When a cartridge containing light-curing material is used with interposition of an adaptor, it may be, for example, provided that the piston rod performs approximately 3 to 20 strokes, preferably 5 to 12 strokes, and especially 8 to 9 strokes, for emptying the cartridge so that the stroke of the piston rod, for each complete travel stroke of the actuating element and an assumed filling length of t