A flossing device having internal floss feed in which floss is advanced from a storage chamber inside the handle of the device, through feed gears, to a pair of spaced apart tines. Spent floss is returned through the return gears, the return drive gear having a greater diameter than the feed drive gear, thus ensuring the floss remains taut between the tines. An integral cutter allows the spent floss to be cut off and discarded. One significant advantage of this device over similar designs is that a floss advance lever advances the floss by a single action when pressed upward, which creates andmaintains sufficient tension on the floss resulting in taut and snug floss between the tines. In a second embodiment, the flossing head has a vibratory device to aid in the flossing action.