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Comment by fdye | Hacker News Reader

So within the existing population today there exist individuals who essentially never get cavities. The hypothesis for this has been 1. they don't eat sugar, or only fibrous foods, etc. 2. They have a genetic difference that builds stronger enamel or similar.

I have never heard of anyone discussing bacteria in the mouth as a possible difference. Be interested to see if there is a natural strand that some people have present that could also be a culprit.

There has been modest support for this concept in term of gut bacteria, i.e. thin people who donate their excrement to fat people seem to inoculate them with a gut biome that helps them lose weight, or deal with digestive issues.

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I am one of those people who naturally are more or less immune to cavities. My dentist tells me it is because of the pH in my mouth.

I _do_ have to brush my teeth etc... though, because i tend to have a lot of plaque if i don't.

Apparently either it is cavities, or plaque. You must take care of your teeth!

I have very strong (and ugly) teeth. The few "cavities" that I had, were actually made by dentists (they do that, y'know), and have resulted in a couple of crowns.

Otherwise, my teeth are great. I now have a dentist that doesn't make cavities, and she seems almost disappointed, when she checks me.

But gum care is every bit as important as tooth care (take it from me, you don't want a gum-scraping), and that is why I need to brush, floss, and mouthwash, twice a day.

> The few "cavities" that I had, were actually made by dentists (they do that, y'know)

You are the only person I have ever heard entertain this idea, so it would be better to spell out how this happened than assume everyone knows it.

Fair ‘nuff, but I’m not gonna bother getting into it. Life’s too short.

Let’s just say that there has been a fair bit of press, over the years on the matter, so it may not be as singular an event as you might think.

I can certainly attest that I've had dentists damage my teeth on more than one occasion.

A dental hygienist (those people who do maintenance cleaning at dentist’s offices) told me that saliva quality is key to cavity and periodontal health. The ability of keep all teeth moist prevents plaque/tartar build up. I don’t know how true that is, but this at least provide an alternative hypothesis to the two that you listed.

I have a surfeit of saliva and get many cavities:(

I'm 40 years old. Never had cavities.

I eat plenty of sugar.

Yeah, it's always baffled me. Growing up I ate snacks and sugar fiendishly, but only ever had maybe one or two cavities in 2nd grade or so.

I had another friend who got cavities on an almost yearly basis. What was really fascinating was how boring her diet was; I never saw her eat anything more complex than a peanut butter sandwich or cheese pizza. She brushed, flossed and mouthwashed every day but could never get ahead of it. Meanwhile I went through all of middle and high school without any major dental work besides getting my wisdom teeth pulled.

It's all very odd, and my personal experiences have also led me to believe that diet plays a smaller role than we might think. I could be wrong though, I'm willing to defer to the most reasonable explanation.

It's genetic, some people just have thicker and strong enamel and salivary activity. Just like some people are scrawny and others are naturally strong without really trying

Are you good about brushing your teeth and flossing on the regular? Having lots of sugar isn't what causes cavities, it's not keeping up your dental hygiene. So if you eat a lot of sugar but brush well on a regular basis, I would expect you to not get cavities.

Genetics play a role as well. My mom never got cavities despite never brushing her teeth, whereas my dad could brush pretty regularly and still have a cavity or two when he got checked up. Sadly I inherited my dad's genes, not my mom's.

Depends. Nowadays yes, but younger no. I lived 2 years in west africa where clean water was a premium: I didn't brush my teeth much and drunk a lot of coke.

Yeah basically the same for me - I had a couple in my baby teeth, but I’ve never had a cavity as an adult.

Scientist lurkers in the thread take note. We have a couple for the first cohort for testing to see if their mouth biome differs from base population. Inquiring minds want to know!

Anecdotally, none of my girlfriends seem to have developped any similar immunity. If the article is right, my flora should have replace theirs on the long run, no?

I'd be willing to bet you drink a lot of water and also brush regularly. Am I right? Because that's what I do and I've 2 cavities in 40 years of life.

You should assume that everything related to digestion is caused by gut bacteria.

Nerds love saying things is "genetics" because they think it'd make humanities types mad if something was genetics. But it's like lupus. It's never genetics. (Except celiac.)

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