Cordless endodontic handpiece (1) with a rotary and reciprocating operating mode for driving an endodontic instrument in an endodontic treatment, comprising:(a) an elongated housing (10) having a proximal end (11) and a distal end (12) the housing containing(a1) a controller (21)(a2) a rechargeable battery (30) provided distally adjacent to the controller (21)(a3) a power electronic device (22) provided distally adjacent to the rechargeable battery (30) and(a4) a motor (40) provided distally adjacent to and contacting the power electronic device (22)the handpiece further comprising(b) a reduction gear (50) provided distally adjacent to the motor (40)wherein- the reduction gear (50) has a reduction gear ratio of at most 12 :1,- the motor has a torque constant in the range of from 2 to 10 mNm/A and- the motor has a phase to phase resistance in the range of from 0.05 Ω to 3.0 Ω.
