Abstract:
A biofunctional dental implant system for affixing a crown to an implant socket that is made in the bone structure within the mouth of a dental patient. A root portion is initially anchored within the implant socket made in the patient&#39;s bone structure. According to a first embodiment of this invention, the crown is secured to the root portion by a flexible abutment post. According to a second embodiment, the crown is secured to the root portion by a hollow abutment tube. The dental implant system of this invention is capable of increasing bone/implant stabilization and providing a supply path through which to evenly distribute human growth factor to the bone structure surrounding the root portion. The system also enables the crown to have a selectively controllable mobility relative to the root portion that is anchored within the implant socket so as to advantageously function like a natural tooth.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a biofunctional dental implant including a dental crown and an implant bone locking mechanism by which to anchor the crown within an installation socket that is made in the patient&#39;s bone structure to facilitate a reliable bone implant, increase bone/implant stabilization and provide a supply path through which human growth factor can be evenly distributed to the bone structure surrounding the locking mechanism. The crown and the implant bone locking mechanism are coupled to one another to permit the crown to have mobility relative to the locking mechanism and thereby function like a natural tooth. 
   2. Background Art 
   Natural teeth in the human mouth are supported in bone by periodontal fibers that function as shock absorbers when a compressive force is applied, such as during chewing. Through disease, accidental injury, anatomical abnormalities, age, and the like, a natural tooth may be removed or missing such that a dental appliance or prosthetic device (e.g. a crown) is implanted in the patient&#39;s bone structure to improve the patient&#39;s physical appearance and/or quality of mastication. However, conventional implants are often too rigid to function like natural teeth. Problems such as crown breakage, screw loosening and screw breakage are inherent problems with a rigid crown implant. Failure is also known to occur when an implant is used in a bridge abutment with a natural tooth or when improper occlusion is created by the implant crown. 
   More particularly, screws associated with conventional crowns sometimes break because of over tightening and due to tension and lateral stress to which the crown is subjected during use. Moreover, a single crown can rotate in response to high lateral and torquing forces encountered while chewing, whereby to rotate and loosen screws. As dental professionals will understand, it is difficult and time consuming to retrieve and/or repair such broken screws. In addition, special purpose torque drivers are required to install the screws. Once the root portion of the implant is installed, it may take several months to achieve suitable bone integration of the root portion with the surrounding bone structure thereby resulting in increased loading time before the crown can be reliably anchored. What is still more, many crowns are not adapted to move under loading conditions and, consequently, they cannot easily absorb and distribute shock and other physical forces that are generated during chewing. Such crowns may be susceptible to damage or reduced life and may be unable to provide the function of a natural tooth and the quality of mastication associated therewith. 
   Accordingly, it would be desirable to overcome the problems associated with conventional crowns by avoiding screws which can break or loosen and the special purpose tools that are needed to install such screws. It would also be desirable to decrease integration time by increasing stabilization between the root portion of the implant and the bone structure of the patient and by promoting tissue growth around the root portion to help anchor the root portion in place and thereby avoid damage to the surrounding bone structure. It would be further desirable that the crown be capable of moving during chewing so as to emulate a natural tooth. Therefore, patient comfort will be enhanced, the life of the crown will be increased, and the need to make repairs (along with the follow-up visits and corresponding cost) can be reduced. 
   In my U.S. Pat. No. 5,890,902 issued Apr. 6, 1999, a reliable solution is provided to overcoming the problems described above. By virtue of the embodiments disclosed below, additional solutions are provided that are characterized by few component parts, relative ease in manufacture and installation, and a correspondingly reduced manufacturing cost. 
   SUMMARY OF THE INVENTION 
   An implant bone locking mechanism is disclosed having a root portion located below a dental patient&#39;s gum line and anchored within an implant socket that is made in the patient&#39;s bone structure. A dental crown is coupled to the root portion so as to have mobility relative thereto and emulate the function of a natural tooth. The root portion includes a generally cylindrical implant casing having an outwardly flared implant cradle at one end upon which the crown portion is slidably supported. The implant cradle includes an installation opening which communicates with a screw threaded central passage that extends longitudinally through the implant casing. The installation opening is sized to receive therein a suitable tool by which to impart a vertical and/or rotational force to the implant casing for advancing the root portion into the implant socket made in the patient&#39;s bone structure. 
   According to a first embodiment of this invention, a plurality of growth factor ports are formed through the implant casing so that a supply of human growth factor can be evenly distributed to the patient&#39;s bone structure. The crown portion is connected to the root portion by means of a flexible abutment post having screw threaded coronal and apical ends. The screw threaded apical end of the abutment post is rotated into mating engagement with the screw threaded central passage that extends longitudinally through the implant casing. The screw threaded coronal end of the abutment post projects upwardly from the implant casing for receipt within a cavity that is formed in the crown portion. A compressible washer is located within the cavity of the crown portion so as to surround the coronal end of the abutment post. A threaded nut is rotated around the screw threaded coronal end and moved against the washer. The mobility of the crown portion over the implant cradle of the implant casing is selectively controlled by tightening the threaded nut and thereby compressing the compressible washer to secure the crown portion against the implant cradle. The cavity formed in the crown portion is then filled and closed by a composite filler. 
   According to a second embodiment of this invention, a plurality of growth factor ports are formed through the implant casing so that a supply of human growth factor can be evenly distributed to the patient&#39;s bone structure. A corresponding plurality of locking pins are slidable outwardly through respective growth factor ports for biting into the patient&#39;s bone structure and thereby anchoring the root portion within the implant socket. The crown portion is connected to the root portion by means of a hollow abutment tube having upper and lower screw threaded cylindrical ends. The lower screw threaded cylindrical end of the abutment tube is rotated into mating engagement with the screw threaded central passage that extends longitudinally through the implant casing. The upper screw threaded cylindrical end of the abutment tube projects upwardly from the implant casing for receipt within a cavity that is formed in the crown portion. A spring-like washer having flexible outstretched arms is located within the cavity of the crown portion so as to surround the upper screw threaded cylindrical end. The flexible arms of the washer are seated upon a compressible base of the crown portion that surrounds the cavity formed therein. A threaded nut is rotated around the screw threaded upper cylindrical end of the abutment tube and moved against the outstretched flexible arms of the washer. The mobility of the crown portion over the implant cradle of the implant casing is selectively controlled by tightening the threaded nut to cause the flexible arms of the spring-like washer to bend against the compressible base for compressing the base to secure the crown portion against the implant cradle. The cavity in the crown portion is then filled and closed with a composite filler. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded view of an implant bone locking mechanism which forms a first embodiment of this invention; 
       FIG. 2  shows a root portion of the implant bone locking mechanism of  FIG. 1  being installed within an implant socket made in the patient&#39;s bone structure; 
       FIG. 3  shows a healing cap to temporarily cover the root portion so as to permit the patient&#39;s bone structure to heal following installation of the root portion within the implant socket; 
       FIG. 4  shows an abutment post of the implant bone locking mechanism of  FIG. 1  being mated to the root portion following installation of the root portion within the implant socket; 
       FIG. 5  shows a dental crown of the first embodiment coupled to the abutment post and thereby connected to the root portion so as to have mobility relative thereto; 
       FIG. 6  is an exploded view of an implant bone locking mechanism which forms a second embodiment of this invention; 
       FIG. 7  is a cross-section of an implant casing of the implant bone locking mechanism of  FIG. 6  taken along lines  7 — 7  of  FIG. 6 ; and 
       FIG. 8  shows a dental crown of the second embodiment coupled to the abutment tube and thereby connected to the root portion so as to have mobility relative thereto. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1  of the drawings, there is shown an exploded view of an implant bone locking mechanism  1  which forms a first embodiment of this invention. The implant bone locking mechanism  1  includes a root portion  3  that is preferably manufactured from a biocompatible metallic (e.g. titanium or titanium alloy) or ceramic material that is adapted to be implanted in a socket formed in the bone structure of a dental patient in a manner that will be described in greater detail when referring to FIG.  2 . The root portion  3  includes a relatively wide, outwardly flared implant cradle  5  and a relatively narrow, generally cylindrical implant casing  7  which depends downwardly therefrom. As is best shown in  FIG. 2 , the implant casing  7  of root portion  3  is implanted (by means of a suitable tool  60 ) within an implant socket that is made in the patient&#39;s bone structure so that the implant cradle  5  can support a crown portion (designated  50  in  FIG. 5 ) above the gum line. 
   As shown in  FIG. 1 , the outwardly flared implant cradle  5  of root portion  3  has a concave shape to receive thereagainst the crown portion  50  (best shown in FIG.  5 ). However, depending upon the configuration of the crown portion, the implant cradle  5  may also have a convex shape to prevent a rotation of the crown portion. It may be desirable to cover the top of implant cradle  5  with a low friction coating (e.g. such as that known as Teflon) so as to minimize friction at the interface of the crown portion with the implant cradle. What is more, a resilient, biocompatible material may be used to cover the aforementioned low friction coating over implant cradle  5  so as to provide the crown portion with a cushion surface on which to be seated. The side walls of implant cradle  5  are preferably smooth and polished so as to facilitate a close fit within an implant socket formed in the patient&#39;s bone structure (best shown in  FIG. 2 ) as well as provide an area to which the patient&#39;s gum tissue can bond and/or allow epithelial attachment of gum tissue. 
   A hexagonal installation opening  8  formed through the top of the implant cradle  5  of root portion  3  communicates with an elongated central passage  9  that extends longitudinally through the interior of implant casing  7  to receive a soon to be described abutment post  18  therewithin. The precise shape of installation opening  8  will depend upon the corresponding shape of the abutment post  18 . 
   The generally cylindrical implant casing  7  of root portion  3  includes a series of sharp threads  10  running circumpherencially therearound and one or more tapping notches  12  formed at the bottom thereof. The sharp threads  10  and tapping notches  12  of implant casing  7  help the root portion  3  of locking mechanism  1  to cut through the patient&#39;s bone structure during installation and then resist being pulled out of the implant socket. Vertical rows of radially extending human growth factor ports  14  are spaced around the implant casing  7 . Each row of ports  14  terminates at a longitudinally extending channel  16  formed in the implant casing  7 . The radially extending ports  14  communicate with the longitudinally extending central passage  9  through the interior of implant casing  7  so that human growth factor can be expulsed and evenly dispersed within the implant socket, the advantages of which will be described in greater detail when referring to FIG.  2 . 
   The abutment post  18  of the implant bone locking mechanism  1  is manufactured from a flexible material, such as a non-metallic composite (e.g. comprising woven carbon fibers) or a metal (e.g. comprising spring steel). The flexible abutment post  18  includes an externally threaded coronal end  20  and an externally threaded apical end  22 . Each of the coronal end  20  and the apical end  22  of abutment post  18  terminates at a tapered tip. Located at the approximate midsection of abutment post  18  between the opposite coronal and apical ends  20  and  22  is a wide, disk-like body  24 . A (e.g. hexagonal) working surface  26  is located between the body  24  and the coronal end  20  of abutment post  18  to which a torquing force is applied by means of a suitable tool (e.g. the socket wrench designated  80  in  FIG. 4 ) in order to cause the threaded apical end  22  of abutment post  18  to be rotated into the installation opening  8  in implant cradle  5  and downwardly through the longitudinally extending central passage  9  in the implant casing  7  of root portion  3 . 
   In this regard, and as is best shown in  FIG. 2 , a series of threads  28  runs along the central passage  9  at the interior of the implant casing  7  by which the threaded apical end  22  of abutment post  18  is moved into mating engagement with the root portion  3 . To facilitate the aforementioned mating relationship with the internal threads  28  of the implant casing  7  via installation opening  8  and central passage  9 , the externally threaded apical end  22  of abutment post  18  may be covered with a low friction (e.g. Teflon) coating. 
   After the threaded apical end  22  of abutment post  18  has been moved past the installation opening  8  of implant cradle  5  and advanced downwardly through the central passage  9  that runs longitudinally through the implant casing  7  of the root portion  3 , the crown portion (designated  50  in  FIG. 5 ) can be mated to the threaded coronal portion  20  of abutment post  18 . To this end, an elastomeric sealing ring  30  is seated within a correspondingly shaped groove  32  that surrounds the abutment post  18  immediately below the body  24  thereof so as to prevent an exchange of fluids and block contaminants from invading the installation opening  8  within which the threaded apical end  22  of abutment post  18  is received. Moreover, a suitable (e.g. polyvinyl) sealant is injected into the installation opening  8  of implant cradle  5  by which to form a solid (e.g. hexagonal) washer  34  to lock the body  24  of abutment post  18  to the implant cradle  5  at the top of root portion  3 . 
   The implant bone locking mechanism  1  also includes the combination of a compressible washer  36  and an adjustable nut  38 . The compressible washer  36  is manufactured from a biocompatible elastomer (e.g. silicone flouro-polyvinyl or rubber). The washer  36  has a cup shape with an opening  40  formed through the bottom thereof. In the installed implant configuration of  FIG. 5 , the cup shaped flexible washer  36  surrounds the abutment post  18  such that the threaded coronal end  20  of the abutment post  18  is received through opening  40 . 
   Seated within the cup shaped compressible washer  36  is the adjustable nut  38 . The nut  38  is manufactured from a relatively hard metal (e.g. titanium or a titanium alloy) or plastic (e.g. polyurethane) material. The bottom  42  of the adjustable nut  38  is bowl shaped and sized to form a snug fit within the cup of compressible washer  36  (best shown in FIG.  5 ). Adjustable nut  38  has a threaded channel  44  running longitudinally through the bottom thereof. In the installed implant configuration of  FIG. 5 , the channel  44  running through the bottom of nut  38  and the opening  40  formed in the bottom of washer  36  are axially aligned with one another so as to receive the threaded coronal end  20  of abutment post  18 . Positioned opposite the bowl shaped bottom  42  and lying across the top of nut  38  is a generally flat, disk shaped cap  46 . A (e.g. hexagonal) aperture  48  is formed through the cap  46  to receive a suitably sized tool therewithin. The functions of the compressible washer  36  and the hard, adjustable nut  38  with each other and with the crown portion  50  will be described hereinafter when referring to FIG.  5 . 
     FIG. 2  of the drawings illustrates the steps for installing the root portion  3  of the implant bone locking mechanism  1  of FIG.  1 . After a portion of the patient&#39;s gum tissue  62  has been removed, a hole is drilled through the underlying bone structure  64  by means of a suitable drilling tool, such as a conventional drill bit (not shown) of the type commonly used in dentistry for the installation of dental implants. Then, a commercially available dental handpiece (e.g. wrench  60 ) having a torque applicator  66  that is sized to be received within the installation opening  8  at the top of the implant cradle  5  of root portion  3  is rotated so as to apply corresponding rotational and vertical forces by which the implant casing  7  is screwed downwardly into the implant socket created in the patient&#39;s bone structure  64 . During installation, the sharp external screw threads  10  of implant casing  7  bite into the surrounding bone structure  64  to prevent an inadvertent removal of the root portion  3  therefrom. 
   Next, a human tissue growth factor, such as bone morphogenic proteins, platelet derived growth factors, insulin derived growth factors, or the like, is injected down the central passage  9  that runs through the interior of implant casing  7  of root portion  3  in communication with the rows of radially extending growth factor ports  14  and the longitudinally extending channels  16 . Thus, a supply of human growth factor can be evenly distributed to the surrounding bone structure  64  for the purpose of decreasing the bone-to-implant integration time. 
   The implant cradle  5  of root portion  3  is now disposed at the top of the implant socket through the patient&#39;s bone structure  64  for receipt of the flexible abutment post  18  of locking mechanism  1 . However, prior to the installation of the abutment post  18  to root portion  3 , it may be desirable to provide the patient with healing time, particularly in situations where the root portion  3  is installed within an implant socket that has been drilled in soft bone. In this case, and referring to  FIG. 3  of the drawings, a biocompatible healing cap  70  is temporarily held in place atop the implant cradle  5  of root portion  3  by means of a suitable threaded fastener  72  so as to cover the central passage  9  through implant casing  7 . The threaded fastener  72  is rotated downwardly through a hole  74  formed in the top of healing cap  70  for receipt by the longitudinally extending central passage  9  at the interior of implant casing  7 . A threaded end  76  of fastener  72  is mated to and retained by the internal threads (designated  28  and best shown in  FIG. 2 ) of central passage  9 . The healing cap  70  may be held in place above implant cradle  5  for a sufficient healing time, such as until the occurrence of bone osseo-integration. At this point, the threaded fastener  72  is rotated out of engagement with the implant casing  7  and the healing cap  70  is removed from the implant cradle  5 . 
   Turning now to  FIG. 4  of the drawings, the flexible abutment post  18  is shown being coupled to the implant casing  7  of root portion  3  that has been installed in the implant socket formed in the patient&#39;s bone structure  64 . More particularly, either the previously described handpiece (designated  60  in  FIG. 2 ) or a different tool (e.g. a socket wrench  80 ) is used to surround the hexagonal working surface  26  of abutment post  18 . The tool  80  includes a torque applicator  82  that is sized to grip and apply a rotational force to working surface  26  by which to cause the abutment post  18  to rotate. Accordingly, the threaded apical end  22  of abutment post  18  is advanced axially and screwed downwardly into the central passage  9  of implant casing  7  so as to be rotated into mating engagement with the internal threads  28  thereof. 
   With the flexible abutment post  18  screwed into the central passage  9  of the implant casing  7 , the crown portion  50  can be attached to the root portion  3  of the implant bone and locking mechanism  1  in a manner that will now be described while referring to  FIG. 5  of the drawings. In the installed implant configuration of  FIG. 5 , with the root portion  3  embedded within an implant socket in the patient&#39;s bone structure  64  and the flexible abutment post  18  secured to implant casing  7 , the crown portion  50  is now ready to be attached to the threaded coronal end of abutment post  18  so as to be seated atop the implant cradle  5 . The solidified hexagonal lock washer  34  (previously described when referring to  FIG. 1 ) prevents the abutment post  18  from being inadvertently rotated out of engagement with the implant casing  7  of root portion  3 . 
   The crown portion  50  is manufactured from a durable crown material (e.g. gold, ceramic or plastic composite) and includes a longitudinally extending cavity  54  running therethrough. The bottom of cavity  54  receives the cup shaped, compressible washer  36  (also previously described when referring to FIG.  1 ). The compressible washer  36  and the cavity  54  in which washer  36  is located function as a ball and socket coupling by which to enable the crown portion  50  to slide laterally over the implant cradle  5  during chewing to emulate a natural tooth. The flexible nature of the abutment post  18  facilitates this lateral mobility of the crown portion  50  relative to the fixed root portion  3  of implant bone locking mechanism  1 . 
   The relatively hard nut  38  is then seated inside the cup shaped compressible washer  36 . As was described when referring to  FIG. 1 , in the installed implant configuration, the threaded coronal end  20  of abutment post  18  is received through an opening  40  and a threaded channel  44  that are axially aligned with one another in the washer  36  and the nut  38  by which the aforementioned ball and socket coupling is established to permit the lateral mobility of crown portion  50  over the implant cradle  5  of root portion  3 . A tool (e.g. a wrench) is then inserted into the aperture  48  in the cap  46  of nut  38  to rotate the nut  38  at the threaded channel  44  thereof into mating engagement with threaded coronal end  20  of abutment post  18 . Inasmuch as the adjustable nut  38  is manufactured from a harder material than the material from which the compressible washer  36  is manufactured, the ability of the crown portion  50  to move is dependent upon the manner in which the adjustable nut  38  is tightened along the coronal end  20  and downwardly against washer  36 . That is to say, the more the adjustable nut  38  is rotated along abutment post  18 , the more the washer  36  will be compressed so as to reduce the mobility of crown portion  50 . 
   Once the position of the nut  38  is selectively adjusted along the threaded coronal end  20  of abutment post  18  to attach the crown and root portions  50  and  3  together, the aperture  48  in the cap  46  of nut  38  is filled with a sealer. Finally, the top of the cavity  54  running longitudinally through crown portion  50  is filled and closed by a suitable composite filler  84 , such as that sold commercially as ESTHET-X. By virtue of the foregoing, the crown portion  50  will closely emulate the movement and appearance of a natural tooth so as to minimize patient discomfort, prolong the life and function of crown portion  50 , increase the quality of mastication, and minimize damage to the patient&#39;s bone structure  64  to which the root portion  3  of locking mechanism  1  is anchored. 
   An exploded view of an implant bone locking mechanism  100  which forms a second embodiment of this invention is now disclosed while referring initially to  FIG. 6  of the drawings. Like the locking mechanism  1  of  FIGS. 1-5 , the implant bone locking mechanism  100  of  FIG. 6  includes a metallic (e.g. titanium or titanium alloy) or ceramic root portion  103  that is adapted to be implanted in a socket formed in the bone structure of a dental patient. The root portion  103  includes a relatively wide, outwardly flared implant cradle  105  and a relatively narrow, generally tubular and slightly tapered implant casing  107  depending downwardly therefrom. With the root portion  103  positioned within the implant socket, the implant cradle  105  will be supported above the patient&#39;s gum line to receive a crown portion (designated  170  in FIG.  8 ). 
   The top of implant cradle  5  may be covered with a low friction (e.g. Teflon) coating to minimize friction at the interface of the crown portion  170  with the implant cradle. What is more, a resilient biocompatible material may be used to cover the low friction coating over implant cradle  105  so as to provide the crown portion with a cushion surface on which to be seated. The side walls of implant cradle  105  are preferably smooth and polished so as to facilitate a close fit within the implant socket formed in the patient&#39;s bone structure as well as provide an area to which the patient&#39;s gum tissue can bond and/or allow epithelial attachment of gum tissue. In this same regard, a notched ring  108  extends around the bottom of the implant casing  107  to be anchored to the patient&#39;s bone structure and prevent an inadvertent removal of root portion  7  from the implant socket following osseo-integration. 
   An elongated central passage  109  extends longitudinally through the implant cradle  105  and the interior of implant casing  107 . The bottom of the central passage  109  is tapered while the top of central passage  109  contains a series of screw threads  110  (best shown in FIG.  7 ). The generally tubular implant casing  107  of root portion  103  includes a rounded bottom end  112  to establish a large surface area for the purpose of absorbing occlusal impaction. Vertical rows of radially extending human growth factor ports  114  (also best shown in  FIG. 7 ) are spaced around the implant casing  107 . Each row of ports  114  terminates at an external channel  116  running along the implant casing  107 . The radially extending ports  114  communicate with the longitudinally extending central passage  109  through the interior of implant casing  107  so that human growth factor can be expulsed and evenly dispersed within the implant socket within which root portion  3  is received. 
   The growth factor ports  114  are sized so as to slidably receive respective locking pins  118  having sharp biting tips that are adapted to bore into the patient&#39;s bone structure to thereby anchor the root portion  103  of locking mechanism  100 . As is best shown in  FIG. 6 , the growth factor ports  114  through which human growth factor is expulsed and within which the locking pins  118  are slidably received may be formed at staggered locations around the implant casing  107 . The locking pins  118  are preferably manufactured from titanium, titanium alloy or hydroxy apatite ceramic. As is also shown in  FIG. 6 , the locking pins  118  are initially retracted inwardly of the radially extending ports  114  through implant casing  107 . However, and as will be explained in greater detail, once the implant casing  107  has been suitably implanted in the patient&#39;s bone structure, the locking pins  118  are forced outwardly from their ports  114  and into locking engagement with the surrounding bone structure. 
   A hollow, sieve-like sleeve  120  is sized and configured to form a snug fit within the central passage  109  of implant casing  107 . An impact tool may be used to drive the sleeve  120  through central passage  109  so as to cause the locking pins  118  to move in a radially outward direction from their respective ports  114  to engage the patient&#39;s bone structure and thereby anchor the root portion  103 . In the alternative, a separate plug (not shown) can be driven downwardly through the central passage  109  of implant casing  107  to cause the locking pins  118  to move radially outward therefrom. A series of seep holes  122  are formed through the sleeve  120 . In either case, sleeve  120  blocks a return of the locking pins  118  to the retracted position. In the installed implant configuration of  FIG. 8 , the sleeve  120  is filled with human growth factor which will drain through seep holes  122  to be delivered to the surrounding bone structure via the radially extending growth factor ports  114  and the longitudinal channels  116  (of  FIG. 7 ) formed in the implant casing  107 . 
   A rigid metal (e.g. titanium or stainless steel) abutment tube  128  is included by which to attach the crown portion (designated  170  in  FIG. 8 ) to the root portion  3  of implant bone locking mechanism  100 . Abutment tube  128  includes upper and lower cylindrical bodies  130  and  132 . Each of the upper and lower cylindrical bodies  130  and  132  has a set of external screw threads  134  and  136  running continuously therearound. The diameter of the upper cylindrical body  130  of abutment tube  128  is smaller than the diameter of the lower cylindrical body  132 . A channel  138  extends longitudinally through the upper and lower cylindrical bodies  130  and  132  of abutment tube  128 . A (e.g. hexagonal) installation opening  140  communicates with the channel  138  at the top of the upper body  130 . 
   To complete the implant configuration of  FIG. 8 , a suitable tool (not shown) is inserted into the installation opening  140  of abutment tube  128 . A rotational force imparted by the tool is transferred to the abutment tube  128 , whereby the lower cylindrical body  132  is rotated downwardly and into the central passage  109  of implant casing  107  so as to be received therein above the sieve-like sleeve  120 . Accordingly, the external screw threads  136  of the lower cylindrical body  132  are mated to the internal screw threads  110  of the central passage  109 . 
   With the abutment tube  128  attached to the implant casing  107  as just described, the lower cylindrical body  132  pushes downwardly on and retains the sieve-like sleeve  120  within the central passage  109  of implant casing  107  to prevent a displacement thereof. Moreover, the upper cylindrical body  130  of abutment tube  128  now projects outwardly from implant casing  107  so as to lie above the implant cradle  105  of root portion  103  to facilitate the connection of the crown portion in a manner to be described when referring to FIG.  8 . The channel  138  extending through the abutment tube  128  creates a supply path for the human growth factor to be delivered to the surrounding bone structure of the patient by way of the seep holes  122  formed in sleeve  120  and the growth factor ports  114  formed in the implant casing  107 . 
   In order to hold the crown portion  170  against the implant cradle  5  of the root portion  3  of implant bone locking mechanism  100 , a spring-like washer  144  is provided to exert a downward pushing force against the crown portion. The spring-like washer  144  is manufactured from a flexible metal (e.g. stainless spring steel) and includes a hollow body  146  and a plurality of spring arms  148  spaced around the hollow body  146  and stretching upwardly and outwardly therefrom. The hollow body  146  of washer  144  is sized to surround the upper cylindrical body  130  of abutment tube  128 . The outwardly stretched spring arms  148  of washer  144  are flexible and adapted to be pushed downwardly and bent against the crown portion to apply a holding pressure thereagainst. 
   To control the holding pressure applied against the crown portion by the flexible spring arms  148  of washer  144  in the installed implant configuration of  FIG. 8 , an adjustable periodontal ligament nut  150  is seated within the spring arms  148 . The adjustable nut  150  is manufactured from metal (e.g. stainless steel) and includes a screw threaded channel  152  extending longitudinally therethrough and a (e.g. hexagonal) installation opening  154  that communicates with the threaded channel  152  at the top of nut  150 . The threaded channel  152  of nut  150  has a diameter that is sized to surround the threaded upper cylindrical body  130  of abutment tube  128 . 
   With the hollow body  146  of spring-like washer  144  surrounding the upper cylindrical body  130  and seated upon the lower cylindrical body  132  of abutment tube  128 , a suitable tool (not shown) is inserted into the installation opening  152  of adjustable nut  150 . A rotational force imparted by the tool is transferred to the adjustable nut  150 , whereby the nut is coupled to the upper cylindrical body  130  of abutment tube  128 . 
   Accordingly, the screw threaded channel  152  of adjustment nut  150  is mated to the external screw threads  134  of the upper cylindrical body  130  of abutment tube  128 . The rotation of the adjustable nut  150  around the upper cylindrical body  130  continues until the nut  150  has been moved downwardly towards and seated within the outwardly stretched spring arms  148  of spring-like washer  144  (best shown in FIG.  8 ). The adjustment nut  150  can be tightened against the abutment tube  128  so as to selectively control the bending force applied to and the corresponding holding pressure generated by the spring arms  148  of washer  144  for causing the crown portion  170  to be retained at the implant cradle  105  of implant casing  107 . 
   The bottom of the adjustable nut  150  includes a set of flat slots  156  formed therein to accommodate respective outstretched arms  148  of the washer  144 . As just described, when the nut  150  is rotated around and tightened downwardly along the upper cylindrical body  130  of abutment tube  128 , a bending force will be applied to the arms  148 . The axial advancement of the adjustable nut  150  continues until the outstretched arms  148  of washer  144  are received within respective ones of the flat slots  156  (best shown in FIG.  8 ). With the flexible arms  148  of the spring-like washer  144  captured by the flat slots  156 , the adjustable nut  150  will be unable to rotate out of engagement with the upper cylindrical body  130  of abutment tube  128  so as to prevent an inadvertent separation or loosening of the crown portion  170  from the root portion  103 . 
   Once the adjustable nut  150  has been advanced so as to cause the outstretched arms  148  of the spring-like washer  144  to bend and thereby generate a holding pressure for retaining the crown portion  170  against the implant cradle  105  of root portion  103 , the installation opening  154  at the top of the nut  150  is closed. The foregoing is accomplished by means of an elastomeric (e.g. rubber) plug  160  having a nub  162  projecting downwardly therefrom and sized for receipt by installation opening  154 . In certain cases, it may be desirable to subsequently remove plug  160  from nut  150  to enable a fresh supply of human growth factor to be supplied to the bone structure surrounding the locking mechanism  100  via the supply path including the axially aligned channel  138  through abutment tube  128 , the seep holes  122  through sleeve  120 , and the growth factor ports  114  through implant casing  107 . 
   Referring now to the installed implant configuration of  FIG. 8 , the root portion  103  of the implant bone locking mechanism  100  of this embodiment is shown anchored within the implant socket formed in the patient&#39;s bone structure  164 , and the crown portion  170  is shown connected to the root portion  103 . The crown portion  170  is manufactured to include a compressible elastomeric base  172  having a longitudinally extending cavity  174 . The bottom of the cavity  174  through base  172  receives therewithin the threaded upper cylindrical body  130  of abutment tube  128  and the spring-like washer  144 . The hollow body  146  of washer  144  is seated upon the lower cylindrical body  132  of abutment tube  128  in surrounding engagement with the upper body  130  thereof. Thus, when the adjustable periodontal ligament nut  150  is tightened downwardly along the upper cylindrical body  130  and into contact with the flexible outstretched spring arms  148  of washer  144 , the corresponding holding force that is generated as the spring arms  148  are bent is transferred to the compressible base  172  of crown portion  170  by which to retain the crown portion against the implant cradle  105  of root portion  103 . 
   The compressible elastomeric base  172  of crown portion  170  is covered by a metallic coping  176 , and the metallic coping  176  is surrounded by a durable crown material  178  (e.g. gold, ceramic or plastic composite). Finally, the top of the longitudinal cavity  174  running through the compressible base  172  is filled and closed with a suitable composite filler  180  (e.g. ESTHET-X) so as to lie above and press downwardly on the rubber plug  160  that is seated atop the adjustable nut  150 . 
   Because of the flexible nature of the spring arms  148  of the washer  144  that generate a holding pressure, the elastomeric base  172  is compressed by which to retain crown portion  170  against the implant cradle  105  of root portion  103 . What is more, the crown portion  170  will be capable of sliding laterally over the implant cradle  105 . In this regard, the mobility of the crown portion  170  can be selectively controlled depending upon the tightness by which the adjustable nut  150  is rotated around the threaded abutment tube  128  and the bending force applied to the flexible arms  148  of the spring-like washer  144 . By virtue of the foregoing, and similar to the crown portion  50  disclosed above when referring above to  FIGS. 1-5 , the crown portion  170  of  FIGS. 6-8  will closely emulate the movement and appearance of a natural tooth so as to minimize patient discomfort, prolong the life and function of the crown portion  170 , increase the quality of mastication, and minimize damage to the patient&#39;s bone structure  164  to which the root portion  103  of locking mechanism  100  is anchored. 
   It is to be understood that this invention has application to single crowns, as illustrated in the drawings, or bridge abutments, partial denture attachments, complete dentures, and other uses where an implant must remain immobile, but when it is also desirable to have a dental appliance or prosthetic device that is capable of mobility so as to closely emulate the natural tooth function.