Surgical handpiece and cooperating rotary tool

A surgical handpiece (100, 100′) comprising a housing (102) and a drive shaft (10, 10′) arranged therein, characterised in that a stem-engaging bore (11) is defined in the drive shaft (10, 10′), said bore being open at a distal end (10a) of the drive shaft (10, 10′) and having a common longitudinal axis (t) with the drive shaft (10, 10′), at least three first flanged bores (12) defined a wall of the drive shaft (10, 10′) along circumference thereof and perpendicular to the longitudinal axis (t), said first flanged bores opening into the stem-engaging bore (11), flanges (12a) of the first flanged bores being on an inner side of the wall of the drive shaft (10, 10′) facing the stem-engaging bore (11), a fixing ball (13) fitted in each of said first flanged bores (12), and a ball retainer (20, 20′) provided at an outer side of the wall of the drive shaft (10, 10′) and said ball retainer (20, 20′) being movable to a closed position and to an open position and arranged to force the fixing balls (13) into the first flanged bores (12) when in the closed position and to allow a partial exit of the fixing balls (13) from the first flanged bores (12) when in the open position.