Abstract:
An insert for an ultrasonic dental unit is provided. The insert includes a transducer for generating ultrasonic vibrations, and a tip for applying the ultrasonic vibrations at a location inside the mouth of a patient. A connecting body is disposed between and attached to the transducer and the tip. The connecting body transmits the ultrasonic vibrations from the transducer to the tip. A retaining ring is snapped onto the connecting body. A hand grip is fitted at least partially over the connecting body and the retaining ring.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the priority to and the benefit of U.S. Provisional Patent Application No. 60/432,653 entitled “Ultrasonic Swivel Insert” filed Dec. 12, 2002 and U.S. Provisional Patent Application No. 60/524,904 entitled “Ultrasonic Inserts for Dental Hygiene Tools” filed Nov. 26, 2003, the entire contents of both of which are incorporated herein by reference. 
   This application contains subject matter related to the subject matter disclosed in a commonly owned U.S. patent application Ser. No. 10/735,050 entitled “Ultrasonic Dental Handpiece Having a Rotatable Head,” filed Dec. 12, 2003, the entire content of which is incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention is related to ultrasonic dental tools, and particularly to an ultrasonic dental insert having a snap-on retaining ring and a hand grip. 
   BACKGROUND 
   Dental practitioners use ultrasonic dental tools (instruments) for dental treatments and procedures, such as scaling, periodontal treatments, root canal therapy, and the like. The ultrasonic dental tools typically include a handpiece coupled at one end (i.e., a proximal end) to an electrical energy and fluid source via a cable. The cable includes a hose to provide fluid (e.g., water) and conductors to provide electrical energy. 
   The other end (i.e., a distal end) of the handpiece has an opening intended to receive a replaceable insert with a transducer (e.g., magnetostrictive) carried on the insert. The transducer extends from a proximal end of the insert into a hollow interior of the handpiece. An ultrasonically vibrated tip extends from a distal end of the insert. 
   The insert typically includes a metal shaft, which is partially enveloped by a hand grip made of resin. The hand grip usually comes in two halves, which must be joined together with the metal shaft in between. Such use of two-piece hand grips results in a cumbersome and lengthy assembly process. Therefore, it is desirable to provide an insert and a corresponding manufacturing process that do not require such two-piece hand grip assembly. 
   SUMMARY 
   In an exemplary embodiment of the present invention, an ultrasonic dental insert includes a transducer for generating ultrasonic vibrations, and a tip for applying the ultrasonic vibrations at a location inside the mouth of a patient. A connecting body is disposed between and attached to the transducer and the tip. The connecting body transmits ultrasonic vibrations from the transducer to the tip. A retaining ring is snapped onto the connecting body. A hand grip is fitted at least partially over the connecting body and the retaining ring. 
   In another exemplary embodiment of the present invention, a method of assembling an ultrasonic dental insert is provided. The ultrasonic dental insert includes a tip attached to a connecting body, a transducer attached to the connecting body, a retaining ring and a hand grip. The method includes: snapping the retaining ring onto the connecting body; and fitting the hand grip to the retaining ring and the connecting body by sliding it at least partially over the connecting body and the retaining ring. 
   In yet another exemplary embodiment of the present invention, an ultrasonic dental unit is provided. The ultrasonic dental unit includes an insert and a handpiece. The insert includes a transducer for generating ultrasonic vibrations, and a tip for applying ultrasonic vibrations at a location inside the mouth of a patient. A connecting body is disposed between and attached to the transducer and the tip. The connecting body transmits ultrasonic vibrations from the transducer to the tip. A retaining ring is snapped onto the connecting body. A hand grip is fitted at least partially over the connecting body and the retaining ring. The handpiece receives the insert, and includes a coil assembly for energizing the transducer, and a body for housing the coil assembly and receiving the insert. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects of the invention may be understood by reference to the following detailed description, taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  illustrates an ultrasonic dental unit (or system) including an ultrasonic dental tool attached to an electrical energy &amp; fluid source; 
       FIG. 2  is a perspective view of an ultrasonic dental insert in an exemplary embodiment of the present invention, which can be used with the ultrasonic dental unit of  FIG. 1 ; 
       FIG. 3  is a side view of the ultrasonic dental insert of  FIG. 2 ; 
       FIG. 4  is an enlarged cross-sectional view of the ultrasonic dental insert of  FIG. 3  taken along the line A—A; 
       FIG. 5  is a top view of the ultrasonic dental insert of  FIG. 2 , which has been rotated approximately 90 degrees from the side view depicted in  FIG. 3 ; 
       FIG. 6  is an enlarged cross-sectional view of the ultrasonic dental insert of  FIG. 5  taken along the line B—B; 
       FIG. 7  is an exploded perspective view of the ultrasonic dental insert of  FIG. 2 ; and 
       FIG. 8  is a side view of an ultrasonic dental handpiece that can be used with the ultrasonic dental insert of  FIG. 2 . 
   

   DETAILED DESCRIPTION 
   In exemplary embodiments of the present invention, an ultrasonic dental insert includes a retaining ring, which snaps onto a connecting body (e.g., a shaft) attached to an ultrasonic transducer. The retaining ring may be made of metal such as stainless steel, or it may be made of a suitable synthetic polymeric material, such as that commonly referred to as “plastic.” Once snapped onto the connecting body, the retaining ring does not rotate. A hand grip, with an undercut on its inside, is fitted over the retaining ring and is locked into place. Such use of the retaining ring and the hand grip (e.g., a one-piece hand grip) permits assembly of the insert in less time and with less effort in comparison to using a two-piece hand grip. 
     FIG. 1  illustrates an ultrasonic dental unit including an ultrasonic dental tool  10  attached to an electrical energy &amp; fluid source  14  via a cable  12 . The cable  12  includes a conduit for carrying fluid as well as wires for carrying electrical signals from the electrical energy &amp; fluid source  14  to the ultrasonic dental tool  10 . The ultrasonic dental tool  10  includes a handpiece  200  and an insert  100  received within the handpiece  200 . 
     FIGS. 2 and 3  illustrate an ultrasonic dental insert  100  in an exemplary embodiment of the present invention.  FIG. 5  is a top view of the dental insert  100 , which has been rotated approximately 90 degrees from the side view depicted in  FIG. 3 . The dental insert  100  includes a tip  102  at its distal end and an ultrasonic transducer  108  at its proximal end. The tip  102  is coupled to the transducer  108  via a connecting body  103 , which may take a form of a shaft. The connecting body is made of material suitable for transmitting ultrasonic vibrations, such as stainless steel, as it is used to deliver ultrasonic vibrations generated by the transducer  108  to the tip  102 . The transducer  108 , for example, may be attached to the connecting body  103  by soldering, welding, laser welding and/or any other suitable method. For example, the joint between the connecting body  103  and the transducer  108  may be a braze joint formed using a braze compound, which includes cadmium free silver solder and high temperature brazing flux. 
   The connecting body  103  has mounted thereon an annular retaining ring  111 , which may also be made of metal such as stainless steel. The retaining ring  111  also has a connecting portion  113 , which defines a generally cylindrical cavity formed therein for receiving a corresponding portion of the connecting body  103  in a force fit relationship. The retaining ring is fixedly attached (e.g., snapped on as described below in reference to  FIGS. 4 ,  6  and  7 ) to the connecting body  103  such that it neither rotates nor moves laterally along the axis of the connecting body. 
   The ultrasonic dental insert  100  also includes a hand grip  104 , which may be made of high temperature resin. For example, the hand grip  104  may be fabricated using ULTEM®, which is an amorphous thermoplastic polyetherimide available from GE Plastics. The hand grip  104  has a generally cylindrical shape, and is fitted over the retaining ring  111  and locked in place, such that the retaining ring  111  and the connecting body  103  are secured to the hand grip  104 . The hand grip  104  is removably coupled to the connecting body  103  and the retaining ring  111 , such that the hand grip can be separated from them. 
   Along its outer surface, the hand grip  104  has a contour and a slightly concave area  107 , enabling it to be easily grasped by a dental practitioner. The hand grip  104  also has formed thereon a plurality of bumps  105  on its external surface to further facilitate grasping of the device by a dental practitioner. The hand grip  104  also has formed thereon (i.e., defines) a passageway  110  at its distal end near the tip  102  for delivering fluid (e.g., water) to the gum or tooth of the patient. 
   The retaining ring  111  has an opening  112  formed thereon for receiving fluid from the handpiece  200 . The fluid may exit through the passageway  110  of the hand grip  104 . In other embodiments, the insert  100  may have an opening at the end of its tip  102 , a groove formed on the tip, or an external tube for enabling the fluid to exit the insert. 
   The transducer  108 , for example, may be formed from a stack of thin nickel plates (e.g., 16 laminated nickel alloy strips, which are 90% nickel manganese (NiMn)) that are arranged in parallel. The nickel plates may be joined together at both ends at a braze joint using, for example, a braze compound including cadmium free silver solder and high temperature brazing flux. The insert  100  is a magnetostrictive type wherein the nickel plates  108  can convert the electrical energy into ultrasonic vibrations when, for example, coils in the handpiece are energized using the electrical signals from the cable. The insert  100  has an O-ring  106  mounted thereon for engaging and pressing against the inner surface of the handpiece  200  such as to form a water tight seal. For handpieces having a rotatable rotator head, the O-ring  106  may engage the rotator head such that the ultrasonic dental insert rotates together with the rotator head. 
   During operation, the stack of thin nickel plates  108  vibrate at a frequency equal to the stack&#39;s natural frequency with excitation induced by coils. After placing the insert in the handpiece and the electrical energy source is powered on, the operator manually tunes the frequency of the electrical energy source until it reaches the resonance frequency, i.e., the natural frequency of the insert. Alternatively, auto-tune units may automatically lock on the insert resonance frequency once powered on. At this time, the stack begins vibrating. This vibration of the stack is amplified and transmitted to the tip  102  through the connecting body  103 . Ultrasonic inserts used in the United States are typically designed to vibrate at 25 kHz or 30 kHz frequencies. 
   Referring now to  FIGS. 4 ,  6  and  7 , the connecting body  103  has formed thereon a circular groove  118  near its distal end. An O-ring  116  is seated in the groove  118 . When the hand grip  104  is fitted onto the connecting member  103 , the O-ring  116  provides a seal between the connecting member  103  and the hand grip  104  so as to prevent undesired fluid leakage. 
   The retaining ring  111  has a generally cylindrical shape, and has formed thereon a connecting portion  113  fitting over a corresponding cylindrical portion of the connecting body  103 . The opening  112  for receiving fluid from the handpiece is formed on the side of the connecting portion  113 . The retaining ring  111  has formed thereon, adjacent to the connecting portion  113 , a circular groove  120  for seating the external O-ring  106 . 
   At the distal end, the retaining ring  111  has formed thereon a pair of gripping elements  132  that face each other. Each gripping element has an end portion that protrudes inwardly toward the end portion of the other gripping element. The connecting body  103  has a pair of indentations  130  formed thereon for receiving the protruding end portions of the gripping elements such that the gripping elements  132  are snapped into the indentations  130 . Thus engaged, the retaining ring  111  of the illustrated embodiment is locked to the connecting body  103 , and neither rotates nor moves laterally with respect to the same. 
   The hand grip  104  on its inner surface may have formed thereon an inward protrusion  133  for guiding the hand grip  104  to fit over the retaining ring  111 . The protrusion  133 , for example, engages a gap between the gripping elements  132  so that the hand grip  104  is not rotatable with respect to the connecting body  103 , once the hand grip  104  is fitted over the connecting body  103 . 
   The retaining ring  111  also has formed thereon circular flanges  121 ,  124  and a circular groove  122 . The circular groove  122  is for seating the O-ring  114 . The hand grip  104  has an undercut  126  formed therein for fitting over the distal end of the retaining ring  111 , and engaging the flange  121 . The undercut, for example, is circular in shape. 
   The hand grip  104  has also formed thereon a depressed region  128  below the undercut on its inner surface, which is used to engage the flange  124  and further prevent the retaining ring  111  from moving into the hand grip  104 . The depressed region  128 , for example, is also circular in shape, wherein the depressed region  128  has a radius larger than that of the undercut  126 . The undercut  126  and the depressed region  128  fit tightly with the flanges  121  and  124 , respectively. 
     FIG. 8  illustrates a side view of a handpiece  200  that can receive the insert  100  as seen, for example, in  FIG. 1 . The handpiece  200  includes a body  202 , a rotator head  204  and an interconnect  206 . The rotator head  204  located at a distal end of the handpiece  200  is rotatably coupled to the rest of the handpiece  200 . When the insert  100  is installed in the handpiece  200 , the O-ring  106  is pressure fitted with an inner surface of the rotator head  204 , such that the insert  100  rotates together with the rotator head  204 . 
   The interconnect  206  located at a proximal end of the handpiece  200  is coupled to a cable (e.g., the cable  12  of  FIG. 1 ) for providing electrical signals as well as fluid (e.g., water) to the handpiece  200 . The interconnect  206  has a strain reliever  207  formed thereon to relieve strain between the interconnect  206  and the cable. 
   Since the body  202  is fixedly coupled to the interconnect  206 , which in turn is fixedly attached to the cable, the handpiece  200  cannot be rotated easily. Therefore, by allowing the rotator head  204  to rotate with respect to the rest of the handpiece  200 , the dental practitioner need not repeatedly re-orient the entire dental tool to treat different teeth and/or different areas of a tooth. Further, since the rotator head  204  of the handpiece  200  can be rotated rather easily with respect to the body  202 , the dental practitioner need not take the insert out of the patient&#39;s mouth and rotate the insert using both hands to re-orient the tip of the insert at a desired angular position. Therefore, time associated with re-orienting the tip a number of times during the dental treatment is reduced, and the flow of work is not interrupted as much, thereby resulting in a smooth work flow and reduction of time. 
   The rotator head  204  has a generally cylindrical shape, a hollow interior, and an opening at each end of the interior, which is used to receive the distal end of the body  202  at one end and a dental insert at the other end. For example, at its distal end, the rotator head  204  has formed thereon an opening  211  for receiving the ultrasonic dental insert  100 . 
   The rotator head  204  has formed around its outer peripheral surface a plurality of indentations  210 . Each indentation  210  has an elongated elliptical (or rectangular) shape with its major axis in the direction parallel to the central axis of the handpiece  200 . The indentations  210  facilitate grasping of the rotator head  204  by a dental practitioner to rotate, for example, it with respect to the body  202  (e.g., using only one hand). In other embodiments, the rotator head  204  may have a number of protrusions formed thereon instead of the indentations. 
   The body  202  has formed thereon a pair of grooves  203  that are equidistant from the top and traverse substantially the whole length of the body  202 . The grooves  203  are used to mount a hand grip  212  on the handpiece  200 . The body  202  has also formed thereon at its bottom near the distal end of the body  202  a plurality of substantially evenly spaced slots  208  that are used to keep the hand grip  212  from moving in the direction of the axis of the handpiece  200 . The body  202  has also formed thereon at its bottom near the proximal end a groove  205  that is co-linear to the slots  208 . The groove  205  engages the hand grip  212  together with the grooves  203  to keep the hand grip  212  from rotating about the central axis of the handpiece  200 . The grooves may not be used in other embodiments. 
   The hand grip  212  has an engagement portion  214 , which has a generally cylindrical shape and a hollow interior. The engagement portion  214  is slipped onto the body  202  similar to a sleeve, and engages the body  202  such that the engagement portion envelopes a portion of the body  202 . The engagement portion has formed thereon a resilient cantilever portion  218 , which is used to engage one of the slots  208  on the body  202 . The engagement portion  214  has attached to its bottom surface a handle  216 , which is used by a dental practitioner to hold the handpiece  200  during dental procedures. The handle also facilitates rotating of the rotator head  204  using one hand. The handle  216  has formed on its back surface a plurality of indentations or protrusions  220 , which are used to facilitate grasping by a dental practitioner. 
   It will be appreciated by those of ordinary skill in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential character hereof. The present description is therefore considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.