Abstract:
An endodontic contra-angle is provided with a head which supports an endodontic instrument having a shank and a blade. A connection associated with the head attaches the shank within the head of the contra-angle. The shank is permanently assembled within the body of the head, and is free to rotate within the head.

Description:
RELATED CASE 
       [0001]    This patent application is a continuation-in-part of prior co-pending U.S. patent application Ser. No. 10/567,166, filed Feb. 3, 2006. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a handpiece or contra-angle used for endodontology. 
         [0003]    Various instruments are known which can be used either to prepare or to bore tooth canals. Such instruments can be mechanized or manual, and can equally operate in continuous rotation or in reciprocating rotation. Rotational movement of the instrument is accomplished by the contra-angle handpiece on which the instrument is positioned. 
         [0004]    Such instruments are generally provided with a shank, defined by the standard ISO 1797, for entering the head of the contra-angle. The head of the contra-angle is equipped with a mechanical device for removably attaching the instrument to the head. 
         [0005]    For known instruments, the practitioner must always remove the instrument from the shank each time an operation to be performed is changed. This, in turn, increases the risk of prick injury and, therefore, the risk of contamination of the practitioner and the patient. 
         [0006]    Furthermore, known devices for clamping the instrument onto the shank are bulky, which prevents small heads from being produced. This, in turn, restricts the visibility available to the practitioner. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with the present invention, these various disadvantages are remedied by providing an endodontic handpiece that does not require a change of the instrument for each new operation which is to be performed. 
         [0008]    To this end, an endodontic contra-angle is provided with a head for supporting an endodontic instrument, and an attachment for the connection of a shank associated with the instrument received in the head of the contra-angle. The shank of the instrument is permanently assembled to the body of the head, and is free to rotate within the head of the contra-angle. 
         [0009]    Further description of the endodontic contra-angle of the present invention is provided with reference to the detailed description which is provided below, together with the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a side elevational view of the endodontic contra-angle handpiece of the present invention. 
           [0011]      FIG. 2  is an exploded, elevational view of the contra-angle handpiece shown in  FIG. 1 , showing the shank of the instrument withdrawn from the head. 
           [0012]      FIG. 3  is a cross-sectional view of the contra-angle handpiece shown in  FIG. 1 . 
           [0013]      FIGS. 4 and 5  are alternative embodiment, plan views of the contra-angle handpiece, showing different configurations for the shank-engaging connection. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0014]    Referring to  FIG. 1 , the endodontic contra-angle handpiece  1  includes a head  2  which receives an instrument  3  for preparing, or boring, a canal. The instrument  3  can be any of a variety of instruments used for such purposes, responsive to the requirements of the practitioner. 
         [0015]    Referring to  FIGS. 2 and 3 , the instrument  3  has a shank  4  which includes a rotational drive  5 , and a blade  6 . The shank  4  of the instrument  3  cooperates with the head  2  of the contra-angle handpiece  1  for supporting the instrument  3  in the head  2 , and includes a smooth surface portion  7  for cooperating with an opening  8  formed in the head  2  to promote rotation of the instrument  3 , and a pivot  9  for cooperating with an axle  10  projecting from upper portions of the head  2  to promote rotation of the instrument  3  and to ensure a proper axial thrust of the instrument  3  in the upper portions of the head. The rotational drive  5  of the shank  4  of the instrument  3  cooperates with the output drive  11  of a drive shaft  12  which extends longitudinally through the contra-angle handpiece  1  to provide rotational movement for operating the instrument  3 . A pinion preferably serves as the rotational drive  5 . 
         [0016]    The head  2  of the contra-angle handpiece  1  has a base  13  which is provided with a connection  14  for assembly of the shank  4  of the instrument  3  within the head  2  of the contra-angle handpiece  1 . The connection  14  cooperates with the shank  4  of the instrument  3  to provide desired rotation of the instrument  3  and to permanently assemble the shank  4  of the instrument  3  and the head  2  of the contra-angle handpiece  1 . 
         [0017]    The contra-angle handpiece  1  is intended for only a single use, and is disposable. The contra-angle handpiece  1  is, therefore, preferably made entirely of a plastic material so that the overall cost of the contra-angle handpiece  1  is limited. The shank  4  of the instrument  3  is preferably made of a material that can be injection molded, such as a plastic, and the blade  6  that constitutes the working part of the instrument  3  is preferably made of steel, to further limit the overall costs associated with a contra-angle handpiece  1  which is intended for only one use. The blade  6  of the instrument  3  is advantageously overmolded by the shank  4  for fixing the blade  6  directly to the shank  4 . 
         [0018]    The connection  14  is axially aligned with the shank  4  of the instrument  3  and the pivot  9  which engages the axle  10  of the head  2  so that the shank  4  of the instrument  3  is free to rotate within the head  2  of the contra-angle handpiece  1 , while permanently fixing the shank  4  of the instrument  3  to the head  2  of the contra-angle handpiece  1 . The connection  14  forms a collar for engaging the shank  4  adjacent to the smooth surface portion  7 , and for retaining the shank  4  within the head  2 . In  FIG. 4 , the connection  14  is substantially rhombic-shaped, and in  FIG. 5 , the connection  14  is substantially oval-shaped. 
         [0019]    A pair of fingers  15  projecting from the connection  14  preferably cooperate with a flange  16  formed on the shank  4 , adjacent to the smooth surface portion  7 , to assist in engagement between the shank  4  and the connection  14 . In  FIG. 4 , the fingers  15  are positioned on opposing sides of the short diagonal of the rhombic-shaped opening, and in  FIG. 5 , the fingers  14  are positioned on opposing sides of the short axis of the oval-shaped opening. 
         [0020]    The contra-angle handpiece  1  of the present invention exhibits an economic advantage in that the instrument  3  and the contra-angle  1  are made in such a way that the resulting assembly can be used only once. As a result, use of the contra-angle handpiece  1  will prevent contamination because the assembly is made disposable, eliminating the need for the practitioner to handle the instrument  3 . 
         [0021]    It will therefore be understood that various changes in the details, materials and arrangement of parts which have been herein described and illustrated in order to explain the nature of this invention may be made by those skilled in the art within the principle and scope of the invention as expressed in the following claims.