Main content
Course: MIT+K12 > Unit 1
Lesson 1: Chemistry and biology- Why we fart
- Solving biology's mysteries with plants
- Why do we have snot?
- How do braces work?
- Squid skin with a mind of its own
- Why can we regrow a liver (but not a limb)?
- MIT's choose-your-own: Chemistry adventure
- The food chain
- Homeostasis
- Bread mold kills bacteria
© 2024 Khan AcademyTerms of usePrivacy PolicyCookie Notice
How do braces work?
Braces are a lot more barbaric - and awesome - than you might think. But they actually just copy the process that the rest of your bones naturally undergo!
Want to join the conversation?
- i have braces and a over bite and they gave rubber bands.what do the bands do?(1 vote)
- If milk makes your bone stronger, than how does your body react?(1 vote)
- What role would a retainer serve after the jawbone has been reformed using braces? Why wouldn't the teeth simply stay in place on their own?(1 vote)
- Maybe because the jaw may still be slightly broken down and need more time to harden, and the retainer is to keep the teeth from slipping out of place during this time. Just a guess, though.(1 vote)
- I have a gap in my teeth .So,if i tied it up with rubber bands for long , can i fix it ??(1 vote)
- you probably could, but it would be better to just get braces, as it is dangerous to put rubber bands on your teeth because it could damage your gums.(1 vote)
- What if I had a group that could not only help you solve some problems? There are many parts of life that I need to learn, you can help me on a scientific level, but my friends can help another way, but only if you have an open mind will this even begin to make a difference.(1 vote)
- If we can't use our teeth under all that pressure because of the tissue if the tissue wasn't there will we be able to crumple things harder than bone?(0 votes)
- No, our jaws would be crushed and absolutely dead if we didn't have the tissue but still tried to crumple something harder than bone!(2 votes)
- what if you have a overbite(0 votes)
- wait our teeth are stronger than iron and steel?(0 votes)
Video transcript
Science Out Loud. Every day, we rely on a
substance that's harder than iron or steel, our teeth. [MUSIC PLAYING] So if teeth are
harder than steel, they must also be
harder than bone. And if they're harder
than bone, then why does your jaw,
which is made of bone, not crumble under
all that pressure? There's a bit of tissue called
the periodontal ligament, or PDL, around your
teeth under your gums. The PDL is a shock absorber,
cushioning your jawbone from all the chewing forces. OK, so far, so good. But what if your teeth
come in all funky? Sure, it looks kind of goofy. But that's not the only
reason that somebody might want to fix it. Funky teeth can interfere
with the way you talk and the way you eat. So how do we fix this? Well, we basically break
our mouths with braces, except it's actually our
bodies that do the breaking. The PDL has these cells
called mechanoreceptors. And when these cells detect
a force on your teeth that's too big, like
if you accidentally bite into your fork,
they signal the brain to stop biting down
before you hurt yourself. Braces tether your teeth,
pulling them together or pushing them apart. Either way, they're applying
a steady force to your teeth. And when mechanoreceptors
in the PDL sense this kind of smaller
but sustained force, they signal cells
called osteoclasts to the area, which spew out
acid and proteins to dissolve parts of your jawbone. Then the mechanoreceptors
signal osteoblasts to come. And those cells deposit
minerals that make bone. Osteoblasts rebuild the
jawbone in a new shape that lets the PDL hold
teeth in the new position. So braces basically
force your body to dissolve itself and
then rebuild itself according to their evil whims. Sounds barbaric, right? But your body is actually
breaking down and rebuilding bone using osteoclasts and
osteoblasts all the time, not just if you have braces. Bone remodeling is just
the way our body grows. The infant body replaces almost
all of its original skeleton by the time it's a year old. And it happens throughout
our entire life. 10% of my bone
material is technically new since last year. We can manipulate the
bone remodeling process to not only get
straighter teeth, but also to treat diseases,
like osteoporosis, which make your bones very brittle. By keeping overactive
osteoclasts from dissolving
the bone so much, or by boosting osteoblasts
to produce more bone, drugs can prevent
bones in those patients from breaking so easily. People with severe
bone injury have to rely on bone transplants,
where they take bone from other parts of their body
and move it to the damaged area, which is sometimes
not even possible and is always painful. So instead, Paula
Hammond's group at MIT has created a new material-- --that very slowly
releases proteins. And these proteins
cause osteoblasts to go right to the site
where the injury happened and generate new bone. Now, this was a really
big deal for us, because it's really hard to
generate something that very slowly releases the protein. Most of the time, the protein
comes out very rapidly and gets swept away in the
body, so that it no longer has any effect. It's easy to write braces off
as a form of medieval torture. But it's kind of amazing that
this mouth torture actually works. And the technology
that makes it possible is not just in your
braces, it's in your bones. Hi, my name is
Andrea, and thank you for watching this episode
of Science Out Loud. If you liked this episode,
why don't you check out some of these other videos. And visit our website. And visit our
website. [LAUGHING] They're separate things?