This study assesses the comparative effectiveness of three types of dental floss and toothbrushing in reducing interproximal bleeding sites, measured by stimulation with wooden interdental cleaners using the interdental bleeding index assessment method. The 119 adult subjects with gingival inflammation were randomly assigned to one of four groups at the beginning of a supervised 2 week clinical trial. The toothbrushing only group achieved a 35% reduction in bleeding sites and the three flossing groups all demonstrated dramatic reductions of about 67%. The three varieties of dental flosses were about equally effective in reducing interproximal bleeding and doubly effective as toothbrushing alone. Compared to probing, the interdental bleeding index method is considered a simplified method of assessing interproximal gingival inflammation.