Grinding your teeth is called bruxism. Stress is one of the causes. Misaligned teeth or sleep issues can also be culprits among adults. (Among kids, causes can include allergies.) Bruxism can give you headaches, a sore jaw, and cracked or loose teeth. If you grind your teeth at night, ask your dentist to fit you with a mouth guard. If it's a daytime problem, try meditation, exercise, or other ways to curb stress.