The invention relates to a method for automatically controlling a root-canal cutting tool (4) of a root canal instrument (2), the root-canal cutting tool (4) being rotatable by a motor (6) and associated with a unit (8) for controlling the cutting torque (CP) or the torque distributed by the motor, the method including: rotating the root-canal cutting tool (4) in a first predetermined cutting direction (SI) until the torque (CP) reaches a predetermined maximum torque value, said maximum value being a function of the root-canal cutting tool (4) or of the motor (6)； and, when the maximum torque value is reached, rotating the root-canal cutting tool (4) in a second direction (S2) opposite to the first cutting direction (SI) at a first predetermined angle of rotation； and then resuming the rotation of the root-canal cutting tool (4) in the first cutting direction (SI).
