WHITE, BACTERIA-RESISTANT, BIOCOMPATIBLE, ADHERENT COATING FOR IMPLANTS, SCREWS AND PLATES INTEGRATED IN HARD AND SOFT TISSUE AND PRODUCTION METHOD

Abstract

The invention relates to a white, bacteria-resistant, biocompatible, adherent coating for an element which can be integrated in hard and soft tissue, in particular an implant, a screw or a plate, having a structure made from metalliferous gradient layers having varying oxygen content, wherein the band gap of the outer-most gradient layer is greater than 3.1 eV, wherein the outer-most gradient layer is crystalline and wherein the gradient layers comprise tantalum and/or niobium and/or zirconium and/or titanium.

Claims

1-21. (canceled)

22. An implant formed by a dental implant having an enossal part and an abutment, characterized in that a white, bacteria-resistant, biocompatible, adherent coating is applied onto both an enossal part and the abutment of the dental implant, wherein the coating has a structure made from metalliferous gradient layers (11, 12, 13) having a varying oxygen content, wherein the band gap (E.sub.g) of the outermost gradient layer (13) is greater than 3.1 eV, wherein the outermost gradient layer is crystalline, and wherein the gradient layers (11, 12, 13) comprise tantalum and/or niobium and/or zirconium and/or titanium.

23. The implant according to claim 22, wherein the lowermost gradient layer (11) applied onto the implant (20) is a metallic adhesive bonding layer, the outermost gradient layer (13) is a metal oxide layer having full stoichiometry, and wherein the intermediate gradient layers (12) have an oxygen content increasing from the lowermost gradient layer (11) applied onto the implant to the outermost gradient layer (13) to the full stoichiometry.

24. The implant according to claim 22, wherein at least one of the gradient layers (12, 13) having an oxygen content, preferably at least the outermost gradient layer (13), has grain sizes of 5 nm or greater.

25. The implant according to claim 22, wherein the gradient layers (11, 12, 13) further have aluminium and/or tin.

26. The implant according to claim 22, wherein the concentration of the metals in the gradient layers (12, 13) is adjusted by at least binary oxides such that the gradient layers (12, 13) having at least binary oxides have a band gap (E.sub.g) of greater than 3.1 eV.

27. The implant according to claim 22, wherein one or more gradient layer/s (11, 12, 13) contain/s carbon and/or nitrogen and/or boron and/or fluor.

28. The implant according to claim 22, wherein the lowermost gradient layer (11) applied onto the implant has a thickness of 50 nm or less.

29. The implant according to claim 22, wherein the entire thickness of the gradient layers (12) having a reduced oxygen stoichiometry amounts to 500 nm or less, preferably 200 nm or less, further preferably 100 nm or less, further preferably 60 nm or less.

30. The implant according to claim 22, wherein the thickness of the outermost gradient layer (13) amounts to 10 μm or less.

31. The implant according to claim 22, wherein the entire thickness of the coating amounts to between 3 μm and 7 μm, preferably between 4 μm and 6 μm, further preferably between 4.5 μm and 5.5 μm.

32. A method for producing a white, bacteria-resistant, biocompatible, adherent coating on an implant according to claim 22, comprising the following steps: applying a metallic adhesion bonding layer as a first gradient layer (11) onto the surface of the implant (20) by means of PVD (physical vapor deposition), applying gradient layers (12, 13) comprising tantalum and/or niobium and/or zirconium and/or titanium, as well as oxygen, onto the metallic adhesion bonding layer (11) having an increasing oxygen content by increasing the oxygen content during the application of the gradient layers (12, 13) until the full stoichiometry of the outermost gradient layer (13) is reached, wherein the band gap (E.sub.g) of the outer gradient layer (13) is greater than 3.1 eV.

33. The method according to claim 32, wherein the application of the gradient layers (11, 12, 13) is performed at a temperature of 300° C. or higher.

34. The method according to claim 32, wherein the gradient layers (11, 12, 13) are cured under an oxygen atmosphere.

35. The method according to claim 32, wherein the gradient layers (11, 12, 13) are formed such that they have grain sizes of 5 nm or greater.

36. The method according to claim 32, wherein the gradient layers (11, 12, 13) comprise tantalum and/or niobium and/or zirconium and/or titanium, as well as oxygen.

37. The method according to claim 32, wherein the gradient layers (11, 12, 13) further comprise aluminium and/or tin.

38. The method according to claim 32, wherein the application of the gradient layers (11, 12, 13) is performed such that the lowermost gradient layer (11) applied onto the implant (20) is a metallic adhesive bonding layer, the outermost gradient layer (13) is a metal oxide layer having full stoichiometry, and wherein the intermediate gradient layers (12) have an oxygen content increasing from the lowermost gradient layer (11) applied onto the implant to the outermost gradient layer (13) to the full stoichiometry.

39. The method according to claim 32, wherein the concentration of the metals in the gradient layers (12, 13) is adjusted by at least binary oxides such that the gradient layers (12, 13) having at least binary oxides have a band gap (E.sub.g) of greater than 3.1 eV.

40. The method according to claim 32, wherein one or more gradient layer/s (11, 12, 13) contain/s carbon and/or nitrogen and/or boron and/or fluor.

Description

[0023] FIG. 1 shows an element 20 formed by an implant such as a screw or plate that can be integrated into hard and soft tissue. A coating according to the invention made of several gradient layers 11, 12, 13 is applied onto the element. The lowermost gradient layer 11 formed on the element 20 is a metallic adhesion bonding layer. The outermost gradient layer 13 is a white layer containing a metal oxide having full stoichiometry. Between the gradient layers 11 and 13, one or more gradient layer/s 12 are formed, the oxygen content of which increases from the lowermost gradient layer 1 formed on the element 20 up to the outermost gradient layer 13 with the full stoichiometry.

[0024] In the simplest case, a white layer of zirconium dioxide is adjusted. Zirconium dioxide is used in the implantology as a full ceramic material. Up to now, however, it has not worked to apply zirconium dioxide onto titanium implant bodies as a tightly adherent white layer. In the embodiment according to the invention, firstly a metallic layer is deposited in a layer thickness of 20 nm as the lowermost gradient layer 11 of zirconium on the element 20, the surface of which preferably is roughened and formed of titanium in a preferred embodiment. In the following, the oxygen is successively supplied by means of a PVD typical reactive process, and the layer is finally formed in the full stoichiometry present in the outermost gradient layer 13, via the gradient layers 12. The entire layer thickness of the coating is preferably adjusted to 5 micrometres. The process control may be made such that the deposition takes place at an increased temperature so that the otherwise PVD typical (x-ray amorphous) layer is not generated but an at least nanocrystalline layer.

[0025] In a second exemplary embodiment, a mixed phase having 20 mol % of Nb.sub.2O.sub.5 and 80 mol % of Ta.sub.2O.sub.5 is adjusted for the outermost gradient layer 13, and the full stoichiometry is established starting from the lowermost, metallic gradient layer 11 via the intermediate gradient layers 12. The layers are characterized by a particularly high biochemical stability and a negative surface potential. The negative surface potential causes a stable adsorption of calcium ions and a therewith associated safe osteointegration.

[0026] In the further example, a layer having the stoichiometry of ZrTi.sub.2O.sub.6 is used as the outermost gradient layer 13. (Ti,Zr)O.sub.2-x layers are highly biocompatible and blue-black due to their high defect structure, their x-ray amorphous morphology and their non-exact composition adjustment. The coating according to the invention has an outer gradient layer 13 having a band gap E.sub.g of 3.1 eV or more, and is adjusted to be exact in stoichiometry. This gradient layer 13 is nanocrystalline. Due to its high negative free enthalpy of formation, the outermost gradient layer 13 in addition has a significantly improved biochemical stability. Its point of zero potential is at pH 6-7.