| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for improving the flexibility of dental files substantially and also increasing the resistance force for separation in the twisted direction or longitudinal direction. <P>SOLUTION: The dental file includes an elongated shaft having a proximal end 12, distal end 14, and tapered shape action part. The outer surface of the action part of the shaft is fixed by a plurality of, at least two, continuing spiral grooves 20 which form a central core part of the action part of the shaft and are positioned at equal intervals. Equal numbers of spiral flanges 22 are provided spaced apart from each other between the grooves, and the each flange 22 has a partially round surface having a front end edge and a rear end edge. The end edges are each in the surface along the longitudinal axis of the shaft 16 or parallel with the surface, and the front end edge and the rear end edge each form the cutting/scraping end edge. <P>COPYRIGHT: (C)2007,JPO&INPIT |
