TMJ also known as tempromandibular jaw displacement is when the person suffering from this cannot do things effectively, such as chew, talk, yawn, eat without a lot of pain and the sound of popping. The popping is the jaw joint where it is connected to the discs of the joint (near your ears) these discs slip out of their connection to cause the noise and the pain. TMJ can be caused by a fall, by improperly fitted braces, by wisdom teeth, by grinding of teeth at night, poor posture, anxiety, stress or depression, and is even in some cases genetic. In my case, all I had to do was lightly press my fingertips to each side of my face right on the discs and it would cause pain. These discs in an unaffected person are perfectly round and fit correctly into the joint sockets, but on a TMJ victim, the discs can be misshapen, or so deteriorated that they cannot bear the weight of the jaw at all. There is a cream out that is new that is supposed to help with the pain called capsacion, but back 7 or 8 years ago, the only way to help me out of the immense pain was the surgery. Since that time, my jaw has only popped twice, and that was right after my accident so I must of dislodged something temporarily. There are dentists that specialize in TMJ patients as the patients are unable to keep their mouths open long periods of time, and sometimes can't even open wide enough to fit that block they put in your mouth to take x-rays. Most dentists if you have TMJ will not even work on you if they don't specialize in doing so.