Patent Publication Number: US-2020275998-A1

Title: Porous implant device with improved core

Description:
BACKGROUND 
     Field of the Invention 
     The present invention relates to porous implants and, in particular, to an implant with a porous material mounted on a core. 
     Description of the Related Art 
     Dental implants are commonly used to anchor dental restorations or prosthetic teeth at one or more edentulous sites in a patient&#39;s dentition at which the patient&#39;s original teeth have been lost or damaged. The dental implant is typically threaded or press-fit into a bore which is drilled into the patient&#39;s mandible or maxilla at the edentulous site. Typically, a dental implant device is provided in one or two pieces. For a two piece device, an anchoring member or implant supports a separate coronal dental abutment, which in turn provides an interface between the implant and a dental restoration. For a one piece integral device, the device has an abutment section coronal to an implant section of the device. In either case, the restoration is typically a porcelain crown fashioned according to known methods. 
     For a two-piece device, there are two-stage surgery implants (also called endosseous implants) that only rise to the crest of the mandible or maxilla. In this case, the surgery is often performed in two stages. In the initial stage, an incision is made in the patient&#39;s gingiva at an edentulous side, and a bore is drilled into the patient&#39;s mandible or maxilla at the edentulous site, followed by threading or impacting a dental implant into the bore using a suitable driver. Thereafter, a cap is fitted onto the implant to close the abutment coupling structure of the implant, and the gingiva is sutured over the implant. Over a period of several months, the patient&#39;s jaw bone grows around the implant to securely anchor the implant in the surrounding bone, a process known as osseointegration. 
     In a second stage of the procedure following osseointegration, the dentist reopens the gingiva at the implant site and secures an abutment and optionally, a temporary prosthesis or temporary healing member, to the implant. Then, a suitable permanent prosthesis or crown is fashioned, such as from one or more impressions taken of the abutment and the surrounding gingival tissue and dentition. The temporary prosthesis or healing member is removed and replaced with the permanent prosthesis, which is attached to the abutment with cement or with a fastener, for example. 
     Alternatively, a one-stage surgery, two-piece implant, also called a transgingival implant, is placed in a single stage because it extends through the gingiva for attachment to an abutment. The one-piece implant also is placed in the jaw in a single stage. 
     Although the osseointegration of existing dental implants into surrounding bone has proven adequate, further improvements in osseointegration of dental implants are desired. For example, patients would prefer the shortest healing time from surgery to the time the implant can be fully impacted by occlusal forces. Also, a desire exists to provide strongly osseointegrated implants for high risk patients, such as smokers, diabetics and/or abnormally slow bone growth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side perspective view of a dental implant device; 
         FIG. 2  is an exploded perspective view of the dental implant device of  FIG. 1 ; 
         FIG. 3  is a bottom, cross-sectional view of the dental implant device of  FIG. 1  taken along the line  3 - 3  shown on  FIG. 1 ; 
         FIG. 4  is a close-up, fragmentary view of a porous material on the dental implant device of  FIG. 1 ; 
         FIG. 5  is a side, cross-sectional view of an alternative dental implant device; 
         FIG. 6  is a side, partially cross-sectional view of yet another alternative dental implant device; and 
         FIG. 7  is a side, cross-sectional view of a further alternative dental implant device. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-3 , to improve osseointegration onto the implant, an implant device  10  for placement in bone has an exterior portion  12  made of a porous material  14  that bone can grow into to improve long term stability of the implant device. Such a porous material may also increase short term stability for immediate loading because of its large friction coefficient with surrounding bone as explained in greater detail below. The exterior portion  12  may be placed on or around an interior portion or core  16  that supports the exterior portion and adds strength to the implant device  10 . The core  16  may have a surface treatment  18  to further improve osseointegration with bone that has grown through the exterior portion  12  and onto the core  16 . Alternatively, or additionally, the core  16  may also have an outer shape or periphery  19  configured to limit rotation of the exterior portion  12  relative to the core  16  for proper placement of the implant  10  in a bore in bone and to increase both long term and short term stability. 
     Now in more detail, in the illustrated example, the implant  10  is a dental implant for insertion into a mandible or maxilla. The implant  10  is used to anchor one or more dental prostheses, and includes a coronal head portion or head  20 . The interior portion or core  16  extends apically from the head  20 . In one form, the head  20  and core  16  are integrally formed but may be separate pieces secured to each other by threading, friction fit, welding (laser or e-beam), and so forth. A separate anchor  22  (also referred to as the stem or apical portion) is configured to engage the core  16  so that the head  20  and the anchor  22  cooperatively retain the porous exterior portion  14  therebetween on the implant  10 . 
     For the illustrated example, the coronal end  24  of the head  20  is configured with male or female engagement structure that receives corresponding structure from a separate abutment. It will be appreciated, however, that instead of the two-stage implant  10  shown, the head  20  may have an extended height to extend through gingiva and form a single-stage implant, or may have an integral abutment to form a one-piece implant. 
     The head  20  has an outer cylindrical or tapering surface  26  that extends to an apical end surface  28 . The core  16  has a reduced outer diameter compared to the diameter of the outer surface  26  and extends apically from an apical end surface  28  of head  20  so that apical end surface  28  forms a shoulder to abut and retain exterior portion  12  on the core  16 . In one specific form, the exterior portion  12  is a sleeve or collar with a bore  30  that receives the core  16 . In one form, the collar  12  has a radial thickness of about 0.03 inches (about 0.75 mm). A coronal end  32  of the exterior portion  12  faces and/or abuts the apical end surface  28 . An apical end  34  of the exterior portion  12  faces and/or engages the anchor  22 . 
     The anchor  22  may be secured to an apical end portion  56  of the core  16  to secure the exterior portion  12  between the head  20  and the anchor  22 . The anchor  22  may have a bore  36  for receiving the core  16 , and the two pieces may then be welded together thereby permanently securing the exterior portion  12  on the core  16 . It will be understood that many alternative configurations are contemplated such as the core  16  and anchor  22  being held together by threads or press-fit, or the core  16  being integral to the anchor  22  or entirely separate instead of integral to the head  20  as mentioned above, and as long as the porous exterior portion  12  is maintained adjacent the core  16 . 
     The core  16 , head  20 , and anchor  22  (whether or not one or more of the pieces are separate or integrally formed) are made of a suitable biocompatible material such as titanium, titanium alloy, stainless steel, zirconium, cobalt-chromium molybdenum alloy, polymers such as polyether ketone ketone (PEKK) for one example, ceramic, and/or composite material. 
     The outer surfaces  26  and  37  of the head  20  and anchor  22  may have threads  38  for threading the implant  10  into a bore in bone or may be press-fit into the bore instead. Thus, the outer surfaces  26  and  37  may alternatively or additionally have surface treatment for promoting cortical bone and/or cancellous bone growth. The head outer surface  26  may additionally or alternatively be treated to promote an epithelium or soft tissue barrier and/or promote soft tissue growth if the head  20  extends into the gingival layer. In this case, barrier or soft tissue growth treatments can be placed adjacent to soft tissue or the interface between bone and soft tissue. Such treatments may include macro or micro threading, or circumferential or annular grooves, other patterned or random recesses caused by etching (such as acid etching), blasting (such as with sand, with or without HA particles, for example), or also coating of titania (titanium oxide) or other materials that create some adhesion between soft tissues and biomaterials. The surface treatment of outer surfaces  26  and  37  may or may not be the same as the surface treatment of the core  16  described below. 
     Referring to  FIG. 4 , the porous material  14  forming the exterior portion  12  may include metal, and in one form, is a porous tantalum portion  40  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 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 a 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. 
     As shown in  FIG. 4 , porous tantalum structure  40  includes a large plurality of interconnected members, ligaments, or beams  42  defining open spaces  44  there between, with each member  42  generally including a carbon core  46  covered by a thin film of metal  48  such as tantalum, for example. The open spaces or passages  44  between members  42  form a matrix of continuous channels having no dead ends, such that growth of cancellous bone entirely through porous tantalum structure  40  is uninhibited. In other words, the bone can grow from an exterior surface  50  of the implant  10  formed by the exterior portion  12 , generally radially through the passages  44  of the exterior portion  12 , and onto the core  16 . 
     The porous tantalum may include up to 75%-85% or more of voids 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 anchor implant  10  into the surrounding bone of a patient&#39;s jaw which increases stability. The rough exterior surface of such porous metal part  12  has a relatively high friction coefficient with adjacent bone forming the bore that receives the implant  10  to further increase initial stability as alluded to above. This structure can produce superior aesthetic results by restricting movement of the implant. These implants can be placed without supplementary surgical procedures, such as bone grafting, and can be placed in areas where traditional implants have been less successful, such as with reduced or decayed alveolar sections, or with patients that have abnormally slow or reduced bone growth. 
     More specifically, the high level of friction between the porous material and the bone provides immediate stability post surgery. The tantalum struts that extend from the surface of the material create a rasping action that may stimulate bone growth and anchor the implant at the time of placement. The extremely biocompatible tantalum metal that the porous material is made from allows bone to directly oppose the material. The tantalum forms a porous scaffolding that allows bone to grow into the material providing a rapid osseointegration response that quickly augments the initial mechanical fixation to secure the implant. The implant with in-grown bone may have stability greater than a comparably sized implant with only on-grown bone. Finally, the composite of in-grown bone and such a porous material has elastic properties much closer to bone than a solid metal implant, creating a loading environment that is conducive to maintaining bone near the implant. 
     Regarding the initial stability, as an implant with the porous material is inserted into the bore or cavity in bone, the porous material will bite into the bone by grating, chipping and/or flaking bone pieces off of the bone sidewalls against which the implant device is being placed. When the implant is inserted into the bore or cavity, this “rasping” action may form slight recesses or indents within the sidewall. This may restrict rotational or twisting motion of the implant device within the bore or cavity 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, the porous material has increased resistance to twisting or rotation, allows for immediate or very early loading, and increases long-term stability due to the improved osseointegration. Such an implant with ingrown bone has stability greater than a comparably sized implant with only on-grown bone. For instance, loads that typically require a 16 mm long implant may be adequately impacted by an 8 mm long implant. These advantages may be realized no matter the form of the porous implant. 
     Porous tantalum structure  40  may be made in a variety of densities in order to selectively tailor the structure for particular applications. In particular, the porous tantalum may be fabricated to virtually any desired porosity and pore size, whether uniform or varying, 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 ingrowth. 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. 
     To provide additional initial mechanical strength and stability to the porous structure, the porous structure may be infiltrated with a 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 polylactic co-glycolic acid (PLGA), polylactic acid (PLA), polyglycolic acid (PGA), polyhydroxybutyrate (PHB), and polyhydroxyvalerate (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 through the entire length of the porous material. The resorbable material would resorb as the bone grows in and replaces it, which maintains the strength and stability of the implant. 
     Referring again to  FIG. 1 , the surface treatment  18  is applied to a treated area  54  on an outer surface  52  of the interior portion or core  16  for direct attachment to bone. Such strong attachment of the core  16  to bone increases stability. Alternatively, or additionally, the type of surface treatment may be selected to promote an epithelium barrier, soft tissue barrier, or soft tissue growth when a core on the implant is extending through the gingiva as explained below for implants  200  and  300  ( FIGS. 6-7 ). 
     The treated area  54  is covered by the exterior portion  12  so that the treated area  54  is accessible for direct contact with bone that grows generally radially through the exterior portion  12 . In one form, the treated area  54  aligns or corresponds to the exterior portion  12  such that the treated area  54  only extends underneath the exterior portion  12  and does not extend beyond the exterior portion  12  where it is uncovered. In this case, the surface area and outer periphery of the treated area  54  are the same or about the same as that of the exterior portion  12 . By another approach, the treated area  54  may be disposed on locations on the core  16  that is not directly covered by the exterior portion  12 . For example, the treated area  54  may cover the entire core  16  while the exterior portion  12  only extends in a coronal-apical direction over a part of the core  16 . Otherwise, the treated area  54  may have a smaller surface area than that of the exterior portion  12  so that it only extends under the exterior portion  12  whether or not the periphery of the treated area  54  is the same shape as the outer periphery of the exterior portion  12 . At a minimum, treated area  54  has at least some part extending underneath the exterior portion  12  and accessible from the exterior surface  50  of the implant  10  through the passages  44 . 
     It will be appreciated that instead of a sleeve or collar, the exterior portion  12  may only form part of the circumference of the implant  10 , or may only be located on one or more sides of the implant  10 . In that case, the treated area  54  of the core  16  may or may not be configured to align only with the area covered by the exterior portion  12 . 
     In one form, the treated area  54  is at least roughened. This may be performed by gritblasting or sandblasting the treated area  54  to create a random pattern of pits on the outer surface  52  of the core  16  with an average roughness (Ra) of about 20 to 50 μm. The blasting may be performed by spraying Hydroxyapatite (HA) or other bio-compatible materials. By one approach, the treated area  54  has only been treated with sandblasting but alternatively could have a variety of different treatments instead of, or in addition to, the sandblasting. This includes acid etching of the treated area  54  to create random or patterned roughening. 
     In another example of a treatment  18 , the treated area  54  may have at least one coating of a bio-compatible material. The coating may include a bio-reactive material such as HA, collagen, peptides, or other growth factors to promote bone growth onto the core  16  (and/or promote soft tissue growth if the core extends through gingiva). The coating could alternatively or additionally be anti-bacterial and include transition metal ions such as Ag, Cu, or Zn, other bactericidel polymers, antibiotics and/or nanoscale roughness to prevent bacterial colonization on the treated area  54 . Other coatings may be applied to form a porosity into the coating for better attachment. This may include Cancellous Structure Titanium (CSTi) provided by Zimmer, Inc. that includes Titanium powder sintered to the core  16  which forms pores through the coating and a roughness to provide improved fixation to the bone or soft tissue. The treated area  54  may alternatively, or additionally, have other roughening treatments such as a circumferentially oriented roughness like threads or annular grooves, or other patterns of roughness (whether on a macro, micro, or nano scale) as long as it intentionally relates to direct attachment to bone (or soft tissue when the core extends near or into the gingiva). 
     Typically an implant is treated with sandblasting and so forth after the implant is fully assembled so that treatment to exposed areas of an implant can take place in a single step. In this case, however, since the outer surface  52  of the core  16  is treated and then covered, the pieces of implant  10  are treated separately before assembly. Thus, first the head  20  with the core  16 , the porous exterior portion  12 , and the anchor  22  are shaped as described above. The head  20  and, in turn, the core  16  are then sandblasted or otherwise treated as described above for direct engagement with bone or soft tissue. The head  20  and core  16  are treated separately from the anchor  22 , before the exterior portion  12  is mounted on the core  16 , and before the head  20  is attached to the anchor  22 . 
     In one form, the entire head  20  including the apical end portion  56  of the core  16  are blasted. It will be appreciated, however, that the core  16  could be the only area treated or blasted while the rest of the head  20  is masked from the treatment. This may be desired if the other exposed areas of the implant  10  receive a different type of treatment that could be damaged by the treatment performed at the core  16 , such as coatings, blasting with different particles or particles of different sizes, patterned etching, and so forth. Also, the sidewall  57  of the apical end portion  56  could be masked since it is unexposed within anchor  22  when the implant  10  is assembled, or to provide a smooth connection surface if needed. 
     Once the treated area  54  is complete, the exterior porous portion  12  is mounted on the core  16 , and then the anchor  22  is mounted to the core  16  and secured thereon by laser welding, threading, or other permanent connection. In the illustrated form, after the apical end portion  56  of the core  16  is placed in the bore  36  on the anchor  22 , the two are laser welded together along a seam  58  at the apical end portion  60  of the anchor  22 . When the head  20  and anchor  22  are laser welded together, the welding process may also undesirably smooth the roughening treatment on the anchor  22  such that sandblasting may need to be reapplied to the anchor  22  on the areas affected by the welding. 
     In another aspect of implant  10 , the core  16  is shaped to limit rotation between the head  20  and the exterior portion  12 . If the exterior portion  12  is able to rotate relative to the core  16  and head  20  while the implant  10  is being inserted into a bore in bone, the exterior portion  12  may undesirably bind with the bone (while the head  20  still rotates) so that the implant  10  cannot be properly inserted all the way into the bone bore. Also, better osseointegration occurs when the position of the porous exterior portion  12  in the mouth is not able to change significantly (by rotating on the implant for example) when impacted by occlusal forces thereby maintaining initially fragile bone growth through the exterior portion  12 . This results in more long term and short term stability for the implant  10 . To accomplish these goals, an anti-rotational connection is formed between the exterior portion  12  and the core  16 . 
     In detail, the implant  10  generally defines a longitudinal axis L while the periphery  19  of the core  16  extends on a cross-section perpendicular to axis L, and the exterior portion  12  has a generally cylindrical wall  62  that defines the bore  30  of the exterior portion  12  and extends around axis L. 
     The outer surface  52  of the core  16  has at least one generally longitudinally extending groove or flute  68 . In the illustrated form, the outer surface  52  forms a circumferential array of the flutes  68  around the core  16 . Thus, the flutes  68  form the sides on the periphery  19  providing the periphery  19  with a generally polygonal shape with relatively sharp corners or edges  64  that cut into the wall  62  of the exterior portion  12  when the exterior portion  12  is being inserted axially onto the core  16 . The edges  64  are formed relatively sharp by forming each flute  68  with a concave curved surface  66  with a radius r. Thus, in one form, the core  16  has at least two adjoining concave surfaces  66  so that the junction of the two adjoining surfaces  66  form the peak or edge  64  for engaging the collar. This generally secures the edges  64  within the wall  62  of the exterior portion  12  to rotationally secure the collar  12  relative to the core  16 . 
     The radius r of the concave surface  66  is set sufficiently small so that the core  16  retains sufficient mass to have strength to adequately absorb occlusal forces. The radius r is also sufficiently large to provide the peaks  64  with a sharp edge to provide a strong, non-rotational connection between the core  16  and collar  12 . In one form, the periphery  19  varies between six and twelve concave sides  66  with a diameter d (from edge to edge) of about 0.060 to 0.230 inches and a radius r from about 0.031 to 0.250 inches depending on the desired size of the implant. In the illustrated form, the eight sides  66  of core  16  have a radius of about 0.0625 inches and an edge to edge diameter of about 0.120 inches. The inner diameter of wall  62  is about 0.114 inches so that each edge  64  cuts into the wall  62  at least about 0.003 inches. Manufacturing tolerances may result in a cut depth of between about 0.002 inches and 0.006 inches. In one form, the edges  64  should cut into the wall  62  at least about 0.002 inches to form a strong anti-rotational engagement. 
     It will be appreciated that while radius r is the same for all of the sides  66  to maintain a generally uniform cutting depth into the porous exterior portion  12 , radius r may be varied as desired instead. This may cause edges that extend farther radially and cut deeper into wall  62  only at certain points around the circumference of the periphery  19  such as two or four opposite sides of the core  16  for a relatively stronger hold. 
     In an alternative form, the periphery  19  may be other non-circular shapes while the wall  62  remains circular. This creates sections of the core  16  with varying radii that do not have the clearance to rotate relative to the exterior portion  12  and vice-versa. In this case, the periphery  19  may be a flat-sided polygon (whether regular or non-regular) or generally ovaline (such as elliptical, oval, obround, and so forth) or may be some other combination of curved and flat sides. In another alternative, the wall  62  and the periphery  19  have different non-circular shapes to better reduce rotation between the core  16  and the wall  62  such as by having an oval periphery and a hexagonal wall in cross-section as one example. In these cases, an initial rotation of the wall  62  against the periphery  19  fixes the wall  62  against the core  16  by friction or by a portion of the core  16  cutting into the wall  62 . 
     In yet another alternative form, the implant may have the opposite configuration where the outer surface  52  of the core  16  is cylindrical while the wall  62  of the exterior portion  12  is non-circular to form a friction fit between the two. 
     In a further alternative form, the periphery  19  may have a non-circular shape that corresponds to a non-circular shape of the wall  62  to limit rotation between the two components. For example, the periphery  19  or core  16  may have an outer surface  52  with at least one flat side or portion that coincides with and engages a flat portion of the wall  62  to resist rotation. In one form, both the core  16  and wall  62  may have aligned polygonal cross-sections. 
     It should also be noted that while the implant  10  may have a generally cylindrical outer surface  50 , the implant  10  may also have a morse-type taper so that its diameter decreases as it extends apically to further increase friction with surrounding bone when the implant  10  is pressed or threaded into a bore in the bone. The outer periphery of the implant  10  may also have a non-cylindrical shape to create more friction with a circular bore in the bone. 
     Referring to  FIG. 5 , an alternative implant  100  may have a porous exterior portion  102  that covers an apical end  104  of a core  106  to form a pocket  108 , and in this example, a tapered generally bullet-shaped pocket  108 . In this case, an outer surface  110  of the core  106  has treatment  112  as with treatment  18  explained above for implant  10  for direct attachment to bone (or soft tissue if the core  106  extends adjacent or through the gingiva) that extends entirely through the porous exterior portion  102  via the passages  44  ( FIG. 4 ). 
     Referring to  FIG. 6 , other implant forms may be provided for the porous exterior portion and a core on the implant to receive soft tissue in addition to, or rather than, bone. For instance, the implant  200  is a one-stage implant with a transgingival flared end  202  that extends coronally from an endosseous portion  212  of the implant  200 . In this case, an exterior portion  204  on the flared end  202  may be in the form of a full or partial ring that is mounted around a core  206 . A treatment  210  is applied to the outer surface  208  of the core  206  as with implant  10 . 
     Referring to  FIG. 7 , in yet another form, the abutment  300  has a porous exterior portion or ring  302  mounted around a core  304  on the abutment to receive soft tissue when the abutment is mounted on a separate two-stage dental implant. The core  302  has an outer surface  306  with a treatment  308  as explained above with implant  10 . 
     By another approach, the treatment areas mentioned herein are zones, and each implant may have a number of zones where each zone has a treatment selected to accomplish a different purpose. In one form, there are at least two distinct zones along the longitudinal axis of the implant, whether the zones are adjacent or spaced from each other. In one case, one or more zones may be placed within bone and its treatment is selected for bone growth, while other zone or zones extend within soft tissue and their treatment is selected for soft tissue growth (or to establish a barrier as mentioned above). The zones in bone may be particularly selected to grow cortical or cancelleous bone. In one form, the implant  10  may have a number of axially spaced partial or full rings for bone growth for example. In the illustrated example, implant  200  may also have one or more zones  214  for soft tissue growth and one or more porous or treated zones  216  (shown in dashed line on  FIG. 6 ) for bone growth. Similarly, abutment  300  may have one or more of the zones and may be supported with an implant that has one or more of the zones. 
     It will also be understood that the combination of a porous exterior portion intentionally covering a treated area of an interior portion may be used on endosseous implants other than dental implants including implants along the length of a bone, or an implant at joints such as for knees, hips, shoulders, elbows, the spine, and so forth. 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.