eli5 Why is it recommended we brush our teeth at night before bed and then in the morning, even when we haven’t eaten in between?


I’m told my my dentist to brush before bed after I’m done eating and then again in the morning. Is bacteria growing while I’m sleeping with a clean mouth?

In: 5

Bacteria and basic scum coating my teeth. It’s good to get in the habit twice a day. If you go off to eat brekky you’ll undoubtedly forget to brush in the morning.

Bacteria and other microbes are in your mouth and some of those are what forms plaque and other stuff you don’t want on your teeth. So even if you haven’t eaten, given enough time your teeth need maintenance.

There’s not really a way to “sanitize” your mouth without damaging the tissue, and some of the stuff in your mouth this would kill is beneficial.

Yes, when you are asleep all the bacteria that normally live in your mouth grow a little faster since you aren’t producing as much saliva. So you have a nice warm, moist environment with less protection. So the bacteria deposits little amounts of minerals that become tartar and plaque after a few hours. This accumulation of tartar and plaque causes your immune system to attack and causes gingivitis and periodontal disease. So by brushing you’re helping stave off this bacterial growth.

i did a science fair project on thisin 1999. i proved that listerine did more harm than good. i spent days swabbing my mouth and watching bacteri grow in agar.

yes, listerine kills 99% of germs in your mouth but it also creates an environment in which bacteria thrives.

bacteris does grow overnight, and my most populated cultures were from swabs the morning after using listerine.

brushing your teeth prior to consuming breakfast or drinking fluids, prevents the bacteria in your mouth from interacting with the microbiome that is you gut.

My impression is that the “in the morning” is supposed to be after breakfast, so would potentially serve the same purpose as the after dinner brushing.

I’m sure if you asked your dentist if you should also brush after lunch, they’d say yes, but for most people that is an inconvenient time (at work or school).

And while on the topic of “if you asked your dentist”… when they were giving you the instruction, that would have been an opportune time to pose this question to them 🙂