| 摘要 |
PROBLEM TO BE SOLVED: To shape the root canal wall through rotary operation, to remove foreign matters inside the root canal and to accurately shape as far as the root tip. SOLUTION: The main body A is formed which consists of a shaft 1 and an operating part 2 having a tip end diameter D preset continuously to the shaft 1; a spiral blade part 2a is formed on a prescribed length from the shaft 1 side of the operating part 2; and a non-spiral part 2b is formed, which consists of a flat surface and a cylindrical surface, between the end of the tip end side of the spiral blade part 2a and the tip end of the operating part 2. On the non-spiral part 2b, an edge is formed which is parallel to the axial center and which generates no driving force at the time of rotation, on both sides in the axial direction of the flat surface. The shaft 1 of the main body A is joined integrally to a shank B and structured so as to be held by a hand piece. The spiral blade part 2a is formed by abutting a grinding stone on a wire rod and moving the wire rod in the axial direction while rotating it, while the non-spiral part 2b is formed by stopping the rotation of the wire rod and moving it in the axial direction. |
