Is there anything I can do to stop grinding my teeth at night?

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Yes. You can see a dentist and get fitted for a "night guard" that you wear, like an orthodontic retainer, while you sleep. Custom-made night guards are pricey ($200 to $600, for more complex devices), but they are covered by some insurers. Alternatively, you could try the cheapo over-the-counter drugstore versions. I did this, but despite trimming it down according to the instructions, it was so bulky and uncomfortable that I threw it out.

Tooth grinding, technically called bruxism, is very common, affecting about 50 percent of adults and children at some point in their lives, said Dr. Stephen DuLong, associate dean for clinical services at the Boston University Goldman School of Dental Medicine. It seems to strike more when people are stressed, and it may actually relieve stress, though it's not clear why. "The good news is that people tend to outgrow the tendency to grind their teeth as they get older," DuLong added.

Grinding one's teeth at night (people tend to inhibit the tendency during the day) can lead to TMD, temporomandibular joint disorder, or pain in the jaw joint and difficulty opening the mouth wide. That's because sliding your teeth around at night and clenching them hard "torques" the jaw joint, said Dr. Luke Matranga, a dentist an associate professor at the Creighton University School of Dentistry in Omaha and a spokesman for the Academy of General Dentistry. It also causes the teeth to wear down significantly, and raises the risk that teeth will develop cracks or even break.

The easiest way to tell if you grind your teeth at night is to ask your bed partner - grinding can be fairly noisy. You probably grind your teeth if you wake up with tight, sensitive jaw muscles. And look in the mirror - if your teeth look shorter than they used to, you're probably grinding them down.

JUDY FOREMAN

E-mail health questions to foreman@globe.com.