Floss first or brush first? What research says

There's a right order, and most people get it backwards. Most of us brush first and floss afterwards, if we floss at all. The research points the other way.

A 2018 randomised trial published in the Journal of Periodontology compared both sequences and found that flossing before brushing left less plaque between the teeth. The reasoning is straightforward. Flossing first loosens the debris packed into the tight spaces, and the brushing that follows sweeps it away instead of leaving it sitting there.

There's a second benefit that's easier to miss. Flossing first opens up the contacts between your teeth, so the fluoride in your toothpaste can actually reach them. The same research measured higher fluoride retention between the teeth when flossing came first. Those tight contacts are exactly where cavities tend to start, so getting fluoride in there is worth the small change.

If you already floss every day, you're doing the hard part. Switching the order costs nothing and takes no extra time. Floss, then brush, then spit without rinsing, and you've got a little more out of the same two minutes.