A toothbrush has a frame, a bristle holder movably mounted to a distal end of the frame, and a power transmission assembly operatively connectable to a drive motor and operatively connected to the bristle holder so as to move bristle tips on the bristle holder along an oval path relative to the frame. In a single cycle of movement along the oval path, the bristles shift away from the frame and towards the teeth, then along and in contact with the teeth in a direction away from the gum line, then back towards the frame and away from the teeth, and subsequently along the frame and out of contact with the teeth.