Abstract:
A dental syringe including a hollow piston having threads on the inner wall thereof, and an exterior threaded rod disposable within the hollow piston and upon rotation of the rod moving the piston longitudinally for dispensing dental material from the syringe.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a dental syringe 
       SUMMARY OF THE INVENTION 
       [0002]    In accordance with one aspect of the present invention there is provided a dental syringe characterized by comprising an outer body having a first end and a second outer end, the outer body containing an elongated hollow section having mounted therein a non-axially rotatable elongated piston, an axially rotatable member being mounted at the first end of the hollow section, the piston containing an axially extending elongated recess which is internally threaded and having a closed end and an opposed open end, an externally threaded rod being connected to the axially rotatable member and being threadedly engaged with the recess contained in the piston, the arrangement being such that axial rotation of the rotatable member is able to cause the piston to move into the hollow section such that dental material contained in the hollow section between the piston and the second end is dispensed from the second outlet end of the outer body. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0003]    The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0004]      FIG. 1   a  is a perspective view of a dental syringe in accordance with the present invention; 
           [0005]      FIG. 1   b  is a view similar to  FIG. 1   a  with a cap removed; 
           [0006]      FIG. 2  is a perspective view of the syringe of  FIGS. 1   a  and  1   b  in disassembled condition; 
           [0007]      FIG. 3   a  is a longitudinal sectional exploded view similar to  FIG. 2  of the dental syringe of  FIGS. 1 and 2 ; 
           [0008]      FIG. 3   b  is a longitudinal assembled sectional view of the dental syringe of  FIG. 3   a;    
           [0009]      FIG. 3   c  is a view similar to  FIG. 3   b  showing the dental syringe in activated condition. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    In  FIGS. 1   a  and  1   b  and  2  of the accompanying drawings there is shown a dental syringe  10  for dispensing dental material comprising an elongated body  12 . The elongated body  12  has a first outlet end  14  having mounted thereto a removable end cap  16  and a second end  18  having mounted thereto an axially rotatable member  20 . 
         [0011]    The elongated body  12  contains an elongated hollow section  22  best seen in  FIG. 3   a , in which is mounted a non-axially rotatable elongated piston  24 . During assembly the hollow section  22  is partially filled with dental material  26  at the outlet end  14  thereof adjacent the end cap  16 . The piston  24  is then inserted into the hollow section  22  as shown in  FIG. 3   b  abutting the dental material  26 . 
         [0012]    As can be seen in  FIG. 3   a  the piston  24  contains an axially extending recess  28  which is internally threaded. The piston  24  also has a closed end  30  and an opposed open end  32 . 
         [0013]    The apparatus  10  further comprises an externally threaded rod  34  which is connected to the rotatable member  20 . 
         [0014]    The piston  24  contains one or more external raised sections  36  (see  FIG. 2 ) which engage with an elongated internal recess  38  in the body  12  (see  FIG. 3   a ). 
         [0015]    The externally threaded rod  34  is arranged to be threadedly engaged with the internally threaded recess  28  of the piston  24 . 
         [0016]    Subsequent to insertion of the piston  24  into the body  12 , the threaded rod  34  is threadedly engaged with the piston  24 . The rod  34  is rotated by rotation of the rotatable member  20  until an inner end  39  of rotatable member  20  engages with the end  18  of the body  12 . In this position, as shown in  FIG. 3   b , the inner end  30  of the piston  24  is in engagement with the dental material  26 . Further, it can be seen that there is an annular gap  40  between the open end  32  of the piston  24  and the end  18  of the body  12 . 
         [0017]    Further, it can be seen in  FIG. 2  that the rotatable member  20  has a ring  42  mounted near the inner end  39  thereof adjacent to the outer body  12 . The ring  42  engages with the end  18  of the outer body  12  in the position shown in  FIG. 3   b  so as to retain the rotatable member  20  in position. In fact, the ring  42  is shaped to engage with an internal circumferential groove  46  within the end  18  of the outer body  12  as shown in  FIGS. 3   a  and  3   b.    
         [0018]    It can also be seen that the end  14  of the body  12  has an outlet portion  48  of reduced internal cross section compared to the remainder of the hollow section  22  of the body  12 . 
         [0019]    In use, the rotatable member  20  is axially rotated as the inner end  39  engages with the end  18  of the body  12 . 
         [0020]    Subsequently the rotatable member  20  may be rotated so as to cause the piston  24  to move further into the body  12  or to move towards the end  18  of the body  12 . This is achieved by variation of the direction of rotation of the member  20  and the threaded engagement of the rod  34  with the recess  28 . 
         [0021]    To eject the dental material from the syringe  10 , the removable end cap  16  has to be removed. Then the piston  24  is urged towards the end  14  by the above described rotation of the rod  34 . As shown in  FIG. 3   c  this causes the dental material  26  to be dispensed through the outlet  48 . The dental material  26  is in this way made available for use by a dentist. 
         [0022]    The outlet  48  could alternatively have an outlet of the same size as the hollow section  22 . The syringe  10  shown in the drawings is not circular in external shape but it could conveniently be made in a circular shape if desired. 
         [0023]    Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.