The condition of grinding the teeth, specially at night is known as bruxism. The process can do a lot of damage to the teeth and cause the reason of annoyance for bed partners in may ways.
It is a fact that there exists a direct relationship between bruxism and TMJ disorders. This can result into various sleep-disordered breathing, and in more severe cases, it can lead to a more intensive obstructive sleep apnea in patients as well.

CAUSES OF BRUXISM
As far as the doctors are concerned, they have blamed stress for the gnawing and gnashing of teeth at night. In this fast growing environment, the chance of an increase in level of physical and emotional stress is always there and the hard reality is that bruxism increases with additional stress level in the body- physically, mentally and emotionally.
As far as the research is concerned, it has now become a fact that there is some kind of relation that exist between bruxism and the body's survival mechanism in order to keep the airway open.
If an adult or a child is involved in grinding the teeth at night, the first causative factor to look whether there is a  obstructed airway or not. Some of the most common symptoms of this disorder is enlarged tonsils and adenoids, specially in children. The factors can even contribute at a greater level and can lead to obstructive sleep apnea.
Also if the jaw is located at a wrong position(TJM), then the local tendency of the body is that it tries to correct it by bruxism. The muscles of the jaw and face spasm and attempt to move the jaw so that it can gain a more accurate position. As these muscles spasm, the teeth grind together as a type of response to that muscle activity . This can occur particularly in a person who have severe dislocation in jaw.

SIGNS OF BRUXISM

• Severely worn teeth
• Receded gums in the absence of gum disease
• Higher incidence of root canals, major dental work on back teeth
• Sore jaw muscles in the morning
• Headaches
• A face that looks shortened between the nose and chin