An automatic dental flosser (10,11,37) includes a floss cartridge or attachment (14,15,17,19) detachably connectable to a power driver (12,13). The attachment comprises a plastic bifurcated member (16,82) supporting a dental floss span for flossing teeth. A rotatably supported floss supply spool (58) is connected to the bifurcated member for continuously replacing used floss spans with clean floss spans. A rotatably supported floss take-up spool (50,72) is connected to the bifurcated member for being driven by the driver to wind used floss drawn from the bifurcated member. Means for encapsulating the used floss and for distributing antimicrobial fluid (69) on the used floss are included to inhibit microbial activity. Means are provided to distribute used floss along a take-up spool for high-capacity used floss storage until disposal of the cartridge. In the unlikely event of a floss snag, such as on a dental appliance, a built-in floss cutter (88) can instantly detach the flosser.
