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Study Finds Human Teeth are as Tough as Shark Teeth

Posted by samzenpus on from the thank-you-science dept.

sciencehabit writes "Don't feel inadequate. Even though your teeth are largely composed of a mineral softer than that found in sharks, new tests suggest that they're just as tough. In sharks, the material coating the teeth is largely composed of fluoroapatite, a fluoridated phosphate mineral that in its pure form is harder than the hydroxyapatite found in the enamel of human teeth. But by pressing tiny metallic pyramids into the surfaces of teeth from a shortfin mako shark and a tiger shark, researchers found that the enameloid coating on shark teeth is no harder than that of the enamel on a human wisdom tooth. The teeth are, in fact, of comparable hardness because their surfaces aren't pure mineral but instead are made of mineral crystals bound together with proteins so that the material doesn't shatter under a sudden impact."

13 of 85 comments (clear)

  1. Bite back by dittbub · · Score: 5, Funny

    So I should bite the shark back?

    1. Re:Bite back by JoeMerchant · · Score: 3, Interesting

      First thing I thought when I read the title was, damn, that sucks.

      I mean, sharks are constantly breaking off their teeth and growing new ones, I'd want my teeth to be considerably stronger than a shark's.

      Then, I realized that the comparison is just as bogus as so many other sensational headline "studies" because of the difference in tooth shape, any "comparison of strength" is going to be completely arbitrary. Is it a straight comparison of enamel hardness? Break-off strength from the root? Mean time (years or % of lifetime) between failure in ordinary daily use? How long one can go without brushing before decay sets in? Which species of shark? Which sub-culture of human?

      Now, get off my lawn!

  2. Great, but.... by Clueless+Moron · · Score: 3, Insightful

    Terrific, but sharks replace their teeth an unlimited number of times during their lifetime. So they get nice new fresh sharp ones all the time. I'm stuck with my adult teeth for my whole life.

    1. Re:Great, but.... by n7ytd · · Score: 2

      Stem cells can be used to regrow teeth.

      I long for the day.

      I had one of my incisors broken out and the root severely injured when I was 14 or so. Since that time, I've endured a partial crown, a full crown, a root canal, and an apicoectomy before earlier this year my dentist and I decided it was finally really dying (I'm 36 now).

      The tooth was extracted in February and the socket packed with cadaver bone, stitched over and left to heal for 3 months. In May, an implant was placed in the bone and then stitched over again, this time to wait for 4 months while the bone hopefully knits successfully around the implant. In a few more months I get to go back to have my gums cut open for the third time this year and have the post and crown installed. If the implant fails, then plan B involves more expense and time.

      I imagine a brave, new, flying-car world of the future, where anything other than a routine cleaning at the dentist will mean an extraction and insertion of a small pellet in the gum that will cause a new tooth to grow within 3 months.

  3. no, it's not fair to the shark by circletimessquare · · Score: 4, Funny

    http://emedicine.medscape.com/article/218901-overview

    The possibility of transmission of disease through human bites must be considered. Human bites have been shown to transmit hepatitis B, hepatitis C, herpes simplex virus (HSV), syphilis, tuberculosis, actinomycosis, and tetanus. Evidence suggests that it is biologically possible to transmit the human immunodeficiency virus (HIV) through human bites, although this is quite unlikely. (SeePathophysiology, Presentation, and Workup.)

    A shark is considerate and will masticate and shred you into edible pieces in the course of minutes, you will be out of your misery in no time.

    But what you are proposing dooms the shark to die a slow miserable death due to the load of nasty diseases you carry in your mouth as a member of diseased lecherous species, homo sapiens.

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    1. Re:no, it's not fair to the shark by circletimessquare · · Score: 4, Funny

      Spoken like a petty homo sapiens. A species should know when it is just food.

      --
      intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
    2. Re:no, it's not fair to the shark by OhSoLaMeow · · Score: 4, Funny

      We're gonna need a bigger mouth.

      --
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    3. Re:no, it's not fair to the shark by wisty · · Score: 2

      So, we should just bite its fin?

  4. Re:Fluoridation by feedayeen · · Score: 2

    Does this mean that fluoridating our water and/or using a fluoride mouthwash are useless?

    Fluoridation replaces the highly reactive hydroxyl group in our teeth's enamel (hydroxyapatite) with a much less reactive fluoride bond which reduces it's vurnability to acid, it's not done to improve the physical durability of our teeth.

  5. Re:But can you put a freaking laser ... by camperdave · · Score: 2

    ... on a person's head? I think not.

    Have you not seen Gates of Borg?

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  6. Re:Wisdom Teeth? Really? by Grishnakh · · Score: 3, Insightful

    I'm guessing they tested on wisdom teeth precisely because lots of people get them removed, so there's probably tons of them available for doing random tests on. Are you volunteering to have your incisors removed so they can do some tests on those instead?

  7. Re:Fluoridation by wisty · · Score: 2

    Exactly. You'd expect human teeth to be "tough" (durable). We only have one adult set.

    You'd expect shark teeth to be maintain a sharp edge, but they don't mind if a few break.

    I'll use an example for slashdot's Nipponophiles - it's like a katana. Human teeth should be like the tough low-carbon hocho-tetsu, which is used in the core of the blade. Shark teeth should be like the higher carbon nabe-gane, which is used to form the sharp outer shell.

  8. Re:Fluoridation by bill_mcgonigle · · Score: 2

    Longer answer: if you buy into the "fluoridation is harmful and doesn't actually do anything to prevent dental caries" you are going against 50 years of worldwide studies.

    Not really. US folks point to the Kingston study, but did not control for refrigeration. Do you have more recent studies? Because there are several showing that the rates of caries do not increase in towns where fluoridation is stopped. Entire countries, such as Sweden have taken this approach, giving xylitol gum in school lunches, which provides a higher level of benefit.

    We also have modern studies showing that silicofluorides transport heavy metals across calcium channels and epidemiological studies show that municipalities that use them have statistically higher levels of violent crimes. The calcium binding may also be a cause of the increase in osteoporosis. Proponents claim without basis that silicofluorides completely dissociate, but that's been shown to be untrue. But silicoflourides are much cheaper than sodium fluoride because it's a toxic waste product extracted from the smokestack scrubbers of fertilizer manufacturing plants.

    And that's ignoring the problems of mass-medicating a population against their will, with wildly uncontrolled dosing.

    Personally, I have well water at home with no fluoride present and I use a distiller at work because the local town puts silicofluorides in their water. I use xylitol toothpaste which interrupts bacterial biofilms. I've had one single-surface cavity in 12 years.

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