It’s almost bed time here at the fort!
But before we get tucked in,
we’ve got to brush our teeth!
Hey，that’s a good question, Squeaks.
We do it a couple of 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!
毕竟 没有它们 你要怎样嚼碎饼干
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 of up different layers.
The part that you can see — on the outside —
is 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 aren’t hard enamel all theway 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 of your teeth,
you have 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.
Well, you might think that you ate every last bite
of those crackers that you had as 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 shinyand smooth.
They have lots of bumps and ridges
that help you grind down your food.
And thereare lots of small spaces between them too.
These are places where it’s easy for food
to get stuck and hang out all day.
Which is kind of gross!
But you know what’seven more gross?
You’re not the only one enjoying those 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’redefinitely in there.
And there are a lot of them!
In just yourmouth alone, there are more bacteria than
there are people on earth.
Some kinds of bacteria are really good tohave!
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
也就是像饼干 薯片 面包
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 with 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 hard 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 feelingon your teeth.
So, we brush our teeth before we go to bed,
to get rid of all those tiny bits of food
we’ve eaten 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 you have less of a chance of getting cavities!
But! You should brush your teeth in the morning,too!
Because even though you brushed 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 that they stay strong and healthy.
So you can keep eating good food — which keeps the rest of youhealthy!
Once our teeth are clean,
it’ll be time for us to head to bed.
But if you have any questions
睡眠 牙齿 星星或其他关于科学的问题
about sleeping or teeth or stars or any kind of science at all,
get help from a grown up and leave a comment below
or send us an email at kids @ thescishow.com.
And we’ll see you next time!