The FDI World Dental Federation, headquartered in Paris and founded in 1900, launched World Oral Health Day in 2007, originally observed on September 12 to mark the birthday of the federation's founder. In 2013, the date moved to March 20 to avoid overlapping with the federation's annual congress, and because the number 20 symbolizes the goal of keeping at least twenty natural teeth into old age as a benchmark of good oral health. The day raises awareness that oral health is an integral part of overall wellbeing, and that gum disease and tooth decay remain among the most widespread chronic conditions worldwide despite being largely preventable. National dental associations in more than 130 countries mark the occasion with free screening campaigns, school workshops teaching children proper brushing techniques, and media campaigns linking diet to oral health.