Is there anyone in the world who doesn’t rinse and spit out the extra toothpaste after brushing their teeth? Well, it seems we're all doing it wrong. Dr. Edmond Hewlett is a professor at the UCLA School of Dentistry and a consumer advisor to the American Dental Association. Hewlett says that leaving the toothpaste in gives the fluoride more opportunity to do its thing to kill bacteria and film from food and sugary drinks. In addition, it’s also recommended that you floss before brushing your teeth rather than after.
Source: CNET