Program: How risky is sharing a toothbrush?

Norman Swan: So Tegan, once you've washed your teeth six times a day, as I do, but once you've washed your teeth, what do you do with your toothbrush?

Tegan Taylor: Put it back in the cupboard.

Norman Swan: Oh, in the cupboard, really?

Tegan Taylor: Like in the little vanity cupboard in my bathroom. 

Norman Swan: And what happens if your loved one says, 'I've lost my toothbrush, can I use yours?'

Tegan Taylor: I see what…you're trying to out me. You're trying to see if I will out myself as a toothbrush sharer. I feel like it's too early…

Norman Swan: Too early in the relationship? You've only been together for about 20 years.

Tegan Taylor: I feel like it's too early in the program for me to show my hand. All right, what the hell. Okay, I wouldn't not share a toothbrush.

Norman Swan: 'I wouldn't not.' Meaning that you would.

Tegan Taylor: I don't routinely, but I wouldn't not with someone who…with my husband who I share a bed with and also smooch on the mouth. So, like, what's the difference? But even…I don't know, I'm pretty sure that as a kid, I would have shared a toothbrush with my sisters at various times, but we're kind of just disgusting anyway. 

Norman Swan: So, how risky is sharing a toothbrush…? 

Tegan Taylor: No, no, wait, I showed you mine. Would you? You've got to tell me now.

Norman Swan: I'd do it, but not feel comfortable about it, I'd go searching for another toothbrush.

Tegan Taylor: Oh yeah, you'd look for another toothbrush first. But if you had to, would you make your loved one go furry-mouthed, or would you let them use your toothbrush?

Norman Swan: No, I'd let them use it in the end.

Tegan Taylor: See, you're not better than me.

Norman Swan: No, I'm not. But how risky is sharing your toothbrush is the question this week on What's That Rash?.

Tegan Taylor: Angela has written in asking about whether we need to educate the public on the risks of sharing toothbrushes, which I kind of feel is pre-empting the endgame. And as we've already revealed, we're not anti sharing toothbrushes, but maybe we should be. So, I'm keen to dig into the research on what maybe lurks within a toothbrush or within our mouths, and whether we need to be keeping that to ourselves. 

Norman Swan: Yeah, and nobody really knows how common toothbrush sharing is. There's been surveys of sorts suggesting that maybe one in two of us have shared their toothbrushes in the past.

Tegan Taylor: These surveys are always like, done by dental care companies, right? Like, it's not the peer reviewed research that we would usually discuss on What's That Rash?.

Norman Swan: No, it's people wanting to sell toothbrushes.

Tegan Taylor: But the fact that they've managed to get a quarter of the people or half the people that they talked to in the survey to admit to sharing a toothbrush says to me that there's a lot more people who would do it but aren't going to say it to a survey taker.

Norman Swan: Correct. Let's assume it's pretty common.

Tegan Taylor: We've talked a lot on this show and on other health shows, like the Health Report, about microbiomes, and I think most people know that there's a pretty vibrant microbiome in your gut, that's the sort of millions or trillions or zillions of bacteria that live in your gut and help your body function. And there's different microbiomes in different parts of your body, and one really prolific microbiome is in your mouth, your oral microbiome.

Norman Swan: It's incredibly complex, and some researchers in the area believe that in different parts of your mouth there's a different microbiome. So there's a different microbiome between your teeth, in different parts of your cheek, and very complex patterns of microorganisms. And of course, the mouth is the source of what's probably the commonest infectious disease affecting humans, dental caries. 

Tegan Taylor: I never think of it as an infectious disease. 

Norman Swan: Yes, when this comes to the toothbrush story, we acquire bugs in our mouth that live on the dental film, the biofilm around your teeth, if one's allowed to grow, and they ferment carbohydrates, particularly highly refined carbohydrates like sugar. So they feed off sugars, produce acid and damage the tooth and cause dental caries and destroy teeth effectively.

Tegan Taylor: But you said it's an infectious disease, which makes me think that you have to get those bacteria from somewhere.

Norman Swan: When a baby's born, research suggests they have few, if any, what's called cariogenic bacteria in their mouth, but they can acquire the cariogenic bacteria very soon after birth. And there are two ways that that's thought to happen. So they pick up vaginal organisms if they've had a natural vaginal birth, but the vagina does not have these organisms in it. So one way is, for example, in a slightly older child, if they drop their pacifier on the floor, you pick it up and you suck it and you put it in the baby's mouth, you are giving the baby part of your microbiome. And if you've got a lot of cariogenic bacteria in your mouth, you are giving it to the baby, and that colonises that baby's mouth, so when teeth come through, they're more prone to get dental caries. Another way is just simply kissing is thought to pass this on. And so it's quite hard to prevent the transmission of cariogenic bacteria. And almost all of us have cariogenic bacteria in our mouths. 

Tegan Taylor: Okay, so what I'm thinking when you're saying that is…kissing is so innate, it feels instinctive to smooch your baby because they're so delicious. Is that maybe not meant to happen? I know you're saying that these bacteria cause caries, but is it not a natural part of life that a baby is going to pick up these colonies of bacteria that are going to live in different parts of their body, just like the rest of us have?

Norman Swan: Yes, but if you talk to dentists, and obstetricians should be onto this as well, your dental health when you're pregnant and your partner's dental health are incredibly important. So the cleaner your mouth, the more you properly wash your teeth, the more you floss, the more you get rid of food substances, the fewer refined carbohydrates you eat in your diet, the fewer cariogenic bacteria you're going to have in your mouth. So if you've got good dental hygiene, good dental health, and you've sorted that out through pregnancy, as has your partner, then you're less likely to pass on a big dose of nasty cariogenic bacteria because you've got fewer in your mouth. So yes, it is inevitable, but you can minimise the risk.

Tegan Taylor: And so in the same way that you might have prebiotic foods that help support your gut microbiome, like high fibre foods, that's also helping support your oral microbiome.

Norman Swan: Yes, and dental hygiene is really important. Now, you don't have to be…I mean, I'm a bit obsessive-compulsive, I have this weird thing that I can't come on air unless I've washed my teeth.

Tegan Taylor: No one can smell your breath through a microphone.

Norman Swan: I know, but I just need clean teeth, I don't know why. But anyway, you should be washing your teeth more than once a day, and it should be after food, so that you're carrying very little food left in your mouth. So anyway, that's the point here. Kissing, yes, is inevitable, and the higher your level of dental hygiene and dental health, the less likely you are to pass on nasty bacteria because you've got fewer of them in your mouth clinging to the dental biofilm.

Tegan Taylor: Okay, so then my question to you is, how much of the bacteria from your mouth stays on your toothbrush between brushes? 

Norman Swan: It's not been well studied. What people have assumed is that there's food particles left on the…I mean, we should have warned people at the beginning…

Tegan Taylor: Content warnings. So gross.

Norman Swan: If you're eating your breakfast…but anyway, it's food particles that carry the bacteria. There's almost certainly bacteria there. It's also wet, and it can be humid, and you can get growth of these organisms on your toothbrush, and it can be a very conducive environment. I had probably one of the most revolting experiences of my life a few weeks ago, walking into the bathroom and finding a cockroach on my toothbrush.

Tegan Taylor: Yuck! Did you throw the toothbrush out?

Norman Swan: I'm not gonna answer that question straight away. 

Tegan Taylor: Argh!

Norman Swan: It seemed to be feeding on the actual remains of the toothpaste on the toothbrush. 

Tegan Taylor: Did you throw the toothbrush out? 

Norman Swan: And I went to sort of…you know, if you go to a cockroach, it runs away. This cockroach was either totally zonked out on whatever was on the toothbrush, or it was so intent on eating it, it didn't move. 

Tegan Taylor: Did you throw the toothbrush out? 

Norman Swan: Actually, I've got a funny toothbrush which is very expensive with a very expensive head, so I just washed it really well.

Tegan Taylor: You put the cockroach toothbrush in your mouth? Again and again by the sounds of it…

Norman Swan: Well, I like to think most of the cockroach had gone.

Tegan Taylor: …you brush your teeth a thousand times a day.

Norman Swan: I'm not sure whether cockroaches have dental caries or not. I haven't spoken to a dentist about whether they've treated any cockroaches or something. 

Tegan Taylor: Yeah, I guess if dental caries is all you're worried about, that's fine, but a cockroach? Yuck. What if it crawled from under the toilet onto your toothbrush?

Norman Swan: Come on. So, you know, this is the person who would think twice about giving their partner their toothbrush, but I was happy to share it with a cockroach.

Tegan Taylor: You wouldn't inflict that on your partner because it's had a cockroach on it. 

Norman Swan: Maybe I shouldn't have told you that story. So look, they have cultured toothbrushes, and they find all sorts of organisms on it, like E coli, pseudomonas, Klebsiella, cockroach…

Tegan Taylor: Cockroach is the least of your worries. E coli is a poo bacteria. 

Norman Swan: They're potentially quite risky, but washing the toothbrush afterwards, making sure it's as dry as possible afterwards minimises that chance.

Tegan Taylor: Okay, so if your toothbrush has been rinsed and dried between brushes, which doesn't sound like yours does, it generally isn't holding on to those bacteria for that long. 

Norman Swan: That, in fact, is the theory. And of course they've come from your mouth originally, so they've had to come from somewhere.

Tegan Taylor: Okay, so then with the sharing thing, is there anything different about the toothbrush than there would be if you were just kissing your partner?

Norman Swan: So is this a European kiss, or is it…?

Tegan Taylor: I don't know, how do you kiss your partner, Norman?

Norman Swan: I'm not divulging that, the cockroach is my biggest declaration of the day.

Tegan Taylor: Your most significant relationship.

Norman Swan: I haven't kissed a cockroach, but I probably have indirectly. So yeah, I think that if you have a passionate kiss, you're probably transmitting important organisms, and you're probably synchronising your microbiome anyway with your partner if you're living in the same household and eating the same food.

Tegan Taylor: All right, so Angela's question was do we need to educate the public on the risks of sharing toothbrushes? And what I'm really hearing is that it's not as risky, it's just kind of mentally gross. Are there people who should be…I mean, I don't think anyone's going to run out and be like, 'Come on, babe, let's share a toothbrush now,' just based on this chat, hopefully. But are there people who should be more cautious than others?

Norman Swan: Yeah, I think that if you've got gum disease…I mean, some people would say this causes gum disease, doing things like sharing toothbrushes, but gum disease is partly genetic, partly to do with dental hygiene, and some people believe it increases the risk of coronary heart disease through increasing inflammation in the body. But I think anybody who is immunocompromised, you should really be protecting your toothbrush. If you are at all vulnerable, you should be keeping your toothbrush to yourself. Now, does that mean you don't kiss somebody? You need comfort in this life, and you can go too far, but there's some things you can prevent.

Tegan Taylor: Fair enough. So, probably not going to cause yourself a huge amount of harm by sharing toothbrushes if you're otherwise healthy. 

Norman Swan: Yep. So Sharon, I hope we've answered your question. What is our mailbag showing this week? Because we had this thing a few weeks ago, we've dealt with the brain teaser, which you've got to listen to a previous episode for if you want the answer to that. But we've also had this request out for n-of-one studies, and this is a phenomenon where nobody's done a randomised trial but you've kind of done an experiment on yourself, and we asked people to send in their n-of-one studies.

Tegan Taylor: See, I jokingly said for people to send in really unhinged ones, thinking that we wouldn't get much. And I don't know why I keep underestimating our audience like this. I don't think you've seen this story, Norman, this is going to be such a treat for me to read to you. It's from Paul who tried a self-experiment to cure himself. So he was getting, a few years ago, some really excruciating bouts of pain around his sternum area, radiating out across his chest and stomach area, usually (but not always) after food, and these attacks could last two or as long as six hours. Would you like to hazard a guest at a diagnosis?

Norman Swan: Well, there are two diagnoses. The one that you should really jump to straight away to be safe is that you're having a heart attack or you've got shortage of blood supply to the heart. The second one would be reflux, acid into your chest. But that's not the first one you'd come to the first the first time you experience it.

Tegan Taylor: Well, Paul went to see his GP and found out that it was gallstones.

Norman Swan: And can I just say, for safety reasons, if you get chest pain and it's the first time you've experienced it, you call the ambulance and you go straight to the emergency department, and they will take you absolutely seriously no matter what age you are or what gender, because it could be a heart attack, and if it's not, then you move on to the next best thing.

Tegan Taylor: In terms of safety warnings. I hope you're ready to issue many, many more, because this story gets so much more hectic. He wanted to try a traditional remedy for gallstone removal instead of taking out the gallbladder. Paul says, 'Wondering why they can put a man on the Moon but not remove gallstones, I went home and started Dr Googling and found an alternative remedy for gallstone removal. The ingredients were…'

Norman Swan: [For personal safety we've redacted this next piece of the description.]

Tegan Taylor: …he had to drink it as quickly as he could, and it had an effect not unlike colon prep, if you know what I'm talking about.

Norman Swan: I was going to say, he's getting ready for a colonoscopy here, rather than gallstone removal. 

Tegan Taylor: Yeah. Anyway, his gallbladder basically has a massive…

Norman Swan: [Redacted again.]

Tegan Taylor: That's disgusting. I shouldn't have to say this, but you guys, do not, do not try this at home, because…

Norman Swan: And they may not have been gallstones, by the way. 

Tegan Taylor: Oh, really?

Norman Swan: No, it could have been anything in the poo. So he might have convinced himself it is. I mean, I don't like to insult our listeners, but you know, n-of-one could mean nut-job-of-one. 

Tegan Taylor: Well, I think Paul's seen the error of his ways, because a few years later he went to see an abdominal surgeon, because it never stopped hurting, he never stopped having these really excruciating gallbladder attacks…

Norman Swan: Why am I not surprised?  And even if it did work, by the way, the risk you take if…

Tegan Taylor: Don't steal my thunder, Norman.

Norman Swan: Okay, go on.

Tegan Taylor: So he went to see an abdominal surgeon who was horrified when he explained he had purged most of his gallstones. Paul says, 'I can still see the look on his face. He asked me if I realised the risk of a gallstone getting stuck in the bile duct needing emergency surgery.' And he explained why he was still having the attacks, the buildup of gallstones over the years, the irritation, the scarring and thickening of the inside of the gallbladder. The gallbladder was just broken and had to be removed, and so he had keyhole day surgery, and has been fine ever since, and has then written in all-caps and bold: DON'T TRY THIS AT HOME.

Norman Swan: Yeah, and we can only endorse that as the weirdest n-of-one story we've had to date. Absolutely do not do this at home. A blocked bile duct is a really bad medical emergency. Also the chronic irritation, if it's ignored, can lead to cancer of the gallbladder, which is a very nasty cancer. And a perforated gallbladder is also a medical emergency with significant mortality. So if you've got gallstones, go and see somebody who knows what they're talking about. 

Tegan Taylor: Don't Dr Google it. Having said that, if you have an n-of-one story that you would like to share…

Norman Swan: Yeah, but don't top it, please don't top it. 

Tegan Taylor: Oh, again, I don't want to underestimate people who are listening, but I hope that there's nothing that could top that. But if there is, thatrash@abc.net.au is the email.

Norman Swan: And we'll see you next week. 

Tegan Taylor: See you then you.