https://health.usnews.com/health-care/patient-advice/articles/tongue-scraping
https://www.webmd.com/oral-health/news/20160802/is-all-that-flossing-really-worth-it?ecd=soc_fb_160803_cons_news_isallthatflossingreallyworthit&fbclid=IwAR0CupysSXGDQynngkSz71XvoZ6Aao2u0AmmV2zVgU3c4tpqf1ewvUjfJvo
http://www.webmd.com/oral-health/guide/dental-health-dental-care-products#1