An endodontic instrument adapted to be axially reciprocated within a root canal to remove material from walls of the root canal, the endodontic instrument comprising: an elongate rod having a proximate end and an opposite distal tip end defining a working portion disposed between the proximate end and the distal tip end, the working portion including an upper region and alower region; a plurality of flutes extending helically around the working portion, each flute including a curved concave flute surface, a pair of flute shoulders (24a,24c) at the peripheral edges of the concave flute surface, a flute width defined by a distance between the pair of flute shoulders (24a,24c), and a flute depth defined by a point of maximum depth between the pair of flute shoulders (24a,24c); and a plurality of lands extending helically around the working portion, each land positioned between a pair of axially adjacent flutes and including a curved concave land surface, a pair of land shoulders (26a,26c) at the peripheral edges of the concave land surface, a land width defined by a distance between the pair of land shoulders (26a,26c), and a land depth defined by a point of maximum depth between the pair of land shoulders (26a,26c), wherein the flute shoulders (24a,24c) and the land shoulders (26a,26c) consist in the peripheral edges of said curved concave flute surfaces and curved concave land surfaces respectively, and wherein each land shoulder (26a,26c) coincides with the corresponding flute shoulder (24a,24c) to form a distinct cutting edge. wherein the land width is less than the flute width and the land depth is less than the flute depth in the upper region of the working portion. an elongate rod having a proximate end and an opposite distal tip end defining a working portion disposed between the proximate end and the distal tip end, the working portion including an upper region and alower region; a plurality of flutes extending helically around the working portion, each flute including a curved concave flute surface, a pair of flute shoulders (24a,24c) at the peripheral edges of the concave flute surface, a flute width defined by a distance between the pair of flute shoulders (24a,24c), and a flute depth defined by a point of maximum depth between the pair of flute shoulders (24a,24c); and a plurality of lands extending helically around the working portion, each land positioned between a pair of axially adjacent flutes and including a curved concave land surface, a pair of land shoulders (26a,26c) at the peripheral edges of the concave land surface, a land width defined by a distance between the pair of land shoulders (26a,26c), and a land depth defined by a point of maximum depth between the pair of land shoulders (26a,26c), wherein the flute shoulders (24a,24c) and the land shoulders (26a,26c) consist in the peripheral edges of said curved concave flute surfaces and curved concave land surfaces respectively, and wherein each land shoulder (26a,26c) coincides with the corresponding flute shoulder (24a,24c) to form a distinct cutting edge. wherein the land width is less than the flute width and the land depth is less than the flute depth in the upper region of the working portion.