Surface area of a ceramic body and ceramic body

Abstract

A dental implant with a post element is inserted into a jawbone with a mounting element attached to the post element, with the post element designed as a ceramic body of yttrium- and/or aluminum oxide stabilized zirconium oxide. The dental implant has improved ingrowth during osseous implant healing. The surface of the dental implant is provided with at least one partial area that has nanoscopic pores or an otherwise executed nanoscopic structure that has a depletion zone with a reduced yttrium- and/or aluminum oxide element.

Claims

1. A dental implant, comprising: a post element insertable into a jawbone, said post element having a mounting element attachable to a dental prosthesis element, said post element having a yttrium-stabilized zirconium oxide-based ceramic body, said body having a surface portion, said surface portion having a depletion zone, said depletion zone depleted of yttrium oxide relative to the body, said depletion zone having irregularly arranged nanoscopic pores, wherein the depletion zone is arranged in a portion of the post, said depletion zone comprising a connection area between said post and said jawbone to facilitate osseointegration, and wherein the depletion zone is depleted of yttrium oxide by at least 5% relative to the body.

2. The dental implant of claim 1, wherein said post element is comprised of the same ceramic base material in its interior volume and on its surface.

3. The dental implant as set forth in claim 1, wherein a content of yttrium oxide on said surface is less than an yttrium oxide content in said internal volume.

4. The dental implant as set forth in claim 1, wherein a crystallographic structure of said surface is different than said internal volume.

5. The dental implant as set forth in claim 1, wherein the surface has a substantially rounded crater structure comprising craters of diameter between 1 m and 60 m and a roughness in the range of 2-6 m and wherein the nanoscopic pores have a depth of less than 1 m.

6. The dental implant as set forth in claim 1, wherein the surface provides for increased bond strength between stabilized zirconia and other material, wherein said stabilized zirconia comprises ZrO.sub.2 and at least one stabilizing compound.

7. The dental implant as set forth in claim 1, further comprising stabilizers selected from the group consisting of MgO, CaO, Y.sub.2O.sub.3, CeO.sub.2, Al.sub.2O.sub.3, Sc.sub.2O.sub.3 and Yb.sub.2O.sub.3.

8. The dental implant as set forth in claim 1, further comprising a stabilizer present in an amount from 0.05 to 10% mol %.

9. The dental implant as set forth in claim 1, wherein at least said ceramic body has a mechanical strength, wherein an initial strength of said ceramic body is increased due to the combination of monocline and tetragonal phase crystalline structure of stabilized zirconium oxide ceramic.

10. The dental implant as set forth in claim 1, wherein said ceramic body comprises 3Y-TZP.

11. The dental implant as set forth in claim 1, wherein a bond strength of said surface is increased due to the nanostructure of said surface, affecting the attainable strength of the bond between bone and implant, wherein said surface has increased surface energy and an increased bond strength as compared to-materials without nanoscopic pores.

12. The dental implant of claim 1, wherein said body has an internal tetragonal crystal structure and said depletion zone has a monocline structure.

Description

BRIEF DESCRIPTION OF THE INVENTION

(1) Sample embodiments of the invention are explained in further detail on the basis of a drawing.

(2) FIG. 1 shows a dental implant in partially sectional side elevation,

(3) FIG. 2 shows electron-microscopic images of implant surfaces produced by means of chemical treatment with the described nanostructure, and

(4) FIG. 3 shows electron-microscopic images of implant surfaces produced by means of chemical treatment with the described microstructure.

(5) FIG. 1, in an elevation and partially in an axial section, shows a two-part dental implant 1 with a post element 2 and with a mounting element 4. The post element 2 and preferably also the head or mounting element 4 consist of ceramic. Here, the post element 2 is formed from yttrium-stabilized zirconium oxide and embodied as a step screw. It contains three steps 6 to 8 which respectively have a self-cutting thread 10 to 12 with equal slope. The step 6 nearest the apical end 14 possesses the smallest diameter. The step 9 nearest the mounting element 4, by contrast, has a smooth, cylindrical outer surface. The post element 2 possesses at the coronal end 15 an internal bore 16 into which the head or mounting element 4 is inserted and which further contains an internal thread 18. The connection of the mounting element 4 with the post element 2 occurs by means of a screw (not shown here) which is fed through a through hole 20 of the mounting element 4 and screwed into the internal thread 18. A crown 22 or the like can be connected in a known manner with the mounting element 4.

(6) The post element 2 and the mounting element 4 can also be embodied as a single-piece variant.

(7) The post element 2 is anchored in an appropriately-prepared implant bed of the jawbone. The thread construction ensures a high level of primary stability and a uniform transfer into the jawbone of the forces occurring during masticatory stress. Moreover, the bone is intended to grow as directly as possible against the implant during the healing phase following the implantation and connect closely therewith. This process, known as osseointegration, is improved considerably through a targeted roughening of the implant surface.

CONTINUED DETAILED DESCRIPTION OF THE INVENTION

(8) To produce this roughening, an appropriately-selected treatment is provided. Through an appropriate etching process, for example in an appropriately-selected acid bath, the depletion zone in the surface of the ceramic body is produced which is characterized by a lower proportion of selected materials in comparison to the internal volume of the ceramic body, particularly of yttrium used for the stabilization of the zirconium oxide, and consequently also by a lower proportion of the crystallographic monocline phase. This results in the very favorable surface roughnesses on a nanoscopic and microscopic scale shown in FIG. 2 and FIG. 3. In one embodiment, a zirconium oxide dental implant comprises yttrium-stabilized TZP, TZP-A and ATZ ceramics. Special features of the surface may include at least one of additives (metals/metal oxides) such as, for example, yttrium/oxide, aluminum/oxide, hafnium/oxide in the TZP zirconium ceramic, reduced at the surface by more than 5%, preferably more than 25% and particularly more than 50%. Additional features may include: a) structuring through selective and/or intercrystalline etching or corrosion through varying etching speeds, and b) isotopes of hafnium can be radioactive. It is noted that hafnium is technically quite difficult to separate from yttrium. This often results in a contamination of yttrium stabilized ceramics with hafnium, which can lead to a radioactive effect, albeit a very slight one. The removal of these materials can have a favorable effect on the radioactive characteristics of the surface. In one embodiment (termed embodiment 2), the proportions of the monocline phase in the surface are increased by at least 0.25%, preferably by 1% and particularly by more than 2%. Such features bring about a lower density in the area of the surface and hence the sealing of microcracks. The result is a greater initial strength. In one embodiment, the surface has a crater structure (termed embodiment 3.) These craters are predominantly rounded. The craters have a diameter of ca. 1 m to ca. 60 m. The roughness depth is 0.5 m to a maximum of 3.9 m. In one embodiment, the surface also has a structural size or porosity of less than 0.5 m, preferably less than 0.2 m and particularly less than 0.1 m. In one embodiment, the structural depth is at least as large as the structural width of the structure in the immediately-preceding sentence. Note that if blood, other secretions or liquids with protein components, preferably the BMP protein, penetrates to the surface through capillary effects, this structure (i.e. that described in this paragraph) encourages the adhesion through mechanical retentions on the surface. The surface can therefore be used as storage for proteins or other additives. In one embodiment, the surface is fluoridated or enriched with fluoride ions and/or modified with fluorine. Note that in order to grow, cells need small quantities of fluorine and/or fluorine ions. The accretion of small quantities of fluorine and/or fluorine ions encourages and/or accelerates cell growth. As a consequence, the healing time of implants can be shortened. One embodiment of a method of manufacturing comprises the following steps: 1. General modification of the surface per any or all of the above embodiments 2. Surface treatment with a surface modification per any or all of the above embodiments in liquid and/or gaseous media. 3. Medium (such as per embodiment 2 above) is one of the elements of the 3.sup.rd to the 7.sup.th main group of the periodic table of elements. 4. Medium (such as per embodiment 2 and/or 3 above) is hydrofluoric acid as the main component. 5. The temperature of the medium is maintained between 30 C. and 300 C., preferably between 50 C. and 130 C. 6. Duration of application longer than 1.1 min., preferably longer than 3 min. and particularly longer than 10 min. 7. Flat surface removal rate of at least 0.1 m, preferably greater than 0.5 m and particularly greater than 2 m.