Abstract:
A dental instrument comprising a handpiece with a threaded extension and a working tool for attachment to the extension includes a wrench mounted on the distal end of the handpiece for use in attaching the tool to the extension. The wrench comprises a nose piece mounted on the front end of the handpiece, said nose piece rotateable radially about the front end of the handpiece as well as longitudinally slidable forward of the distal end of the handpiece so that an opening in a front end of the nose piece extends over the hub of the tool. Rotating the extended nose piece radially around the front end of the handpiece causes the hub of the tool to rotate, attaching the tool to the threaded extension. The nose piece is then retracted to a storage position during use of the tool.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to the attachment of a tool to a handpiece using a tightening tool moveably mounted on the operative end of the handpiece and more particularly to dental tools, particularly ultrasonic dental tools or instruments, and, more particularly, to a moveable structure on the forward end of an ultrasonic instrument handpiece for use in attaching an ultrasonic tip to the ultrasonic handpiece. 
   Ultrasonic devices and their tips are useful in carrying out a variety of dental procedures, such as tooth cleaning, preparation of cavities for filling and are particularly useful in preparing the canal of a tooth during root canal and endodontic procedures. Such ultrasonic dental tips are known, as shown in numerous patents of which U.S. Pat. Nos. 5,094,617, 5,133,661, 5,868,570, 6,722,882 and 6,811,399 and International Publication No. WO 00/74586 are examples. Most prior patents are directed to particular tip shapes to provide better visibility of the tooth and canal, improved maneuverability of the tip into the canal, operative end structure on the tip to provide smoother surfaces of the pulp chamber and prevent ditching, controlling depth of the tip so that the floor of the tooth canal is not penetrated, providing tips for removing, or not removing, different tissue (enamel, dentin, pulp stones) or tips of different materials, having different coatings or operating at specific frequencies for specific procedures such as cutting apically into calcified canals and for digging around posts that may have become embedded in the canal. 
   However, little attention has been provided to tools and procedures for easily and rapidly installing the tip on the handpiece or removing the tip for replacement with alternative functioning, or different size tips. The tips are typically threaded on to the handpiece requiring the dentist to use a separate wrench to grasp flat portions on the hub of the ultrasonic tip to remove the tip. U.S. Pat. Nos. 5,261,922, 5,318,570, 5,324,297 and 6,817,862 are representative of ultrasonic devices which have removable tips that have wrench flats formed on the hub of the tip for grasping with a separate wrench. Another mounting technique is shown in U.S. Pat. No. 5,776,155 which describes a prior art separate tightening tool applied to the tip hub and discloses a torquing device built into an adapter which remains over the tip hub and functions to retain the tip on the handpiece. U.S. Pat. No. 5,359,996 shows a tip with an end flange which is held against the transducer by a retaining nut slipped over the ultrasonic tip. This nut functions to hold the ultrasonic tip in place, does not function as a wrench and requires a separate wrench to apply and tighten the nut. 
   U.S. Pat. No. 4,038,571 to Hellenkamp shows an ultrasonic tool with a tip removeably threaded thereto. The tip base has exterior flats on its circumference. A rotatable cap on the front end of the tool has a hole in its front end to engage the flats on the tip when the tip base is inserted into the cap. When rotated, the cap functions to loosen or tighten the tip. During use as an ultrasonic cleaning tool the cap opening remains over the tip base which can result in biological materials becoming trapped within the cap. 
   My earlier issued patent U.S. Pat. No. 6,722,882, and  FIGS. 1 ,  2  and  3  herein show an example of an ultrasonic dental handpiece and ultrasonic tips for placement thereon. 
   SUMMARY OF THE INVENTION 
   Ultrasonic tips with novel shape at their proximal ends and a tip tightening and loosening tool which interacts with that shape eliminates the need for a separate wrench to attach an ultrasonic tip to the handpiece is provided as a permanent component of the front end of the ultrasonic handpiece. The tool has a forward end with an opening therein sized to receive and act on a like-shaped structure integral with the proximal surface of the hub of the ultrasonic tip such that rotation of the tool around the longitudinal axis of the handpiece will cause the hub of the tip to be threaded onto or into the like-threaded forward end of the ultrasonic transducer. Once the tip is attached, the tool is retracted and it resides on the forward end of the handpiece out of contact with the ultrasonic tip. To use the tool it is moved axially over the attachment end of the tip and rotated in the proper direction to attach or remove the tip, as desired. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partial cross sectional side view of a prior art ultrasonic dental handpiece. 
       FIGS. 2 and 3  are side views of prior art ultrasonic tips having a hub for threadable connection to a transducer enclosed within the handpiece. 
       FIG. 4  is an expanded perspective side view of the ultrasonic tip, nose piece and front end of the handpiece. 
       FIG. 5  is a perspective side view of the ultrasonic tip secured to the handpiece with the nose piece retracted for use of the assembled device. 
       FIG. 6  is a side view of an ultrasonic handpiece incorporating features of the invention, with ultrasonic tip attached, the assembled device being shown in its operative mode. 
       FIG. 7  is a side view of the ultrasonic handpiece and ultrasonic tip of  FIG. 4  with the nose piece moved to a forward position for attachment or removal of the tip. 
       FIG. 8  is an end view of the ultrasonic tip, tip hub and attachment tool on the ultrasonic handpiece. 
       FIG. 9  is a longitudinal cut away view of the front portion of the ultrasonic handpiece with attached ultrasonic tip of  FIG. 4  in its assembled configuration. 
       FIG. 10  is a longitudinal cut away view of the front portion of the ultrasonic handpiece and ultrasonic tip of  FIG. 4  during the attachment of the tip to the threaded stud. 
       FIG. 11  is an enlarged side view of the nose piece which, when mounted on the handpiece, is used to place or remove the threaded tip on the ultrasound transducer. 
       FIG. 12  is longitudinal cross sectional view of the nose piece of  FIG. 9 . 
       FIG. 13  is an enlarged front view of the nose piece of  FIG. 9 . 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1  shows a typical prior art dental ultrasound handpiece  100 . The handpiece  100  has a body  102  which is grasped by a clinician to perform a dental procedure. An ultrasonic transducer  104 , typically comprising a stack of piezoelectric wafers  106  which vibrate upon being energized by oscillating electrical power supplied by a remotely located power supply (not shown) connected to the handpiece  100  by a cable (not shown). However, alternative power delivery means can be provided, such as a rechargeable or disposable battery pack. The piezoelectric wafers  106  are secured between a front retainer  108  and a back retainer  110 . The front retainer  108 , as shown in  FIG. 1 , has a threaded stud  112  extending longitudinally from the handpiece to receive an ultrasonic tip  114  which has a matching internally threaded socket (not shown). Alternative designs include a front retainer  108  with a threaded socket to receive an ultrasonic tip with an externally threaded stem.  FIGS. 2 and 3  show typical prior art ultrasonic tips  114  which thread on to the threaded stud  112  shown in  FIG. 1 . Other alternative designs for connecting the ultrasonic tip to the handpiece are discussed above. 
   These tips are preferably constructed of a medical grade stainless steel, such as 13Cr-8Mo or 17-4PH stainless steel. However, they can alternatively be constructed of other medical grade materials such as titanium alloy, for example CP GR 4 or 5, or 6A14V. The working surface of the tip can also include a suitable micro-abrasive coating bound to the surface thereof, such as diamond particles, Zirconium oxide, or other common abrasive materials having a grit size generally ranging from about 160 and about 260. One skilled in the art will recognize that the grit size of the abrasive coating may vary widely, depending on the preference of the clinician and the procedure to be performed. 
   When power is supplied to the handpiece  100  the piezoelectric wafers  106  are caused to vibrate at ultrasonic frequencies which in turn causes the threaded stud to vibrate at ultrasonic frequencies, generally in the axial direction. This in turn imparts ultrasonic vibrations into the hub of the tip  14 ,  114  threaded on, or otherwise operatively coupled to, the handpiece. This causes the working end of the tip to resonate at its natural frequency generally in the plane of the tip. The amplitude of the vibration of the working tip will vary depending on the geometry of the tip and the power supplied by the handpiece  100 . 
   Referring to  FIGS. 4-10 , a device incorporating features of the present invention is shown. The handpiece  10  is constructed, and functions in the manner demonstrated by prior art devices of which  FIG. 1  is an example. Added to this handpiece  10  is a moveable nosepiece  12  which is provided for use in easily attaching an ultrasonic tip  14  onto the threaded stud  112 . As best shown in  FIGS. 8 ,  12  and  13  the nose piece  12  has a central opening  16  in the forward end thereof. This central opening  16  has a periphery designed to interact with the hub  18  on the ultrasonic tip  14 . The nose piece  12  functions as a wrench to grasp a similar shaped hub  18  on the ultrasonic tip  14 .  FIGS. 4 and 5  show an embodiment of a device incorporating features of the invention in an expanded and assembled view, respectively, with  FIG. 5  showing the nose piece  12  in its retracted position and the dental handpiece with attached ultrasonic tip ready for use. In the embodiment shown in  FIGS. 4 ,  5 ,  8 ,  12  and  13  the periphery of the opening  16  in the nose piece  12  is a six sided polygon designed to mate with a like sized hexagonal shape on the exterior hub  18  of the ultrasonic tip  14 . However, one skilled in the art will recognize that various different peripheries can be used including, but not limited to, ovals, other polygons or a serrated or grooved circular openings. 
   In a preferred embodiment the tip  14  utilized with the present invention has a threaded recess within the hub  18  accessible through its proximal end to receive the external threads on stud  112  for securing the tip to the handpiece. This threaded connection which provides a connection between the stud  112  and the tip, instrument or tool  14  attached to the handpiece effectively transmits vibrations from the transducer to the tool  14 . While the hub  18  is shown to threadably engage to the stud  112  it will be understood that the tip hub  18  can have external threads which thread into a threaded recess in the stud  112  or, within the broader aspects of this invention, any connection which efficiently transmits ultrasonic energy from the handpiece to the attached instrument. For example, in place of a threaded connection a variety of mechanical interlocking arrangements may be used such as are typically to chuck a tool to a drive mechanism. 
     FIG. 11  is a side view and  FIG. 13  is a front end view of a preferred embodiment of the nosepiece  12 . This nose piece is moveably mounted over the front end  11  of the handpiece  10 . The nose piece  12  can be readily grasped between the fingers of the device user and easily rotated in the direction of the arrow shown in  FIG. 8 , around a central axis extending through the front end  11  of the handpiece  10  and the central opening  16 . In addition, the nose piece  12  can be moved a fixed distance longitudinally from a rearward, rest position, as shown in  FIGS. 4 ,  6  and  9 , where there is no contact between the nose piece and the tip hub  18 , to a forward, tip tightening position as shown in  FIGS. 7 and 10 , where the hub  18  on the tip  12  rests within the opening  16  in nose piece  12 . As shown in the sectional view taken along the longitudinal axis of the nose piece,  FIG. 12 , the nose piece  12  comprises a hollow shell which has an inner longitudinal, cylindrical opening throughout its length with an internal diameter  20  which is slightly larger than the external diameter of the front end  11  of the handpiece  10  over which it extends. In the embodiment shown, a portion of the inner surface of the nose piece  12  also has a second, larger diameter  22  portion which provides a sliding zone  24 . The front end  11  of the handpiece  10  has a radial circular groove  26  therein to receive a locking ring  28 . The locking ring  28  has an outer diameter substantially the same as the second larger diameter  22  portion of the sliding zone  24 . The locking ring  28  is preferably a flexible O-ring which also allows the nose piece to slide back and forth and to rotate thereover without obstruction or interfering friction. However, because the diameter of the sliding zone  24  is greater then the first diameter  20  and the locking ring protrudes into this sliding zone  24  the forward and rearward movement of the nose piece is restricted to the width of the sliding zone  24 . In a preferred embodiment the width of the sliding zone  24  is from about 0.15 to 0.25 inches, preferably about 0.18±0.01 inches and the depth  30  of the opening  16 , which is the portion of the nose piece that interacts with the hub  16  of the tip  14 , is about 0.085 inches. However, greater movement longitudinally of the nosepiece, which is provided by widening the sliding zone, and a greater depth  30  of the opening  16  may be provided so that a longer length of the opening  16  in the nose piece can be provided to increase the area of contact with the outer surface of the hub  18 . 
   To aid the operator in manipulating the nose piece  12 , the outer surface thereof has longitudinally extending raised portions or bulges  32  spaced around its periphery to provide gripping features for rotating the nose piece  12  around the handpiece front end  11 . However, numerous alternative structures including, but not limited to, grooves, dimples, a roughened surface, indentations, etc can be used to provide such a gripping surface. Also, raised radial structures  33  or indentations can be included to provide a gripping structure to aid in moving the nose piece longitudinally from its rest position to the forward, tip application position. 
   In a first procedure to use the nose piece  12  as a wrench for application of an ultrasonic tip  14  or other tool to the handpiece, the nosepiece  12  is advanced to its forward-most position. The hub  18  of a tip or tool is placed against the end of the threaded stud  112  and the tip is rotated, causing the threads on the stud  112  and in the hub  18  to mesh. This action causes the hub to become threaded onto the stub, as shown in  FIG. 9 . When the tip  14  is seated on the threaded stud  112  the noise piece is slid longitudinally forward in the direction of the arrow in  FIG. 10  to its active position as shown in  FIG. 10  and it is used as a tightening wrench to firmly engage the tip  14  to stud  112  after which the nose piece  12  is slid back longitudinally in the direction of the arrow in  FIG. 9 . To remove the tip  14  the above procedure is reversed. 
   While the above procedure includes manually returning the nosepiece  12  to its rest position it is also contemplated that a spring mechanism (not shown) can be included so that once the user of the device releases the noise piece it automatically returns to its rest position. This also would prevent the nosepiece  12  from inadvertently sliding forward over the hub during use of the tool in a dental procedure. 
   As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. Also, the term “ultrasonic” generally refers to the use of piezoelectric transducers which vibrate at a frequency above the threshold of human hearing, typically above 20,000 Hz. However, those skilled in the art will recognize that vibrating handpieces suitable for dental or other medical procedures may use transducers other than piezoelectric transducers and these devices may vibrate at lower or higher frequencies and as the invention described herein may be utilized on devices that operate at lower frequencies are also meant to be included within the term “ultrasonic” even if such frequencies are substantially below 20,000 Hz. and substantially above 40,000 Hz., or frequencies therebetween. One such ultrasonic power supply and handpiece that has been successfully used with the instruments of the present invention is commercially available from Spartan Marketing Group, 1663 Fenton Business Park Court, Fenton, Mo. 63026. It is also contemplated that other electrical or mechanical means can be used to create vibration in the tip. It is further contemplated that the tip or tool attachment construction described herein may be used to easily attach a broad variety of operative tools to a handle and the invention described herein is not necessarily limited to the attachment of an ultrasonic tip to an ultrasound delivering handpiece or to the specific shapes or configurations of the interactive pieces.