Abstract:
A retention system connects a dental instrument to a dental component and maintains contact between them during installation of the latter in the oral cavity. The instrument includes a shaft having a shaped driver bit at one end. The dental component includes a head configured to be engaged by the driver bit, a shank that extending outwardly away from the head and a plurality of threads thereon. In a first embodiment, the system includes a clip that is frictionally engaged with the shaft of the instrument and snap fitted to the head of the dental component. In a second embodiment, the system includes a vacuum source operationally connected to a passageway in the dental instrument. A vacuum is generated at the driver bit tip which retains the dental component on the instrument.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    This invention generally relates to dental instruments. More particularly, the invention relates to an instrument used for installing dental components relating to artificial teeth. Specifically, the invention relates to a screw retainer for maintaining contact between threaded prostheses and the dental instruments used to install the same. 
         [0003]    2. Background Information 
         [0004]    The advent of implant prosthodontics has brought about a paradigm shift in the way dentists secure artificial teeth in the oral cavity. In the early 1980&#39;s much of the fixed-detachable bridgework for full arch dental rehabilitation and restoration was attached by means of some type of retaining screw. Depending on the implant system used, the screws were torqued by hand to effect the clamping force necessary for retaining the implant in the jaw bone. Therefore, one of the early prosthetic complications was screw loosening that was caused by lack of initial pre-load of the screw, as well as poor fit and heavy bite forces. 
         [0005]    As the industry moved forward in the early 1990&#39;s, single tooth and partially endentulous applications became commonplace. Torque wrenches were introduced with or without torque controllers. Screw loosening was significantly reduced by utilizing torque values anywhere from 15-35 Ncm and changing the screw composition from gold to alloyed materials. Two retention philosophies grew out of the new protocol, firstly, screw-retained fixed implant prostheses that may involve one or more abutment and retention screws and, secondly, cement-retained prostheses that usually have an abutment screw under one or more cemented crowns. 
         [0006]    There are many competing implant systems currently available on the market for installing the retention and abutment screws and each system has its own unique features. There are different size implant bolts, abutment screws, thread orientations and screw-head driving types. Each manufacturer tends to produce their own types of screwdrivers and torque wrenches for installing and tightening their own particular components. The wrenches and screwdrivers generally cannot be used for universal installation of these components. One of the more popular torque wrench systems on the market today is manufactured by Dentsply International, based out of York, Pennsylvania. Dentsply International manufactures, amongst other products, both a torque screwdriver hub and a ratchet driver for loading dental components. 
         [0007]    The steps to install and torque a retainer screw are typically as follows: 
         [0008]    A cylindrical hole is drilled into the alveolar ridge of the patient and an implant bolt is inserted into that cylindrical hole. The implant bolt typically includes an external thread that allows it to bite into and grip the surrounding bone. The implant bolts generally also include an internally threaded bore that is adapted to receive a male portion of a prosthesis, i.e., an artificial tooth or a post for an artificial tooth. Once the implant bolt is installed in the jaw bone, it is covered and a period of time is allowed to pass so that the implant undergoes osseointegration, i.e., bone tissue infiltrates and surrounds the implant bolt to securely embed the same within the jaw bone. After this has occurred, the prosthesis is installed. This is accomplished as follows:
       1. A screw is placed on the end of a small manual screwdriver. The prosthesis is inserted into position with respect to the implant bolt. The screw is placed into a hole on the prosthesis and the dentist tries to hold the screw and prosthesis on the implant bolt with one finger and with the other hand tries to line up and begin to engage the threads on the screw.   2. Once the screw is started and there is no danger of dropping the screw and prosthesis, the dentist will use a speed wrench to turn the screw. A speed wrench is a 90° screwdriver with a rotary knob on its outer end that allows the dentist to turn the screw the required number of turns until it seats.   3. Once the screw has been seated with the speed wrench, the dentist will change his tool and will use a torque wrench to engage and properly tighten the screw according to the manufacturer&#39;s specifications.       
 
         [0012]    One of the main problems that dentists encounter in installing retaining screws is the limited access that the dentist has to various areas of the mouth, such as the rear molar region. The screws involved are typically around % inch long and the installation must be started by hand with a tiny hand-held screwdriver which is about  4  inches long. The dentist is always concerned that the screw will disengage from the dental instrument before the threads are adequately secured into the jaw bone or implant bore and that the patient will accidentally ingest the components being installed. It is therefore commonplace for the dentist to put a cloth in the back of the patient&#39;s mouth in order to try and catch and retrieve any accidentally dislodged components. It has been noted by the present inventors that these components tend to fall out during initial thread capture approximately 20% of the time. The fall-out rate is dependent upon the manual skills and experience of the dentist. Many dentists use various tricks in an attempt to try and keep the screws on the dental instrument during initial installation. Such tricks have included the use of wax and other sticky materials to retain the screws on the driver bit of the dental instrument. There has been speculation that these materials can, however, compromise the torque settings. 
         [0013]    There is therefore a need in the art for a retainer system that maintains contact between the driver bit of a dental instrument and the dental component being installed thereby. 
       SUMMARY OF THE INVENTION 
       [0014]    The retention system of the present invention selectively attaches a dental instrument to a dental component and serves to maintain contact between the instrument and component during installation of the latter in the oral cavity of a patient. The dental instrument includes a shaft that has a shaped driver bit at one end. The dental component includes a head that is configured to be engaged by the driver bit. A shank extends outwardly away from the head of the dental component and has a plurality of threads formed on at least a portion thereof. In a first embodiment of the invention, the retention system comprises a clip that is frictionally engaged around the shaft of the dental instrument and is snap fitted to the head of the dental component. In a second embodiment of the invention, the retention system comprises a vacuum source that is operationally connected to a passageway formed in the dental instrument and generates a vacuum at the tip of the driver bit. The retention system thereby retains the dental component to the dental instrument by suction. When the vacuum source is deactivated, the suction ceases and the dental component is released from the instrument. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The preferred embodiments of the invention, illustrative of the best mode in which applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
           [0016]      FIG. 1  is an exploded side view of a dental instrument and a first embodiment of a retention system, namely a retention clip, in accordance with the present invention; 
           [0017]      FIG. 2  is a side view of the dental instrument and dental component connected together by the retention clip of the present invention; 
           [0018]      FIG. 3  is a cross-sectional side view of  FIG. 2 ; 
           [0019]      FIG. 4  is a top view of the dental instrument of  FIG. 1 ; 
           [0020]      FIG. 5  is an exploded side view of a dental instrument and a second embodiment of a retention clip in accordance with the present invention; 
           [0021]      FIG. 6  is a side view of the dental instrument and dental component connected together by the retention clip of  FIG. 5 ; 
           [0022]      FIG. 7  is a cross-sectional side view of  FIG. 6 ; 
           [0023]      FIG. 8  is a perspective view of a dental instrument including a second embodiment of a dental component retention system in accordance with the present invention; 
           [0024]      FIG. 9  is a side view of the dental instrument and dental component shown in  FIG. 8 ; 
           [0025]      FIG. 10  is a top view of the dental instrument of  FIG. 8 ; 
           [0026]      FIG. 11  is a cross-sectional side view of the dental instrument through line A-A of  FIG. 10 ; 
           [0027]      FIG. 12  is a perspective view of a dental instrument in accordance with the present invention and showing a finger retainer for holding the device; 
           [0028]      FIG. 13  is an exploded perspective view of the dental instrument as shown in  FIG. 12 ; 
           [0029]      FIG. 14  is a cross-sectional front view of the dental instrument and dental component; and 
           [0030]      FIG. 15  is a cross-sectional side view through line B-B of  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    Referring to  FIGS. 1-4 , there is shown a dental instrument, being a screwdriver  10 , that includes a body  12 , an elongated shaft  14  and a driver bit  16 . A handle  11  is provided to aid in manipulating body  12 . Driver bit includes a tip  18  that is shaped to engage the head of a dental component. Screwdriver  10  illustrated in these figures has an integrally formed body, shaft  14  and driver bit  16 , but any suitable dental screwdriver  10  may be used in conjunction with the retainer of the present invention as described hereafter. Screwdriver  10  may form part of a torque wrench, may include a finger-rotatable barrel that causes shaft  14  and bit  16  to rotate or the rotation of body  12 , shaft  14  and bit  16  may be motor driven. The exact nature of screwdriver  10  does not form part of this application. 
         [0032]    The dental component illustrated in  FIGS. 1-4  is an implant bolt  20  that has a head  22  and a shank  24 . A portion of shank  24  includes a plurality of threads  26  that enable implant bolt  20  to bite into the jaw bone (not shown) of a patient. Implant bolt  20  also has a bore  28  for receiving a male portion of an artificial tooth or of an abutment therein. Implant bolts  20  are well known in the art and the retainer of the present invention may be used with any one of these dental components. Head  22  of implant may be therefore provided with an external hexagonal shape, internal hexagonal shape or any other shape to be engaged by a complementary sized and shaped driver bit  16 . 
         [0033]    In accordance with a specific feature of the present invention, there is provided a retainer for maintaining contact between driver bit  16  and implant bolt  20 . The retainer comprises a clip  30  made from very thin, spring stamped stainless steel. Clip  30  includes a tubular member  32  at a first end and a pair of spaced apart flexible fingers  34 ,  36  at a second end. Tubular member  32  includes an axial bore  38  ( FIG. 3 ) that is sized to frictionally engage and receive shaft  14  and driver bit  16  of screwdriver  10  therethrough. Tubular member  32  preferably is provided with an annular flange  40  that aids the dentist in gripping clip  30  and which can act as a stop to prevent clip  30  from riding too far up shaft  14 . Tubular member  32  preferably is also provided with a longitudinal slot  33  ( FIG. 1 ) therein which extends from annular flange  40  through to an end  35  thereof.  FIG. 3  shows that retainer clip  30  preferably is a unitary and integrally formed component. 
         [0034]    Flexible fingers  34 ,  36  are spaced a distance apart from each other that is very slightly less than the external diameter of head  22  of implant bolt  20 . Fingers  34 ,  36  terminate in flanges  42 ,  44  that aid the dentist in gripping clip  30 , and may also act as a stop to prevent implant bolt  20  from being driven too far into the jaw bone. Fingers  34 ,  36  flex away from each other to receive head  22  of implant bolt  20  therebetween. 
         [0035]    In use, the dentist will grasp tubular member  32  of clip  30  and force fingers  34 ,  36  over head  22  of implant bolt  20 . In some instances, fingers  34 ,  36  may also engage at least an upper portion of shank  24  of implant bolt  20 . Fingers  34 ,  36  essentially snap fit around head  22  and secure implant bolt  20  and clip  30  together. The combined clip  30  and implant bolt  20  are then engaged with screwdriver  10  by inserting tip  18  of driver bit  16  into bore  38  of clip  30  and sliding clip  30  along shaft  14  toward body  12 . Clip  30  is slid along shaft  16  until the tip  18  of driver bit  16  engages head  22  of implant bolt  20 . Screwdriver  10  and clip  30  may be slightly rotated to ensure that the shaped driver bit  16  is firmly engaged with the complementary shaped head  22  of implant bolt  20 . As may be seen from  FIG. 2 , clip  30  has a length “X” that is shorter than the combined length of shaft  14  and driver bit  16 , so that clip  30  slides up shaft  16  but does not engage the body  12  of screwdriver  10 . Consequently, clip  30  is secured to both screwdriver  10  and implant bolt  20  and prevents accidental separation thereof. Clip  30  also maintains contact between driver bit  16  and head  22  of implant bolt  20 . 
         [0036]    Implant bolt  20  is inserted into a pre-drilled hole (not shown) in the patient&#39;s jaw bone by placing the tip  46  of implant bolt  20  into the hole. Shaft  14  and therefore driver bit  16  are rotated and thereby rotate implant bolt  20  so that threads  26  on shank  24  bite into the patient&#39;s jaw bone. When threads are sufficiently engaged with the jaw bone that implant bolt  20  will not slip out of the hole, then the dentist can remove clip  30 . This is accomplished by raising screwdriver  10  sufficiently to allow clip  30  to disengage from shaft  14 . At this point, clip  30  is still in engagement with implant bolt  20 . The dentist then grasps tubular member  32  and pulls upwardly to disengage fingers  34 ,  36  from head  22  of implant bolt  20 . Clip  30  can then be set aside for subsequently sterilization. At this point, the tip  18  of driver bit  16  may be engaged once again with head  22  to finish installing implant bolt  20 . 
         [0037]    A second embodiment of retainer is shown in  FIGS. 5-7 . In these figures, the dental component is an abutment screw that generally indicated at  120 . Screw  120  has a head  122  and a shank  124 , with a plurality of threads  126  being provided on at least a portion of the shank. Screw  120  further includes a bore  128  in head  122  that is configured to engage the driver bit  116  on screwdriver  110 . As with the previous screwdriver, screwdriver  110  includes a shaft  114 , a body  112  and a handle  111 . 
         [0038]    In accordance with a specific feature of the present invention, retainer clip  130  is provided to maintain contact between driver bit  116  and head  122  of screw  120  during installation. Retainer clip  130  comprises an elongated tubular member  132  having an annular flange  140  provided at a first end and a housing  170  provided at a second end thereof. An axial bore  138  extends through clip  130  and is sized to frictionally engage shaft  114  of screwdriver  110 . Flange  140  is of a greater diameter than tubular member  132  and is provided to aid the dentist in gripping clip  130  during insertion and removal and to also act as a stop. 
         [0039]    Referring to  FIG. 7 , housing  170  has a peripheral side wall  170   a  that is concentric with the outer wall  132   a  of tubular member  132 . The diameter of side wall  170   a  is greater than the diameter of outer wall  132   a . Housing  170  also has an upper annular flange  172  and a lower annular lip  174 . The distance between flange  172  and lip  174  is substantially equal to the height “Y” of head  122  of screw  120 . It will be seen from this figure that clip  130  is an integrally formed component. Clip  130  is again manufactured from very thin stainless steel.  FIGS. 5&amp;6  show that housing  170  also includes one or more axial slots  176  which extend from annular flange  172  through to lip  174 . Slots  176  provide housing  170  with sufficient flexibility to allow it to snap-fit around head  122  of screw  120 . Annular lip  174  extends slightly inwardly and consequently, when housing  170  is engaged with head  122 , lip  174  retains head  122  within housing  170  ( FIG. 7 ). 
         [0040]    Retainer clip  130  is used in the following manner. When a dentist wishes to use an abutment screw  120 , to install bridgework for instance, he grasps the screw  120  and secures the same into clip  130  by causing housing  170  to snap-fit over the head  122 . This locks screw  120  and clip  130  together. He then brings the combined clip  130  and screw  120  into engagement with screwdriver  110 . This is accomplished by inserting tip  118  of driver bit  116  into bore  138  and sliding clip  130  along shaft  114  toward body  112  of screwdriver  110 . The interior surface of tubular member  132  of clip  130  frictionally engages the exterior surface of shaft  114 . Clip  130  is slid along shaft  114  until the tip  118  of driver bit  116  is received within aperture  128  in head  122 . The clip  130  can be rotationally manipulated to correctly orient the shaped tip  118  of bit  116  and the shaped aperture  128  of screw  120 . Clip  130  therefore retains screw  120  and maintains the contact between screw  120  and driver bit  116 .  FIG. 7  shows that when fully engaged, clip  130  is shorter than the shaft  114  and driver tip  116  combined, so that clip  130  does not contact body  112 . Clip  130  substantially maintains contact between driver bit  116  and screw  120 . 
         [0041]    The dentist positions the end  146  of screw  120  in an internally threaded bore of an implant that has been previously installed in the patient&#39;s jaw bone. The screwdriver  110  is used to rotate screw  120  until a sufficient portion of threads  126  have engaged the internal threads of the implant. Clip  130  thereby substantially prevents screw  120  from dislodging from driver bit  116  during this procedure and furthermore keeps head  122  of screw  120  in contact with driver bit  116 . When a sufficient portion of threads  126  are engaged with the internal threads of the implant to prevent screw  120  from accidentally disengaging from the implant, the dentist can remove clip  130 . This is accomplished by pulling screwdriver  110  upwardly to release clip  130  from its frictional engagement with shaft  114 . This separates clip  130  from screwdriver  110 , but leaves clip  130  attached to head  122  of screw  120 . The clip  130  is then grasped and pulled upwardly to break housing  170  free of head  122 . If needed, driver bit  116  may be engaged once again with head  122  of screw  120  to complete installation. Clip  130  may be sterilized and reused. 
         [0042]    A third embodiment of a dental-component retainer is shown in  FIGS. 8-11 . In this instance, screwdriver  210  includes a body  212 , a handle  213 , a shaft  214  and a driver bit  216 . The driver bit  216  has a tip  218  ( FIG. 11 ) that is complementary shaped to engage a dental component.  FIGS. 8-11  show that the dental component is an implant  220 , but it will be understood that an abutment screw could also be retained in a similar manner without departing from the spirit of the present invention. 
         [0043]    In accordance with a specific embodiment of the present invention, screwdriver  210  has been modified by the provision of a laser-drilled passageway  280  ( FIG. 11 ) that extends through body  212 , shaft  214  and driver bit  216 . Passageway  280  terminates in an aperture in tip  218 . A cap  282  is seated on screwdriver  210  so that passageway  280  is selectively connectable to a vacuum hose  284 . Cap  282  preferably is manufactured from plastic and is snap-fitted to an upper portion of body  212 . Vacuum hose  284  is connectable at a second end  284 a to a standard vacuum source available in a dentist&#39;s office. The vacuum source is represented in these figures by the block  286 . When activated, vacuum source  286  will evacuated air from hose  284  and passageway  280  and create a vacuum at the tip  218  of driver bit  216 . Vacuum hose  284  preferably is secured to handle  213  by any suitable type of connector  288  so that hose  284  does not impede the dentist&#39;s performance. 
         [0044]    When the dentist is installing implant  220  into a hole (not shown) in the jaw bone of a patient, he will activate vacuum source  286  to create a vacuum at tip  218  of driver bit  216 . Head  222  of implant  220  is then brought into contact with tip  218  of driver bit  216 . Implant  220  may be rotated to align the shaped tip  218  with the complementary shaped head  222  of implant  220 . The vacuum created at tip  218  by vacuum source  286  will maintain the contact between implant  220  and driver bit  216  and will substantially prevent implant  220  from accidentally being dislodged from screwdriver  210 . The dentist may then position the end  246  of implant  220  in the hole (not shown) in the patient&#39;s jaw bone and will use screwdriver  210  to screw implant  220  into place. Once sufficient threads  226  on implant  220  have been engaged in the jaw bone to prevent implant  220  from being accidentally dislodged therefrom, then the dentist can switch off the vacuum source  286 . This restores atmospheric pressure at the tip  218  of driver bit  216  and the head  222  of implant  220  is no longer retained at the tip  218  of bit  216 . 
         [0045]      FIGS. 12-15  show a variation of the vacuum retainer used to maintain contact between an implant  320  and the driver bit  316  of screwdriver  310 . In this instance, cap  382  is provided with a C-shaped finger clip  390 . Finger clip  390  is sized and shaped to receive an index finger (not shown) therein. The vacuum hose  384  is connected to cap  382  and thereby to the passageway  380 . Finger clip  390  provides for an easy way for the dentist to hold and control screwdriver  310 . 
         [0046]    It will be understood that any suitable type of threaded dental component may be used in conjunction with the retainer clip or vacuum system without departing from the spirit of the present invention. 
         [0047]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
         [0048]    Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.