is this a ethos if yes or no why or why not?

"dentists all over the world are telling their patients the same things. you must floss regularly"

Yes, this could be considered an ethos because it is a statement of credibility and authority. It is suggesting that dentists, who are experts in oral health, are all recommending the same practice of regular flossing. This appeals to the trustworthiness and expertise of dentists in promoting good oral hygiene.