What’s that sound? Could it be your teeth grinding?

Teeth grinding can often be found among highly determined people, according to the American Academy of Sleep Medicine, and that’s a population well represented in the Washington, D.C., area.

It’s no wonder, then, that dentists in the nation’s capital find plenty of what they call bruxism, a disorder in which you unconsciously grind or clench your teeth and one that can result in big-time dental problems. Grinding typically occurs at night, clenching at any time.

Washington dentist Harvey Levin says that almost 30 percent of his patients have serious enough bruxism to need night guards, devices that can help reduce the risk of tooth damage, jaw pain and other issues caused by grinding and clenching. “I make more night guards for attorneys than any other group of people,” Levin says. “They have a stressful life.”

Lillian Carpio, a periodontist in McLean,Va., says that almost half of her patients show signs of bruxism. To her, it seems more prevalent than before: “Everywhere is fast-paced, and there’s a lot of pressure to succeed.”

Despite the sense that many a Washingtonian engages in teeth grinding, sleep-related bruxism is estimated to affect only about 10 percent of adults in the general population, according to the American Sleep Association, and 15 percent of children. The rates decrease as children grow older. Many adult cases appear to be caused and exacerbated by stress, but the reasons for bruxism among children are less understood.

The symptoms can include wear on the chewing surfaces of the teeth (more with grinding than clenching), indentations in the teeth, especially at the gum line, cracked teeth, broken fillings or even indentations on the tongue or bite marks on the cheek. It sometimes results in headaches or pain in front of the ear, where the jaw’s temporomandibular joint (often called TMJ) is located.

Noshir Mehta, a professor at Tufts University School of Dental Medicine and the former director of its Craniofacial Pain Center, says, “When you clench your teeth, usually during sleep, there’s about 300 pounds of force on the tooth. That’s like a linebacker standing on it.”

Severe dental damage can result. Courtney Scott, 45, who lives in Alexandria, Va., says that over the past 15 years she has broken three of her teeth from clenching; in one case, she broke into root canal work and the area became infected. She uses a mouth guard religiously now and says, “I can’t go to sleep without a guard — I’d panic without one.” In the rare cases when she hasn’t worn one, she has awakened with headaches and pain in her jaw.

Long-time clenchers

Sue Hollar, 47, says she has been clenching for at least 20 years. During that time, she has had to replace 13 teeth that she has cracked. The problem accelerated in the past five years, to the point where, she says, “I just clenched down so hard, it deteriorated the bone.” She needed an implant in her jaw consisting of pig bone. And now the bone damage from clenching has caused gum recession so serious that her dentist says she needs gum grafting. She has a mouth guard but admits she hasn’t been diligent about wearing it.

A far less common result of intense clenching is a kind of lockjaw. Erika Gordon, 54, a social worker who lives in Chevy Chase, Md., says that she has been clenching for years; when she was in her 20s, it was so bad that her jaw locked to the point where “I could maybe put a finger between my teeth.” Physicians used a nerve-stimulating machine to loosen her jaw and gave her a prescription for muscle relaxants.

Mehta says that in many cases, the person clenches so hard that a piece of cartilage, or disk, that normally sits between the two bones of the jaw joint slides forward and folds on itself. The joint gets caught behind it, preventing the jaw from opening.

Your upper and lower teeth are not supposed to be touching unless you’re chewing, swallowing or, sometimes, talking, Carpio explains. “There should always be a space between the teeth.”

The most common treatment is a combination of medication and a night guard. The point of the night guard, also known as a mouth or occlusal guard, is to be a barrier between the teeth to protect them from wear. It also can prevent pain by maintaining space between the teeth so the muscles of the jaw can’t fully contract.

The mouth guards made to fit at the dentist’s office can be expensive, often $500 or more for what’s usually a hard acrylic device that fits snugly on the top teeth. For temporary use, you can get them online or at the drugstore for less than $50, in kits where you heat and mold them to fit your teeth — though some users find these cheap versions bulky enough to cause drooling or so ill-fitting that they fall out during the night.

But dentists strongly advise patients with severe cases of bruxism to use a professionally made guard — and many bruxers don’t need convincing.

Peg Nichols, 53, a serious teeth-grinder who lives in Washington, says she would wake with a headache if she didn’t use her guard. “It takes some getting used to, but it fits like a glove,” she says, comparing it to the feel of a retainer. Twenty-eight years after receiving her first guard, she wears one every night: “I don’t even think twice about it.”

Children who grind

Ricardo Perez, a pediatric dentist in Chevy Chase, says he has “a significant number of 3-to-5-year-olds who clench and grind,” but it doesn’t last. “At 8 years old, by the time some of their grown-up teeth come in, there’s probably 1 percent or less who grind.” He has no idea why it is more common among little ones but says, “I can’t imagine that most of these 4- and 5-year-olds have much stress.”

One theory, according to Mehta, is that new teeth coming through the child’s gum causes discomfort, “and you know how if you have a little sore or something in the mouth you keep playing with it? Well, it may be that as the teeth are coming up, they’re causing irritation and it feels better to clench on it.” Another theory is that children’s bruxism is related in some way to breathing problems during sleep.

Perez says that he never suggests a mouth guard for these young children because the typically temporary grinding doesn’t create significant wear on the tooth enamel: “We hardly ever see the side effects of that on their primary teeth.”

Bruxism isn’t always a product of stress in adults, either; taking certain medications or having sleep apnea or sleep-disordered breathing is associated with a higher incidence of the disorder.

Clenching and stress

Alan Glaros, a bruxism specialist and psychologist at the Kansas City University of Medicine and Biosciences, says that he and dentist colleagues are studying the relationship between clenching and stress.

“Stress seems to set the stage for more tooth contact,” he says, “and more tooth contact appears to cause more pain. So there’s two ways to reduce pain: Control stress and reduce contact.”

The night guard is one way to reduce contact; another is to try to change behavior.

“You can’t walk around with a night guard 24/7,” Carpio notes, “so we try to teach patients some behavioral interventions to recognize when they do it, and to try to stop it.” If they clench at work, she adds, “we sometimes tell them to put a little note in front of the computer reminding them to relax their jaw muscles.”

How about trying to reduce overall stress levels? Levin is on the cynical side on that subject: “What are you going to do,” he asks, half-joking, “tell somebody to get rid of their wife? Or quit their job? People don’t change their life habits very easily.”