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Comment by bmau5 | Hacker News Reader

This is very interesting and has a lot of potential, especially for people who struggle to brush their teeth, but I think there's another future where brushing and flossing largely become obsolete. If we could develop a more effective mouthwash tailored to restoring each persons oral microbiome we could likely reduce the need for brushing and flossing and instead replace it with a daily mouth rinse that clears out food debris and selectively targets pathogenic bacteria while promoting healthy species.

I'm a bit biased, though, because this is something we're working towards building at my company down the road.

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Wouldn't the mouthwash need abrasive particles as well? Part of why Listerine doesn't replace brushing and flossing is because it has a much smaller mechanical component in the washing process. The physical rubbing of bristles and wire through and around the teeth creates the physical abrasion that is necessary to remove large films of plaque.

I imagine without any sort of abrasive, the liquid would need to be dangerously strong to remove tougher plaque.

Yes. Talk to your dental hygienist and they will confirm this. Mine told me a story recently of when she was in school they were graded on how little plaque they had on their teeth. So her and all her friends did everything they could. New toothbrushes, flossing, the metal scrapers, and helping each other. No one removed everything and I guess that's the point of the lesson. Plaque builds up quickly and over time. What harms teeth and gums is far more than microbes.

But that also seems like where nanobots would come in. If you could have a mouth wash that had nanobots that would perform that abrasive scrubbing and then decay (and not leave byproducts) then it would help and could replace brushing and flossing. But definitely mouthwash is nowhere near the effectiveness of brushing nor flossing. Would be a cool future, but I suspect we're still a long way from that.

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Preventing plaque formation avoids the need to remove it.

Actually accomplishing that seems unlikely, but not impossible.

There has been work done is creating GM S. mutans that don't produce biofilms, and that would replace your native S. mutans. It could be done by just brushing your teeth with a toothbrush treated with the bacteria so it would cost pennies per treatment.

That’s a long way from actually replacing brushing and flossing.

For one thing, streptococcus sobrinus is more closely associated with cavity formation than streptococcus mutans. But more importantly these biofilms are a significant evolutionary advantage so this replacement is an unstable situation. Some positive benefits are likely, just don’t assume it can work alone.

Biofilms are an evolutionary advantage for the bacteria, not the host. Biofilms make the colony much, much harder to kill. How advantageous can it be to the host anyways, if 4 out of 5 dentists recommends obliterating it 2-3x a day?

This is trying to replace the bacteria population not the host.

It’s like trying to stop drug use by busting drug dealers. As long as the niche exists a city can’t stop and say we caught all the bad guys problem is solved.

That analogy doesn't hold - the niche is still being filled. A better equivalent would be the synthol drink from Star Trek - it's the same bacteria, but modified to remove the most problematic part.

It’s the same relationship:

We might call it the same species, but the relevant chararistic changed is detrimental to a [human] host but beneficial to the [bacteria] parasite.

We might call it the same species, but the relevant chararistic changed is detrimental to a [city] host but beneficial to the [drug dealer] parasite.

Consider if you removed all the wings on misquotes in a city. That would be useful on day 1, but not going to do anything a year from now. It’s the same species, but missing a very useful trait means it’s getting outcompeted.

> Consider if you removed all the wings on misquotes in a city.

That's not an accurate analogy for biofilms. Even if it was, I noted below that the mechanical action of brushing your teeth annihilates any biofilm (i.e. plaque) that has built up. That being the case, how do you explain the fact that people who brush their teeth are not suffering from infection from advantageous disease?

If you wipe out your gut flora, there are health serious implications. All evidence seems to point to the opposite case in your mouth.

I think you may have confused me with the other poster: https://news.ycombinator.com/item?id=32007812

Anyway brushing your teeth doesn't sterilize your mouth or even disrupt your mouth flora that much.

But brushing and flossing does do many things. It helps your spit/toothpaste to remineralize your teeth repairing microscopic damage, removes leftover buts of food, and generally makes your mouth noticeably less hospitable to bacteria alongside reducing biofilms.

As soon as you stop bushing things start getting worse, but that's why it's a daily activity.

I'm not confusing you for anyone - I explicitly said I was making the same point. You are arguing that genetically modifying mouth bacteria to not-form biofilms could be detrimental to health, and I pointing out that if that was true, we would already see those affects from daily brushing. You seem to agree that brushing removes biofilms, so I guess I don't understand your original hypothesis.

> modifying mouth bacteria to not-form biofilms could be detrimental to health

I said it would be detrimental to the bacteria’s health not the persons.

Not brushing would be bad for a persons health, and this would still be true after treatment with modified bacteria.

They may indirectly be an advantage for the host because if the bacteria aren't competitive they will get replaced by bacteria that are. The devil you know...

I hear you, but again - the strongly recommended medical advice is to brush your teeth twice a day to remove bacteria before they can form a biofilm, so if that was true, you would expect to see people who brush their teeth have worse problems from advantageous bacteria.

For sure, I don't think it would replace as much as supplement. And obviously your mouth flora can change based on any number of factors, so it might have to be something like a special toothpaste since it likely wouldn't be a one-time treatment.

Plus, I would imagine it would be a hell of a lot cheaper than nanobots once the bacteria strains are developed and tested.

A keto diet without sugar or starch should prevent most plaque formation, shouldn't it?

No, a balanced keto diet might be moderately better than a normal diet in terms of plaque, but even wild cats living on a nearly 100% meat diet still get dental plaque.

reminded - our cat was flossing his teeth using the corn broom that we had. He would press the broom with his paw and would byte a fiber close to the broom root and would move his head away so that the fiber would be flossing the teeth, and he would repeat it multiple times flossing different teeth. Still had perfect teeth at 13 when the cancer took him.

This doesn't sound possible. A big component of oral hygiene is removing the relatively large chunks of food that are hiding invisibly between your teeth. If you leave them there, they will rot and smell bad and cause other issues like infections. You need a physical object like the bristles of a tooth brush and/or floss to physically dislodge the bits of food. That's why every culture developed some way to clean their teeth.

GP did say "replace" but they also said "reduce" so I'm thinking they meant replace the majority of brushing, but probably not all of it. If they had an effective way of removing lettuce from teeth chemically, I'd be afraid of side effects.

Yes, thank you for catching this. As the comment above pointed out there will still be a need for removing larger food particles and hard to reach areas, but ideally with the addition of the mouthwash/intervention I'm mentioning we could drastically reduce the incidence of oral disease.

It doesn't seem far-fetched to imagine a chewing-gum-like substance which achieves this.

Like a dishwasher but for teeth?

Some people rarely brush their teeth and never get cavities. Some people brush thrice daily and floss and still get cavities and need root canals.

The working theory is we could all be in the first group with the right bacteria in our mouth.

That's it exactly. Some beneficial species play an active role in suppressing the pathogenic species (those that release acid or cause gum disease) and have other benefits including helping us break down dietary nitrate into nitric oxide, which is critical for heart/brain health.

My company tests/researches the oral microbiome and we're starting to discover the signatures of what puts people in one group vs. the other, with hopes of helping develop more personalized approaches down the road, but for now helping people understand what will work best for them.

Here's my company for anyone who is interested in learning more: https://www.bristlehealth.com/

What's preventing you from shipping to Canada, and any plans to expand outside the US in the future?

This is very cool.

What’s your take on xytiol gums? Think they’re effective in changing our oral microdiome for the better?

I'm also curious about this, but unfortunately I think that's where it will end for me in practice. Even if xylitol is effective, it seems the xylitol you'll get in any products (at least in the US) is going to be industrial byproduct from sketchy unregulated sources, just with greenwashed packaging. If there is a gum or rinse out there that is transparent and credible about their source of xylitol, and it's a source you can trust with your health, I'd love to try it out.

(I admit that you can probably say the same thing about any toothpaste you can buy in the US. But those have at least some additional benefits from regulation.)

The initial data on xylitol looks promising for reducing cavities! Particularly for stimulating saliva production (dry mouth is a large contributor to cavities risk) and as a sugar substitute that cavity-causing species can't digest into acid. I'm excited to see more research come out and compare it with our data.

Could it also be about the level of salivation in general, since saliva also helps kill some bacteria and keep the mouth cleaner (relatively)?

Definitely! Saliva is our best natural defense against cavities (and harmful bacteria), so we always recommend people who have struggled with cavities or dry mouth to consider options for increasing their saliva production, like chewing sugar-free or xylitol gum.

Those two groups are likely differentiated on diet. For starters, diet can overload your mouth with complex and simple sugars, but diet can also determine the bacterial makeup of your mouth.

No idea where it eventually led, but I read about work done back in the 80s to vaccinate against the bacteria that cause tooth decay. That suggests that some people might have natural immunity to them.

It's also pretty likely that there is variation in enamel formation and hardness (driven by genetic differences).

I was referring to something more along the lines of what the above comment mentions (rebalancing with beneficial bacteria), but there are companies working on something like a dishwasher for teeth, one example is below:

https://freshhealth.com/

Do you have much hope that dentists would cooperate in studying this, possibly disrupting the drill-fill-bill model that supplies their income?

Why not just continue the work that's already been done in developing GM strains of S. mutans that don't produce biofilms?

We think this work is fascinating, but S. mutans isn’t the only species in the oral cavity capable of developing biofilms (nor is it the only cavity-causing species). I think this could be a great first step, but we’re currently more focused on how to cultivate our healthy species than bioengineer alternatives (a question of competencies and priorities)

What is your company? And have you identified anything you could recommend to help “cultivate our healthy species”?

My company is Bristle (bristlehealth.com), and we've found several things that look to cultivate healthy species so far.

Hygiene plays a huge role (of course), but outside of that diet plays a large role. Cheese/dairy has been found to reduce cavity incidence, high fiber vegetables stimulate saliva production and neutralize acid, and a nitrate rich diet has been shown to increase levels of beneficial bacteria (called nitrate reducing species) that help us produce nitric oxide [2].

There's some exciting research on probiotics [3] as potential interventions as well, particularly if used with a proper hygiene regimen.

[1]https://www.bristlehealth.com/post/how-our-diets-can-affect-...

[2]https://pubmed.ncbi.nlm.nih.gov/33742692/

[3]https://www.bristlehealth.com/post/a-guide-to-oral-probiotic...

Interesting. Could you share a bit more, without revealing stuff that you don't want to share in public?

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