A custom-designed oral appliance for simultaneously flossing all the user's teeth. Consists of a custom-fitted polymer mouthpiece containing two corresponding holes located at the gum line between adjacent teeth, where one hole is located on the lingual side and one hole is located on the buccal side of the apparatus. Typical floss is then threaded through the appliance such that it matches the individual user's tooth pattern. New floss can be dispensed through the appliance and spent floss collected by means of a floss distribution system. A further embodiment provides a cross flossing pattern to maximize floss contact with the inter-proximal surfaces of adjacent teeth.