| 摘要 |
An endodontic root canal file having an inner tapered core and a plurality of cutting sections lying between the core and an outer tapered envelope, each progressively decreasing in size from the proximate end to the distal end of the file. Each cutting section of the file having an intermediate cylindrical section extending radially outwardly from the core, a frusto-conical distal section tapering inwardly from the cylindrical section to the core and a planar annular proximate end surface section extending radially inwardly from the proximate end of the intermediate cylindrical section portion to the distal end of the next proximally adjacent cutting section. A plurality of grooves extend longitudinally and radially inwardly through the distal, intermediate and proximal sections of each cutting section and define non-helical flutes which provide distally and radially inwardly inclined cutting edges that lie in planes through the axis of the file and perpendicular to the circular circumference of the file. As a result, the torsional and bending axes of the file substantially coincide with the neutral axis thereof. The annular surface sections define shoulders having radially outer peripheral cutting edges that provide additional cutting action when the file reciprocates axially and aids in the removal of root canal material when the file is withdrawn from the root canal.
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