Abstract:
A healing cap is provided for covering of an implant installed in a patient&#39;s mouth. The healing cap comprises a proximal end and a distal end. The proximal end is adapted to be inserted within a coronal opening formed in the implant. The healing cap further includes resilient fingers for engaging corresponding surfaces formed within the coronal opening of the implant. The distal end of the healing cap can include an indentation for receiving a snapping portion of a removal tool.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority and benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 60/153,843, filed Sep. 14, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to methods and devices that are used in implant dentistry to replace a natural tooth with a prosthetic tooth. More particularly, the invention relates to an improved healing cap that covers a dental implant after stage one surgery. 
     2. Description of the Related Art 
     Implant dentistry involves the restoration of edentulous area(s) in a patient&#39;s mouth using artificial components, including typically an implant fixture or root and a prosthetic tooth and/or final abutment which is secured to the implant fixture. According to state of the art techniques, the process for restoring a tooth and its root is carried out generally in three stages. 
     Stage I involves implanting the dental implant fixture into the bone of a patient&#39;s jaw. The oral surgeon first accesses the patient&#39;s jawbone through the patient&#39;s gum tissue and removes any remains of the tooth to be replaced. Next, the specific site in the patient&#39;s jaw where the implant will be anchored is widened by drilling and/or reaming to accommodate the width of the dental implant fixture to be implanted. Then, the dental implant fixture is inserted into the hole in the jawbone, typically by screwing, although other techniques are known for introducing the implant in the jawbone. 
     The implant fixture itself is typically fabricated from commercially pure titanium or a titanium alloy. Such materials are known to produce osseointegration of the fixture with the patient&#39;s jawbone. The dental implant fixture also typically includes a hollow threaded bore through at least a portion of its body and extending out through its proximal end which is exposed through the crestal bone for receiving and supporting the final tooth prosthesis and/or various intermediate components or attachments. 
     After the implant is initially installed in the jawbone a temporary healing screw or healing cap, which is ordinarily made of a dental grade metal, is secured over the exposed proximal end in order to seal the internal born. The healing screw typically includes a threaded end, which is screwed into the internal bore of the implant. After the healing screw is in place, the surgeon sutures the gum over the implant to allow the implant site to heal and to allow desired osseointegration to occur. Complete osseointegration typically takes anywhere from four to ten months. 
     During stage II, the surgeon re-accesses the implant fixture by making an incision through the patient&#39;s gum tissues. The healing screw is then removed, exposing the proximal end of the implant. A mold or impression is then taken of the patient&#39;s mouth to accurately record the position and orientation of the implant within the mouth. This is used to create a plaster model or analogue of the mouth and/or the implant site and provides the information needed to fabricate the prosthetic replacement tooth and any required intermediate prosthetic components. Stage II is typically completed by attaching to the implant a temporary healing abutment or other transmucosal component to control the healing and growth of the patient&#39;s gum tissue around the implant site. 
     Stage III involves fabrication and placement of a cosmetic tooth prosthesis to the implant fixture. The plaster analogue provides laboratory technicians with a model of the patient&#39;s mouth, including the orientation of the implant fixture relative to the surrounding teeth. Based on this model, the technician constructs a final restoration. The final step in the restorative process is replacing the temporary healing abutment with the final restoration. 
     There are several recurring problems or difficulties associated with securing the healing screw or cap to the implant during stage one and with removing the healing screw or cap during stage two surgery. For example, screwing the healing screw into the implant during stage one is time consuming, difficult and requires a secondary tool such as a screwdriver. Moreover, because the healing screw is small, it is difficult to handle and may be accidentally dropped into the patient&#39;s mouth if adequate care is not taken. Unscrewing the healing screw from the implant during stage two also is time consuming, difficult and requires an additional tool such as a screwdriver. Furthermore, the healing screw also may be accidentally dropped into the patient&#39;s mouth as it is removed from the implant if adequate care is not taken. 
     It should be appreciated that a set of two or more teeth can be replaced using the same procedure outlined above. In such a case, a single implant supports two or more prosthetic teeth. The present invention applies equally to the replacement of one tooth or several teeth. 
     SUMMARY OF THE INVENTION 
     It is an objective of this invention to provide an improved dental implant and healing cap that enables a surgeon to quickly and simply attach the healing cap to the dental implant without the need for an additional tool. It is another object of this invention to provide a healing cap that is quickly and simply removed from the implant. It is yet another object of the invention to provide a healing cap made of an inexpensive injection-molded plastic or any bio-compatible material, such as, for example, titanium, stainless steel, ceramic, or any combination thereof. 
     In one embodiment, the present invention provides a healing cap for covering a top surface of an implant installed in a patient&#39;s jawbone. The healing cap comprises a proximal end and a distal end. The proximal end is configured with one or more resilient prongs adapted to be inserted into a coronal opening formed in the implant and to be snappingly engage and secure the healing cap to the implant. 
     In another embodiment, the present invention provides a healing cap for covering a top surface of an implant installed in a patient&#39;s jawbone. The healing cap comprises a first end adapted to be snappingly mated to the implant and comprises a second end adapted to completely cover the top surface of the implant. 
     In yet another embodiment, the present invention provides an a healing cap for covering a top surface of an implant installed in a patient&#39;s jawbone. The healing cap comprises a proximal end and a distal end. The proximal end is sized and adapted to be inserted within a coronal opening formed in the implant. The healing cap further comprising a resilient snap means for snappingly engaging corresponding surfaces formed within the coronal opening of the implant. The distal end comprising a cover portion adapted to cover the top surface of the implant. 
     In yet another embodiment the present invention provides a removal tool for removing a healing cap that is snappingly mated to a dental implant installed in a patient&#39;s mouth. The removal tool includes a handle and one or more prongs adapted to be matingly and snappingly received in an indentation of the healing cap. 
     In yet another embodiment the present invention provides a method of installing and removing a healing cap that covers a top surface of an implant installed in a patient&#39;s jawbone. A proximal end of the healing cap is inserted into a coronal opening of the implant until the proximal end snappingly engages and secures the healing cap to the implant by applying a latent downward force on the implant. A snapping portion of a removal tool is inserted into a top portion of the healing cap such that a first removal force, which is greater than a second removal force required to remove the healing cap from the implant, is required to remove the removal tool from the top portion. The healing cap is separated from the implant by moving the removal tool away from the implant. 
     For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. 
     All of these embodiments and obvious variations thereof are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of the invention will now be described with reference to the drawings of the preferred embodiments, which are intended to illustrate and not to limit the invention, and in which: 
     FIG. 1 is a side view of a dental implant having certain features and advantages according to the present invention; 
     FIG. 2 is a cross-sectional view of the dental implant of FIG. 1 taken along line  2 — 2  of FIG. 3; 
     FIG. 3 is a top view of the dental implant of FIG. 1; 
     FIG. 4 is a top view of a healing cap having certain features and advantages according to the present invention; 
     FIG. 5 is a side elevational view of the healing cap of FIG. 4; 
     FIG. 6 is a bottom view of the healing cap of FIG. 4; 
     FIG. 7 is a cross-sectional view of the healing cap of FIG. 4 taken along line  7 — 7  of FIG. 4; 
     FIG. 8 A-C are partial cross-sectional time assembly views illustrating the healing cap of FIG. 4 being inserted into the implant; 
     FIG. 9 A and B are detail views of the healing cap in the snapping chamber of implant assembly; 
     FIG. 10 is a side elevational view of a removal tool having certain fetures and advantages according to the present invention; 
     FIG. 11 is a close up view of the snapping portion of the removal tool of FIG. 10; 
     FIG. 12 A-C are partial cross-sectional time assembly views illustrating the removal tool of FIG. 10 being inserted into the healing cap of FIG. 4, which is already inserted into the implant of FIG. 1; 
     FIG. 13 is a modified arrangement of a removal tool having certain features and advantages according to the present invention; and 
     FIG. 14 a close up view of the snapping portion of the removal tool of FIG.  13   
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1-3 illustrate a dental implant  10  particularly suited for receiving a snap-in healing cap having certain features and advantages according to one embodiment of the present invention. The implant  10  has an outer surface that is preferably divided into three regions: a body portion  12 , a neck region  14 , and a top portion  16 . The body portion  12  preferably includes threads, and represents the portion of the implant  10  that is placed in either the mandible or the maxilla. As shown, the body portion  12  of the implant is substantially cylindrical or slightly tapered; however, the body portion  12  could also assume a conical shape or other known implant shapes, as desired. The threads of the body portion  12  preferably match preformed threads formed along the inner surface of an osteotomy formed in the patient&#39;s jawbone. However, the implant  10  could also be designed so as to be self-tapping. Preferably, the top portion  16  of the implant is substantially cylindrical and has a top surface  18  that is substantially flat. 
     As best seen in FIGS. 2 and 3, the implant  10  includes an inner cavity  20 . The inner cavity  20  preferably includes a screw chamber  22 , a snapping chamber  24 , and an indexing chamber  26 . Preferably, the diameter of the screw chamber  22  is smaller than the diameter of the snapping chamber  24 . The snapping chamber  24  preferably includes a recess  25  that has an inner diameter D 1  that is slightly larger than the diameter D 2  of the indexing chamber  26 . 
     The screw chamber  22  is preferably sized and configured so as to receive a bolt (not shown). The bolt can be used to temporarily or permanently attach a dental component, such as, for example, a temporary healing abutment or a final restoration to the implant  10 . As will be described later, the snapping chamber  24  and the recess  25  are sized and configured to engage a corresponding snapping structure in a healing cap. 
     The indexing chamber  26  is best seen in FIGS. 2 and 3. In the illustrated arrangement, the indexing chamber  26  is substantially cylindrical with three lobes  28  that extend from the top surface  18  to the bottom of the indexing portion  26 . The three lobes  28  are preferably substantially half circular in shape and are symmetrically situated around the perimeter of the indexing portion  26 . Preferably, the center of each lobe  28  is about 120° apart from each other relative to a center axis  30  of the implant  10 . It should be appreciated, however, that the indexing chamber  26  can be formed in a wide variety of other suitable symmetric or non-symmetric shapes that may be used with efficacy, giving due consideration to the goals of providing repeatable indexing and anti-rotation of mating components. For example, the indexing chamber  26  could comprise a hexagonal recess. In yet another arrangement, the implant  10  can include or protrusion (e.g., a hexagonal protrusion) that is situated on the top surface  18  of the implant  10 . In which arrangements, the snapping chamber can be located closer to the top surface  18  of the implant  10  and the indexing chamber  26  can be eliminated. It should also be appreciated that the indexing chamber  26  is not a critical aspect of the present invention. In fact, the present invention can be used with an implant  10  that does not include an indexing chamber  26 . 
     FIGS. 4-7 illustrate one embodiment of a healing cap  32  having features and advantages in accordance with the present invention. The healing cap  32  is made of any bio-compatible material, such as, for example, an injection molded dental grade plastic, titanium, stainless steel, ceramics, and any combination thereof Preferably, the healing cap  32  is made of an inexpensive injection molded dental grade plastic because such a material is generally less expensive than metal and ceramic materials. 
     As best shown in FIGS. 5 and 7, the healing cap  32  has two main parts: a cover portion  34  and a snapping portion  50 . The cover portion  34  has a substantially flat lower surface  36  that has a diameter that is approximately the same as the top surface  18  of the implant  10 . The cover portion  34  also includes a top surface  38  that is substantially smooth and in the illustrated arrangement has a diameter slightly larger than the lower surface  36 . In the illustrated arrangement, a side wall  40  connects the top surface  38  to the lower surface  36 . 
     Preferably, the cover portion  34  also includes an indentation  42  which is desirably located near or at the center of the top surface  38 . The indentation  42  includes a neck  44 , which has a diameter that is smaller than a diameter of a lower portion  46  of the indentation  42 . The function of the indentation  42  will be described in detail below. 
     The illustrated snapping portion  50  consists of a plurality of prongs or tangs  52 . Each prong  52  preferably includes a protrusion  54 . The protrusions  54  are preferably sized and configured to snap into and resiliently engage the snapping chamber  24  of the implant  10 . Accordingly, the protrusions  54  have an outer diameter D 3  that is preferably slightly larger than the inner diameter D 1  of the indexing chamber  26  (see FIG.  2 ). Although in the illustrated arrangement the protrusions  54  are beveled (i.e., comprising two slanted sides and one flat side), it should be appreciated that the protrusions can also be fully or partially rounded as desired. 
     Referring to FIGS. 8 A-C, to attach the healing  32  to the implant  10  during stage I, the surgeon simply places healing cap  32  over the implant  10  and pushes the snapping portion  50  of the healing cap  32  into the implant  10 , as will be described in more detail below. As mentioned above, the protrusions  54  of the healing cap  32  preferably, have at least a slightly larger diameter D 3  than the inner diameter D 2  of the indexing chamber  26 . Accordingly, the snapping portion  50  of the healing cap  32  is compressed as it passes through the indexing chamber  26  (see FIG.  8 A and B). Once the prongs  52  reach the snapping chamber  24 , they partially expand forming a snap fit between the healing cap  32  and the implant  10  (see FIG.  8 C). Additionally and advantageously, as the healing cap  32  is mated against the top surface  18  of the implant  10 , the prongs  52  preferably resiliently engage a slanted inner surface  62  of the snapping chamber  22  (see FIG.  9 A). Thus, the pressure exerted against the partially compressed prongs  52  by the slanted inner surface  62  of the snapping chamber  22  creates a reaction downward pulling force. This downward pulling force on the cap  32  causes the lower surface  36  of the healing cap  32  and the top surface  18  of the implant  10  to form a seal (see FIG.  8 C). Advantageously, this prevents and/or minimizes leakage of saliva and bacterial contaminants into the implant  10  and thus prevents infection between stage I surgery and stage II surgery. 
     Clinically and advantageously, the dentist can be assured of the proper placement or seating of the healing cap  32  because as the healing cap  32  is pulled or urged down into the implant  10  the dentist can “feel” the snap fit and hear the audible “click” as the prongs  52  snap into the snapping chamber  24  of the implant  10 . Additionally, the dentist may visually confirm that the healing cap  32  is properly placed or seated by viewing the lower surface  36  of the healing cap  32  and the top surface  18  of the implant  10  using a dental mirror. If desired, the proper placement or engagement of the healing cap  32  may be confirmed by attempting to remove the healing cap  32 . A properly seated coping will have perceivable resistance to removal forces as the prongs  48  become compressed as they are pulled back into the indexing chamber  26  (see FIG.  8 B). 
     To remove the healing cap  32  during stage two, the surgeon may use a removal tool  100 , which is depicted in FIGS. 10 and 11. The handle  100  preferably includes a stem  102  and a snapping portion  104 . The snapping portion  104  is similar in shape and function as the snapping portion  40  of the healing cap  32 . The main difference is that the snapping portion  104  of the removal tool  100  is configured to engage the indentation  42  on top of the healing cap  32  (FIG. 7) in a snap fit. Accordingly, the snapping portion  104  includes a plurality of prongs or tangs  106 . Each prong  106  preferably includes a protrusion  108  that can be beveled (as illustrated) or rounded. As mentioned above, the protrusions  108  are preferably sized and configured to snap into and resiliently engage the indentation  42  of the healing cap  32  (see FIG.  7 ). Accordingly, the protrusions have an outer diameter D 4  that is slightly larger than the diameter of the neck  44  of the indentation  42 . 
     Referring to FIGS. 12A-B, to remove the healing cap  32  from the implant  10  during stage II, the dentist simply places the snapping portion  104  of the removal tool  100  over the indentation  42  and pushes the snapping portion  104  into the indentation  42 . As mentioned above, the protrusions  108  of the handle  100  preferably, have at least a slightly larger diameter D 4  than the neck  44  of the indentation  42 . Accordingly, the snapping portion  104  of the handle  100  is compressed as it passes through the neck  44  (see FIG.  12 B). Once the protrusions  108  reach the lower portion  46  of the indentation  42 , the prongs  106  partially expand forming a snap fit between the handle  100  and the healing cap  32 . 
     The handle  100  and heating cap  32  are preferably configured so that a force required to remove the healing cap  32  from the implant  10  is less than the force required to remove the handle  100  from the healing cap  32 . Therefore, when the dentist lifts the removal tool  100  away from the implant  10 , the healing cap  32  remains attached to the handle  100  but detaches from the implant  10 . 
     The snapping forces between the healing cap  32 , and the implant  10  are determined primarily by the outer diameter of the protrusions  54 , the inner diameter of the recess  25 , the inner diameter of the indexing chamber  26 , and friction between contacting mated surfaces. Similarly, the snapping forces between the handle  100  and the healing cap  32  are determined primarily by the outer diameter D 4  of the protrusions  108 , the inner diameter of the lower potion  46 , the inner diameter of the neck  44 , the friction between contacting mating surfaces. To decrease the snapping force, the inner diameter of the protrusions  54 ,  108  can also be decreased while maintaining the inner diameters of the recess  25  and the indexing chamber  26  and the inner diameters of the lower portion  46  and neck  44 . The snapping force may also be decreased or controlled by increasing the diameter of the indexing chamber  26  (or the neck  44 ) while maintaining the size of the protrusions  43  (or  108 ) and the recess  25  (or lower portion  46 ). 
     As mentioned above, the healing cap can be made of any bio-compatible material, such as, for example, dental grade plastic, titanium, stainless steel, ceramic, or any combination thereof. The healing cap  32  is preferably made of an injection molded dental grade plastic, which is particularly useful for forming the snapping portion  52  because of its resilient properties. Accordingly, in one arrangement of the present invention, the cover  34  of the healing cap  32  is made of a metal or ceramic material while the snapping portion  50  is made a plastic material. 
     If the healing cap  32  and/or the handle  100  and/or parts thereof are made of metal, such as, for example, Titanium or Stainless Steel, the surface of the protrusions  54 ,  108  may preferably be coated or otherwise treated with Teflon, diamond-like carbon coating (e.g. amorphous diamond), or titanium anodic coating, or any other lubricious coating capable of making the surfaces slide easier. See, for example, U.S. Pat. No. 5,833,463 incorporated herein by reference. 
     FIGS. 13 and 14 illustrate a modified arrangement of a removal tool  200 . As with the previous arrangement, the removal tool  200  includes a handle  202  and a snapping portion  204 . The snapping portion includes a prong  206  and a protrusion  208 , which has a diameter D 4  greater than the diameter of the neck  44  of the healing cap  32 . 
     The main difference in this arrangement is that the snapping portion  204  is not resilient. Thus, to remove the healing cap  32  during stage II, the dentist places the snapping portion  204  of the removal tool  200  over the indentation  42  and pushes the snapping portion  204  into the indentation  42 . As mentioned above, the protrusions  208  of the handle  200  preferably, have at least a slightly larger diameter D 4  than the neck  44  of the indentation  42 . Accordingly, the neck  44  is configured to deflect as the protrusion  208  passes through the neck  44 . Once the protrusion  208  reach the lower portion  46  of the indentation  42 , the neck  44  return to its original position thereby forming a snap lit between the handle  200  and the healing cap  32 . In such an arrangement, the healing cap  32  is preferably made of plastic so that the neck is resilient. 
     It should also be noted that although in the illustrated embodiments the healing cap  32  is removed from the implant  10  by engaging a removal tool with the healing cap  32 , the healing cap  32  can also be separated from the implant  10  by using a dental pick (not shown) or other conventional dental implement. Specifically, the dentist can use the dental pick or other implement to pry the healing cap  32  away from the implant  10 . In such an arrangement, the healing cap  32  preferably does not include the indentation  42 . 
     Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.