US20090061389A1 - Dental implant prosthetic device with improved osseointegration and shape for resisting rotation - Google Patents

Abstract

A dental implant has a body that generally defines a coronal-apical axis and a porous tantalum metal portion that is disposed at the body for engaging bone and having a non-circular outer periphery extending around the axis. The non-circular outer periphery is shaped to engage a bore in a bone to resist a torsional force that is applied to the dental implant and around the coronal-apical axis.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation-in-part of pending U.S. patent application Ser. No. 11/847,476, filed Aug. 30, 2007, which is incorporated herein by reference in its entirety for all purposes.
FIELD OF INVENTION
• The present invention relates to bone implant prosthetic devices and, in particular, to a dental prosthetic device with a shape for resisting torsional force applied to the device.
BACKGROUND
• A dental implant or fixture is surgically implanted into a patient's upper or lower jaw to directly or indirectly anchor and support prosthetic devices, such as an artificial tooth. The implants are usually placed at one or more edentulous sites in a patient's dentition at which the patient's original teeth have been lost or damaged in order to restore the patient's chewing function. In many cases, the implant anchors a dental abutment, which in turn provides an interface between the implant and a dental restoration. The restoration is typically a porcelain crown fashioned according to known methods.
• One form of a prosthetic device is a unitary or one-piece implant device with a bone-engaging implant portion and an abutment portion integral with the implant portion. Another form of a prosthetic device is a multiple piece device where the abutment is assembled onto the implant. A desire still exists, however, to improve the osseointegration characteristics of such dental devices.
• One problem with one-piece dental devices is that the titanium and other materials used for such devices often are an unattractive color. Thus, when the abutment portion of the device below a prosthetic tooth but above the gum or gingival tissue is visible and does not have the color of natural teeth, the dental device provides a non-esthetically pleasing appearance in a person's mouth. Other known dental devices that have the color of natural teeth typically provide inadequate strength resulting in relatively frequent replacement or repair of the device.
• Whether or not the dental implant device is a one-piece or part of a multiple piece device where the abutment is assembled onto the implant, the implant is usually either threaded or press-fit into a bore which is drilled into the patient's mandible or maxilla at the edentulous site. The press-fit implant is inserted by applying a force to the coronal end of the implant in an insertion direction. For a threaded implant, self-tapping threads may be provided for initial stability of the implant immediately after surgery. Before biologic integration has time to take place, the threads resist tension, twisting, or bending loads applied to the implant. Additionally, patients prefer to leave the initial surgery with some type of restoration and it has further been shown that the healing of the soft and hard bone tissue is improved if the implant is loaded after surgery.
• The surgical procedure for inserting the threaded implants, however, can be complicated and requires that the threaded implants be turned into place, which further requires the use of special tools and inserts. The torque needed to place the implant into the jaw can be high and may require tapping of the bore on the jaw, which adds yet another step to the surgical procedure where tapping typically is not desired. Also with threaded implants, it is often difficult to achieve optimal esthetics where, for example, a prosthetic is held at an ideal orientation by the implant because the geometry of the thread establishes a fixed relationship between the final vertical and rotational orientation of the implant such that a vertical adjustment requires a rotational adjustment and vice-versa.
• Alternatively, a press fit implant has a much simpler surgical procedure. For a press fit implant, the implant is inserted by applying a force to the coronal end of the implant in an insertion direction. Unlike the self-tapping, threaded dental implants, however, the current press fit designs provide insufficient frictional contact with the bore to adequately restrict the rotation of the implant within the bore or prevent the implant from pulling out of the bore that can be caused by mastication forces. Thus, the current press fit designs provide very little initial stability and are not well suited for early and immediate loading procedures that are currently used in dentistry. A desire still exists, therefore, to provide press fit implants with greater resistance to mastication forces.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a cross-sectional view of a first embodiment of a one-piece dental implant prosthetic device in accordance with the present invention;
• FIG. 2 is an enlarged fragmentary view of a porous tantalum portion for any of the embodiments herein and in accordance with the present invention;
• FIG. 3 is an enlarged sectional view of a porous tantalum portion and a filler material for a number of embodiments herein and in accordance with the present invention;
• FIG. 4 is a cross-sectional view of a second embodiment of a one-piece dental implant prosthetic device in accordance with the present invention;
• FIG. 5 is a cross-sectional view of a third embodiment of a one-piece dental implant prosthetic device in accordance with the present invention;
• FIG. 6 is a side elevational view of an instrument used to aid in press-fitting an implant into a jaw bone in accordance with the present invention;
• FIG. 7 is a side elevational view of an alternative implant configured for press-fitting in accordance with the present invention;
• FIG. 8 is a top view of the alternative implant ofFIG. 7;
• FIG. 9 is a side elevational view of another implant configured for press-fitting in accordance with the present invention;
• FIG. 10 is a top view of the implant ofFIG. 9;
• FIG. 11 is a graphical representation of the overall elastic modulus for a porous metal/composite material structure as a function of an elastic modulus of a filler material for the structure;
• FIG. 12 is a schematic diagram showing the boundary conditions used for computing Young's modulus for the porous metal/composite material structure shown graphically inFIG. 11;
• FIG. 13 is a side elevational view of another implant configured for press-fitting in accordance with the present invention;
• FIG. 14 is a top view of the implant inFIG. 13;
• FIG. 15 a side elevational view of another implant configured for press-fitting in accordance with the present invention;
• FIG. 16 is a side, cross-sectional view of a bore holding the press-fit implant ofFIG. 15 in accordance with the present invention;
• FIG. 17 is a simplified and exaggerated top cross-sectional view taken along line XVII-XVII onFIG. 16;
• FIG. 18 is a side elevational view of another implant configured for press-fitting in accordance with the present invention;
• FIG. 19 is a top view of the implant inFIG. 18;
• FIG. 20 is a side elevational view of a multiple-root implant in accordance with the present invention;
• FIG. 21 is a top view of the multiple-root implant ofFIG. 20 in accordance with the present invention;
• FIG. 22 is a side elevational view of a three-root implant in accordance with the present invention; and
• FIG. 23 is a side, perspective view of a four-root implant in accordance with the present invention.
DETAILED DESCRIPTION
• Referring toFIG. 1, there is illustrated a pre-fabricated one-piecedental prosthetic device20. The one-piecedental device20 has a bone engaging endosseous portion orimplant portion22 on a distal orapical end portion24 of thedevice20 to extend into the maxillae or mandible (either being otherwise generally referred to as the jaw bone). Theimplant portion22 supports anabutment portion26 integrally formed with theimplant portion22 and disposed at a proximal or coronal end portion28 of the one-piecedental device20. Theabutment portion26 may include an abutment, an integrally formed dental restoration (i.e., a (near) net-shape tooth or crown), and/or the transmucosal portion of a single stage dental implant. In the form shown inFIG. 1, theabutment portion26 extends through and above the gingival tissue to support and receive a tooth shaped prosthetic or other types of prosthetic pieces or devices. The one piecedental device20 also has a porous metal portion ormatrix30 to improve the osseointegration of the bone on at least theimplant portion22. Further, the one piecedental device20 may have anouter portion32 that has a color generally replicating the color of natural teeth so that if theabutment portion26 is still exposed after a prosthetic is placed on the abutment portion, it will still have an aesthetic appearance in a person's mouth. The one-piece dental prosthetic device disclosed herein may also have other geometries, such as those found in U.S. patent application Ser. No. 11/380,569, which is incorporated herein by reference. These features are explained in detail below.
• As mentioned, theporous metal portion30 extends on theimplant portion22 where it can be placed in contact with the bone, and in one form, is aporous tantalum portion40 which is a highly porous biomaterial useful as a bone substitute and/or cell and tissue receptive material. An example of such a material is produced using Trabecular Metal™ technology generally available from Zimmer, Inc., of Warsaw, Ind. Trabecular Metal™ is a trademark of Zimmer Technology, Inc. Such a material may be formed from a reticulated vitreous carbon foam substrate which is infiltrated and coated with a biocompatible metal, such as tantalum, etc., by a chemical vapor deposition (“CVD”) process in the manner disclosed in detail in U.S. Pat. No. 5,282,861, the disclosure of which is fully incorporated herein by reference. Other metals such as niobium, or alloys of tantalum and niobium with one another or with other metals may also be used.
• Generally, as shown inFIG. 2, theporous tantalum structure40 includes a large plurality ofligaments42 definingopen spaces44 therebetween, with eachligament42 generally including acarbon core46 covered by a thin film ofmetal48 such as tantalum, for example. The open spaces orpores44 betweenligaments42 form a matrix of continuous channels having substantially no dead ends, such that growth of cancellous bone throughporous tantalum structure40 is uninhibited. The porous tantalum may include up to 75%-85% or more void space therein. Thus, porous tantalum is a lightweight, strong porous structure which is substantially uniform and consistent in composition, and closely resembles the structure of natural cancellous bone, thereby providing a matrix into which cancellous bone may grow to anchordental device20 into the surrounding bone of a patient's jaw.
• Theporous tantalum structure40 may be made in a variety of densities in order to selectively tailor the structure for particular applications. In particular, as discussed in the above-incorporated U.S. Pat. No. 5,282,861, the porous tantalum may be fabricated to many different desired porosity and pore sizes, and can thus be matched with the surrounding natural bone in order to provide an improved matrix for bone in-growth and mineralization. This includes a gradation of pore size on a single implant such that pores are larger on an apical end to match cancellous bone and smaller on a coronal end to match cortical bone, or even to receive soft tissue in growth. Also, the porous tantalum could be made denser with fewer pores in areas of high mechanical stress. Instead of smaller pores in the tantalum, this can also be accomplished by filling all or some of the pores with a solid material which is described in further detail below.
• To provide the additional initial mechanical strength and stability to the porous structure, the porous structure may be infiltrated with filler material such as a non-resorbable polymer or a resorbable polymer. Examples of non-resorbable polymers for infiltration of the porous structure may include a polyaryl ether ketone (PAEK) such as polyether ketone ketone (PEKK), polyether ether ketone (PEEK), polyether ketone ether ketone ketone (PEKEKK), polymethylacrylate (PMMA), polyetherimide, polysulfone, and polyphenolsulfone.
• Examples of resorbable polymers may include PLA, PGA, PLGA, PHB, PHV, and copolymers thereof, polycaprolactone, polyanhydrides, and polyorthoesters. By providing additional initial mechanical strength and stability with a resorbable filler material, a titanium reinforcing implant core may not be required. The resorbable material would resorb titanium as the bone grows in and replaces it, which maintains the strength and stability of the implant.
• Referring toFIG. 1, theporous metal portion30 forms asleeve34 that at least partially surrounds acore36. Thesleeve34,core36, or both as shown may form a strong, reinforcing post that extends into theabutment portion26 to reinforce the abutment. Here, thesleeve34 substantially entirely encapsulates the core36 although many other configurations are possible where theporous metal portion30 covers only a part of the length or circumference of the core36 whether continuously or spaced at intervals.
• Thecore36 is made of a suitable biocompatible material, such as titanium although the core36 may also be made of other biocompatible materials such as at least one of the following: titanium alloy, stainless steel, zirconium, and cobalt-chromium-molybdenum alloy to name a few examples. The core36 can be inserted into thesleeve34 by various known methods such as press-fitting, diffusion bonding, or mechanical threading of the core36 into theporous metal sleeve34. Where thecore36 is press-fit into thesleeve34, a fastening between the two parts is achieved by friction after the two parts are pushed together. The friction that holds the parts together is often greatly increased by compression of one part against the other, which relies on the tensile and compressive strengths of the materials of the engaged parts.
• Diffusion-bonding of thecore36 andsleeve34 is a solid-state joining process that involves holding components under load at an elevated temperature. The process is dependent upon a number of different parameters, such as time, applied pressure, bonding temperature and method of heat application. Alternatively, mechanically threading the core36 into thesleeve34 involves providing the sleeve with a threaded bore formed at its interior35 which mates with a threaded male portion of thecore36. Direct Chemical Vapor Deposition (CVD) bonding can also be used to bond the core36 with thesleeve34. This process, like diffusion bonding, is dependent upon a number of different parameters and involves bonding thecore36 andsleeve34 by depositing a material, such as tantalum, onto the assembly at an elevated temperature.
• The one-piece device20 also may have an esthetic material (also referred to herein as an esthetic portion)38 that has a color generally replicating the color of natural teeth. In this case, if theouter portion32 has theesthetic portion38 and is disposed on theabutment portion26, for example, and theouter portion32 is exposed even when a temporary or final prosthesis is placed on theabutment portion26, the exposedouter portion32 will still provide an esthetically pleasing appearance.
• Theesthetic portion38 may comprise either a polymer, a composite material as disclosed in detail in commonly owned U.S. patent application Ser. Nos. 11/420,024 and 11/622,171, which are fully incorporated herein as mentioned above, or a ceramic material. When theesthetic portion38 comprises composite materials it may include the combination of a matrix material, a reinforcing material and a colorant. The matrix material may be a polyaryl ether ketone (PAEK) such as polyether Ketone Ketone (PEKK), polyether ether ketone (PEEK), polyether ketone ether ketone ketone (PEKEKK), polymethylmethacrylate (PMMA), polyetherimide, polysulfone, and polyphenylsulfone. The polymers can also be a thermoset material including, without limitation, bisphanol glycidyl methacrylate (Bis-GMA), urethane dimethacrylate (UDMA), methylmethacrylate (MMA), triethylene glycol dimethacrylate (TEGDMA), a combination of thermoset plastics, or a combination of thermoset and thermoplastics. Additionally, they can be comprised of, without limitation, a large class of monomers, oligomers and polymers, such as acrylics, styrenics and other vinyls, epoxies, urethanes, polyesters, polycarbonates, polyamides, radiopaque polymers and biomaterials.
• The reinforcing material may comprise, to name a few possible examples, at least one selected from the group comprising carbon, Al2O3, ZrO2, Y2O3, Y2O3-stabilized ZrO2, MgO-stabilized ZrO2, E-glass, S-glass, bioactive glasses, bioactive glass ceramics, calcium phosphate, hydroxyapatite, TiO2, Ti, Ti6Al4V, stainless steel, polyaryl ether ketones (PAEK) such as polyethyl ethyl ketone (PEEK), polyethyl ketone ketone (PEKK), and an aramid. The geometry of the reinforcing material may include fibers, particulates, variable diameter fibers and fibers fused with particulates on the fiber surfaces. The colorant may be titanium dioxide as one example.
• In one example, theesthetic portion38 may comprise about 55% by weight of the composite material PEKK as the matrix material, about 35% by weight of the composite material of E-glass fibers as the reinforcing material, and about 10% by weight of the composite material of titanium dioxide particles as the colorant. In another example, theesthetic portion38 may comprise about 53% by weight of the composite material PEKK as the matrix material, about 35% by weight of the composite material of E-glass fibers as the reinforcing material, and about 12% by weight of the composite material of titanium dioxide particles as the colorant.
• In one form, theouter portion32 has an exterior separate from the porous tantalum portion so that the outer portion is substantially free of the porous tantalum portion. This results in the exterior of theouter portion32 forming a smooth skin layer comprised substantially of the esthetic material, where the skin layer of esthetic material may have a thickness of approximately 0.05 to about 3.0 mm. Furthermore, the smooth skin layer of theouter portion32, when placed along theimplant portion22 or within the transmucosal layer52 (i.e., gingival region of the prosthetic) on theabutment portion26, forms a relatively solid, pore-free outer layer. This limits attachment of soft tissue and bacteria onto theouter portion32 and limits the in-growth of the epithelium so that it does not interfere with bone growth against theimplant portion22. Theouter portion32 may be disposed on at least one of a coronal end of the coronal end portion28, a side of the coronal end portion28, and thetransmucosal layer52 on theabutment portion26, but preferably on substantially all three areas. Thus, a smooth, non-porousouter portion32 may be provided from theupper end50 on theabutment portion26, along thetransmucosal region52 of the abutment portion, and in one case, down to the point where theabutment portion26 narrows and ends and theimplant portion22 begins. In another form, as shown, asmooth surface54 may also be provided on thecoronal end56 of theimplant portion22 if desired.
• Referring toFIGS. 1 and 3, in another form, theesthetic portion38 may at least partially impregnate theporous metal portion30 so that the esthetic portion acts as a filler material and/or theporous metal portion30 reinforces theesthetic portion38. In such cases, theesthetic portion38 fills at least a portion of thepores44 of theporous metal portion30. In one form, theesthetic portion38 substantially completely fills thepores44 near thecoronal end56 of theimplant portion22 and forms the smoothexterior skin layer54 mentioned above. Thepores44 of theporous metal portion30 near the distal end orapical end24 of theimplant portion22 are substantially free of theesthetic material38, which allows in-growth of bone to anchor the one-piecedental device20 to the jaw. Accordingly, there can be a general, internal dividing line above which the porous tantalum is substantially impregnated with esthetic material and below which it is not, similar to the diagram inFIG. 3, and applicable to any of the dental implant devices described herein.
• To impregnate theporous metal portion30 with theesthetic portion38, the polymers or composites that make up the esthetic material can be injection-molded into theporous metal portion30 such as on thesleeve34, so that the polymer or composite material infiltrates the vacantopen spaces44 forming a solid mass of the polymer or composite material with metal reinforcement. Furthermore, injection-molding of the polymer or composite material may also be used to form the non-porous skin layer with theouter portion32 as described above.
• Theesthetic portion38 can also be reinforced by theporous metal portion30 by an insert-molding process. Insert molding is an injection molding process whereby theesthetic portion38 is injected into a cavity and around an insert piece, such as thesleeve34 of porous tantalum, placed into the same cavity just prior to molding, resulting in a single piece with the insert encapsulated by theesthetic portion38. The impregnation of theporous tantalum portion30 as shown inFIG. 3 was performed by insert-molding. Other molding processes such as compression molding, resin transfer molding or any other process known in the art may be employed.
• Mechanical bonding also takes place during the insert molding process. Mechanical bonding can occur by shrinking of theesthetic portion38 around thesleeve34 as the esthetic portion cools or by filling in irregularities in the surface of thesleeve34. Mechanical bonding further can occur when theesthetic material38 infiltrates the open spaces within thepores44 of theporous sleeve34.
• When theesthetic portion38 is composed of a ceramic material, such as dental porcelain, the ceramic material can be placed in theporous metal portion30 via sintering and an enameling process. The enameling process includes fusing powdered glass to theporous metal portion30 by firing at extremely high temperatures. The ceramic powder can melt and flow, and hardens into a smooth, durable ceramic coating that can be placed on the porous tantalum portion and can be inlaid within thepores44 of the porous tantalum portion. The ceramic material, after firing and cooling, becomes a smooth, hard and very durable material.
• A microscopic model can be obtained to predict the overall mechanical properties of the porous metal/composite material-filled structure. For instance, a relationship between the strength of the porous metal/composite material and the strength of a particular filler material (shown inFIG. 11) can be obtained by using a finite element model (as shown inFIG. 12). More specifically, the prediction of the porous metal/composite material structure's overall mechanical behavior can be based on Representative Volume Element (RVE) theory. The RVE theory comprises constructing a representative portion of the material's microstructure (an “RVE”) and subjecting it to virtual testing. The overall mechanical behavior of the RVE is found to be equivalent to the composite material it represents.
• As an example, an RVE program such as commercially available FE software, ANSYS version 10 (available from ANSYS, Inc., Canonsburg, Pa., USA) is used to generate a two-dimensional stochastic Voronoi cell structure based on RVE theory to simulate random microscopic struts of the porous metal at the microscopic level. Specifically, the porous metal/composite material structure was meshed using 8-node hexagon mesh. The porous metal structure was simulated using tantalum metal material properties as a bi-linear, elasto-plastic material (i.e., having Young's Modulus E=179 GPa, Poisson's ratio μ=0.34, Yield stress σy=190 MPa and Tangent Modulus Et=17 GPa). The pores between the struts were modeled to be impregnated with a composite material as a filler material similar to that shown inFIG. 3 except all pores were filled for the test. The filler composite material was modeled as a linear elastic material having a varied elastic modulus and Poisson's ratio equal to 0.4.
• To compute the overall Young's modulus (E) of the structure, a boundary condition was applied to the finite element model as shown inFIG. 12 to simulate compression testing. The finite element model has a fixed, constrained face with an area (Axx) formed by a length in the x direction (Dx) and a length in the y direction (Dy). All other faces are unconstrained along the x-direction. The boundary or test condition used was to apply a uniform strain field with 0.1% strain along the x-direction to the RVE and the finite element model. For instance, in order to compute Exx (Young's modulus along the x-direction), a displacement Ux represents an applied strain where Ux=0.001Dx. Therefore, Exx can be computed as follows:
• $E_{\mathrm{xx}}=1000\times \frac{\sum R_x}{A_{\mathrm{xx}}}$
• where ΣR_xrepresents the summation of reaction forces at the constrained faces. Due to its structural symmetry, the Young's modulus along the x, y and z directions is the same. Therefore, E=E_xx=E_yy=E_zz. As a result, the overall elastic modulus, E, of the porous metal impregnated with the composite material was plotted versus the filler (i.e., composite material) elastic modulus, Ef, and is shown inFIG. 11. A linear regression was used to fit the data points and an equation was obtained expressing the overall elastic modulus, E, for the porous metal/composite material structure as a function of the filler elastic modulus, Ef, or E=1760+1.6563 E_f, and further having an R-squared value of 0.9935, where R-squared is a statistical measure of the fraction of variance expressed by the model.
• In another form, the one-piecedental device20, as well as the other implants described below, may have multiple textured surfaces as described in detail in U.S. Pat. No. 5,989,027, assigned to the assignee of the present invention, the disclosure of which is expressly incorporated herein by reference. For example, thesleeve34 of porous tantalum may have an increasing porosity from the proximal end28 toward thedistal end24 of the one-piecedental device20. Thus, thesleeve34 may be formed of substantially solid, non-porous tantalum near the proximal end28, within thetransmucosal region52 on theabutment portion26, and/or slightly distally of theabutment portion26 to provide a seal with the surrounding gingiva such that plaque or bacteria cannot lodge on or deposit within thesleeve34 near the gumline of the patient should the upper portion of thesleeve34 be exposed to the oral cavity. Alternatively, the surface of theabutment portion26 of the core36 could be formed of smooth, polished titanium or other materials providing such a smooth, solid finish to allow ready removal of bacterial plaque deposits by conventional oral hygiene techniques. As another option, bands of titanium or other materials may be provided with a solid yet roughened surface, such as at thecoronal end56 of theimplant portion22 to promote some bone growth while still limiting at least some soft-tissue and bacterial growth.
• In addition to these approaches, the porosity of theporous metal portion30 of thesleeve34 can increase gradually or at intervals as desired and as thesleeve34 extends distally to promote maximum bone in-growth and osseointegration at thedistal end portion24 of the one-piecedental device20. For this purpose, thepores44 of theporous metal structure30 may be formed with increasingly larger sizes from the proximal end portion28 to thedistal end portion24 of the one-piecedental device20.
• Also, thesleeve34 may be attached to thecore36 of the one-piecedental device20 in a manner wherein, after osseointegration of thesleeve34 into the surrounding bone, thecore36 is slightly movable relative to thesleeve34 in order to dissipate forces which are imposed upon the one-piecedental device20, such as mastication forces, for example. In one embodiment, thesleeve34 may be secured to thecore36 via an adhesive or cement material which is slightly compressible, such that when mastication or other forces are imposed upon theabutment portion26, thecore36 may move slightly relative to thesleeve34 whether within theabutment portion26 or within theimplant portion22. Such adhesive or cement materials include acid-base reaction formulations such as zinc phosphate, zinc oxide/eugenol, zinc polycarboxylate, glass ionomer, or resin based formulations similar to that of resin-based dental restorative filling materials. One specific example is a dental adhesive/bonding agent that is composed of monomers of hydroxyethyl methacrylate (HEMA), 4-methacryloxyethyl trimellitate anhydride (4-META) and an organophosphate (e.g., 10-methacryloyoxydecamethylene phosphoric acid, MDP). In other embodiments, a compression ring, a spring, or another type of “shock absorbing” structure may be fitted between the core36 and thesleeve34 to allow for relative movement therebetween.
• Referring toFIG. 4, there is illustrated a one-piecedental device120 that similarly includes acore122 and aporous metal portion124 in the form of asleeve138 that at least partially surrounds thecore122 and may be made of a porous tantalum such as Trabecular Metal™. Thedental device120 also has anabutment portion126 at aproximal end portion128 of the one-piecedental device120 and animplant portion130 at adistal end portion132 of the one-piecedental device120. Anouter portion134 having anesthetic material142, similar toesthetic material38, has a color generally replicating the color of natural teeth and is disposed at least at theabutment portion126 of thedevice120 as described further below.
• For the one-piecedental device120, thecore122 also is made of a porous metal such as tantalum and may be received by an interior or bore137 of thesleeve138. Thecore122 can be inserted into thesleeve138 by various methods such as press-fit or mechanical threading as described above. Alternatively, thesleeve138 may be integrally formed with thecore122. While theporous metal portion124 generally remains on the implant portion130 (i.e. it does not extend substantially onto theabutment portion126 in this example), theporous metal core122, in one form, widens and forms the bulk of theabutment portion126 and forms a strong, reinforcing post that extends from within theimplant portion130 to within theabutment portion126. Thus, in this case, the porous metal, and therefore, theporous metal portion134, may be described as generally extending throughout theprosthetic device120.
• For thedental device120, thecore122 is impregnated with a filler while theporous metal portion124 forming thesleeve138 and that forms the exterior of theimplant portion130 for engaging bone is substantially free of the esthetic material. The filler may be a composite or polymer material, which may be the same as theesthetic material142, and may fill in the vacant open spaces in the porous tantalum as previously discussed above with the embodiment ofFIG. 1 and as shown inFIG. 3, except that here, the composite or polymer material fills the pores of the entire length of the core122 from theproximal end portion128 to thedistal end portion132. Thecore122 may be impregnated by any of the previously discussed methods, such as by injection-molding.
• The esthetic material oresthetic portion142 of the one-piecedental device120, as mentioned above for thedental device20, may be disposed at least theouter portion134 at theabutment portion126 for esthetics and to at least partially cover the porous tantalum portion of the core122 at theproximal portion128 to limit gingival tissue growth there. Thus, at theproximal end portion128 of thecore122, theouter portion134 forms a smooth esthetic skin layer that is substantially free of porous tantalum, and is located around substantially theentire abutment portion126. Theouter portion134 may have a skin layer that is approximately 0.05 to about 3.0 mm thick. With this configuration, theporous sleeve138 substantially covers theimplant portion130 of the outer layer of theimplant120 to promote bone growth while the exposedabutment portion126 with a solid, smooth esthetic outer surface limits the in-growth of soft tissue and bacterial growth against theabutment portion126.
• In one variation of the one-piecedental device120, a thickened, outer and upper portion orlayer140 is formed coronally of the core122 at thecoronal end portion128 and is made of the esthetic material. Theupper layer140 can be formed by injecting the esthetic material onto the porous structure of thetantalum core122 until a coronal orterminal end136 of thecore122 is coated with several millimeters of esthetic material. Thelayer140 is substantially free of porous metal so that it can be easily shaped by a practitioner for receiving another dental device or restoration such as a dental prosthesis or final crown, for example.
• In another alternative, one ormore gaps144 within theupper layer140 encourages soft tissue in-growth to form a seal around the perimeter of theimplant120 at the location of thegap144. This seal coupled with the non-porous outer surface formed by theesthetic portion142 on theabutment portion126 forms a barrier that limits bacteria, epithelium or other contaminants from passing through the porous metal and into a bone integration area along theimplant portion130. While thegap144 is shown as a continuous gap around theupper layer140 it will be appreciated that many other forms are possible, such as non-continuous gaps, spaced holes, or other uniform or more randomly placed openings, to name a few examples.
• Referring toFIG. 5, there is illustrated a third embodiment of a one-piecedental device220 including aporous metal portion222 of tantalum or other materials as described above, and anouter portion240 having a color generally replicating the color of natural teeth and formed by an esthetic portion ormaterial224 on anabutment portion232. Theporous tantalum portion222 forms animplant portion230 at a distal orapical end portion228 of thedental device220. Theporous metal portion222 also forms a reinforcingcore236 of theabutment portion232 at thecoronal end portion234 of thedental device220. While thecore236 is shown to extend approximately half the height of theabutment portion232, it will be understood that other variations are possible including thecore236 extending at or near the terminalcoronal end234 of theabutment portion232 or being much shorter such that thecore236 extends a relatively small distance into theabutment portion232. In the form illustrated, thecore236 does not extend near the terminalcoronal end234 so that theesthetic portion224 disposed coronally of thecore236 is separate from theporous metal portion222 and is substantially free of porous metal so that theend234 is easily shaped similar to coronalupper layer140 of dental device120 (FIG. 4).
• In one form, pores are provided generally throughout theporous tantalum portion222 from a coronal orproximal end226 of theporous metal portion222 to theapical end portion228, and through theimplant portion230. Theporous metal portion222 has pores at least partially impregnated with theesthetic portion224. The pores at theapical end portion228 are substantially free of esthetic material while the pores at thecoronal end portion226 are at least partially impregnated with the esthetic material. In one form ofdevice220, the pores that are substantially free of esthetic material form the majority of theimplant portion230 although other variations are contemplated.
• It will also be appreciated that while theporous metal portion222 is shown to form substantially theentire implant portion230, other outer sleeves or layers on theporous metal portion222, whether presenting a solid and/or porous outer surface, may be provided as with the other alternative embodiments described.
• It will further be appreciated that theouter portion240 may be located on any outer part of theabutment portion232 and may be substantially free of the porous tantalum portion as with the other embodiments herein. Theouter portion240 may contain a smooth exterior layer that has a minimal width of about 1 mm on the sides of thecore236 and/or may have a substantial thickness of about 1 to about 5 mm above thecoronal end226 of thecore236.
• Referring again toFIG. 1, to surgically implant the one-piecedental device20, or any of the implant devices herein, the one-piecedental device20 may be fitted into a bore drilled into a patient's jaw bone at an edentulous site. In particular, the one-piecedental device20 may be impacted or press-fitted into the bore to provide a firm initial seating of the one-piecedental device20 into the bore. For this purpose, thedental device20 may have a tool or driver-engagingstructure60 such as a bore (shown in dashed line) for receiving a driver to insert thedental device20 into the bone tissue. Thebore60 may use structures, such as an interference fit, for releasably engaging the driver. Thereafter, the bone tissue surrounding the one-piecedental device20 may osseointegrate into theopen spaces44 of theporous sleeve34, thereby firmly anchoring thesleeve34 and the one-piecedental device20 into the surrounding bone structure. Thereafter, a temporary or permanent prosthesis may be secured to theesthetic portion38 in a known manner when theesthetic portion38 includes an abutment.
• Referring toFIGS. 6-10, a press-fittingdriver300 may be used to press fit one-piece dental devices such as those described above or other implants such asimplants320 and340. Thus, whiledriver300 is described with the use ofimplant320, any of the implant-devices described herein may be used similarly with thedriver300.
• When press-fitting adental device320, for example, into a bore on the jaw, it may be desirable to make the fit between the surgical site and the press-fit implant very tight so that thedental device320 can achieve the required degree of stability for immediate or early loading. To achieve the desired tight fit, it may be difficult to press-fit thedental device320 into the bore by hand pressure alone. Therefore, adriver300 may be used to apply pressure to properly press-fit the implant into the bore to achieve a tight fit. In contrast to osteotomes, thedriver300 is fastened directly to thedental device320 or to an implant carrier, rather than to the jaw site. A single drill can be used to create a pilot hole, or bore, in the jaw and thetip324 of animplant320 can be placed into the hole. Thedriver300 can be attached to theimplant320 on theend322 that is opposite theapical tip324 and a proximal portion or handle310 of thedriver300 can then be struck with a mallet or other driving tool to deliver a greater force to theimplant320 than could be done by hand in order to achieve the tight fit with the hole. Thedriver300 may have abent portion312 that extends to, and orients, theproximal portion310. So configured, theproximal portion310 is oriented in a certain position and direction (i.e., facially of the jaw) so that an object, such as the mallet, other tool, or even a person's hand has convenient access to theproximal portion310 away from the area directly between the teeth and outside of the mouth where there is more space to maneuver. Thecoronal end322 of theimplant320 may be flat to engage thedriver300 or may have a bore similar to bore60 on the one-piece dental device20 (FIG. 1) for receiving thedriver300.
• Referring toFIGS. 7-10 and13-23, implant devices also made of porous material as mentioned above are further provided with a shape to increase stability for early and long-term loading as well as to limit unintentional pull out of the implant devices. More specifically, while the implant devices may be generally or substantially cylindrical, in one form, aporous implant device400 as shown inFIG. 18 has abody402 that tapers inwardly as it extends from acoronal end portion404 of thebody402 to anapical end portion406 of thebody402. With this structure, theimplant device400 is configured to have thecoronal end portion404 with a larger width dimension than the width dimension of theapical end portion406. This allows theimplant device400 to expand the bone as thebody402 is inserted into a bore that has a diameter smaller than the maximum width of thebody402, which forms an interference fit. Implant340 (FIG. 7) also is provided with such an optional taper.
• This tapered structure also provides a geometry that is closer to the geometry of the natural tooth. Thus, the slope of the taper may be customized to more closely match the slope of the natural tooth being replaced by theimplant device400. It will be understood that any of the forms of the implant device provided herein may have a taper that forms an interference fit.
• Referring toFIGS. 7-8, additionally or alternatively, the implant devices may have an outer periphery shaped to restrict rotation of the implant device within a bore in the jaw bone to create a further interference fit. In one form,implant device340 has a body portion orbody350 that generally defines a central, coronal-apical axis L1. Theimplant device340 also has aporous portion352 at thebody350 as described above. Theporous portion352 also is disposed at a non-circular,outer periphery portion354 on thebody350. The non-circularouter periphery354 at least extends generally around the coronal-apical axis L1. Thus, while the non-circularouter periphery354 is at least partially made of the porous material, it is entirely made of the porous material in the illustrated form.
• The non-circularouter periphery portion354 is shaped to resist a torsional force that is applied to theimplant device340 and about the axis L1 when thedevice340 is disposed within a bore in the jaw bone. The non-circularouter periphery portion354 has at least threedistinct face portions356. In one form, the outer periphery forms apolygonal portion342 withvertices344 at the edges of sidewalls346 (i.e., the face portions356). Theface portions356 may be made partially or entirely of the porous material or porous tantalum metal that extends along at least one of theface portions356. With this configuration, thevertices344 at the edges offace portions356 penetrate the usually cylindrical or circular sides of a bore in the jaw bone formed by a dental drill.
• Theimplant device340 may have acoronal end portion348 on thebody350 that is configured to receive thedriving tool300 that allows press-fit installation of at least a portion of thebody350 into a bore into the jaw bone. Thebody350 can be press-fit into a bore in the bone by using thedrive tool300 or by exerting other types of pressure on thecoronal end portion348 of thedental implant340 until an interference fit is created between thebody350 and the bone. So configured, the non-circularouter periphery354 can give theimplant device340 additional stability to resist a rotational or torsional force that is applied to theimplant device340 around the coronal-apical axis L1 while theimplant device340 is disposed within a bore in the jaw bone.
• While thenon-circular portion354 may be sized and shaped to resist rotation, it should also have a shape that does not create an unmanageable resistance to translating theimplant device340 for vertically inserting theimplant340 into the bore in the bone. Thus, it will also be understood that while thenon-circular portion354 may axially extend the entire length of theimplant340, or any other length that is advantageous for resisting rotation, the longer the non-circular shape along theimplant340, the more difficult it may be to insert theimplant340 into a circular bore.
• In another aspect, as shown inFIGS. 9 and 10, theimplant device320 has a non-circularouter periphery358 forming apolygonal portion318 that is stopped short of the full axial length of theimplant device320 to provide space for a plurality of (but at least one) radially extendingannular teeth326. Theteeth326 taper outwardly from the coronal-apical axis as the teeth extend coronally. Theannular teeth326 can be configured to securely contact a bone in a bore and to fasten theimplant device320 within the bore. Aporous portion360 may also be disposed partially or entirely on thebody portion358 or the non-circular outer periphery, including theannular teeth326, in order to increase the friction between theimplant device320 and the bone and provide a more secure interference fit. In this configuration, theannular teeth326 are placed into contact with the sidewalls of the bore as the implant device is press-fit into the bore to provide greater stability and increased resistance to the pull-out of theimplant device320 from a bore in the bone.
• Referring toFIGS. 13-14, while the cross-section of the outer periphery in the form of thepolygonal portion318 or342 is shown to be a regular polygon, alternatively,implant device500 has anouter periphery502 that is an irregular polygon or other multi-sided shape withdistinct face portions504 that is asymmetrical about an axis T traverse to the coronal-apical axis L2. In the illustrated form, an irregular hexagon is shown with threesmall face portions506 and threewide face portions508. Otherwise, the structure is that of theimplant device340. It will be understood that many other multi-sided shapes are contemplated.
• Referring toFIGS. 15-19, rather than distinct face portions that form flat sides,implant devices400 and600 respectively havebodies402 and602 with non-circularouter peripheries408 and604 that have a closed, curved shape extending around a coronal-apical axis L3 and L4, respectively. For example,outer periphery604 ofimplant device600 is generally oval for fitting tightly into a circular bore in a jaw bone to resist a torsional force applied to theimplant device600 and about axis L4.Tapered implant device400 is similarly oval (FIGS. 18-19). It will be understood that the non-circular periphery may be any other convexly curved shape such as elliptical or obround. Alternatively, the outer peripheries may have a closed, curved shape that is concavely curved such that a portion on the non-circular outer periphery is shaped to extend inwardly toward the center of the implant device. In another alternative configuration, the non-circular outer periphery may have a number of curves to form a bumped, scalloped, and/or serrated shape. It should also be understood that the non-circular outer periphery could contain a variety of other cross sectional shapes including peripheries that are a combination of flat sides or face portions and curved sections.
• Whether or not the non-circular, outer periphery is curved or has distinct sides, the mechanical fixation of the implant device within a bore by interference fit is strengthened by forming the porous material at the outer periphery because the porous material has such a relatively high co-efficient of friction with bone.
• To further strengthen the interference fit, the outer periphery may be provided with a maximum width slightly greater than the diameter of the bore in the jaw bone that receives the implant device. So configured, as the implant device is inserted into the bore in a jaw bone, the larger outer periphery roughened by the porous material will bite into the bone by grating, chipping and/or flaking bone pieces off of the sidewalls of the bore in which the implant device is being placed. This “rasping” action forms slight recesses or indents within the bore sidewall in which the implant device sits. This further restricts rotational or twisting motion of the implant device within the bore since the implant device does not have the clearance to rotate out of the indents and within the bore.
• The rasping action also accelerates osseointegration onto the implant device and into the pores of the porous material due to the bone compaction into the pores. First, the grating of the bone structure causes the bone to bleed which stimulates bone growth by instigating production of beneficial cells such as osteoblasts and osteoclasts. Second, the bone pieces that fall into the pores on the porous material assist with bone remodeling. In the process of bone remodeling, osteoblast cells use the bone pieces as scaffolding and create new bone material around the bone pieces. Meanwhile osteoclast cells remove the bone pieces through resorption by breaking down bone and releasing minerals, such as calcium, from the bone pieces and back into the blood stream. The osteoblast cells will continue to replace the grated bone pieces from the pores and around the implant device with new and healthy bone within and surrounding the extraction site. Thus, with the porous material, the implant device has increased resistance to twisting or rotation, allows for immediate or very early loading, and increases long-term stability due to the improved osseointegration.
• Referring again toFIGS. 15-17, in one specific example, theimplant device600 is disposed within abore606 in ajaw bone608. The non-circularouter periphery604 may be dimensioned to penetrate the usuallycylindrical side610 of thebore606 formed by a dental drill. Thus, the maximum width dimension W of theimplant device600 is greater than the diameter D of thebore606. The difference between W and D (or 2× the interference length ‘x’—or 2x as shown onFIG. 17) should not be too small or too large. If the difference is too large (i.e., the maximum implant device width W is much longer than the bore diameter D), the practitioner will not be able to pressfit implant device600 intobore606 without using a force that could damage the jaw bone ordental implant device600. If the difference between W and D is too small, theimplant device600 will lack sufficient initial stability and will not grate or scrape a sufficient amount of bone tissue from thebore sidewall610 to stimulate significant bone growth. In one form, the difference between W and D (or in other words, 2×) should be about 0.008 to 0.18 mm when W is 3.7 mm to 6.0 mm. This corresponds to an interference volume of about 5-20 mm³where 2× forms the total width of the interference volume as shown onFIG. 17, and the volume extends generally the height of theimplant device600 as shown in dash line onFIG. 16. These dimensions apply to implants having typical axial lengths of about 8 mm to about 16 mm.
• It will be understood thatimplant device600, as well as any of the other implant devices with anti-rotational features, may have transgingival extensions612 (shown in dash-line onFIG. 15) including one-piece implants with integral abutments or single-stage surgery implants with an integral emergence profile that attaches to a separate abutment.
• It will also be understood that many of the features shown onimplants320,340,400,500, and600 may be provided for any of the implant devices described herein.
• Referring toFIGS. 20-23, another way to restrict rotational movement of an implant device embedded in the jaw bone is to provide the implant device with multiple roots which makes the implant asymmetric at least along the roots. When such a multi-root implant device is placed in a bore in the jaw bone that is shaped to correspond to the shape of the implant device, the roots are each placed in a bore branching off of a main bore. In this case, the dental implant does not have the clearance within the bores to rotate about its coronal-apical axis when a torsional force is applied to the implant device and about its axis.
• A multi-root implant may also simplify the surgery when the implant has the same number of roots and general configuration as the natural tooth it is replacing. For instance, the implant may have two or three roots to correspond to the configuration of a molar or pre-molar with the same number of roots. In this case, the bore receiving the multiple-root implant may require minimal drilling to shape the bore when the bore is at the extraction site of the molar or pre-molar being replaced by the implant. This allows the implant device to be immediately placed into the extraction site, preserves more of the natural gum tissue for the patient, and presents a more aesthetic result.
• Referring toFIGS. 20-21, in one specific example, a multiple-root implant device700 has abody702 that generally defines a coronal-apical axis L5 and aporous portion704, such as the porous tantalum portion described above, disposed at thebody702. Thebody702 has amain portion706 androots708 and710 extending outwardly from themain portion706 and to free, distal ends712 and714, respectively. Theporous portion704 may form substantially thewhole body702, at least part of one ormore roots708, and710, and/or at least part of themain portion706.
• Themain portion706 includes anintermediate portion716 relative to the full coronal-apical length of theimplant device700. Theroots708 and710 extend or branch out from theintermediate portion716. Theroots708 and710 extend in a general apical direction, and in one form generally parallel to the coronal-apical axis L5 of theimplant device700.Implant device700 is shown with two roots to generally correspond to a natural tooth with two roots such as the mandibular molars or maxillary premolars. It will be understood, therefore, that theroots708 and710 could be modified to extend more laterally to match the exact configuration of a particular natural tooth, and in turn, the extraction site to receive theimplant device700. Thus, it will be understood that any of the multiple-root implant devices described herein can be configured such that the multiple roots are arranged and extend in a general direction that corresponds to the arrangement of the roots on the natural tooth that the dental implant replaces.
• In one form, at least one of the plurality ofdistinct roots708 and710 can be integrally formed with themain portion706 but may otherwise be separately formed and connected to themain portion706.
• To insert themulti-root implant device700 into a bore at an extraction site, the roots should be aligned with the separate branch bores. Pressure is then applied to acoronal tip portion718 of theimplant device700 and in an insertion direction as explained above for other press-fit implant devices. As the pressure is applied, the plurality ofdistinct roots708 and710 may engage the bone and fasten theimplant device700 into the bore(s) and create an interference fit as well as a mechanical fixation between theimplant device700 and the bone that restricts substantial rotation of theimplant device700 about its coronal-apical axis L5.
• As mentioned above, theimplant device700 can have a porous portion disposed on at least one of the plurality ofroots708 and710 to strengthen the interference fit with the bore. In one alternative, theroots708 and710 can be configured to taper inwardly as the roots extend outwardly from themain portion706. Specifically, the root or roots have acoronal end portion720 adjacent to themain portion706 and anapical end portion722. In this alternative, thecoronal end portion720 has a width dimension w1 greater than the width dimension w2 of theapical end portion722. Thus, as theimplant device700 is inserted into a bore in the bone, the root will expand the branch bore in which it is inserted, forming a very strong interference fit.
• In addition, or in the alternative, at least one of the plurality ofdistinct roots708 and/or710 can have a cross-sectional dimension greater than a corresponding cross-sectional dimension of a branch bore in bone for receiving theroot708 and/or710 similar to the oversizing provided on theimplant devices320,340,400,500, and600 described above. So dimensioned, as theimplant device700 is moved in an insertion direction, theporous portion704 grates pieces of bone off of a sidewall of the branch bore as described above to stimulate bone remodeling and increase initial stability. This dimensioning also can be applied to themain portion706 as well.
• Referring toFIG. 21, themain portion706 of the multiple-rootdental implant device700 also can include a non-circularouter periphery724 to restrict rotation of theimplant device700 within a bore as previously described above for the other forms of the implant device. In this case, the non-circularouter periphery724 extends about the coronal-apical axis and may have a plurality of convexlycurved portions726 where eachcurved portion726 coronally aligns with a different one of the plurality ofroots708 or710. This forms an elongated indent or groove728 at the intersection of adjacentcurved portions726 and provides the non-circular out periphery with an asymmetric cross-section to resist rotation (where asymmetric means asymmetric about an axis transverse to the apical-coronal axis L5). It will be understood that theroots708 and710 could also have any of the non-circular outer peripheries described above.
• Referring briefly toFIG. 22, a three rootdental implant device800 has threedistinct roots802,804, and806 but is otherwise the same or similar toimplant device700.Implant device800 is particularly useful for replacing natural maxillary first, second, or third molars with three roots or a single or double root tooth that may have grown an extra supernumerary root.
• Referring toFIG. 23, adental implant device900 can have three or more roots. In this case, a fourroot implant device900 is shown. The structure of theimplant device900 is similar or the same as to that described above for the other multi-root implant devices except that here implantdevice900 hasroots902,904,906, and908. Adental device900 may provide more than the normal number of roots to correspond to natural teeth with supernumerary roots. Oftentimes, this condition occurs in mandibular canines, premolars, and maxillary molars, and especially third molars. Thus, the multi-root dental implant devices may match the number of roots no matter what that number or configuration is on the natural tooth, and in turn, at the extraction site. It also will be appreciated that more than the usual number of roots may be used when such structure is deemed beneficial for anchoring the tooth in the jaw bone regardless of the number of roots on the natural tooth to be replaced, if the tooth even existed. This may be used when more surface area on the implant device is desired.
• While theimplant devices320,340,400,500,600,700,800, and900 may be substantially made of the porous material, it will be understood that the implant devices may alternatively have a titanium core with a porous sleeve placed around the core. The porous material may be assembled or bonded to the core by diffusion bonding or direct chemical vapor deposition processes. The porous material and core may also be press-fit together. The stress required to disassemble the bonded or press-fit core to porous material interface, if present, should exceed 20 MPa. The non-porous parts of the dental implants may be machined, EDM cut, or made by using net-shape (custom) manufacturing processes.
• While the illustrated forms are shown to be dental implants, it will be understood that such structures, with porous metal or porous tantalum portions on an implant with a non-circular periphery or multi-root implant to restrict rotation in a bore, may be applied to implants used on other areas of a human body or animal, whether or not such an implant is to be inserted into bone.
• Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of the invention, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept.

Claims (23)

1. An implant, comprising:

a body generally defining a coronal-apical axis; and

a porous tantalum portion disposed at the body for engaging bone and having a non-circular outer periphery extending around the axis.

2. The implant ofclaim 1 wherein the non-circular outer periphery is shaped to engage a bore in bone to resist a torsional force applied to the implant and around the axis while the implant is disposed within the bore.

3. The implant ofclaim 2 wherein the non-circular outer periphery is shaped to resist torsion while disposed in a circular bore.

4. The implant ofclaim 1 wherein the outer periphery has three or more distinct face portions.

5. The implant ofclaim 4 wherein the outer periphery includes a regular polygon.

6. The implant ofclaim 1 wherein the outer periphery is asymmetric about at least one axis of the outer periphery that is transverse to the coronal-apical axis.

7. The implant ofclaim 1 wherein the outer periphery has a closed, curved shape.

8. The implant ofclaim 1 wherein the outer periphery is at least one of elliptical, obround, and oval in cross-section.

9. The implant ofclaim 1 wherein the outer periphery is configured and dimensioned to grate bone pieces off of a sidewall forming a bore in bone that receives the dental implant.

10. The implant ofclaim 1 wherein the outer periphery has a maximum width dimension that is greater than a diameter dimension of the bore.

11. The implant ofclaim 10 wherein the maximum width dimension is greater than the diameter dimension of the bore by approximately 0.008 to 0.18 mm.

12. The implant ofclaim 1 wherein the body has a main portion and a plurality of roots having porous tantalum and extending apically from the main portion wherein the non-circular outer periphery is at the main body and the plurality of roots extend below the non-circular outer periphery.

13. The implant ofclaim 12 wherein at least one of the extending roots has a coronal end portion adjacent the main portion and an apical end portion, and wherein the coronal end portion has a diameter or width dimension greater than the diameter or width dimension of the apical end portion.

14. The implant ofclaim 1 wherein the body comprises a coronal end portion for receiving a driving tool for press-fit installation of at least a portion of the body into a bore in bone.

15. The implant ofclaim 1 wherein the implant has a full length, and wherein the non-circular outer periphery extends axially along the implant less than the full-length.

16. The implant ofclaim 1 wherein the implant has a coronal end portion, and wherein the outer periphery only extends on the coronal end portion.

17. The implant ofclaim 1 wherein the body has at least one outwardly, radially extending annular tooth made of porous metal shaped to resist pull-out of the dental implant from a bore in the bone.

18. The implant ofclaim 17 wherein the body has an array of the teeth spaced along the axis.

19. The implant ofclaim 1 wherein the body has a coronal end portion and an apical end portion, and wherein the body tapers inwardly as it extends from the coronal end portion to the apical end portion.

20. The implant ofclaim 1 wherein the implant is a dental implant.

21. The implant ofclaim 1 wherein the porous tantalum portion is partially filled with a resorbable material.

22. The implant ofclaim 21 wherein the resorbable material comprises at least one of: PLA, PGA, PLGA, PHB, PHV, polycaprolactone, polyanhydrides, and polyorthoesters.

23. An implant, comprising:

a body generally defining a coronal-apical axis; and

a porous tantalum portion disposed at the body for engaging bone within a bore on an animal or human body and having a non-circular outer periphery extending around the axis;

wherein the non-circular outer periphery is shaped to engage the bore in the bone of the animal or human body to resist a torsional force applied to the implant and around the axis while the implant is disposed within the bore.

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