Endodontic file combining active and passive cutting edges
View Patent ↗An endodontic reamer/file for cleaning/shaping a tooth root canal having an elongated shank with a proximal end portion, a distal end and a tapered working portion having a longitudinal axis, the external surface of the shank working portion being defined by a plurality of at least two equally spaced apart continuous concaved helical flutes providing concave flute surfaces, the flute surfaces having therebetween an equal number of spiraled, spaced apart flanges, each flange having in a plane perpendicular the longitudinal axis a single outer end surface having opposed first and second ends, each first end forming an active spiraled leading scraping/cutting edge and each second end forming a passive spiraled edge.
1. An endodontic instrument comprising:
an elongated shank having a proximal end portion, a distal end portion and a tapered working portion having a longitudinal axis extending from said proximal end portion to said distal end portion; and
a plurality of transverse sections along said tapered working portion including a first, a second, and a third traverse section;
said first transverse section being located toward said proximal end portion, said second transverse section being located between said first and third transverse sections, said third transverse section being located toward said distal end portion;
each of said first, second, and third transverse sections including at least two semi-circular concave flute surfaces and an equal number of spiraled, spaced-apart flange surfaces, each said flute surface being defined by a radius R, each said flange surface of said first and second transverse sections being defined by an angle relative to a radius of said elongated shank drawn through said longitudinal axis;
said radius R of each said first, second, and third transverse sections being a different radius R and forming a central core portion of said elongated shank having a greater cross-sectional area at said first transverse section than at said third transverse section, said angle of each said first and second transverse sections being a different angle;
each said flange surface of said first transverse and said second transverse section having a first edge and a second edge, said first edge being an active cutting edge when the instrument is rotated in one direction and a passive cutting edge when the instrument is rotated in an opposite direction, said second edge having no cutting characteristic regardless of the direction of rotation of the instrument; and
said third transverse section being landed and providing a passive cutting edge.
2. An endodontic instrument according to claim 1 further comprising said radius R of said first, second and third transverse sections and said angle of said first and second transverse sections selected to provide a desired torsional strength at each said transverse section.
3. An endodontic instrument according to claim 1 wherein said angle of said first transverse section is less than said angle of said second transverse section.