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Why humans need to brush their teeth

  1. Apr 7, 2017 #1
    Why do humans get cavities if the teeth are not brushed whereas animals like dogs, cats and horses don't have cavities?
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  3. Apr 8, 2017 #2


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    I am told that the Western diet contains a lot of sugar, which feeds bacteria, which produce plaque, which is acidic and which reacts with the soft enamel of the tooth.
  4. Apr 8, 2017 #3


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    That's my understanding as well. I've read of human societies, such as certain tribes in Africa, who have very low rates of tooth decay thanks to their diet containing very little raw sugar or even fruits.
  5. Apr 8, 2017 #4

    jim mcnamara

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    Incidence of dental caries is related to diet. This study indicates pastry consumption is correlated with root caries (root canal, ouch).
    Example: https://www.ncbi.nlm.nih.gov/pubmed/19490135

    This: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3921667/
    discusses how Somali refugees have adapted from using stick brushes to toothbrushes. Tangentially it appears that the original oral health practices were related to religious practice, and so older people were very firm adherents.

    My conclusion: tooth brushing or cleaning is common among many groups of humans.
  6. Apr 8, 2017 #5


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    Dogs and Cats can get cavities.

    "dogs: 5 percent
    cats: very rare (almost nonexistent)"

    I find it interesting that cats cannot taste sweets while dogs can.
  7. Apr 8, 2017 #6
    Bacteria is why humans get dental decay, personally I prefer to just daily use a strong mouthwash instead of a brush.
    Other animals also can dental problems, but don't usually invite bacteria's by thowing a sugar party every day,
  8. Apr 8, 2017 #7


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    Hmmm. It was my understanding that mouthwash doesn't kill the bacteria that cause plaque and tooth decay. I'll have to look into this.
  9. Apr 8, 2017 #8
    Well my understanding is that while this is not guaranteed to be 100% reliable, it's around the same as brushing is.
    Not claiming to be a dental expert though, dental experts feature in my worst nightmares.
  10. Apr 9, 2017 #9


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    Heck, stick with the mouthwash...

    Teeth brushing can actually cause bacteremia.
    Gram positive bacteremia...
  11. Apr 9, 2017 #10


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    ... and ignoring what the dental experts tell you can and often DO lead you to dental decay problems and gum problems which lead to much higher dental and gum disease trouble, so inviting more of those nightmares.
  12. Apr 9, 2017 #11


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    Not everyone would lose their teeth even if they never brushed them (especially if they were on a stone age hunter-gatherer diet) but it's definitely worth it to do that to avoid the risk of huge medical bill from repairing totally destroyed teeth and the risk of sepsis/systemic infection that can happen if you have untreated cavities for a long time.
  13. Apr 9, 2017 #12


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    I might challenge the premise that dogs and cats don't get cavities. I suspect they do - just probably not with the same frequency as humans.

    I know many veterinarians offer tooth cleaning services. And if you've even owned a dog, you'll understand that dogs aren't exactly known for having nice breath. I suspect it's the same with cats - their mouths are just smaller. And animals can't exactly tell you when their teeth are irritating them. They would just live with a tooth problem until it becomes noticeable in behaviour to an owner.

    And you also have to factor in lifespan. A dog does pretty good if it gets into its early teens. Some cat breeds can reach their twenties. But people have much longer lifespans and therefore have a lot longer for teeth to decay, or for other tooth problems to develop.

    I remember with my last dog we had to brush his teeth. He didn't like it that much and kept trying to chew on the toothbrush.
    Last edited: Apr 9, 2017
  14. Apr 9, 2017 #13


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    The reference provided in the bacteremia article talks about transient bacteremia:

    Transient bacteremia from oral cavity related to oral anaerobic bacteria may occur as a result of dental healthcare procedures but also as a result of daily gestures involving the gums (chewing and oral hygiene). The risk of presenting a transient bacteremia is related to oral cavity bacterial load and to the severity of inflammation in the oral cavity.

    The health risks of transient bacteremia are almost certainly minuscule compared to the health risks associated with tooth decay and gingivitis, and the chances of the average person developing those diseases are much higher if they do not brush and floss. In addition, the amount of inflammation in the mouth (and the bacteria load) is increased by not brushing and flossing since it allows plaques to build up, leading to gingivitis, an inflammation of the gums.

    Please don't give out health advice that is contrary to what the mainstream medical community says.
  15. Apr 11, 2017 #14


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    Not just sugar, but simple carbs in general. If you white bread and you let it stick to your teeth, it will do a lot of damage over time.
  16. May 4, 2017 #15
    Are we talking about the net effect of carbs in the blood stream or on the mouth itself? (or both?)
  17. May 13, 2017 #16
    Carb levels can also affect the intestines' microbiome equilibrium (e.g. candida development, or even simple bacteria etc.). I'm not sure though if and how it all starts from the bloodstream and how it affects it etc. . But in any case I think it's much deeper than just "sugar on the mouth" ...

    Anyone knows more about these?

    Another remark: brushing is not just for bacteria. Also for stain, odour etc.
    Last edited: May 13, 2017
  18. May 13, 2017 #17

    jim mcnamara

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    This link indicates changes in gut microbiota induced by altering dietary fiber amount and type - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5331556/
    This is a meta-analysis and no strong conclusion showing x fiber has y result, good association not necessarily causation. Fiber is mostly indigestible carbohydrate, FWIW. This also indicates evidence mapping helps data realization and point to areas for more research: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5331556/

    This link shows that lifestyle changes and changes in digestible carbohydrate and to a lesser degree other macronutrients (fats, proteins) does alter gut microbiota. Again areas for more research indicated. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303825/

    Also - this stuff is not what the thread is about. Getting back on topic would be great.
  19. May 14, 2017 #18

    Fervent Freyja

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    Teeth spacing has a lot to do whether a person develops cavities! The more crowded a tooth is next to another, the higher chance that a cavity will develop in that area.
  20. May 14, 2017 #19
    Thanks for the interesting and useful (in general) references and links. To stay on topic, guts microbiota and microbiome was not directly my main priority here, but rather to answer:
    which no one really answered.

    These are not off-topic, because they try to investigate the deeper causes, regarding to how exactly sugars and carbs consumption relates to tooth decay and other tooth diseases (e.g. gum disease etc.). That relation has been successfully identified by the thread and it seems on the right track.
    But the aspects of this relation and the deeper causes may be multiple. Perhaps there's much more to it than just the effect of sugars and carbs (and relative acids) directly on the mouth [although that's certainly one cause and aspect, but is it the main one?]. Involving the bloodstream, and perhaps much less the intestine balance and health, seems reasonable because these are almost directly affected by our nutrition (e.g. by sugars and carbs), and may thereafter affect the whole organism, not just teeth.
    Thus my main inquiry was regarding to whether anyone knows more about these, and I think that's within topic. (I plan on doing some research on it myself later on, to find helpful references.)

    Because of course teeth are fed (get nutrients) from the blood itself, and futhermore the intestines microbiota balance perhaps may have a feedback effect on the blood (e.g. improper balance could supply the bloodstream with bacteria etc.) ...

    Thus, slightly in other words, regarding the original post
    it may be that humans get cavities even if teeth are brushed (in the case of high sugars and total carbs diets, etc.) ..., [because teeth are really fed through the blood etc.]

    IMO we should really answer those, if we really want to answer this thread adequetly.
  21. May 14, 2017 #20


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    Tooth enamel contains no blood vessels and is not maintained by the body.
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