Why God Why: The Science of a Toothache

The most unbearable pain.

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Feb 14 2015, 11:00am

​Image: Grant, John Charles Boileu/Wiki

I have a toothache. It's a familiar toothache, recurring every few months for the past year or so for no apparent reason (in the sense of direct triggers; it's obviously a cavity). The first time it came around, during a period when I was highly broke, the pain arrived and crested one afternoon mostly out the blue. It was a literal pressure within my face, but also sensory pressure, like pain was a substance coursing through my body, pushing every other feeling and thought away like a muddy-red flash flood full of broken logs and boulders and screaming sensation. It was a primitive agony.

By the next morning, it was gone. That night was a long one, involving semi-regular flushes with Jack Daniels and tissues soaked through with dissolved Benadryl tablets. I cried and may have, at one point, even screamed. Because, fuck, there is nothing worse than tooth pain. And now it's back, albeit currently at bay underneath a prescription-strength dose of Advil. Or maybe I've just beaten this wave, keeping the dentist at bay for another couple of months ... like a complete idiot.

Why is tooth pain so completely miserable? I've weathered third-degree burns, a half-dozen broken bones, and a succession of self-surgeries including but not limited to horrible things with toenails. The short answer is nerves, of course: good old evolution wasn't stingy with the wiring, particularly when it comes to the face, which happens to be close to the brain. And the brain is, of course, everything.

The mouth and jaw are hooked directly to the ​trigeminal nerve, which is one of several cranial nerves: nerves that link directly to the brain rather than link to the spinal cord. So: teeth are linked up to a nervous short-circuit of sorts. ​But that's not quite it.

Image: ​xkcd

Teeth only feel pain. There are no other tooth feelings. If a nerve happens to be exposed in there, everything is pain. Cold is pain. Warm is pain. Wet is pain. Touch is pain. There's just nothing else and that's a pretty unique situation in the human body. Skin, for example, is perfectly capable of communicating "warm" without inflicting torture and the tongue knows "sweet" without the need for a bonus sensation of thermonuclear throb. And those nerves are a hop away from their trigeminal parent, a nerve associated with ​a variety of neurological chronic pain (neuralgia) that comes in bolts severe enough to occasionally drive its victims to suicide. (Whatever your worst tooth pain, there is something far worse that a dentist can't do a thing about.)

But that's still not quite it. Teeth are weird little organs, of sorts. Under that hard shell is a pulp of structural cells, blood vessels, connective tissue, immune cells, and, finally, nerves. It's an odd situation, this mass of living, breathing gunk trapped in a little fortress of mostly crystal calcium and its associated forms. The upshot is that teeth don't swell. If you sprain your ankle, the thing is going to swell up, sometimes a whole lot. But teeth don't have this luxury. The organic guts of a tooth don't have anywhere to go, save for a very tiny hole (a pore, really) all the way at the base of its root.

So, all sorts of bad things can happen as the result of trauma, like abscesses and accumulations of necrotic (dead) tissue. Teeth die, but the dead stuff doesn't really get shuffled away like normal; it just kind of hangs out and gets really gross.

The moral of this story is to not be me, because none of the above is particularly transient. It just gets worse, sometimes much worse. Ugh, I need to make a call.