Pigs grind their teeth when they're bored; cats do it when they're dehydrated; and Stannis Baratheon in "Game of Thrones" gnashes his so loudly it can be heard half a castle away. Grinding teeth and often-associated jaw problems (TMD - temporomandibular disorder, also known as TMJ) can make your face and jaw ache and even break teeth. But though the causes of bruxism (that's doc talk for grinding your teeth) and TMD are not known, a major new study may help the estimated 10 million to 35 million North Americans (mostly women between 18 and 45) who deal with these syndromes. Turns out that people with TMD have heightened pain sensitivity, and may have genetic predispositions that increase their stress response and inflammatory reactions. That may be why TMD is associated with fibromyalgia, headaches, and chronic back pain.

The good news is that the best remedies usually are the simplest. (Try to avoid surgery, implants, and bite or jaw realignments; those procedures often cause more problems than they solve.)

• Use a dental night guard to prevent teeth grinding and jaw clenching.

• Use hot and cold compresses to ease pain.

• NSAIDs, such as ibuprofen and naproxen sodium, reduce inflammation.

• Learn to manage stress. Try progressive relaxation: Start at your feet and move up your body, tensing each muscle group for seven to 10 seconds then releasing it quickly, resting for 15 seconds. Progress to the next muscle group and repeat. Breathe evenly and deeply. If it hurts to tense any area, skip it.

Ahh! Now you're smiling!