BY ALPER ÖZKAN (MSN/PhD)
d_ozkan@ug.bilkent.edu.tr
I am not too fond of dentists.
I don’t think anyone is. In fact, we seem predisposed toward avoiding them by whatever means necessary, in the same way that we tend to avoid heights, large predators and sharp objects. I’m pretty sure that at some point in our evolutionary history, there was a major survival advantage in staying as far away from dentists as possible.
It doesn’t help that my mental image of a dentist is Orin Scrivello of “Little Shop of Horrors” fame. If you aren’t familiar with him, just give a listen to his character song (You’ll be a deeen-teeeeeeeest! You have a talent for causing things pain! Son, be a deeeen-teeeeeeeeeest! People will pay you to be inhumane!), and you’ll see exactly why.
It also doesn’t help that I, for the most part, have the dental hygiene of a komodo dragon—I’m absolutely positive that if I bit, say, a deer or something, it would hardly take three steps before collapsing from sepsis. It’s said that plants that meet my breath wither, rivers that I drink from run dry, and anyone who meets my baleful gaze turns into stone on the spot (no, wait, that’s the basilisk).
So imagine my horror when I woke up one day to find that one of my molars had just up and crumbled, leaving a horribly painful cavity in its place. I got it fixed after a couple of hours (it felt more like a mahakalpa) of sheer unrelenting agony, but in honor of that tooth and the suffering it caused me (and probably still is causing me, since I don’t imagine all those tooth fragments are very kind on my guts), this column will be about teeth, and especially the sort of teeth I envy.
Like, say, regrowing teeth. Continuously regrowing teeth. Teeth that regrow so much you have half a dozen layers at any one time, dropping at least one tooth per week and regenerating them from the back of the mouth like a slow-moving, one-way chainsaw. Also, your skin is literally covered in millions of tiny teeth, each with a tiny crown and a tiny pulp supported by a tiny network of blood vessels. You’re the bone of your teeth, enamel is your body and pulp is your blood.
Man, sharks sure have it easy.
Other cartilaginous fishes, such as rays and chimeras, have similar arrangements, and an extinct shark-like relative of chimeras, Helicoprion, even had its lower jaw modified into a toothy, organic buzzsaw. Helicoprion reconstructions have a long and decorated history, mostly revolving around the core question, “Where do we put the saw?” (honorable mentions include the nose, tail fin, dorsal fin [think spiral Jaws], throat and tongue; I’m surprised nobody placed it on the claspers), and I highly recommend that you check out the illustrations in the paper “Jaws for a Spiral-Tooth Whorl: CT Images Reveal Novel Adaptation and Phylogeny in Fossil Helicoprion” for a review of that history—that’s incidentally also the paper that shows that the animal was more closely related to chimeras than to modern sharks. It seems that the authors behind the study also got their hands on a bigger, more complete chainjaw than that covered in the paper, but they’ve been having trouble analyzing it because it was too big for their equipment—always a problem when you’re trying to stuff long-dead sharks into CT machines.
Also going strong in the regrowing teeth department are the molluscs, which have their teeth set along a tongue-like structure called the radula—these teeth usually all face backward, so by extending and withdrawing the radula, the animal can scrape food from a surface and draw it back to its mouth in a conveyor belt-like fashion. While both the radula and the teeth are typically chitinous, chitons have upped the ante by depositing magnetite into their chitin network, creating a very hard, very wear-resistant structure that is quite well-suited for constantly scraping against rocks for algae, which is how chitons feed. Other alga-feeders, such as the sea hares Aplysia and Bursatella, have in addition secondary and tertiary rows of “teeth” in their gizzards, which crush and filter the plant matter scraped by the radula.
Mineral deposition is also seen in the mouthparts of other invertebrates, such as the zinc-laced mandibles and chelicerae of various insects and arachnids (other arthropod tissues, such as the stingers of scorpions and wasps, are similarly subject to metal reinforcement) and the copper-incorporating jaws of polychaetes, the latter of which are placed on the tip of an eversible pharynx to be shot at potential prey. See, these are the kind of teeth I envy. I wish my teeth were at the back of my throat and I could spit out half my intestinal tract to grab some tangerines or sponge cake (or one of those fat pigeons flocking around the UNAM building) without even moving a finger, and I bet it would be useful in various other ways, too. Remote on the other couch? Shoot your guts at it. Itch on your back that you can’t reach? Just sling your throat over. Screaming infant in the theater? I’m sure his parents won’t miss the brat.
Upon reflection, a moray-like dental arrangement would be good, too—many fish have “teeth” in their throats, which help in swallowing and mastication, but morays have theirs modified into a secondary set of jaws, which shoots out from their throats and grabs prey caught in the primary set, dragging it down the moray’s gullet without giving it a chance to escape (the moray must resort to this mechanism because it cannot create the pressure gradient that helps other fish swallow their prey).
In any case, the moray of the story is that you should take good care of your teeth, unless you want to end up writhing on the floor while praying to every deity you have ever known, as I was doing a short while ago (you know you’re getting desperate when you start expecting help from Nyarlathotep). I’m still experiencing rather nasty dental aftershocks as I’m writing this, and I’m reminded of that quip in “The Screwtape Letters” about how all the clinical depression and existential agony in the world wouldn’t hold a candle to five minutes of genuine, industrial-grade toothache.
Indeed.