DENTAL IMPLANT WITH FUNCTIONAL GRADIENT AND ITS PRODUCTION PROCESS

Abstract

The present disclosure describes a dental implant with functional gradient and respective obtention method, wherein the implant comprises an inner part of metal or metal alloy or titanium-based metal matrix composite which comprises on its surface a transition zone of rugose texture or surface pattern; an outer part composed of a ceramic or zirconia-based ceramic composite, and a diffusion protective film between the transition zone and the outer part described as an oxide and/or nitride protective film.

Claims

1. A dental implant comprising: a metallic interior portion of the implant with an external surface wherein the external surface is rugose or has recesses; a protective film on said external surface; and an exterior portion of the implant; wherein the protective film is selected from the group consisting of: titanium oxide, nitride, oxy-nitride, and combinations thereof as a barrier to the diffusion between the interior and exterior of the implant and the exterior portion of the implant is positioned over said protective film.

2. The dental implant according to claim 1, wherein the rugosity or recesses of the external surface of the metallic interior portion of the implant have corresponding rugosity or recesses in said protective film.

3. The dental implant according to claim 1, wherein the rugose external surface or the recesses of the metallic interior portion have a depth of 1 micrometer to 1.5 millimeters.

4. The dental implant according to claim 1, wherein the rugosity or the recesses of the external surface of the metallic interior portion of the implant form a pattern of grooves.

5. The dental implant according to claim 4, wherein the grooves intersect at a 90 angle.

6. The dental implant according to claim 1, wherein the metallic interior portion of the implant is selected from the group consisting of: a metal, a metal alloy, and a metal matrix composite.

7. The dental implant according to claim 1, wherein the metallic interior portion of the implant comprises titanium.

8. The dental implant according to claim 1, wherein the exterior portion of the implant comprises zirconia.

9. The dental implant according to claim 4, wherein the grooves have a depth of between 0.1 and 1.5 millimeters.

10. The dental implant according to claim 1, wherein the rugosity or the recesses of the external surface of the metallic interior portion of the implant has a thickness between 1 micrometer and 1.5 millimeters.

11. The dental implant according to claim 1, wherein the protective film is composed of a material selected from the group consisting of: titanium oxide, nitride, and titanium oxy-nitride.

12. The dental implant according to 11, wherein the protective film has a thickness between 2 nanometers and 20 micrometers.

13. The dental implant according to claim 1, wherein the metallic interior portion of the implant has a diameter between 1.5 and 8 millimeters.

14. The dental implant according to claim 1, wherein the metallic interior portion has a fracture toughness ranging from 80 to 120 MPa.Math.m.sup.(1/2).

15. The dental implant according to claim 1, wherein the exterior portion is comprised of zirconia containing elements selected from the group consisting of: yttrium, cerium, CaO, MgO alumina, and mixtures thereof.

16. The dental implant according to claim 15, wherein the amount of yttrium on the exterior portion of the implant ranges from 2 to 10% by weight.

17. The dental implant according to claim 15, wherein the amount of cerium on the exterior portion of the implant ranges from 1 to 20% by weight.

18. The dental implant according to claim 15, wherein the amount of alumina on the exterior portion of the implant is up to 20% by weight.

19. The dental implant according to claim 1, wherein the exterior poriton of the implant has a composition selected from the group consisting of: hydroxyapatite, TCP, bioglass, and combinations thereof.

20. The dental implant according to claim 19, wherein the amount of hydroxyapatite, TCP, bioglass, or combinations thereof is at most 50% by volume.

21. The dental implant according to claim 20, wherein the bioglass comprises a compound selected from the group consisting of: compounds comprising silica, compounds comprising SiO.sub.2, compounds comprising calcium oxide, compounds comprising CaO, compounds comprising sodium oxide, compounds comprising Na.sub.2O and mixtures thereof.

22. The dental implant according to claim 1, wherein the exterior portion has a thickness ranging from 0.1 to 1.5 millimeters.

23. A process of forming a dental implant which comprises the following steps: applying a treatment, selected from the group consisting of: a mechanical treatment, a physical treatment, and a chemical treatment, to a titanium rod to form the external surface wherein the external surface is rugose or has recesses; providing a film on the rugose external surface or recesses, by a route selected from the group consisting of: a chemical route, an electrochemical route, a physical route using plasma depositions, a temperature route, and combinations thereof; placing the metal rod with the external surface wherein the external surface is rugose or has recesses and protective film inside the body of the mould; adding ceramic powders in the space between the rod and the interior of the mould, the powders preferably comprising nrconia; adding the upper part of the mould (2); heating the assembly to a temperature between 900 C. and 1600 C., preferably at 1180 C., in an ambient under vacuum and/or controlled atmosphere; during heating, applying a pressure on the powders between 5 MPa and 200 MPa, preferably 60 MPa; and after 5 to 60 minutes, preferably 15 minutes, withdrawing the pressure and to allow to cool down to room temperature.

24. The process according to claim 23. wherein the external surface is rugose or has recesses and comprises a projection of ceramic particles, by a method selected from the group consisting of: an acid treatment, a laser ablation treatment, mechanical machining, and combinations thereof.

25. The process according to claim 23, wherein the protective film is obtained by electrochemical oxidation with electrical potentials between 80 and 120V using as electrolyte phosphoric acid (H.sub.3PO.sub.4), sulfuric acid (H.sub.2SO.sub.4), or both H.sub.3PO.sub.4 and H.sub.2SO.sub.4.

26. The process according to c1aim 23, wherein the protective film is obtained from diffusion by oxidation with temperatures between 200 C. and 1200 C., in the air or in an oxygen enriched environment, and with exposures from a predetermined number of minutes to a predetermined number of days.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] For an easier understanding, the following drawings are attached, which represent preferred embodiments which are not intended to limit the object of the present description.

[0066] FIG. 1 Embodiment of a mould with the main body (1), the upper part (2) and the lower part (3) into which the titanium rod (4) and the zirconia-based powders (5) are placed.

[0067] FIG. 2 Embodiment of application of pressure (6) and temperature (7), for implant consolidation, in which the pressure is applied on the upper part (2) and on the lower part (3) of the mould. Inside the mould there is the metal rod (4) already with treated surface (10) and the ceramic powders (5).

[0068] FIG. 3 Embodiment of dental implants where it can be seen the titanium-based inner metallic part (4), the zirconia-based outer ceramic part (8), the physical transition zone (9) between the inner metallic part and the outer ceramic part, and the diffusion protective film of oxide, nitride or oxy-nitride (10).

DETAILED DESCRIPTION

[0069] The present disclosure describes a dental implant, which is composed of an inner part or core, formed by a metal or metal alloy or titanium-based metal matrix composite, tough and resistant to fracture; by a transition zone which will provide a high mechanical connection between the inner metallic part and the outer ceramic part; and by a film that will prevent the diffusion of materials between them during processing; and by an outer part composed of a ceramic or ceramic composite, biocompatible, with aesthetic function and possibly bioactive, based on zirconia, optionally containing alumina, hydroxyapatite, TCP, bioglass, among other zirconia stabilizing materials and/or bioactive and/or antibacterial.

[0070] This disclosure further relates to a method of producing the dental implant in which the inner, metallic component, and the outer, ceramic component, are consolidated using hot-pressing technology, or spark-plasma-sintering, or equivalent, and wherein the metallic part is already in the solid rod state, and the ceramic part is in powder. The powder is consolidated on the surface of the solid part using pressure and temperature, after preparation of the solid surface, using a mechanical, physical, thermal and/or chemical treatment.

[0071] In one embodiment, according to FIG. 3 the dental implant comprises an inner metallic part (4). This part comprises pure titanium or any other grade, or by a titanium alloy, for example Ti6Al4V, or by a titanium-based metal matrix composite, for example Ti6Al4V containing 0.1% to 5% by volume of Al2O3, or other reinforcement. This metallic interior should have the fracture toughness characteristics of titanium or its alloys, for example between 80 and 120 MPam.sup.(1/2), and has a diameter ranging from 1.5 to 8 millimeters.

[0072] In one embodiment, the physical transition zone (9), created on the inner metallic part is a surface texture or pattern, which will create a strong mechanical connection between the metallic interior and the ceramic exterior, and which has a thickness which can range from 1 micrometer to 1.5 millimeters. This zone, which may consist of some rugosity but will preferably be by a pattern of grooves made by laser ablation, or CNC machining, on the surface of the inner metal rod, with a depth that can reach up to 1,5 millimeters, is intended to create a mechanical interlocking between the material of the inner part and the material of the outer part, which will penetrate the grooves (or texture) when pressure and temperature are applied.

[0073] In one embodiment, the chemical transition barrier (10) consists of a diffusion protective film formed by a titanium oxide and/or nitride or titanium oxi-nitride and which is intended to create a barrier to the diffusion between the materials of the outer ceramic part and of the inner metallic part during processing, and may have a thickness ranging from 2 nanometers to 20 micrometers. This layer is applied to the metallic part after the physical transition zone has been created.

[0074] In one embodiment, the outer part (8) comprises zirconia, which is stabilized with yttria (ranging from 2 to 10% by weight), ceria (from 1 to 20% by weight), or other zirconia stabilizer such as CaO, MgO, among others, and may still contain alumina in percentages up to about 20% by weight.

[0075] In one embodiment, the implant further comprises an outer part, zirconia based, which may contain bioactive or antibacterial materials such as hydroxyapatite, beta tricalcium phosphate (TCP), or Bioglass (compounds based on silica, SiO2, Calcium oxide, CaO, Sodium oxide, Na2O, among others), in percentages that may reach up to 50% by volume. The outer part must have a thickness that can range from about 0.1 mm to about 1.5 mm.

[0076] In one embodiment, the implant of the present disclosure has fracture toughness which comes essentially from the metallic interior, and the biocompatibility; and aesthetics that come from the zirconia exterior, and may be as well bioactive and/or antibacterial through the incorporation of bioactive and/or antibacterial materials on the zirconia-based outer part.

[0077] In one embodiment, according to FIG. 1, the implant is processed within a mould that may comprise the central body (1), the upper part (2), and lower part (3). This mould may be in graphite or in a refractory material such as Tungsten, Niobium, Molybdenum, among others.

[0078] In one embodiment, the implant of the present disclosure may be obtained from a titanium-based metal rod (4) and may be of pure titanium of any grade, or an alloy of titanium, or of a titanium matrix composite, preferably a Ti6Al4V alloy, and surface treated with a mechanical, physical and/or chemical treatment, in order to give rise to a surface texture on the titanium rod (9), which will serve to promote a strong mechanical connection between the parts and create a transition zone between the metal and the outer ceramic.

[0079] In a transition zone, i.e. the external surface wherein the external surface is rugose or has recesses, consisting of a surface texture, can be obtained by projection of ceramic particles, by an acid treatment, using for example sulfuric acid, by a laser ablation treatment, or by mechanical machining, where textures as holes or grooves are created, with certain depth and pattern, and which are intended to create a good mechanical connection between the inner metallic layer and the outer ceramic layer. It should preferably be created a pattern of grooves, with grooves that intersect at 90, by laser ablation or by CNC machining, with a depth of about 0.5 mm. To the transition zone there may further be added a diffusion protective film (10) of oxide, nitride, or oxy-nitride, obtained by conventional chemical or electrochemical route, or physical, also conventional, by plasma depositions, or even by temperature route, also conventional, which is intended to avoid diffusion between the elements of the inner metallic part and of the outer ceramic part during processing.

[0080] Preferably an electrochemical oxidation should be carried out. As an example of electrochemical oxidation there may be mentioned electric potential parameters between 80 and 120V using as electrolyte phosphoric acid (H3PO4) and/or sulfuric acid (H2SO4), giving rise to dense thin films. As an example of oxidation with temperature there may be mentioned temperatures between 200 C. and 1200 C., in the air or in an oxygen enriched environment, and with exposures of some minutes to several days. This diffusion protective film is made over the texture previously performed.

[0081] In one embodiment, in the implant of the present disclosure, the metal rod (4), after being treated superficially, with texture and with protective film, is placed inside the mould body (1). resting on the base of the mould (3) which, however, is secured to the main body of the mould (1), with an existing space between the rod (4) and the interior of the mould. In this space the ceramic powders (5) will be placed. Ceramic powders will be essentially based on zirconia and may contain other elements as described above. Preferably it may be zirconia stabilized with 3% (volume) of yttria,

[0082] After the powders are placed, the upper part of the mould (2) is placed, and the assembly is heated (7) at a temperature between 900 C. and 1600 C., preferably at 1180 C. The heating should preferably take place in an ambient under vacuum and/or controlled atmosphere, for example with argon, to prevent oxidation of the titanium. During the heating process pressure (6) is applied to the powders from the lower (3) and upper (2) parts of the mould, up to values which may oscillate between 5 MPa and 200 MPa, preferably 60 MPa.

[0083] After a period of time, which may range from 5 minutes to 60 minutes, preferably 15 minutes, wherein the powders are subjected to the indicated pressure and temperature, pressure is withdrawn and the temperature will naturally decrease to room temperature.

[0084] In one embodiment, the implant of the present disclosure shown in FIG. 3 illustrates the implant in near-final shape, in which there is the inner part (4), metallic, and the outer part (8), ceramic, and a zone of the physical transition (9) between the two parts and a diffusion protective film (10). The outer geometry of the zirconia part may already contain the final geometry of the implant, including thread or other texture.

[0085] In one embodiment, the implant of the present disclosure has a fracture toughness that comes essentially from the metallic interior and the biocompatibility and aesthetics that comes from the exterior in zirconia, and can also be bioactive and/or antimicrobial by incorporating bioactive and/or antibacterial materials into the zirconia. It also has a high mechanical connection between the inner metallic part and the outer ceramic part and will maintain the aesthetic part of the zirconia.

[0086] The term comprises or comprising when used in this document is intended to indicate the presence of the characteristics, elements, integers, steps and components mentioned, but does not prevent the presence or addition of one or further features, elements, integers, steps and components, or groups of the same.

[0087] The present disclosure is not, of course, in any way restricted to the described embodiments in this document and a person of ordinary skill in the art may foresee many possibilities of modifying it and replacing technical characteristics by equivalent ones, depending on the requirements of each situation, as defined in the appended claims.

[0088] The following claims further define preferred embodiments.