A Problem Squared - 134 = Tooth and Rock Day 2026

Episode Date: May 11, 2026

🤘To mark the May Birthday of Dwayne 'The' 'Tooth Fairy' 'Rock' Johnson, Episode 134 is a Tooth and Rock Special!🪨 Matt answers your rock-based queries and shares a Salt of the Perth update🦷 Bec and Dentist Sophie answer your tooth-based queries and shares an Adult Tooth Fairy updateHead to our socials to look at some incredibly detailed Salt of the Perth imagery.And relatedly…Lead Explained:https://www.scottishwater.co.uk/-/media/ScottishWater/Document-Hub/Factsheets-and-Leaflets/Factsheets/100620SWFactSheet72020v5web.pdfThallium in Salt Substitutes: A Possible Health Hazard:https://www.sciencedirect.com/science/article/pii/0013935177900433And here’s Matt’s Moving Mountains sources:https://ourworldindata.org/energy-production-consumptionhttps://www.eoas.ubc.ca/courses/eosc350/content/foundations/properties/density.htmMatt has extended his tour - and filming the show in London in October - all the dates, venues and tickets can be found here:http://standupmaths.com/shows Join us on Patreon for early releases and our monthly bonus podcast I’m A Wizard!If you’re already on Patreon and have a creative Wizard offer to give Bec and Matt, please comment on our pinned post!  If you want to (we’re not forcing anyone) please do leave us a review, share the podcast with a friend, or give us a rating! Please do that. It really helps. Finally, if you want even more from A Problem Squared you can connect with us and other listeners on BlueSky, Twitter, Instagram, and on Discord.

Hello and welcome to a Problem Squared. You are joining us for our Teeth and Rock special, which we have chosen to celebrate on the birthday of Dwayne the Rock Johnson, on account of him being a rock who also starred in the seminal 2010 classic film The Tooth Fairy. I'm your host, Beck Hill, a comedian, writer and presenter, who is a lot like Dwayne the Rock Johnson, in that I wrestle with a lot of things, and we're both award winners.

Oh. Yeah, in 2016, he won people. People magazine's Sexiest Man Alive Award. Wow. While in 2014, I won WaterAid's only ever Golden Toilet Seat Award. Your other host that you can hear there is Matt Parker, a comedian, mathematician and YouTuber, who is also a lot like Dwayne the Rock Johnson in that he is bald. Yep.

It's only funny because we know that actually there are so many other ways that you are like Dwayne the Rock Johnson. Obviously, all the key ones. And on this episode? Well, I'm on rock duty, so I'm solving a problem involving moving mountains. I've got an update on Salt of the Perth. And I brought along the most recent rock I've collected. Oh, I am on Dwayne Johnson duty. No, no, I'm on tooth duty and have got a bunch of answers from friend of the show, Dr. Sophie, the dentist.

Hello, Matt. Hey, how are we doing? Hey, we're in person. Yes, it's pretty special. Yes, we've managed to grab a moment together before. In our brief UK overlap. You run off to another country. I go back to Australia, yes.

Yeah, yeah, tag team. Well, you got back within the last week. Yes, I did. And I leave within a week. Yeah. So it's nice to see you. Yeah. How have you been?

I've been good. Yesterday, this is in preparation for going to Australia. Oh, yeah. Yesterday I cycled 80 miles. Wow. That's a long way. For our metric friends, 130 kilometers. Yes.

It's a very long way. It took me eight and a half hours of cycling. Yeah, it's a lot. It's too long. Did you do it as a circuit or did you go somewhere and then like train back? I cycled home. We went to visit Lucy's family and they live 80 miles away from where we live. And so yesterday morning

I was like, love to hang out with the fam again But I'm going to hit the road And so I just got on my bicycle in Bedfordshire And started cycling Wow And ended up in Godoming very late I got home at like 9 o'clock at night Oosh

Did you enjoy it? I had a great time You know, I enjoy cycling I enjoy doing ridiculous things This was a good combination How your thighs Okay So the reason I did it

And we've discussed this multiple times in the past is I have foolishly signed up for an endurance gravel cycling race. Oh no. Is this again? Because you've not actually managed to do this one yet, have you? Well, I did it once two years ago, but I did the third level version. Yeah, there's the full one, which is a long way. Then there's like a second tier and a third tier.

And there's a fourth tier as well, actually. And the third tier is just over 30 miles. And that's what I did two years ago. I then got real smug. Yeah. And I was like, you know what? I'm going to go for the main one. And I signed up for the main one.

And then I broke my hand. Yeah. And so. While riding. While riding. Yeah. To the cafe. So last year, I was unable to compete again.

And my brother in, you know, standing with me also decided to postpone his enrollment. Bless. In the ridiculous race. And so the organizers of the seven gravel race in Western Australia let us postpone our booking for a year. And now I had not done enough training. And so I was like, okay, can you just put me in at level two? So I'm going up a level from last time.

Yeah. But it's still not the full thing. But a level I'm doing is still over 55 miles, which is like 89 kilometers. but a lot of up and down hills. Yeah. And I was nervous. I was like, I was only two weeks away. Am I going to survive?

So I thought if I can cycle 80 miles without too many hills. Then this will seem easy. And not die. It's going to be harder. So I did, I worked it out, I did 146% of the distance, almost one and a half times as far. But it was only. 45% of the going up a hillness.

So I did one and a half times the distance, but half the hills. Yeah. And I hope they cancel out. I don't know. I mean, I think if you're having to go up steeper hills, surely that also means you're going to get to go down a lot without having to do much work. Half the time you're going down. Yeah.

Well, not half the time. I'm a lot slower on the way up. Yeah. Not time, but half of you. your journey, you won't have to cycle. Freewheeler, yeah, it's great. So I think you've sorted. That's what I issue.

Do you listen to, you've got your bone conducting headphones? I do have bone conducting headphones, but I don't tend to listen to anything when I cycle. I don't listen to anything and I don't even wear like cycling glasses. Because when I first got into cycling, I was like, oh, you've got to get your cycling glasses and you get like, because it was bugs flying to your eyes. Yeah, yeah, I was going to say, but you love it when bugs are in your eyes. But you know me famously love. Bugs in the face. Yeah, this is stopping the fun part.

You just chuck them off. Get out of here. Rubber men. So, I cycled recycling glasses for a while. And then I realized I preferred cycling way more without them. You look better. Number one, I look better. No, it's because I like being present in the place.

But I don't like having music or glasses or anything else. I wear a helmet, obviously. Part of the fun for me is zipping through the countryside. That's really nice. You're out in the countryside. It's a lot of fun. Yeah, okay. So my theory was if I can do the 80 miles without dying and feel fine.

Because then a while ago, I did some longer rides, and at 20, 30 miles, I was really starting to fatigue. And I was like, oh no, what if my training hasn't helped? So this was a proxy. This was just a sense check. and I'm fine. You've seen me today. I've been walking around like a normal human. Yeah. I did not know that you've been on a bike for a long time. Exactly. You weren't walking around like a cowboy. Not that I'd noticed. Other than the normal amount I do.

Yeah. Yeah. Yeah. Yeah. And I'm mine quick drawing. Yeah. Yeah. I got that big hat on. Whenever you're like, can I get a drink or I'm always like, push you can. You're like squint your eyes. Yeah. Yeah. Yeah. Yeah. Apart for that, it has given me the confidence to go ahead with the race and I'm not doing anything more foolish than normal. No, genuinely, I really hope you get to do it this time. I hope you have a lovely one.

I'm very excited. I hope that any of your anecdotes from it are very, very funny and yet pain free. Oh, it's going to be a whole thing. But if anyone's there, like, it's very unlikely, but this episode goes out days before the ride. Yeah. So it's on the 16th of May. If anyone's at the seven gravel race,

I'll be around before the race. We need to be there for 640 in the morning. But if you happen to be around beforehand, I'll be there probably a bit before that at the starting line. Before 640. I'll be milling around, tall, lanky, bald guy. Come and say hi. Are you sure you want to meet up with the sorts of people

who'd be willing to get up before 640 to see you? Yeah, 100%. Then they have to do the ride. You can't see me unless you're going to cycle the ride. Yeah, yeah, 100%. Yeah, yeah, yeah. Not just rocking up to, you. get you to sign a calculator.

Or you've got to show up in full cycling gear with a bike and then just wheel it back to the car and drive away. If you do that, you deserve a signed calculator. Oh, 100%. 100%. Or you can try and find me a nan up afterwards, but good luck. Spoiler, I'll be in the brewery. Well, I'm glad that you're talking about your gravel ride on the rock episode. I think that sounds right.

That's the best I could do. Yeah. Anyway, how have you been back? I went to visit my nan. Have either of you. played the game sequence sequence no

well we're not going to do it we're not going to do it we haven't finished Connect 4 back at lunch you've got it at lunch we're going to play a game of sequence

wow I forgot how much I love this game this is like Connect 4 but with cards like you're playing cards and then you're putting tokens on a board to try and create

rows but I got real addicted to it and my nan, she's 94 and... Old as a rock. Old as a rock. I think that's young for rock ages, actually. That's a good point. Yeah, I think she's young for a rock.

Yeah. Young for a rock. Young for a rock. And I've been seeing someone and they came out to a rally with me. So they came with me to meet my nan and I went to her. room, she's staying in a care home, went to her room to get sequence from her room so we could play it. And left the two of them alone, which afterwards he said he was quite nervous because you're being a family member, you've never, a major-year-old family.

Yeah, yeah. And she turned to him when I left them alone when, you know, are there any other card games that you play? Because she loves card games and she's like, she was all into her bridge and cribbage and all of like, you know, and she said, oh, do you play any card games? And he said, the moment she has a question, every single card game disappeared from my head. Like, I could not remember any card games I've ever played. And he just went, um, uh, snap. She just went, snap, that was a game for babies.

And I was like, welcome to the family. Like when he told me, I was so proud of her. Yep. I'm excited to share this new addiction. With you both. Shall we just bang through this episode so we can get to the game? Yeah, but you know, by providing quality content for our listeners. But, you know, we just knock it out a bit quicker.

Our first problem, rock-related problem, I should say, comes from Tristan, who asks, how much gravitational potential energy is there on Earth? If we threw all the rocks off of all the mountains into all the valleys and made Earth one perfectly smooth sphere. Not another smooth earth. This is the opposite of flat earth. I don't you hate the smooth earth conspiracies. Or oblate spheroid.

How much energy would that generate? Oh, so it's not enough to make the earth smooth. You want to know how much energy it would generate to throw rocks off mountains into valleys. Okay. And how long could we sustain our current global energy consumption with that? Right. So yet again, a question that I don't understand, even as I'm reading it. Matt, explain more.

You can store energy as potential energy. And places do actually do this. So if you've got more electricity generated at one point in time, then when you need it, which is an issue with some renewables because you get energy when the wind's blowing and maybe you want to use it a different time. Yeah, I mean, that was the big problem for a long time with South Australia. We had the sunlight. Oh, yes. But we didn't have any way of storing our solar energy.

Yep. and it's the one time where the arrogance. Yeah, you know. The arrogance of a billionaire actually. A stopped clock. Let me do this and if I can't do it, I'll pay you back 10-fold or whatever. There's a big old battery. And yeah, now we've got.

I mean, big old battery. Now we all run off of solar. Big old battery. Yeah, it's great. Other places have done a similar thing, but they'll like literally pump water up into a reservoir that's at a higher altitude. So the surplus power runs the pumps to shove the water up there. Okay.

And then when you need the power back, flowing water through a hydro power station is very mature technology. You let the water flow back down again and you use that to drive the turbines and get the power back. It's a potential energy battery. You're spending the energy now, but you can then use it again later. Ah, I've never thought of it. And that's probably what it is. Hey, I think of it like saving money and it just sits somewhere. But it's not really that.

You've got to use it now. Yeah. You've got to use it now, but use it in a way where you can get it back. These are all different ways you can store energy, but the goal in general is to be able to then get it back later. But nothing's perfect. Like the battery one, even a battery is not 100%. You're storing the energy by spending the energy on a chemical reaction

that you can then reverse that chemical reaction later and get a bunch of energy back. I feel so dumb, but I feel like I've never fully understood. I know the battery sounds like, I can't do the chemical. Yeah, but you're going to get a couple dumb because... I'm sure they taught me in school and then I was like, well, don't need to know this. Yeah. That sounds likely.

And your bank account analogy is not a good one. No. The equivalent would be, like, you've got a bunch of money now. You'd have to spend it on some things that you could then sell later. You buy a house and then later you can sell the house. Oh, I'm going to buy a bunch of watches. And then I'm going to sell. sell them later or something like that. I can buy something for a hundred bucks and I can sell it later

for 80 bucks and having 80 bucks in the future is better than having zero. And if the money's going to, like the voucher is going to expire. Yeah. You're like, well, I may as well spend my hundred buck voucher and get 80 back later. That's how a lot of businesses hide money, isn't it? Oh yeah, money laundering. Yeah. Yeah. Yeah. Yeah. In conclusion, money laundering. Batteries are energy laundering is what I'm saying. Yeah, yeah. I love this. And so a type of energy laundering is using potential energy. What Tristan has cracked, Tristan's like, wait a minute, why don't we just use the potential energy that's already stored in a mountain? Yeah, kind of like what we already do with oil and stuff. Yeah, exactly. Hey, there's all this energy

here. Why don't we just use that? Or in this case, push it off the top of a mountain. I don't know. You sense it on the mountain, some guy at the top just starts pushing it down. Yeah, it's got like a big stick. And I don't know if we tie a rope to it Or it lands on a spring or something I don't know I would karate kick it And run up You karate kick it?

And then we got to find a way Because you don't want to waste the energy Not just slamming into the ground We want to then it lands on a lever That generates power somehow Like there's some details to work out later But the point is The point is

You karate drop the top of a mountain Bit by bit And we convert the falling rocks to energy solve the energy crisis. Yeah. Now, there's some problems here. I then had to work out how much potential energy there is in all the mountains. Yeah, sure, easy.

Is it? No. They're weird. Mountains are weird shapes. They overlap with each other. They're all different sides. It's the usual. I was like, well, I reckon I can get a ballpark figure on that.

And I looked into it and I couldn't. You can't even get a reliable, like, what's the volume of Mount Everest or anything like that? It's just an absolute nightmare out there. Wow. Well, it's just a poorly defined question. Like, you know, mountain ranges have multiple peaks. Like, what's the volume of one peak or one mountain when they're all smushed together?

Way every mountain. That's exactly. I thought I would, given the starting at the beginning, was a dead end. I thought, you know, what if I sneak up on this problem from the other side? and then karate kick it. What if I loop around to the other side of the mountain? And I thought, well, hang on, how much energy do humans use?

Ah, I was thinking how much energy would it take to put more rocks on the mountains? To put a bigger mountain. It's real suspiciously in task. To work out how much energy is in a mountain. So the fine people at our world in data have got plots of consumption of energy over time. And at the moment, well, their data goes up to 2024. 2024, 2024 had humans using, in a year, 180,000 terawatt hours. For the record, in the year 2000, so this is like quarter of a century ago, we were at

123,000, and now we're at 180. So it's gone up by like a half. But that's not a huge increase. It is when you consider it's within our lifetime. That is also true. within the lifetime of some of our listeners because we're old. We're old. And so I thought, you know what, I'm going to call it 200,000 terawatt hours for convenience.

Sure. Go up a little, knock it off. And then I thought I'm going to turn it into a real unit. No one's going to complain of us producing more electricity than needed. Yeah, exactly. Yeah, that's overshoot slightly. And I was like, right, switch that to a real unit. So that is approximately 7 times 10 to the 18.

So seven with 18 zeros, joules per year, which is a big number. Okay. That's a lot. And I thought, well, hang on a second. Why don't I just work out how big one mountain would need to be? So if you push that one mountain over, it would give you enough energy for a year. It could end up being comically bigger than all the mountains on Earth, and then I can answer the question. Or could end up being embarrassingly small.

And then I've also answered the question the other way around. Yep. So I approximated a mountain as a cone. That's a fun shape. The center of mass of a cone, delightfully, is exactly a quarter of the way up the cone. In which direction? Up. Well, you see, when you say cone, I'm thinking ice cream cone.

Oh, my goodness. Mountain orientated. What ice cream. You know, you got ice cream? You got a mountain. You got snowman nose. Those are the three orientations of a cone. Okay, no.

So, okay, right. So it's quarter of the way up from the base. A quarter of the way up a cone. Very neat, very neat, bit of maths. Big fan. And the volume of a cone is a third of pi times the radius of the base squared times the height. You know, any base shape with an apex above it to make a whole cone or a pyramid or anything is always just a third of, if it was a prism, if it was like, the same shape at the top as well as the bottom.

Oh, okay, yeah, yeah. The only two things I was missing now was the density of the rock, because you know how heavy it's going to be, and are good friends over at the Department of Earth, Ocean and Atmospheric Sciences at the University of British Columbia in Vancouver. Shout out. Exactly. They estimate that the density of rock. The density of rock is very different to the destiny of rock, I feel like. Yes.

That's a musical album. The rock of destiny. Yeah. And the rock of density. Yeah. They point out actually, they're like, look, in terms of substances, rock is pretty uniform. Your sedimentary rock is the least kind of dense end of the spectrum. That's about 1.6 tons per cubic meter.

And you go all the way up to your real solid rock, three and a half tons per cubic meter. I took the average. I said two and a half tons per cubic meter. And I picked a 30 degree slope for the side of our mountain, which seems to be about right. Some mountains are steeper, some of less steep. That's my angle of repose that I went for. That tends to be like the acceptable one for what we'd expect from mountains. People argue that like, oh, mountains are pointier than we expected, but I wasn't going to get involved in that.

So that's what we've done. which means the base is almost twice as wide as the height. Yeah. I put a bunch of numbers in an equation. Quite nicely, this is just a little side fun fact for everyone. The final equation for the potential energy of a mountain is based on the height to the fourth power. Fourth powers in the real world are a wonderful gem to discover. Okay.

And it's because the volume is a distance cubed. And if I've already converted the width of the base to be a ratio of the height, the volume is a function of the height cubed. And then potential energy is multiplied by height to get how high up it is. So you end up with H to the 4 for your height. Anyway, plug the numbers in, take the fourth route, et cetera, et cetera. 4.4 kilometers. 4,000, 400.

hundred meters is the height of a mountain that it would have the potential energy to fuel humankind for one year. Okay. That is not very tall. No. Everest is about 8,000 meters, twice as high. Oh, because it's the fourth power, Everest is twice as high as we need, and two to the four is 16. It would have six, it could do 16 years. Uh-huh.

Mention that. No Everest, but 16 years of power. I know we're talking about pushing mountains over and some mountains are very important to people. Oh yeah. And climbers would be real upset. And I don't want to anger climbers with their little sinewy fingers. So. They can pitch you so bad.

I know they can poke me. Ow! And climbers really get hung up on stuff. Yeah. Nice. Yeah, no. A mountaineers are not people to get over something easily. There we are.

Hey. Anyway, the point is, there are lots of mountains that big. So I went to the Wikipedia page for Mountains by Heights. Great. And it very clearly says this is not exhaustive. There are a whole load missing. But just of the ones that happen to be on the Wikipedia page, all the ones above are 4.4 kilometre height.

I counted them and there were 425 of them. So it's at least 400 years. of energy. Wow. Now, people are going to say some of these mountains are peaks and they overlap

and I'm like, yeah, but there's ones we're not counting and a bunch of them like of those nearly 300 of them above six kilometers high.

That's way more energy. So given you only need a four kilometer high mountain for a year's worth of power and there are hundreds of mountains that qualify

to answer Tristan's question how long could we sustain our current global energy consumption with that, I would say at least 400 years. In conclusion, centuries. That's probably a bad idea. I'm going to distract you with my new favorite rock. Oh, yeah, yeah, yeah. Okay. Get this rock out. All right, that is a nice, that is a nice looking rock.

You know what? I'm going to moisten my rock. Oh, okay. You know my catchphrase. Yeah, and I keep telling you to change it. You do, you do. And you're right. Look at that. Look at that rock. Matt has produced a really nice palm-sized. It's a good size and shape rock. Yeah, it is good shot. Even before you moistened your rock. Pre-moistening.

It had a lot of different sort of colors and sort of layers to it. Sort of if you could imagine a rock that embodied autumn. Yeah, it's a little time of rock. There's some oranges, some darker reddish brown tones, some lighter, a creamy beige tones. Found that on a beach in Wales. It is a lovely, lovely rock,

very smooth, which is surprising considering how it seems to have lots of different. Yeah, beach rock, classic beach rock. Yeah.

And then when Matt moistened it, the colours really popped. It's got a good future as a paperweight. I've been talking about rocks and minerals. And at a moment, you're going to be talking about teeth. Yeah.

And what's the crossover in the middle? It's rock. you eat with your teeth. Candy. Salt. Oh. Disappointing. Or is it?

Well, probably. Salt of the Perth is back. Yay! So the stickers, you very kindly made me a label so I could smuggle my homemade sea salt. Yes. From the southern hemisphere to the northern hemisphere. Correct. And it worked a treat, by the way.

I got the salt here in the northern hemisphere. I then took it. Which was a surprise. considering, for a recap, if anyone's forgotten, the jar you brought it in was like a pasture jar and the salt only is a fine powder that only filled it up about. It's not good. Like a sixth of the way? Yeah, it went from looking like a suspicious powder.

I thought I'd make it look like a real product, but it went from looking like suspicious powder to looking like a suspicious powder someone was trying to disguise. Yeah, yeah. You made it worse. Yeah, definitely made it worse. And, oh, I had a whole bunch of surplus stickers because I had to buy like 80 to get my custom sticker. I have now run out. Ah.

Do you not know if you were out back? Because we said anyone who comes up to us in real life and says blah, blah, blah, can get a free sticker. I am also out. Yep, done. So they've run that course. Wonderful time. Sorry to everyone who kept asking and I had to disappoint.

because we were done. It was a one-time run. Old salt, the sticker was still good enough to get it into the US and back out again. Oh, great. Wow. I didn't want to post suspicious powders in the post. You wanted to carry it with you? Through international.

I want to carry it with me. During a time where... Traveling into the States is... In no way problematic. I'm not saying any of this was clever. But the reason I wanted to get the salt into the States is that two people... Andrew and Tristan. Same Tristan as...

Different Tristan. Ah, multiple rock Tristan's. Love of rocks and minerals. Yep. Andrew and Tristan both got in touch with different offers. They both had access to lab equipment. That could analyze old salt of the Perth. Amazing.

Both in the States. So I thought I'd get the salt into the States. Then I packaged it up in a suspicious zip-lock baggie. Yeah. Did you whack a sticker in? I put a sticker in. Great. I left it loose so they could decide what they're going to do with that.

The sticker. The sticker. Not the salt. The salt wasn't just tumbling around in the oven. So they're both in the state. So I posted the salt. They both received it fine. And they got to work.

Oh, my goodness. I'm so glad that they were able to do this after we'd ingested it. Yes. Yeah. Yeah, yeah, yeah. I mean, okay, the headline stat is fine. Oh, yeah. Not going to die.

Not going to die. Hooray! Now, there are some nuances within that, however. Go on. So, let's do fun news first. Oh, no. This suggests that there's unfun news. Now, Tristan's main thing was to put it in a scanning electron microscope.

So we can have some cool pictures of the salt. Now, before I show you the cool pictures of the salt, the type of scan they were doing also gives you some information in what's in there. It turns out it's salt. It's mostly table salt, sodium chloride, boom. That's it. It's also got a little bit of calcium sulfate, different salt, perfectly fine salt. It's also got a little bit of magnesium sulfate.

Okay. Which is a mild laxative. Epsom salt, as it's commonly known. But these are in very small quantities. So anyway, we got calcium sulfate and magnesium sulfate kicking around. but they're just like other less fun salts. So that's all good. Just and put it in the old electron microscope.

So we have a little... Do you want to... Do you want a little squiss of that? Whoa. Whoa. It's like Minecraft. They're really cuby, aren't they? They're so cuby.

So there's like the main shot which shows just all the salt. Now, other ones are like close-ups of different bits of this. Like just that main one, like the... the family portrait of all the salt. It looks like an Escher diagram or some kind of collection of broken rubyx cubes. Oh no, you know what it looks like? It looks like an everlasting gobstopper from the original Rilly Wonka film or Charlie and Chocolate Factory film. Ah, yes.

You'll also see a file called not underscore salt. Dot. tiff is a close up of like a clump of other stuff. Yeah. Yeah. Yeah. That would, like, it looks like a bunch of pencil shavings. Yeah. Like, still.

Like the little bits that you haven't cleared up, but like you get the big bits of pencil shavings and then there's all the little bits of graphite and everything. I mean, it's clearly still some kind of crystal structure. And I don't know what that is. I don't know if that's just weirdly formed salt. I mean, Tristan seems to think that's not salt. I don't know if it's one of the other ones. I don't know about you.

I'm more inclined to believe. The science person. Nah. Yeah, we're looking down. So these are on the little scale at the bottom of these. That's 200 micrometers is what we're looking at. That's nuts. That is some small salt.

But it does bring me to the conversation about not salt. So Andrew also did some analysis of salt of the Perth and looked at what other elements. So not just salt, just straight up atoms. What other elements are actually in there? Obviously, sodium chloride. That's no one surprise there.

Then, as we were just discussing, calcium and magnesium are both there in pretty big quantities, as is potassium. You need those in your diet. They're fine. Yep. Then there's some other ones. This is less fun.

Now, there's a big drop-off after we go past potassium. These are in comically small amounts. Okay. These are parts per million measurements. Like I might get this from everyday drinking water or whatever. In fact, the only ones that are more than one part per million are strontium. Great name. That just makes you stronger.

Yeah, sure. That's why it's called strong. I believe that. Strontium is fine, pretty inert. And silver. 13 parts per million silver. Now, I did look up silver. It's pretty low toxicity in general, but enough of it will cause problems.

Sure. As with anything. We're talking parts per million in salt that you're then going to dissolve further and other stuff. This isn't like parts per million in any food or anything it ends up in. This is in the actual salt itself. Right. There's also some zinc in there. 0.138 parts per million.

I mean, we need zinc. Zinc's good to eat in small amounts, but this is not going to fulfill your zinc requirements. Not your RDI. Which brings us down to the bad news. Right. There are, however, two elements in there you'd probably not want to eat. You've got some lead. Point two parts per million lead.

No, you don't want lead. No. I then looked up, what is? like a safe amount of lead to be to be chowing down on and are good friends over at Scottish water. I mean, there are other water bodies. They just had a really nice information booklet. So I found Scottish waters.

Fact sheet number seven, lead explained. If you're reading along at home. Yep. And they talk about how they analyze how much lead's in the water they're supplying in Scotland. kind. And in fact sheet 7, sub.7 is the legality of what are the regulatory standards for the amount of lead we can have in drinking water. Can't say I'm in love with the word legality. I weren't like safely.

Safely. Legally. The maximum safe amount. The maximum amount that you're allowed to put in there without someone suing. you. Correct. Is 0.01 parts per million. And we're running at 0.2 parts per million. Oh, that's more lead than you're allowed. But that's lead in drinking water. That's true. We're not drinking at all. Well, it depends how much you dissolve. So if you put it in food where there's 20 times or more food per salt. then you're well within the normal recommended healthy limits.

Yeah. If you were just eating spoonfuls of the salt. I mean, you'd have health issues. Like the salt would get you before the lead does. But yeah, there's, you know, it's on the order of, if you're doing a 20 to 1 mix, it's on the order of what you'd get in normal drinking water. But it's not zero.

Yeah. There's also thallium. Fun, fun word. Thallium is particularly bad for you. Oh. I can't find out where that really sits on the thallium scale. So I found a 1977 paper called thallium in salt substitutes, a possible health hazard. Oh.

Yep. They were worried that these were like alternate salts to get down your sodium intake. And they're like, some of these have thallium levels up around 0.4 parts per million. And sold to the Perth is 0.416 parts per million. Oh. Oh. So, I mean, that was 50 years ago. Mm-hmm. Now, I don't know if this is like, you know, a bit of knowledge is a dangerous thing.

And you can get paranoid about, it's like, when people discover about the notion of background radiation and how we're constantly exposed to radiation in our entire lives, but there's just different levels of it. Yeah. I don't know if this is a background radiation thing where now I've just seen a number and I haven't got the context for that number, I'm going to worry. Or I don't know if it's actually something to be worried about. Yeah. Both Tristan and Andrew did make it very clear that they are not qualified to speak as to. the health of any of these things.

Oh, I thought you're going to say they made it very clear that they are not going to eat it. No, nor did they panic, nor did they be like, whoa, watch out, buddy. So, you know. I'm just going to read you a little line that I found from the centres for disease control and prevention. CDC.gov. Is it something like, there's no safe amount of thallium? This line has just made me laugh, given that you're giving it to us in food. Thallium is tasteless and odourless and has been used by murderers as a difficult

to detect poison. I knew it. I knew it. But this might put off investors. Yes, we might struggle for the next round of seed funding for salt to the Perth. So anyway, that's where we're at with Salt to the Perth. I'm going to keep eating it in moderation. Yeah, which I mean, when salt's concerned, yeah.

Yes, which is good in general. If anyone else out there is a thallium expert, get in touch. And I look forward to getting back to Perth to check in on your crystal on version 2. Extra Flaky Edition. Yeah. See how that's looking. There you go. Pretty pictures.

Yeah. A little bit of lead and valium. I wonder how that would affect your teeth. Segway. Beck. Yes. It's tooth time. Yay.

We have so many teeth questions. Yeah. It's almost like we solicited them by saying there's going to be a special episode about teeth. Yeah, and people showed up in force. Yep. So, first problem comes from Daniel. Daniel has a problem that they say combines two a problem squared favorites, oral hygiene and probability. The situation they're facing is they currently brush their teeth right after breakfast slash coffee in the morning.

But that's not ideal. Apparently, it's best to wait about 30 minutes. after eating before brushing your teeth. Now, these days they work from home. So they could wait those 30 minutes, but they're distractible enough that they know they'll sometimes forget to brush their teeth if it's not like an immediate part of their pre-work morning routine.

This is where the probability comes in. Obviously, if they never forget to brush, delaying would be the optimal way to go. They give the hypothetical if delaying brushing meant they forgot 100% of the time, it would be a bad idea. That's very true, Daniel. We don't think we need a dentist to say brushing your teeth zero percent of the time is not good. Yeah.

So they want to know what's the tipping point? How often, I'm paraphrasing here, how often would they have to forget to brush their teeth 30 minutes later to negate the benefits of waiting at all? And I believe you've got a solution for us. Yeah, the way I came to understand it, the way I paraphrased it for dentist Sophie, the doctor Sophie, as an example. would it make more sense to brush your teeth 30 minutes after eating, let's say, Monday to Friday, but you forget to do it on the weekends in the mornings? Yep. Then it would to brush your teeth immediately after eating every day.

Yep. And Sophie's answer was really interesting because I was thinking this is a probability thing. We could have to look at ratios or not. But it's based on so many variables that you can't really, like unless you had a control group of like everybody has the exact same food and it affects their teeth in the exact same way and all this sort of stuff. But because everyone's teeth are different, you know, everybody's bodies are different. Whoa, you're saying there's too many factors.

Way too many factors. That's not our attitude around here. So if you really enjoyed having a think about this one, so the reason you're supposed to wait at least 30 minutes after eating is because food often has an acidic level. so it lowers the pH level. So it lowers the pH level and the acidity is, you know, it starts to wear away at the enamel and makes it sort of softer. So if you have something that's quite acidic,

especially if you're having like orange juice or something like that and then you brush your teeth immediately afterwards, the enamel is already soft and you are then rubbing on soft enamel. So you're actually more likely to start wearing away at the stuff that is good for your teeth. So that's why you're supposed to wait 30 minutes. Now, the reason of wait 30 minutes is because your saliva, saliva is so magical. Saliva produce the thing that rebuilds your teeth on its own. So our bodies have created a way of neutralizing acid, of remineralizing teeth.

And so our saliva is filled with all these amazing things, which, Sophie will go more into detail on one of the other problems. but saliva is incredible. Yep. So when you wait 30 minutes, it gives your mouth chance to neutralize all the acidity and then brush your teeth. Dentist Sophie said

generally she would always advocate for brushing your teeth than not brushing your teeth. Classic dentist. So even if you are slightly damaging the enamel, brushing them arguably will... be more beneficial.

So Sophie suggested that next time, Daniel, you go to your dentist, you get your teeth check, ask if there's been like any signs of erosion or abrasion or anything like that. Yep. Because if you've got like particularly strong teeth, brushing it immediately after breakfast might be okay.

I'm into it. She said, actually, if you want to speed up the process of neutralizing the acid in your mouth, after eating. Cheese or a glass of milk will really speed that up. So I asked Sophie, what if it's coffee? Will that help?

So Sophie looked into it. And does it have to be cow's milk, by the way? Right. Would you like to hear from Dr. Soffi? I love to hear from Dr. Sophie. Coffee with milk, regardless of whether it is cow's milk or otherwise, is almost neutral. So it sits in that sort of mid to high sixes range. The critical pH for dissolving enamel is 5.5 or if you use fluoride on a regular basis, it's 4.5.

So you'd be very safe to have coffee with milk and then be brushing straight after that. It's not going to create an acidic enough environment to do enamel damage. Like with most of these questions, I think the safest bet is always just to speak to your dentist and see if your individual risk factors put you at risk for that kind of wear. It's not saying necessarily that the coffee will neutralise all the acidity from your breakfast, but if you're just having a coffee, you could in theory probably brush your teeth straight off the coffee. Now, dentist Sophie keeps saying that we should just talk to our own dentist. But what she's forgetting is that she is everybody's dentist now.

Yeah, that's right, yeah. And that's why we're asking her. Why wouldn't she put us all in the same box? I know. Now you phrase this as forgetting twice a week on the weekends. As an example. As an example. Exactly.

And that happens to be about 14%. And obviously, dentist Sophie is like, it's better to brush your teeth than not. But depending on your teeth, there could be some advantage to brushing your teeth later than. immediately. Like, we all agree on that. And if you were to forget to brush your teeth one time in a million, that would not counteract that benefit. So there is, there is a value somewhere in there. But what we're saying is it's so small, it's not worth worrying about. Yeah. You should just brush your teeth.

If you're aware that you could even forget, the, the probability is too high for it to be worth it. Also, talk to you don't exist. Yeah. Because sometimes some people might have teeth that are a little bit more smushy than others. That's me. I got weak enamel. Yeah. I have to use low abrasion toothpaste. If you are likely to forget if you don't do it immediately afterwards, then finish up your breakfast with something that will neutralize that acid.

You know what I do? Brush my teeth before breakfast. The thing is, that's what I do too. It's bold. Now, I'd like to thank Daniel for having the last reasonable name we're going to. going to see in a while. Up next from The Fart King, one of your fans back. Someone once asked XKCD. Oh, so Randall Munro. Who's a very good sort of cartoonist with a science twist. That's him. So someone asked

Randall if you could shatter your teeth with thermal stress by drinking or eating something cold and then something hot all the other way around. XKCD just labelled it as distilled. but I think it would be very interesting to get an answer. So my question is, this is still the fart king speaking, is it possible to shatter your teeth or damage them by thermal stress by eating or drinking, excluding stuff like liquid nitrogen, kind regards the fart king. Would you like to hear from Dr. Sophie? This is a very interesting question.

I don't believe it would be possible to shatter a tooth through thermal stress. with food and drink because obviously there's quite a hard limit on what you can ingest without burning your soft tissues or freezing your soft tissues. So I would have thought that the temperature range from the coldest thing you could eat or drink to the hottest thing you could tolerate wouldn't be enough to damage your teeth. But certainly teeth are prone to thermal stress and there's two things that it made me think of. One is that when you cut a tooth, for example, taking out decay from a tooth and you're using a drill, so you're using a diamond to cut away the damaged part of the enamel, you need to use water to spray onto the bear at the same time. Because if you don't, the pulp of the tooth, which is the fleshy part with the nerves and the blood supply within the tooth, sits like a cave in the middle of the tooth.

The pulp will become damaged. and sometimes that's a reversible damage, which means that that person might have sensitivity from that tooth short term after the filling. And sometimes it is a permanent damage. You can actually cause pulp necrosis, so death of the pulp, which would then lead to that person needing

a root canal treatment or an extraction. So it's very important to irrigate the burr while you cut a tooth, which is why for anyone out there that's had a filling, It always feels like your mouth is full of water. And there's just water spraying all over your lips and your cheeks and, you know, filling up your mouth. And hopefully you've got a lovely dental nurse there who's helping to manage that amount of water. But it's actually a really important part of the process.

Certainly you can damage a tooth with heat, but I would argue through food and drink, that would be quite challenging. The other part is that because teeth are in three parts, because they have enamel denteen and pulp, each of those things. three parts have a different thermal resilience. Enamel is going to be a lot more resilient to thermal stress than the pulp of being a soft tissue. So I think the idea that your teeth could shatter is quite unlikely because you might be able to create cracks through the enamel or cause pulple necrosis. But to be able to create a condition where all three of those structures shatter, I think would be quite unlikely. Okay, that's interesting.

So you can damage your teeth with temperatures. I like that Dennis Huffy's like, you know when you're drilling into a tooth? Yeah. And we're like, yeah, normal everyday activities. I was wondering why they're always, I was like, gosh, how dirty is my mouth that they am to spray in all this water? But no, it's so that my tooth doesn't burn from the drill. I always assumed it was like when you're machining something on a lathe.

Now, you know how you just had a go at Sophie? Perfectly normal activity. When you're machining something on a lake. No. So the moral of that is pulp will heat itself. And if it gets too hot, it'll be damaged. Yeah. So you're going to keep it cool.

But it takes drilling or cutting the tooth to cause that. And normal temperatures in food won't cause that much of a swing. And I'd be lying if I said I hadn't asked this, like mentally asked myself this question while like going from a hot drink to like an ice cream or something. Oh really? Yeah. Oh, okay. So it's a common, common fear.

Well, because I do get, I get sensitivity sometimes and I was like, uh-oh, is this the beginning feeling of my tooth smashing? Okay. So you and everyone else can now rest easy. Yeah. Up next from pie not tau. P&T says there is this craze going around at the moment for revitalizing gum, in quotes, that claims to be far superior to brushing your.

your teeth, dang, and reverse cavities, quite bold statements if you ask me, and that's if you ask pine, not tau. I want to know if it is even possible to reverse, in quotes, cavities, and they're under the impression that it's not. And if chewing this kind of gum is in fact better for your teeth than brushing them. What did you find out? Okay, so I had also been targeted with some of these ads. Oh, really? This woman who was saying, like, how this gum was so amazing that her cavities were gone. And, like, within a few months of chewing this gum regularly, her fillings just came out because they'd been, like, pushed out by the teeth here. By the teeth growing back.

Wow. And as soon as I heard that, I was like, I think her gum has pulled out her fillings. Like, I don't think anything can do this. I don't think anything was pushed. And if her feelings have come out. They were pulled. And I say this is someone who, I think at least twice, I've pulled out fillings with my gum. Right, right.

As an expert filling remover. But I tried to find that particular ad. I couldn't, but I did find these. Pye NotTow did say revitalizing gum. Most of the ads I found were for remineralizing gum. Oh. That was a big term. But they're minerals back.

Yeah. That's a piece of gum that's single-handedly putting the dental industry. A business. How's that even possible because it's remineralizing? If you've been to the dentist recently, you'll notice that when they detect very small cavities just starting, there's some stuff on it called nanohydroxy appetite that they put on that just starting cavity that remineralizes your teeth. And guess what's in this stuff? Nanohydroxyapatite. Along with a whole lot of other stuff, xylitol, arithratol, mastogum, acacia gum, spruce gum.

You'll notice that's all stuff that comes from nature. If you want to pick some of this stuff up, it's on sale right now. They got free shipping too. I got a link below. Yeah, it's funny. It's always like a link in there. Oh, just listening to any of that made my teeth hurt. Yeah, yeah, exactly.

So we heard from Dr. Sophie about that too. Oh, she had thoughts. Yeah, and I think she's going to say it much better than I ever could. This is a complicated question, and I think it helps a little bit to understand what remineralizing means, because the short answer to this question is that any chewing gum that doesn't have sugar in it is remineralizing. what this product is claiming to do is very well founded in science that's been decades long but that's been a known a known thing so this is not new but there's a pretty hard limitation to what it can do so your teeth are made of a crystal and that crystal is called hydroxyapatate and it is

susceptible to acid damage and the way that that acid damage occurs is that there's a that lives in your mouth called streptococcus mutants. And that's the main cornerstone bacteria of plaque, which is the fairy feeling that builds up on your teeth each day. There are other bacteria that are involved in decay, and this is a very, very simplified version of this. Basically, the streptococcus mutants in your plaque, that bacteria, sit on the surface of your teeth.

And then when you give them a fuel source, which for them is a sugar, they metabolize that sugar and they create an acid, which then sits on the surface of the tooth. That acid then dissolves those hydroxyapotite crystals, and that process is called demineralization, because you're taking mineral out of the tooth. So if that process continues over time

and you continue to get demineralization of that surface, eventually you'll lose enough crystal that the surface of the tooth, will collapse into a hole or a cavity. The reverse process of that is when the surface is still intact, there's been some demineralization occurring, but the ions that make up enamel, so calcium, phosphate, and fluoride, which is sort of chemically a little bit different, but regardless, those ions can come in and repair that mineral damage to the surface of the tooth. And that process is called remineralization.

And your teeth are in quite a constant state of de-mineralization and remineralization. You eat some sugar, you create an acidic environment in your mouth, that plaque starts to demineralize your teeth, and then your saliva comes in and helps to buffer those acids. The physical chewing action of foods that don't have sugar in them, abrades the plaque off your teeth, you brush your teeth, you drink water, and then all of that remineralization occurs. So this happens every day in our mouths, back and forth between demineralization and remineralization. And the summary of it is that if you have more de-mineralization over time, then you can remineralize, you get a hole. And there are areas of your mouth that are more prone to that, so that are in between your teeth that are harder to get to.

surface of your teeth where you chew, and if you have braces, the areas around the brackets. So we can see that pattern happening in the mouth every day. The reason why chewing gum is remineralizing is because it's just as simple as it's stimulating your saliva. saliva is incredible and has so many amazing properties to it that help to reduce decay in our mouths. It contains bicarbonate, which is a buffer that helps to buffer the acids and return our mouth to a neutral pH. It's got calcium and phosphate in it, which are the building blocks for enamel. It's got components to it that help to break down the glyco protein that holds the plaque together. So the glue that holds all the bacteria together, it's incredible. And so anything that's going to stimulate more

saliva is going to be remineralizing. It's going to be positive for your oral health because it's reducing the amount of plaque on your teeth through all those mechanisms. So all of these products that claim that this is new technology that's, you know, capable of reversing all of this damage. We've known about this a long time. It's a very well-established evidence-backed mechanism. And yes, chewing any type of sugar-free chewing gum will reduce your decay risk and encourage remineralization through this.

of saliva. That being said, the other thing that these products are putting forward as their star player is xylitol, which is a sugar alcohol. And again, this is decades old research. I remember learning about this in dental school and them citing studies from the 80s that we're talking about xylitol as an anti-day ingredient. And it's very well established as well that zylotol has a capacity to reduce decay. And the way that it does that is that streptococcus mutants, the bacteria in plaque, identify xylitol as a fuel source

and will actually take it up into the cell, but they can't metabolize it into an acid. So it basically just gets in the way of that metabolic process that normally would result in an acid when you're metabolizing sugar. But because it's not a sugar, it's a sugar, it's a sugar alcohol, then the bacteria, take it up, can't metabolize it.

and then aren't able to produce as much acid. So in that way, xylitol is known as anti-cariogenic, which means not producing caries, which is the dental word for decay. However, the dosage of xylitol is quite important for it to be effective, and the evidence shows a small decrease in decay across the board, but not a compelling amount. And that's the reason why it's not sort of pushed as a dental product for everybody,

The other thing with xylitol is that it can cause gastrointestinal upset and higher doses. So there's always a balance. But it's not something that I routinely recommend to my patients. Chewing sugar-free chewing gum is absolutely something I recommend. The products themselves, looking at a few of their websites, I think it's always good to be skeptical of things that look too good to be true. One of the things that really bothers me about whenever a product says this, I'm already very skeptical is when they say this will put dentists out of business.

And that's not because I'm a dentist and I want to be in business. I take such personal offence to that because dentists want you to have healthy teeth. That is our entire job. We spend all of our working days motivating people to look after their mouths better. And the aim is to get you to a point where you have no decay every time you come in. As soon as somebody says this is going to put dentists out of business, I'm always on the skeptical side. Just looking through the ingredients, they've done it really well.

It looks very compelling because for each ingredient, they've then got a list of scientific articles that back up the evidence that that ingredient is beneficial for your oral health. But if you look at a lot of the studies, a lot of them are very old. A lot of them are low-grade evidence. So on the hierarchy of evidence, we're looking for randomized control trials, systematic reviews. as our gold standard of evidence.

And a lot of these are sort of case studies, cohort reports, like not huge and don't carry as much weight. I went down a bit of a rabbit hole on this particular product. And I'm very unconvinced. I think it's very good marketing. I think we're probably looking at a similar thing to when the charcoal toothpaste came through and everyone was behind that.

Looking after your teeth in some ways is very complicated, microbiologically and like I said, our individual risk factors can very much impact our own individual oral health. But at the end of the day, you want mechanical plaque removal in brushing, which is why chewing gum alone is not enough. So you want that mechanical removal with your brush, using a soft tooth brush, 45 degrees to the gum line and a very gentle circular motion going round each surface of the tooth. You want saliva stimulation, so anything that's going to stimulate your saliva that's sugar-free and not too acidic is going to be wonderful. And you want fluoride, which I know is a contentious topic and something that people feel very passionately

about. I believe in the net gain of fluoride, but the mechanical removal of plaque is what you're really focusing on. So to answer this person's question, yes, chewing gum can reverse de-mineralization on your teeth that is not the same as a cavity. It is not the same as a hole. Once the tooth has broken down into a hole, it cannot be repaired by anything other than restorative dentistry. So anything other than a filling. But yes, it can help remineralize the teeth before that damage occurs through saliva

stimulation. No, you don't want to replace your toothbrushing with chewing gum alone because you need that mechanical removal of plaque. that's critical to reducing your risk for decay. And then I think the last part was that a lot of these products contain nano-hydroxyapatite, which is a really interesting space in the dental worlds at the moment. As you might have already picked up,

hydroxy-appetites what the teeth are made of. And there's not a small amount of evidence coming through that's showing that using a nano-hydroxy-apotype product, which can be found in some toothpaste and some chewing gums, and some mouth rinses can help to rebuild those teeth more effectively than what we're currently using, which is a calcium phosphate. There's a few different sort of chemical arrangements that deliver those ions to the mouth through those products. But the hydroxy appetite is interesting. Again, it's not compelling enough that it would be my only recommendation. And certainly,

you can maintain great oral health without it. But that's probably the only part of this product that I think is really compelling is the nanohadroxy appetite. And the research is still coming out on that. So, yeah, certainly not a bad thing for your mouth. And if it's in a product that you're using, I would be happy with that. But not critical to run out and get it, I don't think, at this stage. Now, first of all, that's what a dentist would say. I'm a dentist.

It's my job to make sure that your teeth are nice. Yeah, yeah, keep coming to me, give me money, don't use the magic gun. Secondly, you know what is a great source of calcium? Your salt. Salt of the purr, yeah. And you're it. Just saying, it's complicated, you know, pros and cons. I can't wait to you bring out your stand-up maths gum.

Oh, yeah, with all the salt of the purse. Nano-salt of the perthicles. Yeah. I suspect that the idea. idea of a gum that reverses cavities has just broken down into people. And I'm including myself in this as well, not being 100% clear of what the difference is between cavities and decay. Yep.

Because you can reverse decay is what I've learned. You cannot reverse cavities. You can stop cavities from occurring. Yep. But once you've got them. But once you've got them. And if you lose a filling, it's not your teeth. being so healthy they're pushing them out.

Yeah, the cavity hasn't reversed. Yeah, exactly. Yeah. So, in conclusion, gum in itself, not necessarily a bad thing. Yeah. Some, if anything, probably a good thing. But it's not really the gum itself either. Like, it's got a few properties, but it's your saliva doing all the hard work.

Once again, saliva is the true hero. Yeah. Okay. Now, I'm going to do a condensed set of three people at once. Okay. Because they've all got, yes, technically, questions about teeth. But if you drill down into them, they're about you collecting teeth. So I feel like that's a sub-sub-category.

Rachel is concerned that Beck might be contravening the Human Tissue Act. What with all her buying and storing a teeth could call Rachel. Doron has a six-year-old who just lost his second tooth. As the closest real thing Doren has seen to the tooth fairy, they're passing a question onto you, which is, what does the tooth fairy do with all the teeth? Classic. And finally, Alexander, in this sub-sub-section,

would like to know what will Beck do with all the teeth. And, and I agree with you here, Alexander, how creepy will it be? Firstly, for any new listeners who decided, I'll come in on the tooth and rock episode. It's like a nice normal entry point. I buy teeth For money So I've looked into this

Because in speaking to Dr. Sophie Dr Sophie alerted me to something that is very interesting Oh Dr Sophie casually mentioned That she was going to do a special dentist course in London briefly And in order to do the course You had to bring your own teeth To practice on

Now, now, in my, now, everywhere I go when I travel, I bring my own teeth. I bring my teeth. Yeah, when I say her own teeth, I mean not the ones in her mouth. Oh. So she had to bring ones to practice on. And I quizzed her on this. And she said, you know, obviously you need to practice on teeth before you, she said, before you start, you know, drilling into.

She said teeth. Teeth still in use. When people have their teeth extracted. Yeah. If you're not given the option to hold on to your tooth or you haven't specifically requested. Now, I think in some, and it depends on countries and all this sort of thing. In some circumstances, depending on why the tooth is being extracted, like if there is, especially with older teeth, there is a particular type of like a ceiling or something. Oh, yeah.

Something that used to rebuild them that had like mercury or something in it. So like they do have to be, some of them definitely have to get rid of carefully. But when the teeth are taken out, with the patient's permission, they can be used to practice on. I want my dentist to have practiced before they get to my mouth. Exactly. Now, if they don't have permission from a patient, those teeth have to be disposed of. However, I had a little quick look into the human tissue act and looked into other things about disposals. of teeth in the UK specifically,

you don't have to dispose of them in a special way if there is like nothing wrong with them, so to speak. You can just chuck them in the bin. Just throw them in the hedge. Which when you think about like as a person, if you like baby teeth and stuff can just be thrown in the bin. There's no law saying you can't.

You can do whatever you want with them. You can just chuck them in the bin. You can sell them to someone else. Yeah. But what was really interesting is there was an article in the British Dental Journal in 2020 titled Collection of Extracted Human Teeth In Decline

Working Knowledge and Understanding of the Human Tissue Act by UK registered dentists Oh Basically there's not enough They're not getting enough teeth to practice on Because people aren't sure of what the rules are Right, yep And to be safe, they're throwing them in a hedge

So what they're saying is like actually more dentists need to get permission of patients and say, can we collect your teeth to practice on? And it was something that Sophie did when she was training. And that's what she was able to do when she was doing a big trip. So you can also give other people, like if you're a working dentist and you've got a, so she worked at one place where they basically,

they had a jar of them. Yeah, spare teeth. and they could then say to trainee, like trainee dentists could go to a dentist and say like, can I have some teeth to practice on basically? And the way they do it as well is they put them into like a resin jaw. So they would have to collect all.

It was like Pokemon. They'd have to collect the whole set. To get a whole set together. Which is amazing. So you can legally collect teeth. I've come to find. A bit defensive. So Sophie to go back to Sophie,

taking her teeth to the UK, she declared them on her form. No one questioned her about it. That's great. So she just brought them in. So there was no issues with that. She didn't find any issues. She said if there were any legal issues, then certainly no one made it. If they had any questions for her, would she have answered them using the practice teeth like a puppet to explain?

I'm here. That should be the law. Because dentists need training. You can only do it if you can explain yourself using. Via, yeah. Yeah, the teeth. Yeah. I did also look into like how do you trans, what's the best way to transport?

What's the best way to transport teeth? Which is how I found. Did you know this? I don't want to know this. If you have a tooth knocked out, like an adult permanent tooth. There's many street fights I get into. Yeah. Yeah.

Or if you come off your bike in a gravel race. That's extremely likely. Okay. Carry on. I'm listening now. Yep. If your tooth comes out, the full tooth, firstly, if it is clean, or if you have cleaned it, and it says you can clean it with saliva, because that's, it's the thing, you can just, if it fits,

put it straight back in and then go straight to a dentist. And time to lock it in. Your teeth can be put back in. That's great. So if you're transporting a tooth that's been knocked out, let's say for some reason your mouth is super dry, And you're like, I can't, I don't have enough spit to keep this fully soaked. Milk. Yeah, put it in milk.

Classic. And then get straight to a dentist. So yeah. So there's a little tip for anyone listening. Also, don't handle it by the root if possible. Pick it up by the crown. Pick it up by the crown. But don't pick it up by the root if you have a choice.

I hope this is not useful information for me. Look, I hope. Two weeks time. Yeah, I hope no one has to ever use this information. You're straight into a carry tree. You never know. At one point someone might come back and go, you know what, actually. Well, you're right.

You're right. This would be putting me out of business. You know it's... Putting the tooth fairy out of business. I want you to hold onto your teeth naturally for as long as they are useful to you. And if you can't do anything with it, then you know who to come to. So that's to do with the human tissue act. Right.

I'm also covering that with what does the tooth fairy do with all the teeth. Yep. I've done a lot of research into that. And if you do want to know more about that, see my mind. next show. Oh yeah. I, as a qualified tooth fairy, currently just keep them in the receptacle that I received them in.

Yep. But I am looking into the best way to do something. What I would like to do is store them in a way or display them in a way that is the least damaging. And I did actually ask Dr. Sophie about this. In dental school, we would store them in bleach. and that was to make sure that they were properly disinfected. At the children's hospital, when we have teeth that we want to send for pathology, we saw them in formalin to preserve the cellular structure

if you were then going to do histology and pathology on it. So I would say formalin is probably your best bet for long-term storage, but it sort of depends what you're doing with them. Otherwise, if you just want to keep them from smelling gross, I'd say removing all the soft tissue, so making sure there's no gum attached to the roots of the teeth anymore and storing them in bleach is probably your best bet. Storing them dry will mean that they dehydrate and become very brittle. Obviously teeth are incredibly hardy. I think you'd definitely be safe just to keep them in a jar or however you want to store them or display them.

I don't think they're going to go to pieces on you. But if you wanted to preserve any of the cellular structure, you probably want something liquid. So I thinking maybe I could do a Damien Hirst style display with them. The inconceivability of teeth in the head of the living. Your teeth are already dry. Yes. Yeah. So it's a bit late.

A bit late. Yeah. So I think maybe like putting them in a little resin cubes that I could then display might be the thing. I have told everyone I've purchased teeth from so far that I wouldn't do anything with them before. checking in with them. Right. Clear the resin with everyone. Yeah, they will stay in their current state until I have done that.

But yes, hopefully that answers the question so far about what the tooth fairy does with the teeth and what I plan on to do with the teeth and whether that is creepy enough or not. That's for everyone else to decide. Yeah. Speaking of which, by the way, of what the tooth fairy does with the teeth and storing teeth and transporting teeth. We did hear from Jenny, which I want to add in. Jenny had written in to let us know that in Curtin University, yes, the one in Perth, Matt.

I'm familiar with their work. Building 405 has a teeth vending machine. I don't know what any of those words mean. Now, when I heard this, I thought, oh, is this like an art project or something? No, it's a school of nursing. Yep. And it goes back into what I was saying about Dr. Sophie and student dentists and stuff.

It's so that they can put the extracted teeth in there and any students that need to practice on teeth, and they'll list what tooth it is. So you can complete your set. I want to eat one of these. Put a coin in. Yeah. They say it's about $9 for a pack of two teeth. So I appreciate that people brought this machine to my attention. However, I'm going to leave that for its sole purpose.

Yeah, it's not for you to buy. James wants to know what does a click? of teeth smell like? So far, I don't recall ever having a scent because usually it's like one tooth or a couple of teeth and I haven't taken a big. A big old whiff of them all at once. Great. Dr. Sophie said her only memory of the smell of teeth is either bleach because that's what

they've been keeping them in or if the drill while doing the drilling, if they haven't kept a cold enough, you can smell the smell of burning tooth. I don't want to know that. That's the thing I don't need to know. That concludes problems sent in by listeners, but what about problems sent in from podcasters? Yes. I have posed a question because we did actually receive way more questions about teeth

to do with my buying of teeth. That seems to draw a lot of attention. I don't want to be taking up all this space in the ProblemSquared Problems database. Yeah, yeah, yeah. For my side hustle. So I'd like to set up a website for people who are willing to sell me their teeth. Right. So I can keep track of whose teeth and how I'm getting them and where they're from, etc.

But I need help deciding on a domain name. Oh, okay, okay, right, yep. And I've got, I've boiled it down to two options. Right. One is mular for molars. Ah, got it. Or molars for mullah. Yep.

Yep. The other one is incisor trading. Incisor trading is very good. Yeah. What about chomp change? Oh, oh gosh. This is now making the problem even more. Sorry. Chomp change is fun. Yeah, I like chump change.

Inciser trading is very good though. I do feel like... I feel like... that'd be hard to top. I feel like Bitcoin is definitely taken. I'm very happy with incisor trading when I thought of that I was... I congratulated myself. You took the rest of the day. didn't you?

I did. I did. The only thing is for pedantics, I'm not just buying incisors. Oh, I don't. Also, I feel like the spelling will get in the way of people finding the website easily. That's why you redirect chomp change. That's why I think chomchange could work. To incisor trading.

Or, yeah, mullah for molars, mola's for mullah. But then again, molars, same problem. No problem. Should I open this up to the listeners? Yes, yes. Oh, let's do it. Okay. If you have a very, very strong feeling about any of those,

please write into a problem squared.com, click solution in the drop down and just tell us whether any of those you thought was really great. Or your own suggestions. Or your own. Do let us know if you think any of those, or if you do happen to pitch one, which just seems absolutely perfect. And if I didn't answer your tooth-related question,

Well, you're just going to have to wait until May the 2nd next year, which is Dwayne the Rock Johnson's birthday. So next year, we'll see you next year for any teeth-related questions. Also rocks. We are teeth and rocked out. And so all we're going to do is say thank you to all of our lovely problem poses, to all of our lovely listeners. That's you.

And you. And you. Don't forget you, but a special thank you to the patron. supporters who make this podcast possible. We thank them with various things, like a bonus podcast that you can listen to. Go to patreon.com forward slash a problem squared if you're interested. We've got various other perks and that sort of thing. And amongst those perks, we choose three of our Patreon supporters at random and thank them

at the end of every episode by mispronouncing their names. And on this episode, those supporters are... Anna Zilinek. Jal? Escaran. Roe. I also like to thank my co-host Matt Parker. That's me. I've been Beck Hill and continued to be.

And I'd also like to thank... Without relent. Without relent. I'd also like to thank our wonderful... Well, do you know what? If anyone, rocks and is a bit of a tooth fairy, heavy on the fairy. It's our wonderful, magical producer, Laura Grimshaw, who leaves a lovely podcast under every listener's pillow.

She does. And she has the same diet as the rock. Which is? Like four boiled chickens. Boiled chickens. She's a salmonella has it in the making. Laura Grimshaw. Good, but rock bar.

Rock on. Rock on. In real life, connect four. This is the theme. Matt, it is your go. I'm going to go center. Oh, yeah. I see what you're doing here.

Go over it. Wham. Gross.