Patent Publication Number: US-2005142516-A1

Title: Dental handpiece and kit including same

Description:
RELATED APPLICATION  
      This application claims priority from Israel Patent Application No. 159,652 filed Dec. 30, 2003, which is still pending.  
     FIELD AND BACKGROUND OF THE INVENTION  
      The present invention relates to dental handpieces, and also to kits including such dental handpieces. The invention is particularly useful with respect to the dental handpiece described in Israel Patent 107202 of Oct. 6, 1993, and corresponding U.S. Pat. No. 5,549,474 of Aug. 27, 1996 and U.S. Pat. No. 5,810,588 of Sep. 22, 1998, the invention is therefore described below, for purposes of example only, with respect to such dental handpieces.  
      The above-cited Israel and U.S. Patents describe a dental handpiece comprising a housing including a hand-gripping section at one end, and a tool-clamping section at the opposite end. The tool-clamping section includes a sleeve for receiving a shaft of a dental tool, such as a drill or bur, and a collet for clamping the shaft of the dental tool within the sleeve. The dental handpiece further includes a button carried by the housing and depressible to cause the collet to release the shaft of the dental tool in order to permit convenient removable and replacement of the dental tool. The dental handpiece described therein is particularly useful for one including an air turbine for driving the dental tool at extremely high speeds, in the order of 400,000 rpm.  
      It has been found that the use of dental handpieces in general, and particularly the dental handpiece described in the above-cited patents, can be easily adapted for many different dental operation if the effective length of the dental tool can be increased in a quick and convenient manner. This is particularly true when the dental handpiece is used for preparing implants involving drilling holes of different depths into the patient&#39;s bone for receiving the implant.  
     OBJECTS AND BRIEF SUMMARY OF THE PRESENT INVENTION  
      An object of the present invention is to provide a dental handpiece which permits the effective length of the dental tooth to be increased in a convenient manner, and thereby permits more convenient use of the dental handpiece for many different dental operations. Another object of the invention is to provide a kit including a dental handpiece and a plurality of extension pieces which may be selectively used for changing the effective length of the dental tool.  
      According to one aspect of the present invention, there is provided a dental handpiece, comprising: a housing including a hand-gripping section at one end, and a tool-clamping section at the opposite end; the tool-clamping section including a sleeve for receiving a shaft of a dental tool, and a collet for clamping the shaft of the dental tool within the sleeve; characterized in that the dental handpiece further comprises an extension piece selectively receivable within the tool-clamping section for extending the effective length of the dental tool; one end of the extension piece including a shaft receiveable with the sleeve of the tool-clamping section for clamping therein by the collet; the opposite end of the extension piece being formed with a sleeve for receiving the shaft of the dental tool, and having a clamping element for clamping the shaft of the dental tool within the sleeve of the extension piece.  
      According to further features in the preferred embodiment of the invention described below, the sleeve of the extension piece is integrally formed with the shaft of the extension piece. In addition, the sleeve of the extension piece is formed with an externally threaded section, and the clamping element includes an internally threaded section receivable on the externally threaded section of the sleeve for clamping the shaft of the dental tool within the sleeve of the extension piece.  
      According to still further features in the described preferred embodiment, the sleeve of the extension piece if further formed with a radially-contractible end section at the end thereof opposite to its shaft and formed with an external conical surface; the clamping element including an inner surface of complementary conical configuration engageable with the external conical surface of the end section for radially-contracting the end section to clamp the shaft of the tool therein when the internally-threaded section of clamping element is threaded on the externally-threaded section of the sleeve of the extension piece. In addition, the end section of the extension piece formed with the external conical surface is longitudinally split to facilitate the radial contraction of the end section. In addition, the sleeve of the extension piece is further formed with an externally ribbed surface at the end thereof joined to the shaft of the extension piece to facilitate manipulating the extension piece when applying it to the tool-clamping section of the housing, while the clamping element is formed with an outer ribbed surface to facilitate its application to the extension piece for clamping the shaft of the tool within the sleeve of the extension piece.  
      The invention is particularly useful in a dental piece including an air turbine for rotating the dental tool, e.g., a drill or bur, at high speed.  
      According to a further aspect of the invention, there is provided a dental kit including a dental handpiece as described above, the dental kit further including a plurality of extension pieces of different lengths selectively receivable within the tool-clamping section of the housing for extending the effective length of the dental tool clamped therein according to the extension piece selected.  
      As will be described more particularly below, the invention permits dental handpieces, particularly (but not exclusively) those driven by air turbines, to be more conveniently used in a wide variety of dental operation, especially in drilling holes for implants. In addition, providing such extension pieces of different length saves the substantial expense that would be involved in providing the various dental tools in different lengths.  
      Further features and advantages of the invention will be apparent from the description below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:  
       FIG. 1  illustrates a prior art construction of a dental handpiece which the invention of the present application is particularly useful;  
       FIG. 2  is a side view, partly in section, illustrating an implementation of the present invention in the prior art dental handpiece of  FIG. 1 ;  
       FIG. 3  is a three-dimensional view illustrating only the extension piece and the dental tool in the handpiece of  FIG. 2 ;  
       FIG. 4  is a three-dimensional view illustrating the various elements of the extension piece and dental tool of  FIG. 3  in an exploded condition; and  
       FIGS. 5 and 6  illustrate extension pieces of different lengths that may be included in the kit for selective application to the dental tool in order to change its effective length as desired according to the particular dental operation to be performed with the dental tool. 
    
    
      It is to be understood that the foregoing drawings, and the description below, are provided primarily for purposes of facilitating understanding the conceptual aspects of the invention and various possible embodiments thereof, including what is presently considered to be a preferred embodiment. In the interest of clarity and brevity, no attempt is made to provide more details than necessary to enable one skilled in the art, using routine skill and design, to understand and practice the described invention. It is to be further understood that the embodiments described are for purposes of example only, and that the invention is capable of being embodied in other forms and applications than described herein.  
     DESCRIPTION OF A PRIOR ART DENTAL TOOL (FIG.  1 )  
      As indicated earlier, the invention of the present application is particularly (but not exclusively) useful with the dental handpiece illustrated in the above-cited patents incorporated herein by reference.  FIG. 1  illustrates the construction of such a prior art dental handpiece.  
      With reference first to  FIG. 1 , there is illustrated a dental handpiece including a housing, generally designated  2 , having a hand-gripping section  4  at one end, and a tool-holding section  6  at the opposite end for holding a dental tool  8 , such as a bur or drill. Section  6  of housing  2  is further formed with a water spray nozzle  10  for discharging a water spray onto the site being worked by the dental tool  8 . The dental handpiece illustrated in  FIG. 1  is an air turbine handpiece in which compressed air is supplied, via a conduit (not shown) at the back end of the handpiece, to an air turbine  20  within housing section  6  to rotate the dental tool  8  at a very high speed, e.g. in the order of 400,000 rpm. The rear end of the dental handpiece includes a further conduit (not shown) for introducing the water discharged in the form of a spray via nozzle  10  onto the working site of the dental tool.  
      For purposes of example, the dental tool  8  is shown as being of the bur type, including a shaft  8   a  of uniform diameter at one end, a bur  8   b  of spherical (or disc) shape at the opposite end, and a tapered juncture  8   c  between the shaft  8   a  and the bur  8   b.    
      Air turbine  20  is formed with a plurality of blades  22  impinged by compressed air flowing from its inlet conduit to its outlet conduit (not shown) in order to rotate the air turbine at a very high speed. Air turbine  20  is integrally formed with a sleeve  28  of tapered configuration. One end of sleeve  28  is open, as shown at  28   a,  for receiving the shaft  8   a  of the dental tool  8 . The inner diameter of tapered sleeve  28  decreases from its open end  28   a  to its opposite end  28   b,  which is also open.  
      Tapered sleeve  28  receives a tapered collet  30 , which is also formed with an open end  30   a  received within the open end  28   a  of the tapered sleeve  28  for receiving the shaft  8   a  of the dental tool  8 . The outer diameter of tapered collet  30  decreases from its open end  30   a  to its opposite end  30   b.  The latter end  30   b  is closed by an end wall or plug  32  formed within an enlarged head  34 .  
      Tapered collet  30  is further formed with three axial slits  36  equally-spaced around its circumference. Slits  36  start at open end  30   a  and extend only for a part of the length of the collet towards the opposite end  30   b.  Slits  36  preferably extend about two-thirds the length of the tapered collet  30 . They permit the respective section of the tapered collet to contract in order to firmly clamp therein the shaft  8   a  of the dental tool, or to expand in order to release the shaft for purposes of removing the dental tool or reinserting another dental tool in its place.  
      Two ball-bearing assemblies  40 ,  42 , are provided at the opposite ends of housing section  6  for rotatably mounting the air turbine  20 , its tapered sleeve  28 , the tapered collet  30 , and the dental tool  8  when clamped therein, with respect to the housing. Thus, each ball-bearing assembly  40 ,  42  includes: a rotary ring  40   a,    42   a;  a static ring  40   b,    42   b;  and a plurality of balls  40   c,    42   c  interposed between both rings. Housing section  6  further includes a vibration-absorbing  0 -ring  44 ,  46 , for each of the ball-bearing assemblies  40 ,  42 , received within an annular recess  44   a,    46   a,  and a spring  48  baring against a plastic ring  50  for preloading the static part of the bearing in order to reduce vibration during the high-speed rotation of the dental tool. A similar plastic ring  52  is provided at the opposite end of the housing section  6  cooperable with bearing assembly  40 .  
      The latter end of housing section  6  is closed by a collar  54  threadedly attached to the housing section and formed with a central opening  55  in which a button  56  is mounted to project through the opening. Button  56  is formed with an outwardly-projecting rim  58  around its circumference engageable by the edge of collar  54  circumscribing opening  55  receiving the button. An annular spring  60  is interposed between the housing section  6  and button  56 . Spring  60  is engageable within inner surface  56   a  of the button to urge the button outwardly, limited by the engagement of rim  58  of the button with the undersurface of collar  54 . Pressing against the outer surface  56   b  of the button brings its inner surface  56   a  into engagement with the enlarged head  34  of the tapered collet  30 , and thereby moves the tapered collet outwardly of the tapered sleeve  28 . When this occurs, slits  36  formed in the outer section of the tapered collet  30  permit that section of the tapered collet, moving outwardly of the tapered sleeve  28 , to expand and thereby to release the shaft  8   a  of the dental tool. The dental tool may then be manually grasped and removed from the tapered collet  30 .  
      To insert another dental tool  8 , button  56  is again depressed to move the tapered collet  30  outwardly of the tapered sleeve  28 , and the dental tool is pushed inwardly into the tapered collet  30  until the end of the dental tool shaft  8   a  limits against the end wall  32  of the tapered collet. At that time, button  56  is released, whereupon spring  60  moves the button  56  slightly outwardly of the housing. The user then manually pushes the dental tool shaft  8   a  further inwardly into the housing. This also moves the tapered collet  30  further into the housing, until the enlarged head  34  of the tapered collet limits against the inner surface  56   a  of the button  56 , at which time the dental tool  8  is firmly clamped in housing section  6  by the wedging action between the tapered collet  30  and the tapered sleeve  28 .  
      Further details of the construction and operation of such dental handpieces are set forth in the above-cited patents, the contents of which are incorporated herein by reference.  
     DESCRIPTION OF PREFERRED EMBODIMENTS OF THE PRESENT INVENTION  
      According to the present invention, the dental handpiece illustrated in  FIG. 1  is adapted for many different dental operations, particularly in preparing implants, by providing one or more extension pieces for changing the effective length of the dental tool in a quick and convenient manner. Preferably, a plurality of such extension pieces are provided in different lengths in the form of a kit, each being selectively receivable within the tool-clamping section of the housing for extending the effective length of the dental tool clamped therein according to the extension piece selected. Such an arrangement not only adapts the dental handpiece for more convenient use in various dental operations, but also saves the substantial expense that would be involved if the various dental tools are provided in different lengths for the various dental operations.  
       FIG. 2  illustrates an extension piece, therein generally designated  70 , constructed in accordance with the present invention so as to be receivable within the tool-clamping section  6  of the dental handpiece for extending the effective length of the dental tool  8 . Also shown in  FIG. 2  is a clamping element, generally designated  80 , for clamping the shaft  8   a  of the dental tool  8  to the extension piece  70 .  
       FIG. 3  illustrates the extension piece  70 , its clamping element  80 , and the dental tool  8  in an assembled condition; whereas  FIG. 4  illustrates the foregoing elements in an exploded condition.  
      As shown particularly in  FIG. 4 , extension piece  70  includes: a shaft  71  at one end receiveable within sleeve  30  of the tool-clamping section  6  of the dental handpiece, in lieu of shaft  8   a  of the dental tool  8 ; and a sleeve at the opposite end for receiving shaft  8   a  of the dental tool  8 . The latter sleeve includes a finger-piece section  72  adjacent the shaft  71 ; an externally threaded section  73  for receiving the clamping element  80 ; and a radially-contractible end section  74 , at the opposite end of extension piece  70  from its shaft  71 , for engaging the outer surface of shaft  8   a  of the dental tool  8  and for clamping the dental tool within the extension piece  70 .  
      Shaft  71  of extension piece  70  is of the appropriate diameter and length corresponding to shaft  8   a  of the dental tool  8  so as to be receivable within sleeve  30  of the tool-clamping section  6  of the dental handpiece in lieu of shaft  8   a  of the dental tool  8 . Sleeve  72  is integrally formed with shaft  71  of the extension piece  70 . Its finger-piece section is further formed with an externally ribbed surface, as shown at  72   a,  to facilitate manipulating the extension piece when applying it to the tool-clamping section  6  of the housing.  
      The radially-contractible end section  74  is split at its end by a plurality of longitudinally-extending slots  74   a,  each terminating in a circular opening  74   b  to increase the radial contractibility of the end section. The outer portion of end section  74  is formed with an outer conical surface  74   c  cooperable with a complementary conical surface within clamping element  80 , to securely engage the dental tool shaft  8   a,  and to clamp it within the sleeve  70 , when the clamping element  80  is applied to that end of the sleeve.  
      As shown particularly in  FIG. 2 , clamping element  80  is internally threaded at one end as shown at  81 , for engagement with the external threads  73  of extension piece  70 . The opposite end of clamping element  80  is formed with an internal conical surface, as shown at  82 , for engagement with the external conical surface  74   c  of extension piece  70  when the clamping element is threaded onto the outer threaded surface  73  of the extension piece, in order to contract the end section  74  into firm engagement with the dental tool shaft  8   a.  As shown in  FIGS. 3 and 4 , the outer surface of clamping element  80  is also formed with an outer ribbed surface  83  to facilitate application to the extension piece  70  for clamping the shaft  8   a  of the dental tool  8  within sleeve  72  of the extension piece.  
      The manner of using the extension piece  70  and clamping element  80  for changing the effective length of the dental tool  8  will be apparent from the above description.  
      Assume the dental tool  8  is clamped within the tool-clamping section  6  of the dental handpiece, and it is desired to change the effective length of the dental tool in order to enable it to be used for drilling a relatively deep hole in an implant operation. This may be done in the following manner:  
      First, button  56  is depressed to release shaft  8   a  of the dental tool  8  from collet  30  of the sleeve  28  within the tool-clamping section  6  of the dental handpiece, in the manner described above. With the button  56  depressed, shaft  71  of the extension piece  70  is inserted into the collet  30  of the tool-clamping section  6  of the dental handpiece, in the manner described above with respect to dental shaft  8   a.  The button is then released, thereby firmly clamping the extension piece  70  within the tool-clamping section  6  of the dental handpiece. The dental tool shaft  8   a  is then received within sleeve  72  of the extension piece  70  and moved to the end of the sleeve, as shown in  FIG. 2 . The clamping element  80  is then applied with its internally-threaded end  81  threaded over the externally-threaded section  73  of sleeve  72 . This causes the internal conical surface  82  of the clamping element  80  to engage the external conical surface  74   c  of the end section  74  of the extension piece sleeve  72 , to firmly clamp the dental tool shaft  8   a  within sleeve  72 .  
      As indicated earlier, the invention is preferably included in a dental tool kit which includes a plurality of extension pieces  70  of different lengths to thereby enable the user to change the effective length of the dental tool by selecting the appropriate extension piece.  FIGS. 5 and 6  illustrate two such extension pieces which may be included in such a kit together with extension piece  70  described above with respect to  FIGS. 2-4 . To change the effective length of the respective extension piece, only the length of the ribbed section  72  of the extension piece is changed. Thus, in the extension piece illustrated in  FIG. 5 , the ribbed section of the sleeve  72  is of substantially shorter length, as shown at  72 ′, than in  FIG. 4 ; whereas in the extension piece illustrated in  FIG. 6 , the ribbed section, shown at  72 ″, is of longer length than in  FIG. 5  but shorter than in  FIG. 4 .  
      It will be appreciated that the dental kit could be supplied with a smaller number or a larger number of extension pieces of different lengths to thereby enable the effective length of the dental tool to be varied as desired according to the particular dental operation to be performed with the dental handpiece.  
      While the invention has been described with respect to one preferred embodiment, it will be appreciated that this is set forth merely for purposes of example, and that many other variations, modifications and applications of the invention may be made.