An Inquiring Mind Visits the Dentist….

21 Mar

…and then engages in Nerdery of the Highest Degree. Because this is how my brain works. You know how in science class you’d be studying something and your teacher would off-handedly mention, “Oh, by the way, this is how the stoplight down the street works” or “that’s what makes your ears ring” or some other random everyday thing that you never would have thought about, and probably never will think about again?

Yeah, this is why.

Star Ten Thousand Proudly Presents:
Sudden Science! At the dentist!

Lead vests. You know, that heavy thing they pin you under while they stab the inside of your mouth with photographic plates? Maybe it’s just me, but those corners are sharp. Most people are probably too distracted by the stabby thing in their mouth, or else are trying to sleep through the process, but not me. Oh no. I was thinking:

My lead vest is flexible. Lead is not flexible. How does that work? I can’t even feel small plates or scales or anything. Is there even lead in this? Is it like a powder or something? It doesn’t feel like it’s full of sand or anything…

So, like the good little geek that I am, I got home and got on the Google. 20 minutes of creative searching lead me to the following understanding:

—Vests may or may not have actual lead (although most do), but regardless of what the vest is made of, its resistance to x-rays is expressed in Pb equivalence; that is, a vest with a 0.5 mm Pb equivalence absorbs as much of the x-rays as a 0.5 mm-thick sheet of lead would.
—In addition to or instead of lead, other dense elements may be used. Basically what you want to absorb x-rays is something with a highish atomic number (lead is 82) and a smallish atomic radius (so something on the right-hand side of the periodic table. If you don’t remember why, find the nearest 10th-grader and ask them; I’ve been doing this with my students all week). These two factors help the elements siphon off more of the energy from the x-rays. Specifically, the small atomic radius means you can get more atoms into a given area, which means more chances for one of them to interact with the x-ray.
—Since lead is rather brittle, making an actual apron out of it (or another heavy metal) doesn’t really work. Instead, the shielding element is mixed in with some kind of rubber, which is why the vest ends up feeling the way it does. The vests end up being a couple centimeters thick because the lower concentration of lead means you need a thicker vest to get a Pb equivalence of around 0.2 – 0.5 mm.
-for more information, including instructions for performing your own lead equivalency test, check out this surprisingly useful site.

Sickle Probes. Because apparently that’s the official name for that pointy curved wire-on-a-stick they use to scrape your teeth and stab your gums. I suspect most people, like me, really hate the feel of that thing scraping along your tooth. Probably fewer people began to wonder, like me:

This really doesn’t feel good…I hope she’s not hurting my teeth! Which is harder, tooth enamel or the metal picks they use to clean your teeth? Do they have rankings on Moh’s scale? I would think they would want to use something of the same hardness as tooth enamel, so as not to damage anything, but maybe it’s something really hard! Ahhhh! Okay, don’t think about it, go back to inventing characters for that NaNo novel you still need to finish…

This one took considerably more effort to find out; it is nigh-on impossible to find out what most dental tools are made of. You would think, looking at a medical supply store online, that they would list the material of the tool you’re going to buy. After all, there’s going to be a big difference between one made of titanium and one made of bamboo. But noooo. After much searching, I finally found:

-most dental tools are made of stainless steel or titanium.
-Stainless steel is not one substance; there are lots of different kinds, which makes finding the Moh’s hardness even more of a pain.
-Moh’s hardness scale is really a pretty crap measurement system

But it’s also the only one I have any familiarity with, so I went with those numbers. And they are:

Tooth enamel: 5 (Wikipedia)
Stainless steel: 5.5 – 6.5 (general interweb consensus)
Titanium: 6 (Wikipedia)

So, basically, the tools the dental hygienist uses to clean your teeth are in fact harder than your teeth, so if s/he doesn’t know what s/he’s doing, s/he could do a fair bit of damage. Let’s hope I can forget that before my next cleaning in September…

And if you’re wondering how I finally figured out they were made of stainless steel…this is where I got the info, after much searching. For shame, interwebs, for shame.


So, hooray for sudden science. Or maybe not so much hooray, as my first though upon my mother mentioning she had veal for lunch was, “How would you breed for good veal? Is that even possible? Is it a thing? There are some logistical issues.” Mom did not find this to be terribly appropriate dinner conversation. But I’m curious

1 Comment

Posted by on 21.3.2012 in Education and Teaching, Sciences


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One response to “An Inquiring Mind Visits the Dentist….

  1. mitukagome

    21.3.2012 at 8:34 pm

    I hate dentists. It doesn’t help that they always gouge my teeth out with their shiny stabby sickle thingy. The worst is whenever I have a cavity and they have to fill it, cause it hurts! Apparently the novocaine should numb it to the point where you can’t actually feel pain, just maybe feel something moving in your mouth, but I’ve got the feeling that novocaine doesn’t work so well on me. CAUSE I CAN ALWAYS FEEL PAIN. and they’re cold and drills make creepy whirrry noises that just oh god I’m freaking myself out just thinking about it and my neighbors have super cute puppies and puppies are adorable. ADORABLE PUPPIES MYRIAD, ADORABLE.


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