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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."

61 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. Re:Bite back by antdude · · Score: 1

      Just bust its eyes like MythBusters did. ;)

      --
      Ant(Dude) @ Quality Foraged Links (AQFL.net) & The Ant Farm (antfarm.ma.cx / antfarm.home.dhs.org).
    3. Re:Bite back by somersault · · Score: 1

      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.

      --
      which is totally what she said
    4. Re:Bite back by worf_mo · · Score: 1

      How long one can go without brushing before decay sets in? Which species of shark?

      My sharks brush their teeth regularly! Independently of their species.

    5. Re:Bite back by somersault · · Score: 1

      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.

      --
      which is totally what she said
    6. Re:Bite back by jellomizer · · Score: 1

      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.

      --
      If something is so important that you feel the need to post it on the internet... It probably isn't that important.
    7. Re:Bite back by Guignol · · Score: 1

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

    8. Re:Bite back by TheLink · · Score: 1

      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.

      --
  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 TemperedAlchemist · · Score: 1

      Stem cells can be used to regrow teeth.

    2. Re:Great, but.... by Anonymous Coward · · Score: 1

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

    3. 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.

    4. Re:Great, but.... by ArsonSmith · · Score: 1

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

      Thanks, I work out.

      --
      Paying taxes to buy civilization is like paying a hooker to buy love.
  3. Fluoridation by hotdoghead · · Score: 1

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

    1. 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.

    2. Re:Fluoridation by bmo · · Score: 1

      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

    3. Re:Fluoridation by hotdoghead · · Score: 1

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

    4. Re:Fluoridation by JoeMerchant · · Score: 1

      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...

    5. Re:Fluoridation by bmo · · Score: 1

      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

      --
      BMO

    6. Re:Fluoridation by Grishnakh · · Score: 1

      The article is totally full of shit, at least if the summary is anything to go by, and provides little real information, because they conflate the terms "hardness", "toughness", and "strength", which are all totally different material properties.

    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.

      --
      My God, it's Full of Source!
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    9. Re:Fluoridation by tbird81 · · Score: 1

      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.

    10. Re:Fluoridation by bmo · · Score: 1

      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 smokestack scrubbers of fertilizer manufacturing plants.

      Oh come on. I read a site claiming exactly that and they said it was just taken unrefined from the waste stream and put into the water supply. Yeah, really.

      From waterloowatch.com

      Hydrofluorosilicic acid is drawn from open air cooling lakes, as is. It is containerized in tankers, and shipped to your municipal drinking water supply. Hydrofluorosilicic acid remains contaminated with trace amounts of lead, arsenic, mercury and radioactive materials. It is delivered unrefined, and in none-pharmaceutical grade, to be used as water fluoridation 'product'.

      What. That doesn't even make fucking sense.

      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

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

      YMMV.

      I use a distiller at work because the local town puts silicofluorides in their water.

      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?

      bragging that you haven't had a cavitiy in 12 years.

      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.

      --
      BMO

    11. Re:Fluoridation by bmo · · Score: 1

      >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

    12. Re:Fluoridation by bill_mcgonigle · · Score: 1

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

      Are you sure your information isn't dated? WHO Data.

      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.

      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. Studies listed at previous link.

      --
      My God, it's Full of Source!
      OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
  4. But can you put a freaking laser ... by Zordak · · Score: 1

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

    --

    Today's Sesame Street was brought to you by the number e.
    1. 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?

      --
      When our name is on the back of your car, we're behind you all the way!
  5. Wish I had rows of teeth... by ackthpt · · Score: 1

    Getting tired of having the same old ones filled.

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

    --

    A feeling of having made the same mistake before: Deja Foobar
    1. Re:Wish I had rows of teeth... by Immerman · · Score: 1

      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 out so a a brand new one grows it. Heh, regenerative medicine is going to be fun, and I just don't see the spammers doing nearly so well with it: "We can chop it off and grow it back twice the size!"

      --
      --- Most topics have many sides worth arguing, allow me to take one opposite you.
    2. Re:Wish I had rows of teeth... by JoeMerchant · · Score: 1

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

  6. 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.

    --
    intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
    1. Re:no, it's not fair to the shark by Bucky24 · · Score: 1

      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.

      So.... I should bite the shark back? Sounds like plenty good revenge. You know, considering that the shark has just "masticated and shredded" me.

      --
      All the world's a CPU, and all the men and women merely AI agents
    2. 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
    3. Re:no, it's not fair to the shark by evilviper · · Score: 1

      Under a few inches of salty sea-water, I think it's unlikely that any saliva-born diseases would be transmitted by a bite, successfully.

      --
      Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
    4. Re:no, it's not fair to the shark by OhSoLaMeow · · Score: 4, Funny

      We're gonna need a bigger mouth.

      --
      They can take my LifeAlert pendant when they pry it from my cold dead fingers.
    5. Re:no, it's not fair to the shark by drkim · · Score: 1

      ...Human bites have been shown to transmit...

      Yes, but although sharks do catch diseases, their biochemistry is so ancient and different than human, I wonder if they would be likely to catch traditional human diseases.

      Any marine pathologists reading this thread?

    6. Re:no, it's not fair to the shark by manu0601 · · Score: 1

      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.

      But are sharks susceptible to theses human viruses?

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

      So, we should just bite its fin?

    8. Re:no, it's not fair to the shark by azalin · · Score: 1

      If humans are one thing, they are pretty bad losers.

    9. Re:no, it's not fair to the shark by Em+Adespoton · · Score: 1

      So you're saying we should hoist the shark out of the water before we bite it?

      Unfortunately, we've only got 4 bicuspids, which means we're at a bit of a disadvantage going up against most sharks -- we can't puncture and shred their skin very quickly.

  7. it's not the hardness by ne0n · · Score: 1

    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.

    --
    $ :(){ :|:& };:
  8. Shark teeth? by ndogg · · Score: 1

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

    --
    // file: mice.h
    #include "frickin_lasers.h"
    1. Re:Shark teeth? by Immerman · · Score: 1

      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!

      --
      --- Most topics have many sides worth arguing, allow me to take one opposite you.
  9. Re:Well then. by The+Grim+Reefer · · Score: 1

    Be right back, dumping several countries worth of Coca Cola into the ocean.

    Let's see you try and gum us to death now. YOUR MOVE, SHARKS.

    Too bad a shark continually grows new teeth throughout it's entire life.

  10. WTF are they talking about? by HornWumpus · · Score: 1

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

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

    --
    John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
    1. Re:WTF are they talking about? by tocsy · · Score: 1

      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.

    2. Re:WTF are they talking about? by Grishnakh · · Score: 1

      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.

  11. Oh, just great... by Penurious+Penguin · · Score: 1

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

    --
    Forward! -- Emperor Norton, 2012
  12. Article headline isn't quite finished. by AbRASiON · · Score: 1

    Should read:

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

  13. Pocketknife by istartedi · · Score: 1

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

    --
    For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
  14. Misleading title is misleading. by Phase+Shifter · · Score: 1
    Granted /. got the error from their source but apparently someone didn't bother checking the abstract to the original paper.

    Toughness and hardness are not the same thing.

  15. OTOH by Nom+du+Keyboard · · Score: 1

    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)

    --
    "It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
  16. 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?

  17. Ha that explain it by aepervius · · Score: 1

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

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  18. Haven't we exterminated them, yet? by Impy+the+Impiuos+Imp · · Score: 1

    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.

    --
    (-1: Post disagrees with my already-settled worldview) is not a valid mod option.
  19. Re:Wisdom Teeth? Really? by aurispector · · Score: 1

    Yes, they use wisdom teeth because they're readily available. But really all the study says is "apples are not oranges".

    --
    I have mod points. The reign of terror begins now.
  20. This also can be read as... by flirno · · Score: 1

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

    However sharks replace their teeth throughout their life.

  21. This has been well known by Khyber · · Score: 1

    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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  22. Re:Wisdom Teeth? Really? by Grishnakh · · Score: 1

    I'm not a dentist, but I seriously doubt wisdom teeth are substantially different in composition from any other tooth, especially the other molars.