WO2013004361A2

WO2013004361A2 - Composite ceramic for dental implants

Info

Publication number: WO2013004361A2
Application number: PCT/EP2012/002721
Authority: WO
Inventors: Daniel Grüner; Jenny FÄLDT; Erik Adolfsson; Zhijan Shen
Original assignee: Nobel Biocare Services Ag
Priority date: 2011-07-06
Filing date: 2012-06-28
Publication date: 2013-01-10
Also published as: GB201111549D0; WO2013004361A3

Abstract

As described, a bioactive ceramic nanocomposite is described as follows. The composite material comprises a ceramic nanocomposite including a plurality of first grains which include calcium phosphate. The grain size may be one micron or less. The calcium phosphate may be present in the nanocomposite material in the range of 10% by weight to 70% by weight based on the total weight of the nanocomposite material. A plurality of second grains may be rapid sintered to the calcium phosphate-containing grains. The second grains may be selected from the group consisting of zirconia and alumina.

Description

COMPOSITE CERAMIC FOR DENTAL IMPLANTS

BACKGROUND

Field of the Invention

[0001] The present inventions relate generally to implant dentistry and, more specifically, to a ceramic composite for a dental implant.

Description of the Related Art

[0002] Implant dentistry involves the restoration of one or more teeth in a patient's mouth using artificial components. Such artificial components typically include a dental implant that supports a prosthetic tooth (e.g., a crown), an implant-supported bridge or an implant-supported denture. A dental implant is typically fabricated from pure titanium or a titanium alloy. The body portion is configured to extend into and osseointegrate with the alveolar bone.

[0003] Various platforms made of such materials as titanium or titanium alloys are known in the art for providing a connection interface between the implant and the alveolar bone. Ceramic implants have been known to be used for such applications, but their level of osseointegration has historically been considered less satisfactory than that of metal implants such as titanium or titanium alloys.

[0004] It has been known that ceramics may be used to create a bioactive material. For example, U.S. 5,232,878 discloses a type of glass-ceramic is formed by sintering a bioactive glass ceramic with either zirconia or alumina. U.S. 5,032,552 discloses a ceramic composite which includes an apatite as a matrix and an inorganic aluminosilicate whisker dispersed therein.

[0005] While such prior art materials suitable for use in medical applications have been successful, there is a continuing desire to improve the osseointegration between dental implants and the alveolar bone through the use of an improved bioactive material. Such an improved platform would advantageously provide a successful integration between an implant and the body. It would also be desirable for the implant to be made of a chemically inert material, thus resulting in a low allergy risk. It would also be desirable for the implant to be made of a material that is aesthetically pleasing, as it could be made to look white or tooth-like. It would also be advantageous for the implant to be soft tissue friendly, that is, that plaque and bacteria content is generally low to reduce the risk of the inflammatory response of adjacent soft tissue. In addition, it would be advantageous to continue to improve the dental implant's ability to osseointegrate with the alveolar bone and to generally promote gingival health and beauty. It would also be advantageous for the implant to be mechanically stronger, so it can have improved load-bearing capacity.

GAO et al. "Fabrication of HAp-Zr0₂ (3Y) nano-composite by SPS", Biomaterials 24 (2003) 937-940 discloses the fabrication of Nano-HAp-Zr0₂ powders and HAp-TZP(3Y) composites. HAp-TZP(3Y) composites with small grain size could be sintered at relatively low temperatures and very short dwelling time by using SPS technology.

SHEN et al. "Dense Hydroxyapatite-Zirconia Ceramic with High Strength for Biological Applications" Advanced Materials, Volume 13, Issue 3, pages 214-216, February, 2001, discloses dioactive composites, where the deleterious reactions between hydroxyapatite and the composite matrix (in this case zirconia) are kinetically inhibited by employing a super-fast consolidation technique, spark plasma sintering (SPS).

GUO et al. "Laminated and functionally graded hydroxyapatite/yttria stabilized tetragonal zirconia composites fabricated by spark plasma sintering", Biomaterials 24 (2003) 667-675 discloses laminated and functionally graded hydroxyapatite (HA)/yttria stabilized tetragonal zirconia (Y -TZP) composites prepared by the process of spark plasma sintering.

SUMMARY

[0006] Accordingly, one embodiment of the present invention comprises a bioactive ceramic nanocomposite suitable for a dental implant. The material comprises a plurality of first grains, the first grains comprising calcium phosphate and having an average grain size of one micron or less, the calcium phosphate being present in the ceramic nanocomposite material in an amount in the range of 10% by weight to 70% by weight based on the total weight of the bioactive ceramic nanocomposite material. The material also comprises a plurality of second grains dynamic-sintered to said plurality of first grains, the second grains comprising a ceramic and having an average grain size of one micron or less. The ceramic is selected from a group consisting of zirconia and alumina. [0007] In some embodiments, the calcium phosphate comprises hydroxyapatite. The calcium phosphate may comprise tricalcium phosphate or mixtures of tricalcium phosphate and hydroxyapatite. In further embodiments, the second grains comprise alumina or mixtures of alumina or zirconia. The second grains may also further comprise Y₂0₃ (3 Y- TZP) in an amount in the range of 2% by weight to 10% by weight based on the total weight of the second grains in the bioactive ceramic nanocomposite material. The calcium phosphate may be present in the ceramic nanocomposite material in an amount in the range of 15% by weight to 60% by weight based on the total weight of the bioactive ceramic nanocomposite material. In other embodiments, the calcium phosphate may be present in an amount in the range of 25% by weight to 45% by weight based on the total weight of the bioactive ceramic nanocomposite material.

Another aspect relates to the use of a bioactive ceramic nanocomposite material as described above, which bioactive ceramic nanocomposite material is comprised in a dental implant for enhancing in vivo osseointegration when (the dental implant is) implanted into bone. The osseointegration may comprise both ingrowth and direct bone precipitation.

[0008] A process of making a bioactive ceramic nanocomposite material may comprise providing a powder composition, where the powder composition comprises particles of calcium phosphate have an average particle size of less than one micron and particles of ceramic having an average particle size of less than one micron, and the ceramic may be selected from the group consisting of zirconia and alumina. The particles of calcium phosphate are present in the powder composition in an amount in the range of 10% by weight to 70% by weight based on the total weight of the powder composition. The powder composition is dynamic sintered to form the bioactive ceramic nanocomposite material. The dynamic sintering may comprise placing the powder composition into a die and passing a pulsed DC current through the die under conditions that are effective to sinter the particles of calcium phosphate to the particles of ceramic without initiating the reactions between the calcium phosphate and ceramic. The dynamic sintering may also comprise applying pressure to the powder composition while passing the pulsed DC current through the die.

[0009] In accordance with another embodiment, a dental implant comprises the bioactive ceramic nanocomposite material. In the dental implant, the bioactive ceramic nanocomposite material may be able to generate surface voids of 1 micron or less and a porosity in the range of 10% to 80% of the total surface area in vitro or in vivo that provide anchoring sites for newly formed bone.

[0010] These and other embodiments are described in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above-mentioned and other features of the inventions disclosed herein are described below with reference to the drawings of the preferred embodiments. The drawings contain the following figures:

[0012] FIG. 1 is a schematic view of the osseointegration resulting from an embodiment of a dental implant of the invention.

[0013] FIGS. 2A and 2B are scanning electron microscopy (SEM) images of an interface between bone tissue and an implant according to an embodiment of the invention.

[0014] FIG. 3A-3C are SEM images of an interface between bone tissue and an implant according to a comparative example.

[0015] FIG. 4 illustrates a top front perspective view of a dental implant in accordance with an embodiment of the present invention.

[0016] FIG. 5A is a SEM image of calcium phosphate formed on an implant according to an embodiment of the invention.

[0017] FIG. 5B is a SEM image of calcium phosphate formed on an implant according to an embodiment of the invention.

[0018] FIG. 5C is a SEM image of calcium phosphate formed on an implant according to an embodiment of the invention.

[0019] FIG. 5D is a SEM image of calcium phosphate formed on an implant according to an embodiment of the invention.

[0020] FIG. 6 is a SEM image of voids formed on the surface of an implant according to an embodiment of the invention. DETAILED DESCRIPTION

[0021] The bioactive ceramic nanocomposite described above is now described in greater detail, as follows. The composite material comprises a ceramic nanocomposite that includes a plurality of first grains which include a calcium phosphate ("CP"), such as, for example, hydroxyapatite, and a plurality of second grains dynamic- sintered to the plurality of first grains. The grain size for both the first and second grains may vary, but for many applications it is desirable that the average grain size of the first grains is less than one micron and the average grain size of the second grains is less than one micron. Alternatively, the average grain size of the first grains may be larger than one micron. The calcium phosphate is present in the nanocomposite material in an amount in the range of 10 wt% to 70 wt% based on the total weight of the composition. The possible chemical reactions between the calcium phosphate and the second grains may be avoided by the manipulation of the process parameters. Process parameters can be adjusted in a manner known to those of skill of the art, as guided by the teachings provided herein. The second grains include a ceramic that comprises zirconia or alumina or a mixture of zirconia and alumina. Various descriptions of the composite materials described herein relate to their use in dental implants, but they can be used in any application where a material is desired that has good mechanical properties and/or exhibits osseointegration. The bioactive ceramic nanocomposite can be used in a variety of applications, including a dental implant. The resulting nanocomposite may exhibit enhanced in vivo osseointegration. The enhanced osseointegration may include direct bone precipitation.

[0022] In preferred embodiments the ceramic nanocomposite materials described herein are bioactive. The term "bioactive" as used in the present application has its ordinary meaning and thus will be understood to include references to materials on which bone-like CP forms selectively when the material is immersed in a serum-like CP solution. Thus, a bioactive nanocomposite material may exhibit accelerated heterogeneous CP crystallization on its surface in a solution supersaturated with CP.

[0023] The term "calcium phosphate" or "CP" as used herein has its ordinary meaning and thus includes reference to various minerals containing calcium ions in combination with a phosphate such as orthophosphates, metaphosphates, and/or pyrophosphates. Examples of calcium phosphates include calcium dihydrogen phosphate, calcium hydrogen phosphate, tricalcium phosphate, apatite, hydroxyapatite, and octacalcium phosphate. Hydroxyapatite ("HA"), also known as calcium phosphate hydroxide, has the chemical formula typically expressed as Caio(P0₄)6(OH)₂ or Ca₅(P0₄)₃(OH) and is known to be a bioactive material. HA belongs to a class of materials known as apatites. Calcium phosphates promote osseointegration when put in contact with the body and bones, but lack significant mechanical strength. Calcium phosphate may be provided in a stiochiometric form. Descriptions or references herein to calcium phosphate will be understood to apply to HA as well, and vice versa, unless otherwise stated.

[0024] Calcium phosphate can be processed to include or includes grains that are micron-sized. According to one embodiment, the average grain size of the calcium phosphate may be less than 1 micron. According to yet another embodiment, the average grain size may be less than 0.5 micron. Also, the sizes of the grains of calcium phosphate (in the composite material or in the powder used to make the composite) may be in the range of 1 micron and 50 microns.

[0025] The term "ceramic" as used herein has its ordinary meaning and thus includes reference to various inorganic, non-metallic solids. Ceramics may comprise several different materials in the form of small grains that are attached to each other. The ceramic grains useful in the composite materials described herein may comprise any suitable ceramic material that can be processed to have a small grain size, e.g., an average grain size of one micron or less. According to certain embodiments, the ceramic may be zirconia. According to yet another embodiment, the ceramic may be alumnia. The ceramic used may also be any of the above mentioned materials alone or in combination. In general, ceramic materials useful in the composite materials described herein have a relatively high mechanical strength and appear white or like white, suitable for use in dental implants.

[0026] Ceramic grains may have or be processed to have various grain sizes, e.g., an average grain size (in the composite material or in the powder used to make the composite) of less than one micron. According to some embodiments, the average ceramic grain size is any of less than 750 nanometers, less than 500 nanometers, less than 250 nanometers, or less than 100 nanometers. A ceramic grain size may be greater than 100 angstroms. According to some embodiments, the ceramic grain size may be in the range of 0.1 micron to 1 micron. A smaller grain size has the advantage of better dispersing materials that may be disposed on the surface of the ceramic. The grains of ceramic may have various grain morphologies. In some embodiments this morphology is tetragonal. In another embodiment this morphology is hexagonal. In another embodiment this morphology is a mixture of tetragonal and hexagonal.

[0027] The ceramic grains may also be doped with a material such as one containing yttrium, for example, Y₂0₃ (3Y-TZP). The ceramic may be doped with this yttrium-containing compound in the range of 2% by weight to 10% by weight based on the total weight of the ceramic in the composition. According to other embodiments the ceramic may be doped in the range of 3% by weight to 6% by weight based on the total weight of the ceramic in the composition. According to other embodiments, the ceramic may not be doped at all.

[0028] The calcium phosphate (e.g., HA) grains and ceramic (e.g., zirconia and/or alumina) grains are combined to form the nanocomposite by employing a sintering process. The calcium phosphate grains and the ceramic grains may be combined such that the calcium phosphate is present in the nanocomposite material in an amount in the range of 10% by weight to 70% by weight based on the total weight of the nanocomposite material. According to another embodiment, the calcium phosphate is present in the nanocomposite material in an amount in the range of 15% by weight to 60% by weight based on the total weight of the nanocomposite material. According to yet another embodiment, the calcium phosphate is present in a range of 25% by weight to 45% by weight based on the total weight of the nanocomposite material. The desired percentage of calcium phosphate to be incorporated into the nanocomposite may be determined based on consideration of a variety of factors including, but not limited to: the amount and speed of osseointegration desired, the intended placement of the nanocomposite in a body, and/or the degree or extent to which the grains or calcium phosphate and ceramic pack together within the composite material.

[0029] The calcium phosphate grains, when combined with the ceramic grains, are attached together in such a way as to form a material that is continuous on a macroscopic scale. On a microscopic scale, the proportions and grain sizes of the calcium phosphate and ceramic components can be adjusted so that, to a lesser or greater extent, isolated grains or groups or grains of one component are embedded or dispersed in a more or less continuous matrix of the other component. According to one embodiment, the calcium phosphate grains are dispersed or embedded in a continuous or semi-continuous matrix of the ceramic grains.

[0030] The bioactive ceramic nanocomposite is formed by a process that includes dynamic sintering the calcium phosphate grains to the ceramic grains. Dynamic sintering may be broadly defined as a sintering process which employs external driving forces rather than thermal, for example, by incorporating the use of high mechanical pressure, electric current and/or electromagnetic fields to activate sintering. Various dynamic sintering techniques are known, see, e.g., Zuhair A. Munior, Dav V. Quach and Manshi Ohyanagi, "Electrical Current Activation of Sintering: A Review of the Pulsed Electric Current Sintering Process," J. Am. Cream. Soc, 94 [1] 1-19 (2011). Known names for dynamic sintering processes include spark plasma sintering, pulsed electric current sintering, field- activated sintering, current-activated pressure-assisted densification and the like. For example, a calcium phosphate powder may be combined with a ceramic powder to form a powder composition. The powder composition may include the weight percentages of calcium phosphate as described above. This powder composition may then be dynamically sintered to form the bioactive nanocomposite ceramic material. The dynamic sintering process may include placing the powder composition into a die and passing a pulsed DC current through the die under conditions effective to sinter the particles of CP to the ceramic particles while avoiding the possible reaction between them. According to some embodiments, this process may effectively sinter the CP and ceramic particles together without initiating significant reactions between the CP and the ceramic grains. This result is unexpected from thermodynamic prediction, given the initial larger grain size of the CP and the smaller initial grain size of the ceramic. While this invention is not limited by theory of operation, it is believed that by limiting the initiation of significant reactions, although a physical bond may be present between the two grains in the nanocomposite after dynamic sintering, the CP will not be chemically bonded to the ceramic grains and will more easily dissolve when in place in a body. [0031] As used herein, "without initiating significant reactions" is broadly defined as limiting the amount of chemical reaction between the grains of calcium phosphate and the grains of ceramic during the dynamic sintering process, thus resulting in no or a minimal reaction product being present in the final product. The reaction product resulting from the reaction of calcium phosphate and ceramic and/or the other materials in the composite material may include, but are not limited to cubic zirconia, calcium aluminates, and/or a glass phase. For example, according to an embodiment, no more than 5 wt% of the calcium phosphate based on the total weight of calcium phosphate in the composition will react with the ceramic grains through the dynamic sintering process, as determined by X-ray diffraction analysis. For example, according to another embodiment, no more than 4 wt%, no more than 3 wt%, no more than 2 wt%, no more than 1 wt%, no more than 0.5 wt%, or 0 wt% of the calcium phosphate based on the total weight of calcium phosphate in the composition will react with the ceramic grains through the dynamic sintering process. In an embodiment, the amount of CP reaction product (if any) in the final product composite material is 5 wt% or less, based on the amount of CP in the composite material. According to other embodiments the amount of reaction product in the final product is any of 4 wt% or less, 3 wt% or less, 2 wt% or less, 1 wt% or less, based on the amount of CP in the composite material. Alternatively, the amount of reaction product in the final product may be in the range of 0.5 wt% to 5 wt%, 1 wt% to 4 wt%, 2 wt% to 3 wt%, or any combination of the listed ranges based on the amount of CP in the composite material. The amount of reaction product in the final product may constitute 0 wt% or only a negligible amount by weight based on the amount of CP in the composite material.

[0032] The amount of reaction product present in the final product may be determined as follows: the overall weight percentage of the calcium phosphate present in a final product may be determined by x-ray diffraction. The overall weight percentage of reaction product present in the final product may also be determined by x-ray diffraction by its characteristic diffraction pattern. The overall weight percentage of the reaction product present in the final product may then be compared to the overall weight percentage of calcium phosphate present in the final product. [0033] The dynamic sintering process is advantageous because it tends to avoid degradation that may result from other sintering processes. It may also keep the stoichiometric composition of the calcium phosphate phases, it may reduce or eliminate unwanted reactions, and it may preserve nano-sized grains in consolidated composites, which can otherwise hardly be achieved by other sintering processes. It may also minimize the microscopic defects and ensure full densification, thus achieving high mechanical strength and mechanical reliability.

[0034] According to an embodiment, a dental implant, such as a single piece dental implant, may be comprised of bioactive ceramic nanomaterials as described herein. A dental implant may comprise a configuration as illustrated in FIG. 4. The dental implant 40 can include a body 42 that extends along a longitudinal axis from a proximal end 43 to a distal end 44 of the implant. The dental implant 40 can also comprise a top surface 45. An open socket 46 may be formed in the top surface 45. The open socket 46 may have an inner surface 47 extending from the distal end 44 of the body 42 towards the proximal end 43 of the body 42 along the longitudinal axis of the body 42. The dental implant 40, including the inner surface 47, can be made of the ceramic nanocomposite material, or it may be made of a combination of the ceramic nanocomposite material and another material such as titanium, zirconium, or various alloys that comprise titanium and or zirconium.

[0035] The dental implants described herein may be configured to have shapes and dimensions similar to those that are commercially available, e.g., such as those manufactured and sold under various different trade names, some of which include NobelActive™, NobelReplace™, NobelSpeedy™, and Branemark System™. The diameter of such dental implants may vary, but are generally in the range of between 3.0 mm and 5.0 mm. Normally, the overall length of the implant is in the range of 6.0 mm to 20.0 mm.

[0036] The dental implant may be configured such that, upon implantation, osseointegration may occur. According to an embodiment, osseointegration by more than one growth mechanism is achieved. According to another embodiment, both ingrowth and direct bone precipitation are achieved with the bioactive ceramic nanocomposite. Differences between these two bone formation mechanisms are illustrated in FIG. 1. As shown, ingrowth yielding the formation of a type I bone may be exhibited as newly formed bone 2 growing out from the existing bone 1 and growing into an implant surface 3, implying that a rough and/or porous surface will receive an increased amount of newly formed bone. Direct bone precipitation yielding the formation of the type II bone may be exhibited where newly formed bone 4 precipitates directly on an implant surface 3 via kinetically favored heterogeneous nucleation of calcium phosphate. As shown, newly formed bone 4 tends to grow in a generally opposite direction newly formed bone 2, outward from the implant surface 3 toward the existing bone 1.

[0037] In use in vitro or in vivo, voids may be formed in the surface of the bioactive ceramic nanocomposite that may form sites where bone may grow. The voids may have a dimension in the range of 1 micron to 50 microns. The bioactive ceramic nanocomposite material may, after exposure to the body or body-imitating fluid, exhibit a porosity in the range of 10% to 80% of total surface area of the material sample.

EXAMPLE 1

[0038] A ceramic nanocomposite material is formed by dynamic sintering 34 wt% of micron-sized HA to a 66 wt% of nano sized, tetragonal grains of ziconia doped with 5.4 % by weight of yttrium by a spark plasma sintering procedure. A disk shaped sample with a diameter of 35 mm and thickness of 5mm was prepared by applying a heating rate of 100 °C/min and holding at the sintering temperature of 1150 °C for 5 min under a uniaxial pressure of 50 MPa. The resulting material was subjected to in vitro testing.

EXAMPLE 2

[0039] Generally rectangular test bars of a ceramic nanocompsite with an overall composition of 26 wt% HA and 74 wt% zirconia were made via a dynamic sintering process. The resulting material was subjected to in vivo testing in the manner described in Example 5 below. EXAMPLE 3

[0040] As a comparative example, monophasic zirconium (3Y-TZP) was used as a reference. The monophasic zirconia ceramic was composed of submicron size grains having a size of about 0.3 μιη.

EXAMPLE 4

[0041] In the in vitro testing, samples prepared as described in Examples 1 and 3 were evaluated by the ability of apatite formation on their surfaces in two types of SBFs supersaturated towards HA, namely SBF-JL2 and C-SBF2. For SBF-JL2, the p(C0₂) was controlled to 5% to mimic the physiological conditions of human serum that is in equilibrium with such a partial pressure. The formation of the HA phase was verified by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR).

[0042] Scanning electron micrographs (SEMs) were taken of the surface of the surfaces of the samples prepared as described in Examples 1 and 3, after immersing in both solutions.

[0043] A thick HA layer was formed on the sample prepared as described in Example 1 (containing 34 wt% HA in SBF-JL2) after one week. In contrast, a loosely coherent fragment-type of HA was formed on the bio-inert monophasic zirconia. SEM images depicting the HA layer formed on the implant surface are shown in FIG. 5A-5D. FIG. 5A shows HA and bone formation after one week. FIG. 5B illustrates HA and bone formation after two weeks. FIG. 5C depicts HA and bone formation after three weeks. FIG. 5D shows HA and bone formation after four weeks.

EXAMPLE 5

[0044] In the in vivo study, a mini-pig model was used. Mini pigs were selected to ensure adequate alveolar ride size and height for implant placement. Implants of the test bars of Example 2 and comparative implants made from monophasic zirconia ceramic prepared as described in Example 3 were implanted into the jaw of the pigs. After a four week healing time, the samples were extracted and the following results were observed through SEM images as shown in FIGS. 2-3. An Argon ion milling technique was used to achieve a delicate cross section polishing that enables high-resolution microscopic investigations under scanning electron microscopes.

[0045] As illustrated in FIG. 3, the monophasic zirconia sample showed an approximately 50 μηι thick layer of new bone formed along the flanks of the implant and on the surface of the existing bone. Rough surfaces indicate that in those regions, there has been no bone/implant contact: the morphology of the rough surface is very similar to the outer surface of the bone layer, away from the interface.

[0046] The SEM images as illustrated in FIG. 2 were taken on an ion polished cross-section of the test bar of Example 2 after the in vivo testing. A detailed inspection of a bone/implant contact surface revealed differences as compared to the monophasic zirconia sample illustrated in FIG. 3. At the bone/composite implant interface shown in FIG. 2, a very dense, up to 10 μιη thick layer of bone is observed, whereas the remainder of the new bone is less dense. The surface of the bone layer resembles the implant's surface and small pieces of composite are attached to the bone layer, indicating that a narrow gap less than 10 μιη in breadth between bone and implant has formed during sample preparation. As can be seen from the results of the in vivo study, two bone growth mechanisms, namely ingrowth yielding the formation of type 1 bone and direct bone precipitation on the implant surface yielding the formation of the type 2 bone was present in the sample containing HA, but both were not present in the sample that contained only monophasic zirconia. Thus the HA containing zirconia ceramic nanocomposite was shown to be both bioactive and osseoconductive.

EXAMPLE 6

[0047] A ceramic nanocomposite with an overall composition of 15 wt% tricalcium phosphate and 85 wt% zirconia were made by a spark plasma sintering procedure. A disk shaped sample with a diameter of 20 mm and thickness of 5mm was prepared by applying a heating rate of 100 °C/min and holding at the sintering temperature of 1050 °C for 5 min under a uniaxial pressure of 50 MPa. The resulting material was subjected to in vitro and in vivo testing in the manner described above.

[0048] Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while the number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments can be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to perform varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims.

Claims

WHAT IS CLAIMED IS:

1. A bioactive ceramic nanocomposite material suitable for a dental implant, comprising:

a plurality of first grains, the first grains comprising calcium phosphate and having an average grain size of one micron or less, the calcium phosphate being present in the ceramic nanocomposite material in an amount in the range of 10% by weight to 70% by weight based on the total weight of the bioactive ceramic nanocomposite material; and

a plurality of second grains dynamic-sintered to said plurality of first grains, the second grains comprising a ceramic and having an average grain size of one micron or less, the ceramic being selected from the group consisting of zirconia and alumina.

2. The bioactive ceramic nanocomposite material of Claim 1, wherein the calcium phosphate comprises hydroxyapatite (HA).

3. The bioactive ceramic nanocomposite material of Claim 2, wherein the calcium phosphate comprises tricalcium phosphate or mixtures of tricalcium phosphate and hydroxyapatite.

4. The bioactive ceramic nanocomposite material of any of Claims 1 to 3, wherein the second grains further comprise alumina or mixtures of alumina and zirconia.

5. The bioactive ceramic nanocomposite material of any one of Claims 1 to 4, wherein the second grains further comprise Y₂0₃ (3Y-TZP) in an amount in the range of 2% by weight to 10% by weight based on the total weight of the second grains in the bioactive ceramic nanocomposite material.

6. The bioactive ceramic nanocomposite material of any one of Claims 1 to 5, wherein the calcium phosphate is present in the ceramic nanocomposite material in an amount in the range of 15% by weight to 60% by weight based on the total weight of the bioactive ceramic nanocomposite material.

7. The bioactive ceramic nanocomposite material of any one of Claims 1 to 6, wherein the calcium phosphate is present in the ceramic nanocomposite material in an amount in the range of 25% by weight to 45% by weight based on the total weight of the bioactive ceramic nanocomposite material.

8. Use of a bioactive ceramic nanocomposite material of any one of Claims 1 to 7 comprised in a dental implant for enhancing in vivo osseointegration when implanted into bone.

9. Use according to Claim 8, wherein the osseointegration comprises direct bone precipitation.

10. Use according to Claim 9, wherein the osseointegration also comprises ingrowth.

11. A process of making the bioactive ceramic nanocomposite material of any one of Claims 1 to 7, comprising:

providing a powder composition, wherein the powder composition comprises particles of calcium phosphate having an average particle size of less than one micron and particles of ceramic having an average particle size of less than one micron, the ceramic being selected from the group consisting of zirconia and alumina;

wherein particles of calcium phosphate are present in the powder composition in an amount in the range of 10% by weight to 70% by weight based on the total weight of the powder composition; and

dynamic sintering the powder composition to form the bioactive ceramic nanocomposite material.

12. The process of Claim 1 1, wherein dynamic sintering the powder composition comprises placing the powder composition into a die and passing a pulsed DC current through the die under conditions that are effective to sinter the particles of calcium phosphate to the particles of ceramic without initiating the reactions between the calcium phosphate and ceramic.

13. The process of Claim 12, wherein dynamic sintering the powder composition comprises applying pressure to the powder composition while passing the pulsed DC current through the die.

14. A dental implant comprising the bioactive ceramic nanocomposite material of any one of Claims 1 to 7.

15. The dental implant of Claim 14, wherein the bioactive ceramic nanocomposite material is able to generate surface voids of 1 micron or less and a porosity in the range of 10% to 80% of the total surface area in vitro or in vivo that provide anchoring sites for newly formed bone.