Abstract
An implant system including a dental implant and an abutment produced from a ceramic material, wherein the abutment includes a first anti-rotation element with multiple grooves and the dental implant includes a second anti-rotation element, which is complementary thereto, with multiple ribs, wherein the grooves are open toward a proximal end of the abutment.
Claims
1. An implant system including a dental implant and an abutment produced from a ceramic material, wherein the dental implant extends along a longitudinal center axis L.sub.I from an apical end toward a coronal end and comprises an axial blind bore which is open toward the coronal end and, on an outer surface, a screw thread for anchoring in a jaw bone, the abutment comprises a distal end with a head portion for receiving a prosthetic element, a proximal end, which is situated opposite the distal end and has a connecting portion for insertion into the blind bore of the dental implant, and a through-bore which extends from the distal end to the proximal end for receiving a connecting screw, a first anti-rotation element is realized on the outside of the connecting portion and a second anti-rotation element, which is complementary to said first anti-rotation element, is realized on the inside in the blind bore, wherein: the first anti-rotation element of the abutment includes a hollow cylindrical first basic body with an outer shell surface and with multiple grooves which extend in the longitudinal direction and, proceeding from the outer shell surface, project into the first basic body, wherein the grooves are open toward the proximal end, and the second anti-rotation element of the dental implant includes a hollow cylindrical second basic body with an inner shell surface and multiple ribs which extend in the longitudinal direction and, proceeding from the inner shell surface, project into the axial blind bore.
2. The implant system as claimed in claim 1, wherein the dental implant includes an internal threaded portion, which is arranged apically of the second anti-rotation element, for connection to a connecting screw.
3. The implant system as claimed in claim 1, wherein two adjacent grooves or ribs are spaced apart from one another in each case portions of the outer or inner shell surface of the corresponding hollow cylindrical basic body and the width of the portions measured in the circumferential direction is greater than the width of the grooves or ribs.
4. The implant system as claimed in claim 1, wherein the grooves extend substantially up to the proximal end of the abutment.
5. The implant system as claimed in claim 1, wherein the grooves and the ribs each comprise a cross section that is in the shape of a segmental arch at least in portions.
6. The implant system as claimed in claim 1, wherein the cross-sectional surface of the grooves and ribs comprise at least one base line which is formed through the outer or rather inner shell surface of the corresponding hollow cylindrical basic body of the respective anti-rotation element and the end points of which are connected by means of a connecting line which is accurate at least in portions.
7. The implant system as claimed in claim 6, wherein the connecting line includes a circular arc with a uniform radius.
8. The implant system as claimed in claim 1, wherein the grooves or the ribs comprise a width-length ratio of between 1:3 and 1:6.
9. The implant system as claimed in claim 1, wherein the axial blind bore comprises a hollow cylindrical end portion coronally of the second anti-rotation element and, distally of the first anti-rotation element, the abutment comprises a complementary hollow cylindrical neck portion which is arranged inside the end portion once the connecting portion has been inserted into the blind bore.
10. The implant system as claimed in claim 9, further comprising a tapered section that is provided coronally of the hollow cylindrical end portion within the blind bore of the dental implant and has a diameter that increases in the coronal direction, and the implant system further comprising a complementary tapered section that is provided coronally of the cylindrical neck portion on the connecting portion of the abutment, wherein the surfaces of the two tapered sections contact each other after full insertion of the connecting portion of the abutment into the blind bore of the implant.
11. The implant system as claimed in claim 10, wherein the hollow cylindrical end portion of the dental implant extends substantially up to the coronal end of the axial blind bore and its length, is at least half as long as the length of the second anti-rotation element.
12. The implant system as claimed in claim 1, wherein the connecting portion extends in the proximal direction up to a ring-shaped end face which is delimited on the outside by a circumferential rounded end edge.
13. The implant system as claimed in claim 1, wherein the connecting portion extends in the distal direction up to a circumferential shoulder which, in the connected state of the implant system, rests on the coronal end of the dental implant and, as a result, surrounds the opening of the axial blind bore.
14. The implant system as claimed in claim 1, wherein the second anti-rotation element is arranged completely in the region of the threaded portion.
15. The implant system as claimed in claim 1, wherein the dental implant and/or the abutment are produced using a (powder) injection molding method.
16. The implant system as claimed in claim 1, wherein the first anti-rotation element and the second anti-rotation element include an identical number of grooves or ribs.
Description
[0048] The invention is described in detail by way of the accompanying figures, in which:
[0049] FIG. 1 shows a side view of an implant system according to a first embodiment of the invention;
[0050] FIG. 2 shows a top view of the implant system according to FIG. 1;
[0051] FIG. 3 shows a section through the implant system according to FIG. 1 along a longitudinal center axis A-A;
[0052] FIG. 4 shows a section through the implant system according to FIG. 3 along a plane B-B perpendicular to the longitudinal center axis;
[0053] FIG. 5 shows a side view of the dental implant according to FIG. 1 on its own;
[0054] FIG. 6 shows a top view of the dental implant according to FIG. 5;
[0055] FIG. 7 shows a section through the dental implant according to FIG. 5 along the longitudinal center axis A-A;
[0056] FIG. 8 shows a side view of the abutment according to FIG. 1 on its own;
[0057] FIG. 9 shows a section through the abutment according to FIG. 8 along the longitudinal center axis A-A;
[0058] FIG. 10 shows a section through the abutment according to FIG. 8 along the plane B-B;
[0059] FIG. 11 shows a section through an implant system according to an alternative embodiment; and
[0060] FIG. 11a shows an enlarged view of a detail of FIG. 11.
[0061] FIG. 1 shows an embodiment of an implant system according to the present invention. The implant system includes a dental implant 10 and an abutment 12 produced from a ceramic material, both of which are connected together in a sturdy manner by means of a connecting screw 14 (see FIG. 3). The ceramic components 10, 12 of the implant system, i.e. the dental implant 10 and the abutment 12, are produced in a preferred manner using an injection molding process. An yttrium-stabilized and/or cerium-stabilized zirconium oxide ceramic is used preferably in its production. As an alternative to this, other biocompatible ceramic materials that are suitable for use in the dental field are also conceivable.
[0062] The dental implant 10 is provided for anchoring in a jaw bone and extends along a longitudinal axis L.sub.I from an apical end 16 to a coronal end 18. In addition, it comprises a blind bore 20 which is open toward the coronal end 18, extends coaxially to the longitudinal axis L.sub.I of the dental implant 10 and has a coronal opening 22 (see FIG. 3) into which the abutment 12 is inserted. The blind bore 20 is realized in a cylindrically stepped manner and includes a ring-shaped shoulder surface 23 (see FIG. 7) which serves for support of the abutment 12.
[0063] The abutment 12, which is shown as a whole unit in FIGS. 3, 8 and 9, comprises a distal end 24 with a head portion 26 for receiving a prosthetic element, e.g. a tooth crown (not shown), and an oppositely situated proximal end 28 with a connecting portion 30. The connecting portion 30 is provided for insertion into the blind bore 20 of the dental implant 10 and comprises a ring-shaped shoulder 31 (see FIG. 8) which, in the connected state of the implant system, is supported on the shoulder surface 23 of the dental implant 10 (see FIG. 3). In the proximal direction, the connecting portion 30 extends up to a ring-shaped end face 33 (see FIG. 10) which is delimited on the outside by a circumferential end edge 35. Said end edge 35 is rounded such that, in the connected state of the implant system, it does not come into contact with the inner wall of the axial blind bore 20 (see FIG. 3). On the outside, the connecting portion 30 additionally comprises a first anti-rotation element 32, which is described in detail in conjunction with FIGS. 8-10. The first anti-rotation element 32 is intended to interact with a complementary second anti-rotation element 34, which is realized in the blind bore 20 of the dental implant 10, in order to prevent the abutment 12 rotating about a longitudinal axis once it has been inserted into the blind bore 20 of the dental implant 10.
[0064] The abutment 12 additionally includes a through-bore 36, which extends from the distal head portion 26 up toward the proximal end 28 (see also FIG. 9) and which consequently penetrates the abutment 12 completely and serves for receiving a connecting screw 14 (see FIG. 3). In the embodiment shown, the through-bore 36 extends along the longitudinal axis L.sub.A of the abutment 12 and is aligned with the longitudinal axis L.sub.I of the dental implant 10. In the event of an angled abutment (not shown), the through-bore 36 is certainly also in alignment, as a rule, with the longitudinal axis L.sub.I of the dental implant 10, but is positioned with reference to the longitudinal axis L.sub.A of the abutment 12 in such a manner that it encloses an angle with this latter. In a middle region of the through-bore 36, the abutment 12 comprises a shoulder 38 which serves as contact surface for the underside of a screw head 40 of the connecting screw 14 (see FIG. 3). The diameter of the through-bore 36 is narrower proximally of the shoulder 38 than in a region 39 which is located distally of the shoulder 38.
[0065] The connecting screw 14 is produced, as a rule, from metal, in a preferred manner titanium, which is advantageous as regards stability. As can be seen the best from FIG. 3, the connecting screw 14 includes a distal screw head 40 and a shank 42 with an external threaded portion 44 located proximally. The diameter of the shank 42 is smaller than that of the through-bore 36. The diameter of the screw head 40 is smaller than the diameter of the region 39 which adjoins the shoulder 38 of the abutment 12 distally and is greater than that of a region of the through-bore 36 which adjoins the shoulder 38 proximally. Consequently, the connecting screw 14 can only be inserted into the through-bore 36 until the underside of the screw head 40 rests on the shoulder 38. The length of the connecting screw 14 is chosen such that the proximal external threaded portion 44, once the connecting screw 14 has been inserted into the abutment 12 (until the screw head 40 rests on the shoulder 38) projects proximally out of the through-bore 36. Thus, the external threaded portion 44 can be screwed in a known manner into an internal threaded portion 46, which is arranged apically of the second anti-rotation element 34 in the blind bore 20 of the dental implant 10, in order to connect the abutment 12 to the dental implant 10 in a reversible manner.
[0066] As can be seen best in FIGS. 1 and 5, on the outside the dental implant 10 comprises a threaded portion 48, which is self-tapping in a preferred manner and extends in large parts over the length of the dental implant 10. On the coronal end 18, the dental implant 10 includes a thread-free portion 50. As the second anti-rotation element 34 also serves, as a rule, as a contact point for an insertion tool for screwing the dental implant 10 into the jaw bone, it is not realized directly in the coronal end region 19, but further apically in the blind bore 20 (see FIG. 7). Thus, the thin-walled coronal end region 19 is largely protected from the torsional forces which arise when the dental implant 10 is screwed-in. In the case of the embodiment shown in FIG. 7, the second anti-rotation element 34 is arranged further down in the blind bore for this reason and consequently completely in the region of the threaded portion 48.
[0067] With regard to the greatest possible reduction in the forces acting on the material in the region 19 of the second anti-rotation element 34, a thread-free, hollow cylindrical portion 52 is arranged between the second anti-rotation element 34 and the internal threaded portion 46 that is realized in the blind bore 20, (see FIG. 7). As a result, stresses, which can arise when the connected screw 14 is screwed-in, are kept away as much as possible from the region 19 of the second anti-rotation element 34. In addition, the internal threaded portion 46 is positioned exclusively in the lower, i.e. apical, half of the blind bore 20 in order to relieve the coronal end region 19 of the implant 10.
[0068] On the coronal end 18, the dental implant 10 additionally comprises a hollow cylindrical end portion 54 which extends substantially up to the coronal end 18 of the axial blind bore 20 and to which the second anti-rotation element 34 is attached in the apical direction. In a complementary manner to the end portion 54, a hollow cylindrical neck portion 56 is realized distally of the first anti-rotation element 32 of the abutment 12, the neck portion 56 being positioned inside the end portion 54 in the connected state of the implant system components 10, 12 (see FIG. 3). As a consequence, the inner radius of the end portion 54 is realized in a complementary manner to the outer radius of the neck portion such that a precisely-fitting connection between abutment and implant is achieved. In the case of said embodiment, the second anti-rotation element 34 consequently does not extend up to the coronal end 18 of the dental implant 10, but simply up to the hollow cylindrical end portion 54. As a result, it is ensured that the coronal anti-rotation element 34 is positioned sufficiently deeply in the blind bore 20, i.e. sufficiently far away from the coronal end 18 in order to keep the forces acting on the material in the coronal end region 19 as small as possible.
[0069] The form of the anti-rotation elements 32, 34 is advantageous with regard to increased stability and reduced fracture susceptibility of the implant system components that are to be connected (that is to say of the dental implant 10 and of the abutment 12):
[0070] As can be seen the best in FIGS. 8, 9 and 10, the first anti-rotation element 32 of the abutment 12 includes a hollow cylindrical first basic body 58 with an outer shell surface 60 and additionally comprises multiple grooves 62 which extend in the longitudinal direction L and, proceeding from the outer shell surface 60, project into the first basic body 58. Said grooves 62 are open toward the proximal end 28 of the abutment 12 and, in the embodiment shown, extend up to the proximal end 28 of the abutment 12.
[0071] The second anti-rotation element 34 of the dental implant also comprises, correspondingly, a hollow cylindrical second basic body 64 with an inner shell surface 66 and with multiple ribs 68 which extend in the longitudinal direction and project, proceeding from the inner shell surface 66, into the interior of the axial blind bore 20 (see FIG. 6). In the connected state, the ribs 68 of the dental implant 10 engage in the grooves 62 of the abutment and form an anti-rotation connection between the two ceramic components 10, 12 of the implant system (see FIG. 3).
[0072] The advantage of the design according to the invention of the anti-rotation device produced from interlocking grooves 62 and ribs 68 is that, in contrast to otherwise often used anti-rotation devices with a polygonal cross section, it is possible to dispense with the realization of sharp edges and corners and, as a result, to avoid load peaks. In addition, two adjacent grooves 62 or ribs 68 are spaced apart from one another in each case by portions 70/72 of the inner shell surface 60/68 of the corresponding hollow cylindrical basic body 58/64 and the width of the portions 70/72 measured in the circumferential direction is greater than the width of the grooves 62 or ribs 68. As a result, the stability bestowed by the hollow cylindrical basic body 58/64 in the region of the corresponding anti-rotation element 32/34 is maintained.
[0073] The downwardly open design of the grooves 62 extending up to the proximal end 28 enables simple insertion of the ribs 68 of the second anti-rotation element 34 into the grooves 62 when the connecting portion 30 of the abutment is inserted into the blind bore 20 of the dental implant 10.
[0074] As can be seen well in FIGS. 4 and 6, the grooves 62 and ribs 68 each comprise an approximately semi-circular cross section. Both the grooves 62 and the ribs 68 are consequently in the form of a cylinder which is cut in the longitudinal direction, the concavely or convexly curved basic area of which is formed by a portion of the respective shell surface 60/68 of the associated basic body 58/64. Said form allows the forces acting on the anti-rotation elements 32/34 to be distributed in a homogeneous manner.
[0075] In a possible embodiment, the second anti-rotation element 34 extends over a length of approximately 2 mm and comprises six ribs 68 which are uniformly spaced apart from one another in the circumferential direction (see FIG. 6). The first anti-rotation element 32 comprises, correspondingly, six grooves 62 which are uniformly spaced apart from one another in the circumferential direction (see FIG. 10). It is, however, also conceivable to provide a smaller number of ribs 68 than grooves 62. The ribs 68 define the number of possible alignment possibilities for the abutment 12 in relation to the dental implant 10. With reference to the stability of the anti-rotation device, it has been shown that a higher number of grooves 62 or ribs (three or more) in place of just one or two grooves 62 or ribs 68 is advantageous. In addition, the grooves 62 in the embodiment shown are realized in a relatively narrow manner in order to impair the wall thickness and consequently the stability of the wall in the region of the first anti-rotation element as little as possible. It has also been shown that a width-length ratio of the grooves 62 or ribs 68 of at least 1:3 is advantageous with reference to the stability of the anti-rotation device, on the one hand, and to the fracture strength of the material in the region of the anti-rotation elements 32, 34 on the other hand.
[0076] As can be seen from FIGS. 8 and 9, the head portion 26 of the abutment 12 is realized in a substantially cylindrical manner and on its circumferential surface comprises a region with an external thread 74. The external thread 74 serves for fastening a prosthetic element, such as a crown or a bridge element (not shown). Said external thread 74 can also be replaced by notches or ribs as an alternative to this. A further anti-rotation element in the form of three cams 76, which are uniformly spaced apart from one another in the circumferential direction, is realized proximally of the external thread 74 (see FIG. 2). Thanks to the cams 76, a prosthetic element is able to be fastened non-rotatably on the abutment 12.
[0077] A truncated cone-shaped transition portion 78, to which a ring-shaped platform 80 is attached distally, is realized between the head portion 26 and the connecting portion 30. The ring-shaped platform 80 extends radially with respect to the longitudinal axis L.sub.A of the abutment 12 and serves as a contact surface for a prosthetic element.
[0078] FIG. 11 shows further an alternative embodiment to the implant system shown in FIG. 3. Most features are the same in both embodiments. The implant system according to FIG. 11 differs from the embodiments shown in FIGS. 1 to 10 particularly in that the blind bore 20 of the dental implant 10 further comprises a tapered section 82, which is provided coronally of the hollow cylindrical end portion 54 and which has a diameter that increases in the coronal direction. In addition, the connecting portion 30 of the abutment 12 comprises a complementary tapered section 84 that is located coronally of the cylindrical neck portion 56, such that the tapered surfaces 82, 84 contact each other after full insertion of the connecting portion 30 of the abutment 12 into the blind bore 20 of the implant 10. Thanks to the tapered contact surfaces 82, 84 the transmission of forces from the abutment 12 to the dental implant 10 is improved. The tapered contact surfaces 82, 84 also assist centering of the abutment 12 when the latter is inserted into the blind bore 20 of the dental implant 10.
[0079] The taper angle of the tapered sections 82, 84 is usually 5 to 35, in the shown example it is about 20.
[0080] The axial length L.sub.I3 of the tapered section 82 of the blind bore 20 of the implant 10 is smaller than the axial length L.sub.I2 of the hollow cylindrical end portion 54, and also than the axial length L.sub.I1 of the coronal anti-rotation element 34. L.sub.I2 is also smaller than L.sub.I1. In the shown embodiment, the length L.sub.I3 is about of the length L.sub.I2.
[0081] Similarly, the axial length L.sub.A3 of the tapered connection portion 84 of the abutment 12 is smaller than the axial length L.sub.A2 of the cylindrical neck portion 56, and also than the axial length L.sub.A1 of the first anti-rotation element 32. L.sub.A2 is also smaller than L.sub.A1. In the shown embodiment, the length L.sub.A3 is about of the length L.sub.A2.
[0082] Comparing the embodiments of the dental implant 10 and the abutment 12 shown in FIGS. 1 to 10 with the embodiment of the dental implant 10 it is evident that the axial length L.sub.I2 of the hollow cylindrical end portion 54 is reduced, since the tapered section 82 replaces part of the hollow cylindrical end portion 54. For that reason, the axial length L.sub.I2 of the hollow cylindrical end portion 54 or the axial length L.sub.I2 of the neck portion 56 can in such embodiments be less than half of the length L.sub.A1, L.sub.I1 of the first and the second anti-rotation element 32, 34, respectively. However, the combined axial lengths L.sub.I3 and L.sub.I2 of the tapered section 82 and the hollow cylindrical end portion 56 of the blind bore 20 are at least half as long as the axial length L.sub.I1 of the second anti-rotation element 34. Similarly, the combined axial lengths L.sub.A3 and L.sub.A2 of the tapered section 82 and the neck portion 56 of the abutment 12 are at least half as long as the axial length L.sub.A1 of the first anti-rotation element 32.
[0083] As can also be seen in FIG. 11, the connecting screw 14 has a screw head 40 with a conically tapered underside 86. Said underside 86 abuts or rests on a complementary tapered screw seat 88 in the bore 36 of the abutment 12. The connection of the tapered underside 86 with the tapered screw seat 88 facilitates the force transmission and further helps the transmission of the forces from the screw 14 to the abutment towards the tapered sections 82, of the blind bore 20 and of the connecting portion 30, respectively.
[0084] The taper angle on the screw head 40 is usually about 10 to 70. In the shown embodiment the head has a taper angle of about 20. Alternatively, a taper angle of about 60 is particularly preferred.
