By Meredith Bryan

May 20, 2008 | 12:28 p.m

“I don’t know if you’ve ever had jaw pain, but you can’t think about anything else,” said Christine Smallwood, 27, describing the discomfort that drove her to see a dentist about a year ago. It was “this sort of throbbing, throbbing, throbbing pain that would run all the way up to my ears and all the way down into my chin,” she said. “I would start to cry on the subway. I would break down in tears at my desk. I was in total agony.”

Ms. Smallwood, an associate literary editor at The Nation who lives in Greenpoint, was sipping iced coffee at 71 Irving the other day with a lovely, red-lipsticked mouth full of white, straight chompers, describing how a dentist had quickly diagnosed the source of her “debilitating” pain: nighttime teeth grinding, or bruxism.

“I had just moved in with my boyfriend, and they seemed to think that there must have been so much stress or whatever,” she said, with a shrug.

The dentist prescribed a custom-fit hard plastic “nightguard”—essentially, a mouth guard for sleeping, which doesn’t stop the grinding but does prevent enthusiastic grinders from totally eroding their teeth. Ms. Smallwood conceded that the nightguard was “gross,” but said she wears it religiously due to her dentist’s “absolutist scare tactics.” And she’s not alone. “Once you get a nightguard and you start telling people you have a nightguard, you find out that other people you know have nightguards,” she said.

Do they ever.

“It feels a little it’s like the hypoglycemia of our generation,” said teeth grinder and nightguard-wearer Hailey Eber, 27, a freelance researcher, by phone.

Bruxism is associated in the popular consciousness with a related malady, TMJ, an umbrella term for pain or disorders of the temporomandibular joint. (Dentists are quick to point out that we all technically have TMJ joints, and that TMD, or temporomandibular disorder, is the correct term. TMD can cause bruxism, or result from it.)

“If you say the word “TMJ” at a party,” Ms Eber said, “everyone pipes up and starts talking about it, but they don’t really know what they’re talking about—like, ‘Oh, I have TMJ, too!’

“I have neurotic friends,” she admitted.’

BRUXISM AND ITS DISCONTENTS

New Yorkers did not invent bruxism—the Journal of the American Dental Association states that the condition has been present throughout all of human history and according to wildly divergent estimates, it afflicts anywhere from 15 to 96 percent of the adult population at some point in their lives—but we might be its most dogged practitioners.

“We live in a very high-stress environment,” said a Park Avenue dentist, Dr. Joseph Osipow, who has treated patients here for two decades. “The incidence is much greater in the last, say, 10 years. I never used to see the volume of problem that I see now.” He estimated that 30 percent of his patients grind or clench.

“I’ve seen more grinding in the last 5 to 10 years,” agreed Dr. Madeline Apfel, D.D.S., whose office is in Gramercy Park. “Actually, I noticed it after 9/11, believe it or not.” Currently, she treats “a lot of young people,” for bruxism; she said its primary demographic extends from 20 to 40. “I think it goes on everywhere, but I think we’re more aware of it here,” she said.