There’s no definitive proof that you should floss your teeth. All the medical research that’s been used by the US government to recommend flossing in the Dietary Guidelines for Americans has been described as ‘inconsistent,’ ‘weak,’ ‘unreliable,’ and carrying a ‘large potential for bias.’ The Associated Press recently called them on it, and when the 2016 edition of the guidelines was released, the flossing recommendation had been removed. Source Source 2