Abstract: An individualizable flossing mouthpiece for simultaneously flossing a plurality of spaces between adjacent pairs of a person's teeth is a channel shaped member with an outer wall portion, and inner wall portion having free edges and a gap therebetween. The mouthpiece can receive a set of teeth in the gap. The wall portions have outer and inner series of closely spaced slots to receive dental floss therein. The distance between adjacent ones of the slots is less than the average tooth width, and dental floss can be impositively trapped in selected ones of the slots. The material of the channel shaped member is such that it can receive and permanently retain markings identifying certain ones of the slots in the outer wall portion. The mouthpiece can be individualized by placing the same in the person's mouth with the person's teeth in the gap and identifying those slots (less than all) in the outer wall portion corresponding to the edges of the person's teeth.