The present invention provides a system for the endodontictreatment of a root canal, comprising (i) an endodontic instrument；(ii) an endodontic handpiece having a drive motor for rotatingthe endodontic instrument releasably attached to the handpiece；(iii) a control unit for controlling the rotation of the endodonticinstrument according to one or more predetermined rotationalsequences； the rotational sequences comprising reciprocatingthe endodontic instrument by continuously sequentially rotating theendodontic instrument in a first direction followed by reversing thedirection of rotation so that 0.5x.PSI.<；=.alpha.<；.PSI. and3<；=.alpha../beta.<；=20, wherein arepresents a rotational angle in a direction in which the rotating endodonticinstrument removes debris from the root canal, .beta. representsa rotational angle in the opposite direction, and .PSI. representsthe elastic angle of the endodontic instrument at which plastic deformationoccurs in the direction of .alpha..
