OSTEOSYNTHESIS BODY OF ZIRCONIUM DIOXIDE CERAMIC

Abstract

An osteosynthesis body consisting of a zirconium dioxide ceramic in the form of a screw or a shaped body for osteosynthesis such as a panel or a strip in a planar or three-dimensionally curved form which is provided in at least some sections with holes through which screws can be passed. This is preferably produced from TZP powder by means of HIP and a subsequent post-processing step in order to achieve the highest possible mechanical resilience from the finest possible powders, with an average specific surface area of, for example, 30 to 50 m2/g.

Claims

1. An osteosynthesis body made of zirconium dioxide ceramic, in the form of a screw, consisting of a highly dense zirconium dioxide ceramic having a porosity of less than 0.01%, made of tetragonal, polycrystalline zirconium dioxide (TZP) or made of zirconium dioxide mixture ceramic with Al.sub.2O.sub.3 (ATZ), wherein an outer surface of the screw is etched or blasted.

2. The osteosynthesis body of claim 1, in the form of a non self-tapping screw.

3. The osteosynthesis body of claim 1, in the form of a self-tapping screw.

4. The osteosynthesis body of claim 1, wherein said osteosynthesis body is configured for fixing bone substitute material in bone build-up for setting dental implants.

5. The osteosynthesis body of claim 1, wherein the outer surface is sand blasted and etched.

6. An osteosynthesis body made of zirconium dioxide ceramic, in the form of a screw, consisting of a highly dense zirconium dioxide ceramic having a porosity of less than 0.1%, made of tetragonal, polycrystalline zirconium dioxide (TZP) or made of zirconium dioxide mixture ceramic with Al.sub.2O.sub.3 (ATZ).

7. The osteosynthesis body of claim 6 having a porosity of less than 0.01%.

8. The osteosynthesis body of claim 6, wherein the outer surface is roughened.

9. The osteosynthesis body of claim 6, wherein the outer surface is etched.

10. The osteosynthesis body of claim 6, wherein the outer surface is sand blasted.

11. The osteosynthesis body of claim 6, wherein said osteosynthesis body is configured for fixing bone substitute material in bone build-up for setting dental implants.

12. A method for producing an osteosynthesis body of a zirconium dioxide ceramic, wherein from a powder of tetragonal, polycrystalline zirconium dioxide (TZP), or of a zirconium dioxide mixture ceramic powder (ATZ) an osteosynthesis body is formed and sintered.

13. The method of claim 11, wherein the shaping is performed by a method selected from the group consisting of HIP, slip casting, centrifugal casting, uniaxial pressing, isostatic pressing, and electrophoretic deposition (EPD).

14. The method of claim 11, wherein initially a preform is formed from powder, is pre-sintered to a green body, is subsequently in the green state mechanically machined, and is finally sintered to its final state.

15. The method of claim 11, wherein the powder is mixed with a binder to a printable paste, is applied by means of a 3D printer and is sintered thereafter.

16. The method of claim 11, wherein a microscale powder having an average specific surface area in the range of 5 to 100 m g.sup.2/g is used.

17. The method of claim 11, wherein a nanoscale powder having a specific surface area of more than 100 m.sup.2/g, preferably of more than 200 m.sup.2/g is used.

18. The method of claim 11, wherein microscale and nanoscale powders are mixed.

19. The method of claim 11, wherein the sintering is performed in the 850 C. to 1350 C.

20. The method of claim 11, wherein a pre-sintering to a green body is performed, the green body is mechanically machined thereafter, and is sintered thereafter to its final state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Further features and advantages of the invention can be taken from the subsequent description of preferred embodiments with reference to the drawings. In the drawings show:

[0044] FIG. 1 an exemplary embodiment of an osteosynthesis plate according to the invention consisting of TZP; and

[0045] FIG. 2 a perspective view of a bone screw according to the invention, made of zirconium dioxide, intended for osteosynthesis, which is provided with a self-cutting thread.

PREFERRED EMBODIMENTS

[0046] In FIG. 1 an osteosynthesis plate 10 is shown which is configured as an angularly stable plate, such as for instance be used in mandibular fracture treatment. The osteosynthesis plate 10 has two cone-shaped recessed screw holes 12 for receiving osteosynthesis screws 14 according to FIG. 2.

[0047] For preparing the osteosynthesis plate 10 initially a commercial available TCP zirconium dioxide powder (stabilized with 3 weight-% Y2O3) with an average specific surface area of about 50 m2/g is isostatically pressed (pressure about 1000 to 3000 bars, for 1 to 100 seconds), is thereafter sintered at about 900 C., for about 30 minutes.

[0048] The green body obtained in this way is machined to the desired final shape by means of an automatically controlled milling device, wherein the degree of shrinkage is taken into account for the subsequent sintering process. Thereafter, a final sintering is carried out at about 1350 C. over a period of about 30 to 60 minutes.

[0049] A particularly cost-effective manufacture is obtained, in case the pre-sintered green body is prepared by slip casting.

[0050] By means of an automatically controlled high-speed milling cutter or grinder with a diamond tool, the osteosynthesis plate 10 is prepared therefrom.

[0051] To prepare the osteosynthesis screws 14 for the purpose of very high strength, TCP powder according to the above example is pressed by HIP (e.g. 1000 to 3000 bars, 1200 to 1300 C., 2-30 minutes). From this the screw 14 is prepared by milling or grinding using diamond tools.

[0052] It is basically possible to use osteosynthesis screws 14 as shown in FIG. 2, which are provided with a self-cutting thread.

[0053] Due to the thereby occurring higher surface pressure, partially non-self-cutting screws are preferred which for example have a fine thread and slightly taper conically (not shown). Although this means higher demands on the operator, as a thread cutting is required, however it means a higher load safety.

[0054] If the osteosynthesis system consisting of the osteosynthesis plate 10 and the respective screws is intended only for temporary fixation, then the surface of the osteosynthesis plate 10 must not be additionally surface-treated after sintering. Possibly a machine smoothing by a grinding treatment is performed.

[0055] By contrast, in case of permanent implantation the surfaces of the osteosynthesis body (that is plates 10 and screws 14) undergo a mild sandblast treatment, followed by an etching treatment using hydrofluoric acid, to effect a particularly good osteointegration.