaced apart from each other in the circumferential direction of the main body 106, as is shown in FIG. 11(c). Each of the four bone removing elements 108 has an elongate shape (e.g., FIG. 12(b)). The four bone removing elements 108 are movably attached to the main body 106 so that their longitudinal axes are parallel to the axial direction of the preparation tool 100. The main body 106 substantially has the shape of a hollow tube (e.g., FIGS. 10(a) and 11(b)).

[0170] Each of the four bone removing elements 108 extends, in a width direction thereof, along a portion of the outer circumference of the main body 106 in the circumferential direction of the main body 106 (see FIG. 11(c)). The width direction of each of the four bone removing elements 108 extends along a direction substantially perpendicular to the axial direction of the preparation tool 100. As is shown in FIG. 11(c), the four bone removing elements 108 are arranged so that two respective bone removing elements 108 are positioned opposite to each other.

[0171] The main body 106 and the four bone removing elements 108 may be made of the same material or of different materials.

[0172] The main body 106 may be made of, for example, a metal, such as titanium, a titanium alloy or stainless steel, a polymer, a ceramic or a composite material. The main body 106 may be manufactured, for example, by moulding, such as injection moulding, milling, such as CNC milling, etc.

[0173] Each of the four bone removing elements 108 may be made of, for example, a metal, such as titanium, a titanium alloy or stainless steel, a polymer, a ceramic or a composite material. Each of the four bone removing elements 108 may be manufactured, for example, by moulding, such as injection moulding, milling, such as CNC milling, etc.

[0174] The four bone removing elements 108 are movable relative to the main body 106 in the axial direction of the preparation tool 100. The four bone removing elements 108 are movably attached to the main body 106. Specifically, each of the four bone removing elements 108 is movably received in a corresponding channel or slit 110 formed in the main body 106, as is shown, for example, in FIGS. 9(b), 10(b) and 11(b). Each of the channels or slits 110 has an elongate shape. The channels or slits 110 are formed in the main body 106 so that their longitudinal axes are parallel to the axial direction of the preparation tool 100. Each of the four bone removing elements 108 is slidably arranged in the corresponding channel or slit 110, so as to be slidable relative to the main body 106 in the axial direction of the preparation tool 100.

[0175] The preparation tool 100 is configured so that the distal portion 104 thereof can be at least partly inserted into a pilot hole (not shown) in the bone tissue, e.g., in the jaw bone of a patient. The pilot hole may be prepared by drilling a hole in the bone tissue, e.g., following a drill protocol, as has been detailed above. The preparation tool 100 is configured to remove bone material at the inner wall of the pilot hole by means of the four bone removing elements 108, thereby forming the non-circular cavity in the bone tissue.

[0176] In order to facilitate the at least partial insertion of the distal portion 104 into the pilot hole, each of the four bone removing elements 108 has a tapered or chamfered portion 112 in which the radial extension of the respective bone removing element 108 in the directions perpendicular to the axial direction of the preparation tool 100 decreases in the direction from the proximal portion 102 towards the distal portion 104 of the preparation tool 100 (see, for example, FIGS. 11(a) and 12(b)). Further, each of the four bone removing elements 108 has a straight portion 114 which is arranged adjacent to the tapered or chamfered portion 112 in the direction from the distal portion 104 towards the proximal portion 102. In the straight portion 114, the radial extension of the respective bone removing element 108 in the directions perpendicular to the axial direction of the preparation tool 100 is constant in the direction from the proximal portion 102 towards the distal portion 104 (see, for example, FIGS. 11(a) and 12(b)).

[0177] The main body 106 has four fixation elements 116 for rotational fixation of the main body 106 in the pilot hole so as to prevent rotation of the main body 106 relative to the bone tissue in the circumferential direction of the main body 106. The four fixation elements 116 are arranged so as to be equidistantly spaced apart from each other in the circumferential direction of the main body 106, as is shown in FIG. 11(c). Each of the four fixation elements 116 is a ridge that protrudes from a remainder of the main body 106 in the radial direction of the main body 106 and extends along the axial direction of the main body 106, as is shown in FIGS. 10(a), 10(b) and 11(c). The fixation elements 116 are integrally formed with the remainder of the main body 106.

[0178] The fixation elements 116 can engage the bone tissue of the inner wall of the pilot hole, thus keeping the main body 106 substantially stationary relative to the bone tissue in the circumferential direction of the main body 106. The non-circular cavity is formed by moving the four bone removing elements 108 relative to the main body 106, while any rotational movement between main body 106 and bone tissue can be reliably avoided due to the presence of the fixation elements 116. Hence, the cavity can be formed with a particularly high degree of precision.

[0179] The preparation tool 100 further comprises an intermediate portion 118 which is arranged between the proximal portion 102 and the distal portion 104 (see, for example, FIGS. 9(a) and (b)). The intermediate portion 118 has a non-circular cross-section perpendicular to the axial direction of the preparation tool 100. Specifically, the intermediate portion 118 has a substantially square cross-section with rounded edges, as is shown in FIG. 11(c). The intermediate portion 118 is fixedly attached to the distal portion 104, in particular, the main body 106.

[0180] In addition or alternatively to the fixation elements 116, also the intermediate portion 118 of the preparation tool 100 allows for a rotation of the main body 106 relative to the bone tissue in the circumferential direction of the main body 106 to be reliably prevented when forming the non-circular cavity. In particular, the preparation tool 100 may be used together with a tool guiding means (not shown), such as a surgical template for guided surgery. The tool guiding means may have a receiving portion into which the preparation tool 100 can be at least partly inserted. This receiving portion may be configured to prevent rotation of the main body 106 of the preparation tool 100 relative to the tool guiding means and, thus, also relative to the bone tissue, by cooperation with the intermediate portion 118 which has the non-circular, i.e., substantially square, cross-section.

[0181] The bone removing elements 108 are configured to remove bone material, i.e., to take off bone material from the bone tissue, thereby forming the non-circular cavity in the bone tissue, for example, in the jaw bone of a patient. The part of each bone removing element 108 which extends radially outward beyond the outer circumference of the main body 106 is a bone removing part. The bone removing part is configured to remove bone material. The bone material may be removed, for example, by reaming bone tissue, rasping bone tissue or grinding bone tissue.

[0182] For the purpose of bone material removal, each of the bone removing elements 108, including the part thereof which extends radially outward beyond the outer circumference of the main body 106, has an abrasive surface 120 (see, for example, FIGS. 9(a), 9(b), 11(a) and 12(b)). The abrasive surface 120 is a rough surface which is configured to remove bone material, e.g., by reaming the bone tissue, rasping the bone tissue or grinding the bone tissue. Further, the abrasive surface 120 is configured to provide, in those areas or regions of the pilot hole where it comes into contact with the bone tissue and removes bone material, a rough surface of the inner wall of the cavity. The abrasive surface 120 may be a coarse abrasive surface, e.g., an abrasive surface for coarse reaming, coarse rasping or coarse grinding.

[0183] By employing the bone removing elements 108, each having the abrasive surface 120 which enables the provision of a rough surface of the inner wall of the cavity, osseointegration of the implant in the cavity can be further improved. In particular, in this way, the cells of the bone tissue can be opened, further promoting osseointegration.

[0184] As is shown, for example, in FIG. 11(c), the abrasive surface 120 is a curved surface. Specifically, the abrasive surface 120 is curved so that the radial extension of the respective bone removing element 108 in the directions perpendicular to the axial direction of the preparation tool 100 decreases from a center of the bone removing element 108 in the width direction thereof towards the edges of the bone removing element 108 in the width direction thereof (see FIG. 11(c)). By providing the abrasive surface 120 with such a curvature, the bone removal efficiency can be further enhanced.

[0185] The preparation tool 100 comprises a shaft 122 extending in the axial direction of the tool 100. The shaft 122 extends from the proximal portion 102 to the distal portion 104 of the preparation tool 100. Specifically, a proximal portion of the shaft 122 forms the proximal portion 102 of the preparation tool 100 (see, for example, FIGS. 9(a), 9(b) and 12(a)). A distal portion of the shaft 122 is received within the main body 106 (e.g., FIGS. 9(b) and 11(b)).

[0186] The shaft 122 is rotatable relative to the main body 106 and relative to the intermediate portion 118. Specifically, the shaft 122 is rotatable relative to the main body 106 and the intermediate portion 118 in a rotational direction around the axial direction of the preparation tool 100. The shaft 122 is arranged so as to be coaxial with the main body 106 and the intermediate portion 118, i.e., so that the axial direction of the shaft 122 is the same as the axial direction of the main body 106 and the intermediate portion 118. The shaft 122 is rotatable relative to the main body 106 and the intermediate portion 118 around this axial direction. The shaft 122 is also rotatable relative to the four bone removing elements 108.

[0187] The shaft 122 is held in the intermediate portion 118 in a rotatable manner by means of a connection part 123 of the shaft 122 and a corresponding bearing part of the intermediate portion 118 (see FIGS. 11(b) and 12(a)). The connection part 123 is rotatably supported by the bearing part.

[0188] The shaft 122 is connected to the four bone removing elements 108 so that rotation of the shaft 122 relative to the main body 106 causes the four bone removing elements 108 to move relative to the main body 106 in the axial direction of the preparation tool 100.

[0189] Specifically, the shaft 122 has two recesses 124 extending in the radial directions of the shaft 122 and in the circumferential direction of the shaft 122 (see FIG. 12(a)). The two recesses 124 extend along the entire circumference of the shaft 122. Further, each of the four bone removing elements 108 has two protrusions 126 extending in the radial direction of the bone removing element 108 and the radial direction of the shaft 122 (see FIGS. 11(a), 11(b) and 12(b)). Each of the two protrusions 126 is received within a corresponding one of the two recesses 124, as is shown in FIGS. 11(a) and 11(b). The two recesses 124 extend along the circumference of the shaft 122 in an undulating, wavelike or sinusoidal manner, as is indicated in FIGS. 11(a), 11(b) and 12(a).

[0190] Hence, a connection between the shaft 122 and the four bone removing elements 108 is provided which enables a reciprocating movement of the bone removing elements 108 relative to the main body 106 in the axial direction of the preparation tool 100 upon continuous rotation of the shaft 122 relative to the main body 106. In particular, the recesses 124 and the protrusions 126 are arranged so that continuous rotation of the shaft 122 relative to the main body 106 causes the four bone removing elements 108 to reciprocate relative to the main body 106 in the axial direction of the preparation tool 100, wherein the movements of the bone removing elements 108 relative to the main body 106 are out of phase with each other. In this way, a balance between the forces acting on different parts of the bone tissue when forming the non-circular cavity can be achieved in an efficient manner.

[0191] The shaft 122 can be rotated relative to the main body 106, e.g., by driving the shaft 122 by hand or with a motor (not shown), such as a rotation motor, so as to cause the bone removing elements 108 to move relative to the main body 106 in the axial direction of the preparation tool 100. For this purpose, the shaft 122 of the preparation tool 100 of the present embodiment has, at its proximal end, a coupling part 128 which allows for the shaft 122 to be coupled to a motor (see, for example, FIGS. 9(a), 9(b) and 12(a)).

[0192] The reciprocating movement of the bone removing elements 108 relative to the main body 106 in the axial direction of the preparation tool 100 allows for the non-circular cavity to be formed in a particularly simple and reliable manner. Further, this reciprocating movement can be effected in a simple way, by continuously rotating the shaft 122 relative to the main body 106, e.g., manually or by using a rotation motor or the like.

[0193] FIGS. 13(a) and (b) show perspective overlay views of the preparation tool 100 and an implant 130, which is a threaded dental implant, in order to illustrate the relative dimensions of the implant 130 and the preparation tool 100, in particular, the distal portion 104 thereof. The preparation tool 100 and the implant 130 together form a kit according to an embodiment of the present invention.

[0194] The implant 130 has a circular cross-section perpendicular to the axial direction of the implant 130. By using the preparation tool 100 together with the implant 130 having a circular cross-section, i.e., by forming a non-circular cavity in bone tissue by means of the tool 100 and inserting the implant 130 therein, a particularly high degree of stability and improved osseointegration of the implant 130 can be ensured, as has been detailed above.

[0195] The distal portion 104 of the preparation tool 100 has a radial extension in some directions perpendicular to the axial direction of the preparation tool 100 which is larger than a radial extension of the implant 130 in the directions perpendicular to the axial direction of the implant 130 and a radial extension in other directions perpendicular to the axial direction of the preparation tool 100 which is smaller than the radial extension of the implant 130 in the directions perpendicular to the axial direction of the implant 130. Specifically, as is shown in the illustrative overlay views of FIGS. 13(a) and (b), parts of the bone removing elements 108 of the distal portion 104 have larger radial extensions than the implant 130.

[0196] In this way, it can be ensured that both biologic zones and mechanical zones are introduced when inserting the implant 130 into the non-circular cavity prepared by the preparation tool 100. Since the rate of bone resorption and remodelling is different for these two types of zones, the implant 130 will always be in contact with the bone tissue and, therefore, not become loose or unstable. Hence, a particularly high degree of stability and good osseointegration of the implant 130 can be ensured.

[0197] It should be emphasized that many variations and modifications may be made to the herein-described embodiments, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims. Moreover, any of the steps described herein can be performed simultaneously or in an order different from the steps as ordered herein. Moreover, as should be apparent, the features and attributes of the specific embodiments disclosed herein may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure.