Teeth grinding (bruxism) is involuntary clenching, grinding and gnashing of the teeth. It generally happens during sleep, but some people experience it when they are awake. Symptoms may include headache, jaw joint or ear pain, aching teeth, cracked or chipped tooth enamel and mobile (loose) teeth.

Signs and symptoms of bruxism include:
Audible grinding sounds while the person is asleep
Headache, jaw joint and/or ear pain
Aching teeth, particularly upon waking
Aching and/or stiffness of the face and temples upon waking
Aching or stiffness in the jaws while chewing, particularly during breakfast
Clenching the jaw when angry, anxious or concentrating
Temperature-sensitive teeth
Cracked or chipped tooth enamel
Tooth indentations on the tongue
Raised tissue on the cheek mucosa caused by cheek biting (linea alba)
Mobile teeth.

You should consult your dental professional for their recommended course of treatment. Dental treatment options include:
Repair of tooth damage
Adjustment of fillings that may be too high and interfering with the bite (not adjustment of teeth)
Mouth appliances to be worn at night (bite splints), so that you grind the appliance and not your teeth. In most cases, these appliances will only provide relief from the associated symptoms and will not stop you from grinding your teeth.