Fluoride Day, observed every January 25, is celebrated primarily in the United States to highlight the importance of fluoride for dental health. The day commemorates the contributions of American dentists Frederick McKay and Henry Trendley Dean, who established the link between fluoride and reduced tooth decay, leading to the practice of water fluoridation. This public health initiative, recognized by the CDC as one of the 10 great public health achievements of the 20th century, has resulted in nearly 73% of Americans having access to fluoridated water. On Fluoride Day, individuals are encouraged to learn about the benefits of fluoride, purchase fluoride-containing dental care products, and share information on social media using the hashtag #FluorideDay. The holiday is promoted by dental health organizations and toothpaste manufacturers, although water fluoridation remains less common globally.