Oral B HummingBird 15 Flosser Refills Clinically proven to improve gum health. How to use: Insert so that flosser firmly clicks into place on the handle. When flossing upper teeth, place forefinger on button with thumb supporting underside of flosser. When flossing lower teeth, rotate device so that thumb is on button with forrefinger supporting topside of flosser. Slide floss between teeth and under the gumline, using an up-and-down motion to remove plague and debris. Pull off and discard when finished.