[Intro Music]

Jessi: *yawns* It’s almost bedtime here at the fort. But before we get tucked in, we’ve got to brush our teeth.

Squeaks: *squeaks*

Jessi: Hey, that’s a good question, Squeaks. We do it a couple times a day but we should really understand why we do it. So, why do we have to brush our teeth?

Well, have your teeth ever felt just yucky? Like at the end of the day. Or first thing in the morning. I really like brushing my teeth because it gets rid of that icky feeling. And it feels good because it is good.

We brush our teeth to keep them clean and healthy so they can keep helping us our whole lives. After all, how would you crunch up a cracker or bite into an apple without them. Without teeth, you’d have very few choices of foods that you could eat. So you’ve got to take care of them.

Now, you can’t tell just by looking at them, but your teeth are actually made up of different layers. The part that you can see on the outside is a super hard shell called enamel, which is mostly made of minerals. Enamel is the strongest stuff in your whole body, even stronger than bone. But unlike your bones, a tooth can’t heal itself if it’s broken.

And your teeth are not hard enamel all the way through. Just below that tough outer layer, there’s another layer called dentin, that’s not as hard. And below that, there’s the inner layer of the tooth called the pulp, which has blood vessels and nerves inside it. And this part of your tooth is super sensitive. So in order to protect the delicate pulp inside your teeth, you have to take really good care of the outside. And the best way to do that is to clean them up after you eat, because food can damage even those tough outer layers of your teeth.

How? Well, you might think you ate every last bite of those crackers that you had for a snack, but the truth is some very small pieces of food are still hanging around in your teeth. That’s because your teeth aren’t all shiny and smooth. They have lots of bumps and ridges that help you grind down your food. And there are lots of small places between them too. These are places where it’s easy for food to get stuck and hang out all day. Which is kinda gross but you know what’s even more gross? You’re not the only one enjoying these leftovers.

There are lots of tiny little things that call your mouth home. These are called bacteria. They’re way too small to see but they’re definitely in there. And there are a lot of them. In just your mouth alone, there are more bacteria than there are people on earth. Some kinds of bacteria are really good to have. Others just kind of hang around and are neither good nor bad. And then, there are some who are pretty bad house guests and you don’t want them staying in your mouth for too long.

One type of bacteria loves to eat the same stuff that you do, especially sugars and starches. That means things like cookies, chips, bread, candy, and cereal. These bacteria hang around on your teeth and in your mouth, basically eating your leftovers. And once they’re done eating those tiny bits of food, they release acid which can really hurt your teeth. This acid can cause holes, called cavities, to form in the enamel of your teeth. And cavities can really hurt. They might even make it harder for you to eat if they get too big. But the good news is that when you brush your teeth, you clean away the food that those bacteria love so much and you sweep away some of the bacteria themselves. And with them goes that icky, gross feeling on your teeth.

So we brush our teeth before we go to bed to get rid of all those tiny bits of food we’ve been eating during the day and to clean out the bacteria that are hiding in our mouths. Fewer bits of food in there and fewer bacteria, meaning a less of a chance of getting cavities.

But you should brush your teeth in the morning too. Because even though you brush the night before, there are always some bacteria sticking around in your mouth and while you were sleeping, those little guys were partying it up. So when you brush in the morning, you’re starting the day off with a nice clean mouth. That’s why you should brush your teeth at least twice a day, in the morning and at bedtime. Taking care of your teeth will make sure they stay strong and healthy, so you can keep eating good food, which keeps the rest of you healthy. Once our teeth are clean, it’ll be time for us to head to bed.

But if you have any questions about sleeping or teeth or stars or any kind of science at all, get help from a grown-up and leave a comment bellow. Or send us an email at kids@thescishow.com. I’ll see you next time.

[Outro Music]