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Shark Science

Study Finds Human Teeth are as Tough as Shark Teeth 85

Posted by samzenpus 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."
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Study Finds Human Teeth are as Tough as Shark Teeth More

Study Finds Human Teeth are as Tough as Shark Teeth

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  • Bite back (Score:5, Funny)

    by dittbub ( 2425592 ) on Thursday August 02, 2012 @05:54PM (#40861749)
    So I should bite the shark back?

    • http://emedicine.medscape.com/article/218901-overview [medscape.com]

      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.

    • Re:Bite back (Score:4, Interesting)

      by JoeMerchant ( 803320 ) on Thursday August 02, 2012 @06:39PM (#40862217)

      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!

      • Generally the harder a substance is, the more brittle it is.. they said that our teeth are a little stretch because of the proteins in them.. not sure they were even doing a "hardness" test. Of course, I haven't RTFA.

        • Now I have RTFA, and I see that the summary was talking about both shark and human teeth as being shock resistant due to their structure.

      • Comment removed based on user account deletion

      • Re: (Score:2)

        by Guignol ( 159087 )
        First thing I thought was "people are paying to do such studies ?"
        And to think I was complaining about the olympics...

    • Re: (Score:2)

      by antdude ( 79039 )

      Just bust its eyes like MythBusters did. ;)

    • Shark Teeth vs Human Teeth. Is like a Steel Sword vs. a Steel Hammer.

      They are designed to work differently.

      A sharks teeth are much sharper, and designed to rip flesh past normal skin.

      Human teeth are general purpose, so we don't eat meat or vegetables as efficiently as other that have specialized teeth. However we can eat more.

      In general our teeth don't perform that well as a weapon. We are better off punching, kicking, and using tools to fight back.

      • Re: (Score:2)

        by TheLink ( 130905 )

        Human teeth are general purpose, so we don't eat meat or vegetables as efficiently as other that have specialized teeth. However we can eat more.

        Human beings are one of the few animals in the world with digestive systems that are partly located outside their bodies. We call some of them kitchens and abattoirs.

        This allows us to eat a wider variety of stuff, without having to carry around as many stomachs, gizzards etc, or directly support those metabolically.

  • Great, but.... (Score:4, Insightful)

    by Clueless Moron ( 548336 ) on Thursday August 02, 2012 @05:58PM (#40861803)
    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.

    • Stem cells can be used to regrow teeth.

      • Re: (Score:1)

        by Anonymous Coward

        There is no viable treatment to do that now. Sure, it 20 years maybe, but that doesn't help anyone losing teeth now.

      • Re: (Score:3)

        by n7ytd ( 230708 )

        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 m

        • 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

          In developing countries, that is what a trip to the dentist often means, frequently without significant anesthesia. Feel lucky you are born in America (or whatever rich country you live in).

    • "Great, but....
          Terrific, but..."

      Thanks, I work out.

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

    • 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.

      • But, it does protect against acid, and with rising CO2 levels, the oceans are becoming more acidic... should we set up humanitarian shark tooth flouridation stations? We can make swimming robots that look and act like cleaner fish...

    • Re: (Score:2)

      by bmo ( 77928 )

      No.

      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.

      --
      BMO

      • Never said I didn't buy into it. I use a fluoride mouthwash. Just curious.

        • Re: (Score:2)

          by bmo ( 77928 )

          Keep using it then. If your teeth have turned brown, you're overdoing it. If your teeth are not brown, then don't worry about it.

          It's just that without more description in your initial message, it was too easy to attribute an anti-fluoridation intent to your message.

          What you might want to look into is getting your teeth sealed. Doing this drops incidence of caries by 60 percent.

          http://en.wikipedia.org/wiki/Dental_sealant [wikipedia.org]

          --
          BMO

          • Re: (Score:2)

            by tbird81 ( 946205 )

            I had fissure sealants as a teenager. I asked my dentist about whether I needed new ones, she said there was no that much evidence about them.

      • 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, whi

        • Re: (Score:2)

          by bmo ( 77928 )

          Entire countries, such as Sweden have taken this approach, giving xylitol gum in school lunches, which provides a higher level of benefit.

          This is just wrong. Sweden puts it in table salt, like we put iodide in table salt. It's actually more effective this way, and gets fluoride to people who have well water. Many countries do this. Germany, Spain, Switzerland, etc.

          But silicoflourides are much cheaper than sodium fluoride

          I'm ok with this logic here...

          because it's a toxic waste product extracted from the

          • Re: (Score:2)

            by bmo ( 77928 )

            >You do realize that an activated charcoal filter (brita pitcher) is more than adequate for removing fluoride and that you're trying way too hard, yes?

            Disregard, this is wrong. Bone char is much more effective.

            www.de-fluoride.net/3rdproceedings/80-83.pdf

            --
            BMO

          • This is just wrong. Sweden puts it in table salt,

            Are you sure your information isn't dated? WHO Data [scribd.com].

            Yeah, we have the Boston study, but I'm skeptical that they adequately controlled for lead paint.

            FYI, a bunch of references at the bottom of this article [fluoridealert.org].

            I'm 47. I haven't had one, ever. I don't know what it's like to have one. Compare and contrast to my parents who had mouths full of metal by the time they hit 20 years old.

            Yup, and mine too. Caries have decreased over time, independent of fluoridation. S

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

  • Getting tired of having the same old ones filled.

    Could be worse .. could be having the old one pulled.

    • Not so sure I'd like the rows of teeth thing, seems like it would severely limit tongue mobility. I think dolphins are the ones with the right idea, just keep regrowing teeth whenever you lose one. It does take a little longer to get the replacement, but it's a lot easier on your conversation skills.

      But man, talk about giving dentists a hard time - well yeah, I *could* pay you $500 to fill a cavity, OR I could spend $50 to get plastered on some nice scotch and have some guy with a pair of pliers rip it ou

    • Implants suck, don't go there unless you have to.

  • To misquote an old saw, it's not how hard it is -- it's how many you have and how you use them that matters. This is why sharks are above us in the Australian food chain.

  • Don't shark teeth fall out a lot? I don't know if I would consider this high praise...

    • What does falling out have to do with hardness? That's all about connective tissue. And frankly if you were to regularly take blows to the teeth from the tails of dolphins and large fish, I doubt your teeth would stay in your mouth either. Shoot, a strong blow from a comparatively wimpy human can easily knock out your teeth!

  • Toughness, strength or hardness. TFS seems to use the terms interchangeably.

    I didn't RTFA. Hopefully the /. editor that is the only idiot.

    • Re: (Score:1)

      by tocsy ( 2489832 )

      I noticed that too, and it bothered me enough to comment. From the synopsis, "pressing tiny metallic pyramids into the surfaces" makes it sound as if they're doing hardness testing. I took a quick look at the actual scientific article and yes, they're doing micro- and nanohardness tests.

      • Yep, and then the shitty summary talks about strength and toughness, which are totally different materials properties. You'd think a techie site could at least get technical terminology correct, but I guess not.

  • ...in this new epoch of bath-salts and cannibalism! This is a prime example of the dangers of open-source information.

  • Should read:

    "Study finds Human Teeth are as Tough as Shark Teeth, both inferior to Thompsons Teeth"
    http://www.youtube.com/watch?v=Lzw6nRnaQG0 [youtube.com]

  • A pocketknife is as sharp as a sword. Chose your weapons.

  • Granted /. got the error from their source but apparently someone didn't bother checking the abstract to the original paper.

    Toughness [wikipedia.org] and hardness [wikipedia.org] are not the same thing.

  • Or on the other hand, the headline could have been: STUDY FINDS SHARK'S TEETH AS WEAK AS HUMAN TEETH.

    (filter bypass lower case filler)

  • In a way we are the predatory land shark, eating everything which is in our way :).

  • I was unaware a shark's teeth were particularly tough. Sharp, sure. But since they were constantly being replaced, if anything, they'd be crapper quality, grown much faster.

  • ...shark teeth are just as weak as human teeth.

    However sharks replace their teeth throughout their life.

  • We've got enough force to bite through steel, but our teeth can't stand up to the long-term stress. Short-term (as in bite down and get hit hard enough in the jaw,) we could probably cut clean through, but risk shattering our jawbone since it's not as tough as our teeth.

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