Abstract:
The present invention is prosthetic tooth replacement including a dental crown portion and a joining portion adapted to fixedly attach to a dental implant. Further, present invention also comprises the combination of a prosthetic tooth replacement and a dental implant. Additionally, the present includes a method for making an oral surgical guide stint by vacuum forming a thermoplastic material over a model of an implant target area. Finally, the present invention includes a method of inserting the combination of the prosthetic tooth replacement and implant into the jaw of a patient.

Description:
FIELD OF THE INVENTION 
   The present invention relates to the field of oral prostheses. More specifically, the present invention relates to the field of dental implants and attached dental crown prostheses. In addition, the present invention relates to oral surgical procedures, more specifically, to surgical procedures enabling the secure attachment of dental crown prostheses in one surgical session in which patient discomfort is reduced. 
   BACKGROUND OF THE INVENTION 
   Dental implants are well known devices used in dental surgery to restore patients&#39; lost, broken or decayed teeth. The essential function of a dental implant is to act as an anchor to hold in place a prosthetic device such as a fixed or removable denture appliance or single prosthetic tooth. Implants attain stability by being embedded in the patient&#39;s jawbone, thereby giving a firm foundation to the prosthetic device that protrudes above a patient&#39;s gum line. 
   Implants seen in the prior art have several disadvantages. First, to bring an implant procedure to completion requires several patient visits. Usually five to seven or more visits are necessary as well as possible referrals to specialists. The implant procedure itself requires surgery with flap and sutures leading to both significant patient discomfort, temporary restrictions on the types of food patients are permitted to eat, and a four to twelve month time period before the entire procedure is completed. In addition, there is a 10–15% failure rate. Failure of the procedure requires the use of alternative procedures over and above the failed implant surgery. Finally, the complete implant procedure, including the prosthetic device, can entail a high cost often out of the range of the average patient. 
   Typical of implants found in the prior art are those disclosed in U.S. Pat. Nos. 6,217,331 and 6,394,809 as well as United States Patent Application No. 2002/0142266, all to Rogers, et al. This series discloses a dental implant supporting a single prosthetic crown. The implant is described as having a threaded portion with a self-tapping region which allows insertion into the jawbone of a patient. The gingival portion is flared with a threaded bore that accepts a prosthetic device that extends above the gum line. The size of these implants mandate a waiting period of approximately 3–6 months before the prosthetic device is installed after the implant is first placed into the patient&#39;s jaw. This hold period allows ossification of the bone material around the inserted implant to ensure it is sufficiently secured in the bone structure. During this time, a flap is sewn over the implant to prevent infection during the ossification process. The required hold period delays the final installation of the dental prosthesis while the surgery can contribute to significant patient discomfort. 
   A similar implant is disclosed in United States Patent Application No. 2003/0068599 to Balfour, et al. The implant disclosed in the &#39;599 application includes scalloped buccal and lingual portions that allow for tissue attachment to create a natural appearing gum line. However, the size of the implant disclosed in the &#39;599 application necessitates the use of an insertion procedure that incorporates an extended waiting period to ensure sufficient ossification around the implant occurs. 
   Vigolo, et al. discloses the use of implants having a diameter in the range of 2.9 mm as supports for prosthetic crowns. [See  The Journal of Prosthetic Dentistry,  84(1):50–54 (July 2000) which is hereby incorporated by reference in its entirety.] However, use of implants of this size still require a two month waiting period before a prosthesis can be attached to the implant. Similarly, U.S. Pat. No. 4,313,696 to Kasama, et al., which is hereby incorporated by reference in its entirety, discloses an implant supporting a single prosthetic crown. However, the &#39;696 patent discloses that a period of wound healing must occur after the implant is placed in a patient&#39;s jaw. In addition, the device disclosed in the &#39;696 patent includes an elastomeric cushion placed between the prosthetic crown and the implant. 
   The use of mini dental implants (MDIs) has been disclosed in U.S. Pat. No. 5,749,732 to Sendax, which patent is hereby incorporated by reference in its entirety. The &#39;732 patent discloses an implant having a length of in the range of 17–19 mm, a threaded shaft diameter of about 1.8 mm with the threaded area having an unthreaded chord shaped section. Integral in the MDI of the &#39;732 patent is an abutment end to which a dental prosthesis can be attached. The &#39;732 patent discloses the use of the MDI to anchor a denture appliance holding a plurality of prosthetic teeth and requiring either a second MDI or another anchor such as a natural tooth to hold the denture. Also disclosed in the &#39;732 patent is an implantation procedure for the MDI that eliminates the need for a surgical incision, flap and sutures, and the consequent ossification period before installing the dental prosthesis. However, the advantage of MDIs in enabling fast, relatively pain free insertion of dental prostheses is somewhat negated by their confinement to use with dentures supporting a plurality of artificial crowns and the need to use at least two anchors to support the denture. 
   Therefore, there exists in the field a need for a dental implant that can be used to securely support single dental crown prosthesis and that can be secured in a patient&#39;s jawbone using a procedure that reduces the time to complete installation of the prosthesis and patient discomfort and pain. 
   SUMMARY OF THE INVENTION 
   The present invention broadly comprises a preformed prosthetic tooth comprising a dental crown portion and a joining portion that is adapted to fixedly attach to a dental implant. The joining portion is configured to receive the abutment end of a mini dental implant (MDI). The dental crown portion may be formed into the shape of a particular tooth. 
   The present invention also broadly comprises, in combination, a prosthetic tooth and at least one dental implant having a preformed prosthetic tooth with a dental crown portion and a joining portion that is adapted to fixedly attach to a dental implant. In a preferred embodiment, the dental implant will be a mini dental implant having an integral abutment end. 
   The present invention also broadly comprises a method of forming a surgical guide stint comprising taking an impression of the target area and opposing jaw area, pouring a model of the bite impression, placing at least one implant analog into position in the model and vacuum forming a stint over the model. 
   The present invention also broadly comprises a method of attaching a preformed prosthetic tooth to a jawbone of a patient comprising placing an oral surgical stint over a target region of a jawbone, drilling at least one hole having a first diameter into the jawbone through at least one implant analog hole in the oral surgical stint, threading a threaded dental implant having a larger second diameter and an integral abutment end into each drilled hole until only the abutment end protrudes above the gum line of the jawbone and attaching a single prosthetic crown onto the at least one abutment end. 
   A general object of the invention is to provide a nonsurgical procedure that enables the attachment of a prosthetic crown to the jawbone of a patient. 
   A second object of the invention is to provide a prosthetic crown securely attached to a self-tapping dental implant. 
   An additional object of the invention is to provide a preformed prosthetic crown able to be fixedly attached to a dental implant without attachment to an intermediate material. 
   A further object of the invention is to provide a surgical guide stint to guide the installation of a dental implant into the desired position on a patient&#39;s jaw. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The nature and mode of the operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing Figures, in which: 
       FIG. 1  is a front view of both upper and lower jaws of a human mouth containing implants of the present invention; 
       FIG. 2  is a top view of a lower jaw depicting a gap suitable for placement of the dental implant and upper crown of the present invention; 
       FIGS. 3   a – 3   c  are front views of various embodiments of the implant of the present invention; 
       FIG. 4   a  is side view of a molar-shaped dental crown portion of the present invention; 
       FIG. 4   b  is a cross section of the molar-shaped crown portion depicted in  FIG. 4   a;    
       FIG. 4   c  is a side view of an incisor-shaped crown portion of the present invention; 
       FIG. 4   d  is a cross section of the incisor shaped crown portion depicted in  FIG. 4   c;    
       FIG. 5   a  is a side view of a molar-shaped crown portion of the present invention showing attachment to an implant of the present invention; 
       FIG. 5   b  is cross section of a magnified view of the receiving tube and implant abutment end of the present invention shown in  FIG. 5   a;    
       FIG. 5   c  is a side view of an incisor-shaped crown portion of the present invention showing attachment to an implant of the present invention; 
       FIG. 5   d  is cross section of a magnified view of the receiving tube and implant abutment end of the present invention shown in  FIG. 5   c;    
       FIG. 6  depicts attached models of lower and upper jaws fabricated from impressions taken from a typical patient; 
       FIG. 6   a  depicts the lower and upper jaw models shown in  FIG. 6  in a closed position; 
       FIG. 7  is a top view of a model of a lower jaw depicting the position of a single implant hole; 
       FIG. 7   a  is a top view of a model of a lower jaw depicting the position of two implant holes; 
       FIG. 8  is a side perspective view of a model of a lower jaw showing implant analogs placed in implant analog holes; 
       FIG. 9  is a top view of a model of a lower jaw showing a stint placed in position around implant analogs; 
       FIG. 10  is a top perspective view of an oral surgery guide stint of the present invention; 
       FIG. 11  is a side view depicting the preparation for placement of the implant of the present invention in a lower jaw; 
       FIG. 12  is a side view depicting the implant of the present invention embedded in the lower jaw; 
       FIG. 13  depicts the attachment of a prosthetic tooth of the present invention to a dental implant; and, 
       FIG. 14  is a bottom perspective view of two embodiments of prosthetic crowns of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical structural elements of the invention. It also should be appreciated that figure proportions and angles are not always to scale in order to clearly portray the attributes of the present invention. 
   While the present invention is described with respect to what is presently considered to be the preferred embodiments, it is understood that the invention is not limited to the disclosed embodiments. The present invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
   Adverting to the drawings,  FIG. 1  is a front view of lower jaw  15  and upper jaw  18 , each supporting implants  11  of the present invention. Implants  11  are inserted into the bone material of lower jaw  15  and/or upper jaw  18  in gap  16  between teeth  17 . Implants may also be inserted in gaps  16  which are not flanked by teeth  17 . Gap  16  may be of varying size providing there is sufficient space to contain a preformed crown  21  (not shown in  FIG. 1 . 
     FIG. 2  is a top view of teeth  17  of lower jaw  15 . Implant  11  is found in gap  16  among teeth  17 . It should be understood that implant  11  may be located between any teeth of either upper jaw  18  (not seen in  FIG. 2 ) or lower jaw  15 . In addition, placement of implant  11  is not restricted to a gap  16  created by a single missing tooth  17 . Implants  11  may be placed any area where one or more teeth are missing.  FIGS. 3   a ,  3   b , and  3   c  are side views of several embodiments of implant  11 . Implant  11  is a shaft ranging in diameter from 1.6 to 2.5 mm. A more preferred diameter is 1.8–2.2 mm depending on the density of the bone material that will support implant  11 . Threaded section  13  extends from tip  19  to carrier section  20 . Tip  19  has a point sufficient to enable implant  11  to be self-tapping when it is inserted into lower jawbone  15  or upper jawbone  18 . Carrier section  20  is configured in such a way as to allow instruments such as suitably sized wrenches, ratchets, or similar tools to grab and turn implant  11  in order to screw implant  11  into bone material. Abutment end  12  is at the opposite end of implant  11  from tip  19 . Abutment end  12  is configured to be inserted into crown  21  (not shown in  FIGS. 3   a–c .) Abutment end  12  may have any shape including a spherical abutment end  12   a  as seen in  FIG. 3   a , a square or rectangular solid abutment end  12   b  as seen in  FIG. 3   b , or a polygonal tapered end, such as a pyramidal shaped abutment end  12   c , one side of which is seen in  FIG. 3   c . Other embodiments of abutment end  12  can include a cone configuration and multisided (polygonal) configurations. Any shape of abutment end  12  should be such as to enable insertion into receiving tube  24  of crown  21  as seen below. 
     FIGS. 4   a–d  depict various views of crown  21 . Upper portion  22  of crown  21  may be fabricated from any material used in the manufacture of tooth prostheses. Preferably, suitable resins, porcelain, or a porcelain fused to metal (PFM) combination, all of which are well known to persons of ordinary skill in the art, may be used for forming the upper portion  22 . Methods of fabrication of upper portion  22  of crown  21  are well known to those of ordinary skill in the art. Joining portion  23  is located at that part of crown  21  that will contact implant  11  and the gum line (base) of space  16 . Joining portion  23  also comprises cavity  24  bored or drilled into upper portion  22  of crown  21 . In a preferred embodiment, cavity  24  is a tube with a closed end. Tube  24  is sized to be larger than abutment end  12  so that it may contain not only abutment end  12  but also dental cement  26  that securely holds implant  11  to crown  21 . Although dual cured cements are preferred, other dental cements known to those having ordinary skill in the art maybe used.  FIGS. 4   a  and  4   b  depict a side view and cross section view, respectively of a molar crown  21 . Tube  24  of joining portion  23  must be of sufficient length to provide secure support to crown  21  after implant  11  is attached to crown  21 . Preferably, tube  24  of joining portion  23  extends to about half of the length of crown  21  as measured from joining portion  23  to top  25  of crown  21 . It can be seen that in a preferred embodiment, molar shaped crowns  21 , as seen in  FIGS. 5   a  and  5   b  have two or more tubes  24 , while crowns  21  shaped as incisors, bicuspids, and/or cuspids may have one tube  24 . 
     FIGS. 5   a  through  5   d  depict crown  21  joined to implant  11  to form the combination prosthesis of the present invention that is fitted into lower jawbone  15  and or upper jawbone  18 . Tube  24  is filled with dental cement  26 . Implant  11  is then inserted into tube  24  such that abutment end  12  contacts or almost contacts the closed end of tube  24 . Excess dental cement  26  is removed.  FIG. 5   a  depicts as shadow implants  11  inserted into tubes  24  of molar crown  21 . As mentioned above, molar crown  21 , because of the greater surface area of joining portion  23  relatively to nonmolar crowns  21 , preferably comprises at least two tubes  24  to receive two implants  11  to ensure molar crown  21  is securely attached to bone material.  FIG. 5   b  depicts the circled area of  FIG. 5   a  showing in greater detail the joining of abutment end  12  with crown  21 . Abutment end  12  reaches to the closed end of tube  24  and is surrounded by dental cement  26  which was previously placed into tube  24 . In a preferred embodiment, threaded section  13  of implant  11  is embedded entirely below the gum line after being threaded into the bone material.  FIG. 5   c  depicts a nonmolar crown  21 , such as an incisor, bicuspid, or cuspid, joined to implant  11 . In the preferred embodiment shown, one implant  11  is combined with nonmolar crown  21  to form the combination prosthesis of the present invention.  FIG. 5   d  depicts the circled area of  FIG. 5   c  showing in greater detail the joining of abutment end  12  with crown  21 . Abutment end  12  reaches to the closed end of tube  24  and is surrounded by dental cement  26  which was previously placed into tube  24 . In a preferred embodiment, threaded section  13  of implant  11  is embedded entirely below the gum line after being threaded into the bone material. To correctly position the dental prosthesis of the present invention on a patient&#39;s jaw, an impression is made of the area that will receive the prosthesis. The impression should be of the type to include not only the receiving area but also the region opposite the receiving area. By “opposite” is meant the region directly located above or below the receiving area on the opposite jaw bone. Typical impressions can be a triple tray impression or full arch impressions with full bite registration. Such impressions are well known to those skilled in the art. 
     FIGS. 6 and 6   a  depict a model created from an impression(s) made of both the target area, gap  16 , in lower jaw  15  and the region on upper jaw  18  directly opposing gap  16 . The fabrication of such models are well known to those skilled in the art. The opposing region is used as an aid to determine the alignment of the prosthesis in relation to the gum line of jaw  15  and proper bite occlusion. 
     FIG. 7  is a top view of gap  16  of lower jaw  15 . To determine the position  27  of single implant  11 , the center of the dental ridge  26  is located on model  25 . A single implant  11  is placed on the center of dental ridge  37  equidistant between the mesial (front) side, labeled M, and distal (back) side, labeled D, of gap  16 . 
     FIG. 7   a  depicts the positions  27  of gap  16  in which two implants  11  are located. As mentioned above, in a preferred embodiment, at least two implants  11  are used to hold a molar crown  21 . Again, the position of the centerline  28  of dental ridge  37  is ascertained. Gap  16  is divided into thirds along the mesial-distal axis to enable implants  11  to be placed equidistant from the mesial and distal ends of gap  16  as well as equidistant from each other. A preferred method of determining the implant position is to divide gap  16  into three equal sized sections using cross-lines  36  and then placing implants  11  at the point  27  where cross lines  36  intersect the center line  28  of dental ridge  26 . 
   The angle of the tapping hole for implant  11  is found by determining that angle which will maintain an equal quantity of bone material on both the buccal (B) and lingual side (L) of the implant hole  29 . Using this method, implant(s)  11  are positioned so as to absorb equal amounts of pressure and wear from all sides of gap  16 . 
   As seen in  FIG. 8 , implant orifices or hole(s)  29  are drilled or bored into model  25  and implant analog(s)  11   a  are placed into hole(s)  29 . Implant analogs  11   a  have abutment ends  12  and carrier sections  20  similar in size to actual implants, but they may lack threaded section  13  as there is no need to tap into model  25 . As seen in  FIG. 9 , stint  30  is then placed over gap  16  so as to rest on teeth  17  on either side of gap  16 . Stint  30  is made from any suitable thermoplastic material capable of vacuum forming over model  25 . The vacuum process acts to mold stint  30  into the shape of the implant receiving area comprising gap  16 , implant analog(s)  11   a , and surrounding teeth  17 . In a preferred embodiment of the stint forming procedure, cylinders  31  are placed around implant analogs  11   a  and into hole(s)  29  so that the cylindrical wall of cylinder(s)  31  surrounds the shaft of implant analog(s)  11   a  with abutment end  12  of implant analog  11   a  remaining uncovered. With cylinder(s)  31  in place, the vacuum forming process incorporates cylinder(s)  31  into molded stint  30  creating guide hole(s)  32  as part of molded stint  30 .  FIG. 10  is a top perspective view of stint  30  with incorporated guide hole(s)  32  which is molded to the shape of the area of a patient&#39;s jaw where implant(s)  11  are to be placed. 
   To insert implant(s)  11  into lower jaw  15  or upper jaw  18 , molded stint  30  is placed over gap  16  where implant(s)  11  are to be inserted. As a result of the vacuum forming process described above, the configuration of molded stint  30  enables it to fit or overlay snugly on adjacent teeth  17  on the mesial and distal sides of gap  16  as well as on the surface of gap  16 . Again, as a result of the vacuum forming process, guide hole(s)  32  are positioned within gap  16  at the predetermined location(s) analogous to the positions of implant analog(s)  11   a  in model  25 . Moreover, in the preferred embodiment, the incorporation of cylinder(s)  31  into stint  30  orients guide hole(s)  32  into the desired angle for inserting implant(s)  11  into the bone material. 
     FIG. 11  is a side view of lower jaw  15  depicting the preparation for inserting implant  11  into bone material below the gum line of gap  16 . After using a local anesthetic to desensitize the area, drill  33  with drill bit  34  is used to prepare a starter hole by positioning drill bit  34  through guide hole(s)  32  and drilling through the gum and about 4–8 mm into the underlying bone. By drilling through guide hole(s)  32 , the operator and patient are assured that the starter hole is placed at the desired location and is drilled at the desired angle to ensure, as much as possible, that the starter is surrounded by bone material of equal mass on the buccal and lingual sides and on the mesial and distal sides respectively. Drill bit  34  has a smaller diameter than that of implants(s)  11 . After preparing the starter holes, implant(s)  11  are threaded or screwed into the starter holes until carrier section  20  contacts the gum line of gap  16 . Wrenches, ratchets and similar tools may be used to screw implant(s)  11  into the bone material.  FIG. 12  depicts a side view of implant  11  after insertion into gap  16  in lower jaw  15 . 
     FIG. 13  depicts the view from  FIG. 12  in which Crown  21  is placed on implant  11  after the attachment of implant  11  into lower jaw  15 . As described above, tube  24  of crown  21  is filed with dental cement  26  and placed onto abutment end  12  of implant  11 . Preferably, abutment end  12  is of such a size that it holds crown  21  in place without dental cement  26 . However, in a more preferred embodiment, dental cement  26  is used to ensure a more durable fixed attachment. Preferably, the entire procedure from drilling the starter hole into a patient&#39;s gum tissue to fixedly attaching crown  21  onto implant  11  may be performed in one continuous process without the need for additional visits or months-long waiting periods before performing the next step in the installation procedure. Moreover, patient discomfort is reduced and a patient may eat normal food within hours after the completion of the operation. 
     FIG. 14  is a bottom perspective showing crowns  21  fabricated from resin or porcelain fused metal. Clearly demonstrated are joining portion  23  and tube  24  extending from joining portion  23 . 
   Thus it is seen that the objects of the invention are efficiently obtained, although changes and modifications to the invention should be readily apparent to those having ordinary skill in the art, which changes would not depart from the spirit and scope of the invention as claimed.