SciShow Tangents - SciShow Tangents Classics - Teeth

Episode Date: November 1, 2022

It's the day after Halloween, which means you might have a surplus of candy in your house. But before you start digging in to those sugary treat, spare a thought for your teeth, won't you? And to help you with that, today we have a classic episode all about your pearly whites! SciShow Tangents is on YouTube! Go to www.youtube.com/scishowtangents to check out this episode with the added bonus of seeing our faces! Head to www.patreon.com/SciShowTangents to find out how you can help support SciShow Tangents, and see all the cool perks you’ll get in return, like bonus episodes and a monthly newsletter!And go to https://store.dftba.com/collections/scishow-tangents to buy your very own, genuine SciShow Tangents sticker!A big thank you to Patreon subscribers Garth Riley and Tom Mosner for helping to make the show possible!Follow us on Twitter @SciShowTangents, where we’ll tweet out topics for upcoming episodes and you can ask the science couch questions! While you're at it, check out the Tangents crew on Twitter: Ceri: @ceriley Sam: @im_sam_schultz Hank: @hankgreen

Last night was Halloween, and it may have been full of spooky fun for you, but today is when the real nightmare begins. For your teeth, that is. So while you're digging into that trick-or-treat bag, going to town on chocolate bars and Skittles, spare a thought for your poor chompers. And to help you do that, today we have a classic episode all about teeth. Happy day after Halloween, and see you next week. hello and welcome to sci-show tangents the lightly competitive knowledge showcase i'm

your host hank green and joining me this week as always is, is our science expert, Sari Reilly. Hello. Hello. I'm glad you're here for our radio DJ time. Wham, wham, wham. Fart noise. Okay. And also joining us, as always, is our resident everyman, Sam Schultz. Hello, Sam. Hello.

If you had a radio DJ control board, Sam, what would the most used sound be on it for you? Toilet flushing. No hesitation. For sure. just because you think other people's thoughts are toilet worthy yeah yeah when you hang up on them you could be like toilet yeah or like like the foghorn stink sound uh-huh i definitely i feel like you would toilet flush me like three times an episode oh you're you're a big name guest i wouldn't toilet flush me like three times an episode. Oh, you're a big name guest. I wouldn't toilet flush you.

No, I'm not saying you would kick me off the podcast or the radio show. You'd toilet flush an idea that I had. You'd be like, that was a real stinker. Yeah, you're probably right. I probably would. There's times that when I'm listening to you while I'm editing the podcast, I think,

oh, big toilet flush for that idea you just had. And you just cut it right out don't you yeah it's not in there anymore no one gets to know about those sari what what's your favorite thing to chew on oh we get two different questions okay well i figured sari wasn't gonna have a lot of radio dj experience you might have a good one let her try no no don't skip me i was trying to think of one and i was like i can't even think of sounds anymore what is a radio no i know what i like chewing on i think like a good taco i like chewing on it and then swallowing because it's not that many juice like a crunchy taco like a soft taco i don't like a crunchy taco i almost never think of any normal food as something that is good to chew on it's always like like straws or like gum and stuff i'm not really a

big gum fan i didn't i didn't have a good answer neither am i until i heard tacos but i i agree but disagree because the best chew experience is the is the fresh crunchy taco like the crunch then the soft oh that's an amazing chew. Texture is such a huge part of food. That's why I don't really like beans. They're too pasty. Doesn't belong in my mouth. But other foods.

You think all foods should be crunchy? Is that what you're saying? No, it's just something about the bean texture that's not good. Oh, that's one of my favorite textures. I also love beans a lot. So again again we agree and disagree and isn't that just the way of the world every week here on tangents we get together to try to one of amazing delight each other with science facts while trying to stay on topic but

the podcast is called tangents so we aren't always great at that our panelists are playing for glory and for hank bucks which i'll be awarding as we play. And at the end of the episode, one of them will be crowned the winner. And as always, we're going to introduce this week's topic with the traditional science poem. This week is going to be from me. You want to hear my science poem? No, toilet flush. So often in life, as you go on living, you have to replenish your energy. A tiny snack or a whole Thanksgiving,

you need to fight against entropy. But food can be hard or stringy or tough. It isn't just mush and your tongue's not enough. Mice or people or fish or crocs, all of us need our mouth rocks. Mouth rocks help us form our words. Without them, we look a little absurd, but mostly they're useful for when we eat pizza or wheat or carrots or meat mice or people fish or crocs all of us need our mouth rocks i love that that was great it was like a little jingle all of us need our mouth rocks yeah brought to you by the american mouth rock association take care of those boys gosh and so the topic for the day is teeth which uh has a fairly specific definition but then it gets wibbly because we call some things teeth

that aren't teeth but also some things that we don't think our teeth are teeth and so that's just it's it's complicated ain't that just the way it always goes yeah but i love that we have a special kind of bone that sticks out of our flesh. Is that fair to say, Sari? I don't know. What is a tooth? So I think anyone who studies bones specifically would be like, a tooth is not quite a bone. But for our purposes, if we can call them mouth rocks, we can call them mouth bones as well.

Because they are made of similar, and I guess also also this is where it gets a little wibbly they're made of similar things so bones are mostly made of calcium phosphate and those are the same two atoms like calcium and phosphate that make up hydroxyapatite crystals which are the key structural components of tooth both in the dentine part which is like above the nerves below the surface and the really hard enamel part which is the top layer that makes teeth so strong so the same same ish composition but different enough from bones that scientists are like teeth are not quite bones right but bony ish yeah well and it's clear like i've touched a bone and i've touched a tooth and there is a difference they're definitely chemically different

from each other even if they're composed of the same atoms uh and unlike bones i'm pretty sure teeth don't repair themselves because if i break a bone it'll just it'll just heal but if i chip a tooth i have a chipped tooth forever yeah they're non-living tissue on the top bit. So there are like three chunks of the tissue is the crown, the neck, and the root. The crown is like what sticks up above the gum. The neck is like what embeds itself into your gum. And then the root is what's embedded in your jaw. Inside your tooth, there are blood vessels and things like that.

So like that is the living tissue. But like the surface layer, if your enamel wears down, there's no way to redeposit it or like fix a crack in it, which is why dentistry fillings are a thing. Because we have to go in there artificially and be like, well, you're out of enamel. So let's squeeze something else in there because your body's not going to make anything else to fix it. Inconvenient. Yeah, I'm glad that we have dentistry though because for all the years when we didn't that sounds very bad yeah and and it's like i tried to sort through this this wealth of fighting on the internet because people are like well

earlier humans or earlier hominids had straighter teeth than us and like didn't need to brush their teeth and from my understanding yes our modern diets do contain a lot more processed sugars so like our teeth do get cavities maybe more often right but humans were not regularly doing dental hygiene activities like some populations were would like rinse out their mouths but it wasn't super super common and they still had mouth problems like they had rotten teeth the the idea of cavities has gone back thousands of years because people thought they were like mouth worms that were burrowing into your teeth so people got infections all the time yes because of not great oral hygiene yeah no i think it's i think it's pretty safe to say that uh tooth problems were a thing that

people died from a lot in the past and the less so now which is great sari where does the word tooth come from sounds like a good one it is kind of a good one but also kind of a boring one because we just had teeth and so we were like that's a tooth uh and so it came from the word or the the proto-indo-european root dent which makes sense because that's where we get dental and dentist denture indent uh and then at some point i don't know when when it went from proto-indo-european to like norse and dutch then we put in a t instead of a d and started calling it something closer to tooth. But the most interesting thing I learned from this is that dandelion also comes from dent for tooth. It comes from tooth and lion. So because of the little, like the way the petals are shaped, people are like, this is a lion's tooth flower.

And now we just think it's a shitty weed. Sorry, dandelions. tooth flower um and now we just think it's a shitty weed so sorry dandy lions i'm a little disappointed in that origin of the word that's a that's a leap i feel like there's a missing gap from dent to tooth yeah it is it does have it ended with a ent and now it's with an ooth that seems like a big jump but look that's how it works somebody was shouting from one side of a river to the other they were like we call these dents and the other guy was like you call them teeth what okay bye i think it's i think it's the people who are looking there like that doesn't sound like

when i say dent it doesn't sound like that when i say tooth these look more like a tooth to me yeah they've got the two part and the ooth part. The two part is the hard part, and then the ooth is the part that goes into your body. Exactly. I think it's the opposite. I think the ooth part is the nice round top, and the two part is the sharp roots.

Okay. All right. There are two of them. Oh, my God. Oh, God. Oh, God. let's move on it means that that means that it's time for the quiz portion of our show this week we are playing get ready for it tooth or fail so teeth are primarily associated with vertebrates uh vertebrate because they're they're like bone like but there are invertebrates who

have structures that are toothy enough that we call them teeth, even though they might not really be teeth. And of course, those teeth are particularly fascinating when we get to the world of marine invertebrates, because of course they are, because marine invertebrates are so weird. The following are three descriptions of marine invertebrate teeth, but only one of them is true. Which one is it? We're going to start out with fact number one. Chiton, a large mollusk, changed their teeth with the seasons, altering the chemical composition of their teeth to withstand the fluctuations in temperature and salinity around them.

Or fact number two. The pink sea urchin's teeth are self-sharpening. They maintain their own razor-like edge thanks to the arrangement of plates that are structured to chip away as the sea urchin nibbles on coral reefs. Or fact number three, the acorn worm has a tooth inside a tooth, forming a concentric dental structure that gathers water in the empty space, and the can use that to sift food through icky as a tooth of the tooth so these are all teeth in quotes or or not well we call them teeth and i'd think that tooth might be a thing where there's not like a super technical definition okay okay but they're doing tooth jobs of being a hard thing that helps you eat so maybe some people's teeth some people some sea urchin's teeth can grow back. Or if you were sharpening it, wouldn't you sharpen it to a little nub of nothing?

I think that they grow. And this is also true of some animals. Rodents' teeth grow. Oh, sure. Like a rabbit. The beaver, for instance. The beaver. Okay.

I know chitons have very strong teeth. What do they do with their very strong teeth? They sit on rocks and they like grind. They scrape stuff up. They got to have teeth that are strong enough that when they scrape their food off of their surfaces, they don't like chip their teeth. Like I can scrape my teeth on rock for very long

without big consequences, but they do it all the time. And so they're fine fine but i know nothing about whether they change depending on the seasons they're tidal animals so that makes sense kind of i don't know there's tougher stuff to scrape off of rocks in the winter or something or yeah or like the seawater composition is different so like you could your teeth could be more susceptible the the second one sounds the weirdest to me like self-sharpening teeth so like mouth rocks if you call them mouth rocks humans developed weapons with rocks by like chipping them off to make a sharp edge something that wouldn't just grow sharp teeth is what you're what you're saying everything else grows sharp teeth so why doesn't

this thing grow sharp teeth yeah it you're saying? Everything else grows sharp teeth, so why doesn't this thing grow sharp teeth? Yeah, it is an interesting adaptation, though, because usually when teeth get dull, animals die, or they grow new teeth. Those are the two main evolutionary ways to get new teeth, is either get rid of them or you just die because you can't eat anymore. So this would be a good adaptation, if needed it to, like, hone your teeth. Okay, what's an acorn worm? And what's a tooth inside another tooth? What does that even mean?

My guess is that there's just a tooth wearing another tooth as, like, a little hat. But then there's a little, like, a little roller coaster in there where water can go through and go, woo! Oh, okay. I think I'm going to pick the chitin one because it's boring-ish kind of in a convincing way i'm gonna pick the second one sea urchin because i always want to divide and conquer and i truly have no idea i think it would be really cool if it was true i'd be most excited if this one was true that's a good way to pick them i like that sari and it is it's the true fact

pixie urchins have self-sharpening teeth they have five teeth that are arranged in a circle it's kind of creepy looking and scientists suspected that the teeth are self-sharpening so they used a combination of mechanical testing and electron microscopy to look at how the teeth are structured and it turns out that the tooth has two sides. There's a stronger side made up of calcite fibers, and the other side is made up of inclined plates that chip away when the tooth scrapes against hard surfaces. And that structure makes it so that the teeth get chipped away on one side, maintaining the sharpness of the overall tooth. They also continuously continuously grow so even as it chips away there is still more tooth left for future times when the sea urchin will continue to need to eat imagine if our mouths

just had a ring of teeth i can't even oh no because there's like a they have a ring of teeth ring of teeth layers it's yeah it's just a big it's just a tooth circle where are they even keeping their mouths oh a little butthole mouth yeah in the middle i see they actually yeah they actually have a separate butthole oh really that's on the top yeah but i've actually i got in trouble because i thought that that was the case and i made a tiktok where i talked about how how starfish poop out of their mouths and the lovely people at the Monterey Bay Aquarium were like, ah, nope. And then he showed me a starfish pooping. Cool.

I was wrong. That should be a much more widely circulated thing. I feel like I've never seen a starfish poop. I've never seen a sea anemone poop. I just like spew out these facts about mouths and butts, but we need more documentation of things pooping so that we know which hole it comes out of. Every animal's Wikipedia page should have a video of it eating

and a video of it pooping, just so you know for sure. That'd be great. Where it comes from. That's the kind of information we need to know. What hole does it come from? This can be your science coffee table book. Well, I've got a, and I've got a great name for it. Now that I have a great name for it now that i have a great

name we're gonna have to do it it's called poopy ppdia i can't wait for you to do the audiobook for that poopy ppdia a journey through the digestive systems of all life i'm your host hank green well that's our new Patreon-only podcast. It's called Poopy Peepypedia. And you can sign up at patreon.com slash scishowtangents where if we get just, I think, 100 more Patreon patrons, we can finally do our commentary of Cars Mater to the Future or whatever it's called.

Cars 2 and Time Travel Mater. Two distinct films. Okay. A short film and a feature length film. Get it straight for once in your life. So chitons, Sarah, you are right. They do have to do a lot of work with their teeth, but they do not change their teeth over the seasons.

They do. Their teeth are made of a rare iron mineral called santa barbaraite that it was only found in rocks before it was found in their in their mouths and it's in a long hollow structure called the stylus which links the teeth to a tongue-like structure called the radula and this was just inspired by the fact that i would like to have teeth that change with the seasons so that i can uh have like enjoy a hot drink and then a cold drink and not have my teeth hurt. As for the acorn worm, it does eat by filtering food from seawater, but it doesn't have teeth. But there is a thing in humans where people have a tooth inside of a

tooth where the enamel folds into the bony tissue underneath, forming a pocket underneath the surface of the tooth. It affects around 0.3 percent of the population all right sari is coming out of that with one point and sam's got nothing next up we're going to take a short break and then it'll be time for the fact off Welcome back, everybody. It is time for the fact-off. Our panelists have brought science facts to present in an attempt to blow my mind. And after they've presented their facts,

I will judge them and award Hank Bucks any way I see fit. And to decide who goes first, I have a trivia question. The giant armadillo is the largest living armadillo measuring up to a meter long, not including their 20 centimeter tail. And it weighs between 18 and 33 kilograms when fully grown. Giant armadillos also have the most permanent teeth of any terrestrial mammal. What is the most amount of teeth giant armadillos are known to have oh how many teeth do we have 32 including wisdom teeth i'm gonna guess 56 okay just out of out of nothing apropos

of nothing 56 i'm gonna guess 44 you are both pretty wrong but sari is closer it's about a hundred oh how do they pack it in there i don't know look at a giant armadillo mouth sari would you like to go first or would you like sam to go first i'll go first different animals keep or replace their teeth for different reasons throughout their lifetimes so-called monophyodonts are stuck with one set of teeth for their whole life while diphyodontsonts are stuck with one set of teeth for their whole life, while diphyodonts, like humans, often have a primary set of teeth that gets replaced by the permanent teeth as they grow up. But some animals are polyphyodonts and replace their teeth as needed throughout their lives. But they all have slightly different strategies. So sharks, for

example, have multiple rows of teeth like a rainbow, and when they lose one from the outermost row, which can happen as often as every week or so, the teeth from the inner rows shift over to fill the gap. While alligators, on the other hand, just have one row of teeth, and they do something called tooth cycling, where they're replaced one by one in a wave from back to front over months to years.

I'm not here to get too deep into shark or alligator mouths because I think there's a much... Sorry, I'm going to interrupt you. Did you just tell me that alligators have a conveyor belt of teeth? Is that what you mean? to get too deep into shark or alligator mouths because sorry i'm gonna interrupt you are you did you just tell me that that alligators have a conveyor belt of teeth is that what you mean like they start in the back and they move to the front they don't move to the front they they like lose their teeth in a wave so they like start losing them towards the back and then they lose them one by one also you shouldn't get too deep into alligator mouths that's dangerous

well okay i'm not getting alligator mouse. That's dangerous. Well, okay. I'm not getting into it because it's dangerous. And because I think there's a much weirder animal out there with fun, weird polyphiodont teeth, piranhas, and the closely related pacus. They're famous for having very sharp chompers and eat all kinds of meat or plant matter. So if you imagine your teeth as two halves, you have like the left side of your mouth and the right side of your mouth. And multiple times throughout piranhas lives, they lose all the teeth on one side of their mouth at once.

And that seems very silly. Like losing half of your teeth at once would mean very lopsided eating if they all just like popped out of there. And there aren't any museum specimens of piranhas missing half their teeth so scientists were like very skeptical about whether this was real or just a myth that got passed down through literature etc but in a 2019 study a team looked more closely at piranha mouths including using imaging techniques like ct scans which are

basically fancy x-rays and found a couple One, that all of the teeth on each side of the mouth interlock, making it physically impossible for just one tooth to pop out if it's dull or otherwise bad. And this interlocking of teeth also creates a much stronger chomping surface because it distributes the pressure across the whole half of the mouth rather than one single crackable tooth. And this lets piranhas tear through carcasses or crack on seeds or whatever they come across with less risk and number two as the old dull teeth are reaching the end of their lifespan the new sharp teeth layer is right underneath them the article described it as the new teeth were wearing the old teeth like hats when the old teeth

pop off the new ones are already underneath and sharp and ready to go they're never left with bare gums like humans losing teeth even though it takes quite a lot of energy to grow half a mouth of replacement teeth multiple times in their lives they've made an evolutionary trade-off for super chomping power great always sharp teeth at least on one side you know i've seen a lot of people being worried about piranhas because it's kind of it's kind of a scary name they eat a lot of meat and i've just looked at i think probably my first ever picture a close-up picture of piranha teeth and i'm terrified they are cartoonishly evil looking those teeth are like wow that would be great

at ripping something to shreds yeah and now you know that those teeth you can't just like break one off they're digging into you you can kind of see it in in the pictures when you google piranha teeth like where they interlock there's a little spike that like leans into the next tooth down and then there's paku which uh don't have sharp teeth like that uh they appear to have teeth that look like mine which also is upsetting do they do the same thing yeah they're related to piranhas and so their teeth are also interlocked and also fall out half at one time all right sari that was exceptionally good sam what do you got for us that was exceptionally good oh no i like that okay so hey when you think of your average baby of any species not just the

human baby what do you think of i'm averaging all babies together of all species that's gonna be that's gonna freak me out that's gonna be a freaky thing. Every baby averaged together. Uh-huh. Are we counting fish? What are we counting? No. I shouldn't have said of any species. Let's just do mammals.

How about that? Big eyes, big head, gummy mouth. Gummy mouth, eh? Yeah, that's right. You don't think of lots of teeth. You played directly into my hand. I was trying to guess what you wanted me to do. But in 2009, a research team made a discovery that shattered everything you think you know

about babies' gummy mouths. What this research team found were the fossilized remains of 19 theropod dinosaurs. So theropods are the bipedal, like T-Rex, Velociraptor, body-type dinosaurs that evolved into birds question mark some of which evolved into birds uh and they named this this these fossilized remains were a new discovery so they named them limosaurus inextricabilis so their name reflects how they died and how and why they were preserved so it means a mire lizard who could not

escape and it seems like lemasaurus were social and they lived in big groups and this particular group lived around a big mud pit that their children their family members and their friends kept walking into and sinking into and so these 19 sets of remains ranged in age like perfectly from baby to through adolescent to adult to like elderly adult of this dinosaur so they found a perfect age range of this dinosaur so the find provided a look at the entire life cycle of this species all in one place which is super uncommon and really cool and for the most part the skeletons reflected all the normal things you would expect to happen as an animal grows into an adult. Except for one pretty huge exception.

Baby lemurs had a mouth full of sharp teeth and the adults were completely toothless. In fact, their mouths seemed to transform into what we would recognize as like a beak, maybe like a duck beak kind of. Since they could trace basically the entire growth cycle of the dinosaur, they could see it losing teeth in each step that it got older it started with 42 teeth and then had zero teeth by the time it was an adult so they looked at the chemical composition of the bones and they found that the isotopes in the older lemurs bones match other dinosaur herbivores but baby lemurs had a whole bunch of isotopes, which is more common, I guess, in predators or things that eat like insects and all kinds of stuff. Also, they found that older lemurs had gastroliths, which are like the rocks that certain animals, most notably birds,

swallow to help with their digestion, but the younger ones didn't have any. So the researchers think that the animals shift from predator when they're younger to eating plants when they're older. They don't think that they were insectivores because lemurs are probably too big to be insectivores when they grew up. And the adults just got this like went totally vegan when they were grown up. So they think this happened to make sure that the babies could get all the nutrients that they needed since the adult animals weren't going after the same food sources as the baby. So they could just chow down on whatever they wanted to until they grew up. And then they're just like, oh, it's time to eat plants.

And that's something that I think happens in other animal species today. The paper cites catfish that turn from predators when they're babies to filter feeders when they get older. So I think for similar reasons, possibly. And since this was the first time this was discovered, like a toothy dinosaur turning into a beaky dinosaur, they don't know if it's like that's why, where beaks come from or anything like that. But it might be. So we need to find more pits full of dead dinosaur families to find out if that's the case.

Thank you for your sacrifice, dead dinosaur family.'s so cool that's it's super weird and it's also like uh like the idea of all these like babies running around eating up lizards and insects and stuff there's a there's somebody who's done a little cute art of of baby lemurs with these giant eyes with just like a lizard half in its mouth it makes me want to give them a cuddle but uh they had little needle needle teeth so that's you know wait till they're older and then you can cuddle them exactly and they'll just give you a little gumming yeah i do like the like the personality implications too that like these babies are frantically running around and just like eating whatever they can. So they need sharp teeth. And then the adults are like, I don't have the energy for that. I'm going to eat this leaf, but I don't have to hunt.

It's just here because I feel the same way about my excitement for getting food. So and so why doesn't this happen to people where we've got little two yearolds running around with needle teeth and us just with beaks grinding up give me applesauce so okay so that leaves me with sari telling me about how piranhas lose one side of their teeth all at once and then their teeth were had tooth hats And then Sam with a species of dinosaur that has meat eating tooth having babies and beak having herbivore adults. I like them so much. Any final words? Well, I mean, you said hers was outstanding or something like that. So just give it to her.

Well, I like yours a lot, too. But the thing is that if I give you equal points, Sari does come out the winner. Oh, that's fine. I think that that is what is going to her. Well, I like yours a lot too. But the thing is that if I give you equal points, Sari does come out the winner. Oh, that's fine. I think that that is what is going to happen. Sari, congratulations. Thank you. I needed redemption after my very poor performance last week.

Yeah, you did have a lot of misses last week. It's time now for Ask the Science Couch. We've got a listener question for our couch of finely honed scientific minds. This question comes from Care Bear Ritual. How do braces even work? Why do we need to wear retainers after wearing braces? How do braces even work? I kind of have a vague idea of this, which is that if you put pressure on the bones of your jaw, the bone will erode where the pressure is being put and then bone will reform where there is no pressure your your mouth isn't laid out by a like blueprint

it just does whatever uh makes sense for what's going on there so if you push stuff around your bones actually reshape and reform and that would should be a reason why we wouldn't need a retainer. But apparently you do still need a retainer, as I am evidence of having had braces and do have much straighter teeth now, but they have floated back a little bit to be kind of crooked, especially on the bottom. So Hank's basically right. And I think that you said it in a very matter-of-fact way, and I was probably going to say it in a very matter of fact way,

but listening to you say it, it's like very weird that your mouth dissolves the bone and then adds more bone. But that's basically right. I'll just add more science-y words to Hank's description. So underneath our gums, there is a membrane called the periodontal membrane, which like surrounds, I think, the root of the teeth. I've not gone to dental school. So this is from basic research. The combination of that membrane and its contact with the alveolar bone is what positions the teeth within your jaw, within your mouth. And so braces, when you, when you put them in, you put pressure on different sides of your

teeth and it causes one side of the tooth to compress against one side of the periodontal membrane, which creates a little bit of empty space on the other side. And so there are two types of cells that are in your body all the time because bone is living tissue. There are osteoblasts, which are bone growing cells called deposition. you like deposit more bone tissue and then there are osteoclasts which are bone destroying cells and reabsorb bone tissue and so then those cells are just like i'm gonna spew more bone into the empty side and i'm gonna like break down cells on the compressed side to try and relieve this pressure and in in that process, your teeth gradually move because bone is being created and destroyed in your jaw. And then the retainer is for that reason.

Because after you've applied pressure, my guess is that your mouth applies pressure in natural ways as well so like just your teeth and your mouth structure probably puts pressure in some certain ways that gaps more naturally form and then bone tissue just like gets produced there because that's what it's been doing your whole life and that's what leads it to a crooked confirmation it's like the lowest energy state of your mouth that i'm not sure but it makes sense right logically in my head. That also makes sense to me too. And then a retainer or Invisalign or braces or anything, like a retainer is just like theoretically

just to keep your teeth where they are. And then braces, like the reason it hurts is because like you have to put pressure on your bones, enough pressure to dissolve them. So a significant amount of pressure. If you want to ask the Science Couch your question, follow us on Twitter at SciShowTangents where we'll tweet out topics for upcoming episodes every week.

Thank you to Adam Moskowitz, at Shrew Sophie, and everybody else who tweeted us your questions for this episode. If you like this show and you want to help us out, it's very easy to do that. First, you can go to patreon.com slash SciShowTangents. You can become a patron and get access to things like our newsletter and our bonus episodes and our brand new podcast, Poopy Peepypedia. You can leave us a review wherever you listen.

That's super helpful and it lets us know what you like about the show. And finally, if you want to show your love for SciShow Tangents, just tell people about us. Thank you for joining us. I've been Hank Green. I've been Sari Reilly. And I've been Sam Schultz. SciShow Tangents was created by all of us and produced by Caitlin Hoffmeister and Sam Schultz,

who edits a lot of these episodes. Our social media organizer is Pala Garcia-Pietro. Our editorial assistant is Deboki Chakravarti. Our sound design is by Joseph Tuna-Medish, and we couldn't make any of this without our patrons on Patreon. Thank you, and remember, the mind is not a vessel to be filled, but a fire to be lighted.

But, one more thing. In 2015, researchers from Quinnipiac University reported that in communal bathrooms, which had an average of 9.4 occupants per bathroom, that's a lot of people per bathroom, fecal bacteria were found on 54.58% of toothbrushes. However, as the American Dental Association notes, there is no evidence that this contamination leads to bad health effects. And they note that it's better to leave your toothbrush stored in a way that exposes it to open air because some kind of closed container is exactly the kind of place bacteria like to grow. And they also discourage the use of microwaves and dishwashers to clean your toothbrush. But I don't know why that one.

That seems like it'll be fine to me. Melt your toothbrush, I guess. So there you go. You can have all the poop on your toothbrush you want to and it's fine. I don't think that's what they said. Just stick your toothbrush in the toilet and swish it around and then brush your teeth.

You know all that toothpaste that you swallow? Well, it's in your poop now just use it again don't make it a waste in this economy