Abstract:
A dental tool for guiding a drill bit during a dental implant procedure includes a drill bushing that is pivotally attached to a stent, wherein the drill bushing has a generally spherical surface that directly engages the stent.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The subject invention generally pertains to dental implants and more specifically to a tool for installing them.  
         [0003]     2. Description of Related Art  
         [0004]     Various dental implant methods and devices have been developed for replacing one or more missing teeth in a person&#39;s jaw with prosthetic teeth. For many prosthetic teeth, a final product comprises three basic components: an implant, an abutment, and a crown. The crown is the exposed portion of the prosthesis that resembles one or more teeth. The implant is an anchor that becomes attached to the jawbone, and the abutment couples the crown to the implant.  
         [0005]     To install the implant, a hole is usually drilled into the patient&#39;s jawbone, and the implant is inserted into the hole.  
         [0006]     A drill bushing attached to a stent can be used to help guide the drill bit, as disclosed in PCT Publication WO 99/26540 and U.S. Pat. Nos. 5,015,183; 5,133,660; 5,718,579. A drill bushing, unfortunately, can be difficult to attach to a stent, particularly if the drill bushing is to be pivotal relative to the stent as is the case in the U.S. Pat. No. 5,718,579 patent.  
         [0007]     Thus, a need exists for a pivotal drill bushing that includes a feature for allowing the bushing to be readily attached to a stent.  
       SUMMARY OF THE INVENTION  
       [0008]     To attach a pivotal drill bushing to a surgical dental stent, it is an object of some embodiments of the invention to provide the bushing with a generally spherical surface that directly engages the stent.  
         [0009]     Another object of some embodiments is to eliminate the need for a transitional piece between the bushing and the stent.  
         [0010]     Another object of some embodiments is to create a ball-and-socket joint between a drill bushing and a stent.  
         [0011]     Another object of some embodiments is to provide the ball-and-socket joint with an interference fit that prevents the drill bushing from pivoting too freely.  
         [0012]     Another object of some embodiments to provide a drill bushing with pivotal freedom by press-fitting a spherical surface of the bushing into a cylindrical hole in a stent.  
         [0013]     One or more of these and other objects of the invention are provided by a dental tool that includes a drill bushing pivotally attached to a stent, wherein the bushing has a generally spherical surface that directly engages the stent. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0014]      FIG. 1  is a perspective view showing stent being formed over a model jaw.  
         [0015]      FIG. 2  is a perspective view showing the stent being removed from the model jaw.  
         [0016]      FIG. 3  is a perspective view showing a drill bushing being inserted into a stent.  
         [0017]      FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 5 .  
         [0018]      FIG. 5  is a perspective view showing a drill bit about to be inserted into a drill busing.  
         [0019]      FIG. 6  is a cross-sectional view similar to  FIG. 4  but showing the drill bit inserted into the drill bushing.  
         [0020]      FIG. 7  is a cross-sectional view similar to  FIG. 4  but of another embodiment.  
         [0021]      FIG. 8  is a cross-sectional view similar to  FIG. 8  but showing the pivoting freedom of the drill bushing.  
         [0022]      FIG. 9  is a cross-sectional view similar to  FIG. 7  but showing an alternate drill bushing.  
         [0023]      FIG. 10  is a cross-sectional view similar to  FIG. 8  but showing the drill bushing of  FIG. 9 .  
         [0024]      FIG. 11  is a cross-sectional view similar to  FIG. 7  but showing an alternate drill bushing.  
         [0025]      FIG. 12  is a cross-sectional view similar to  FIG. 8  but showing the drill bushing of  FIG. 11 .  
         [0026]      FIG. 13  is a diagram showing how a “generally spherical surface” can curve at different radiuses about two perpendicular axes, wherein the radius of curvature about axis  64  is less than the radius of curvature about axis  66 .  
         [0027]      FIG. 14  is a perspective view of a drill bushing that has opposite facing flat surfaces. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]      FIG. 1  shows a surgical dental stent  10  being formed over a model  12  of a patient&#39;s actual upper or lower jaw  14  ( FIG. 5 ). Model  12  can be cast or otherwise made in a conventional manner well known to those skilled in the art. The term, “jaw” refers to that part of a patient&#39;s body that comprises one or more of the following: teeth, gums, and/or jawbone (upper or lower). Stent  10  is a conventional surgical dental stent that can be produced in various ways that are well known to those skilled in the art. Arrows  16  schematically represent a vacuum forming process as well as other common methods of making a stent. Stent  10  can be hollow or solid in an area  18  of the missing tooth.  
         [0029]     In some cases, a plug  20  is placed on model  12  in the area of the missing tooth to create a concavity  22  in stent  10  as stent  10  is being formed. Concavity  22  preferably has a substantially spherical concave surface  24 ; however other surface shapes are possible.  
         [0030]      FIG. 2  shows stent  10  with concavity  22  being lifted from model  12 .  
         [0031]     A hole  26 , which is in area  18  of the missing tooth, can be created in stent  10  by various methods including, but not limited to, drilling, punching, cutting, etc. This step is represented by arrow  28  of  FIG. 3 .  
         [0032]     Also shown in  FIG. 3  is a dental tool or drill bushing  30  being inserted into the concavity of stent  10 . Bushing  30  has a generally spherical surface  32  that when inserted into concavity  22  creates a ball-and-socket joint  34  between bushing  30  and stent  10 , as shown in  FIG. 4 . The term, “generally spherical,” as used herein and throughout, refers to any surface that curves about two axes that are at right angles to each other, which includes but is not limited to purely spherical surfaces. Although the radii of curvature of about each axis are preferably equivalent, that does not necessarily have to be the case. In  FIG. 13 , for example, generally spherical surface  62  curves about axes  64  and  66 , wherein axes  64  and  66  are perpendicular to each other, but they do not necessarily intersect. Referring to  FIGS. 5 and 6 , joint  34  allows bushing  30  to pivot relative to stent  10 , whereby bushing  30  can help aim and guide a drill bit  36  directly into jaw  14 . Once drill bushing  30  is aimed in the right direction, a bonding material  38  can be used to affix bushing  30  to stent  10 . In some cases, bushing  30  may comprise a plastic body  40  with a metal sleeve  42 ; however, drill bushings made entirely of plastic or entirely of metal are also well within the scope of the invention.  
         [0033]     During the period of adjusting the angular position of bushing  30  relative to stent  10 , bushing  30  can be prevented from pivoting too freely within stent  10  by providing joint  34  with an interference fit between bushing  30  and stent  10 . Such an interference fit is readily achieved by providing bushing  30  with an outside diameter  44  that is slightly larger than an outside diameter  46  of plug  20 .  
         [0034]     To ensure sufficient clearance between bushing  30  and the gum tissue of jaw  12 , a stub portion  48  of bushing  30  is preferably slightly shorter than a corresponding stub portion  50  of plug  20 .  
         [0035]     In cases where a stent  10  is generally solid in the area of the missing tooth, thereby precluding the use of plug  20 , bushing  30  can be inserted into a hole  52  drilled into stent  10 ′, as shown in  FIGS. 7 and 8 . The size of hole  52  is preferably smaller than the outside diameter  44  of bushing  30  to create an interference fit between bushing  30  and stent  10 ′, yet spherical surface  32  still allows bushing  30  to pivot within hole  52 . Once bushing  30  is pivoted to a desired orientation, bonding material  38  can affix bushing  30  to stent  10 ′.  
         [0036]     In some cases, a drill bushing  30 ′ may not have a stub portion  48  as shown in  FIGS. 9 and 10 .  
         [0037]     In  FIGS. 11 and 12 , a drill bushing  54  includes an O-ring  56  that provides an interference fit between bushing  54  and stent  10 ′. The entire drill bushing, including O-ring  56  can pivot within stent  10 ′. O-ring  56  provides a generally spherical surface in that the surface curves about axis  58  and curves around an axes  60  or annular centerline that runs through the center of the O-ring.  
         [0038]     Once bushing  30 ′ or  54  are aimed in the desired direction, the bushings can be bonded to stent  10 ′ 
         [0039]     Referring to  FIG. 14 , in cases where a missing tooth leaves a very limited space between two existing teeth, a modified drill bushing  68  (and similarly modified plug) can be used instead of bushing  30 . Bushing  68  is similar to bushing  30  except that bushing  68  has two opposite-facing flat surfaces  70  that can be positioned to face the two existing teeth. A plug for bushing  68  could be similar to plug  20  but with two flat surfaces corresponding to surfaces  70 . Due to flat surfaces  70 , bushing  30  has greater freedom within a stent to pivot in one direction  72  than in another direction  74  perpendicular thereto.  
         [0040]     Although the invention is described with reference to a preferred embodiment, it should be appreciated by those skilled in the art that various modifications are well within the scope of the invention. Therefore, the scope of the invention is to be determined by reference to the following claims.