TMJ is the abbreviation for Temporal Mandibular Joint. It is the joint directly in front of your ear that is used by your body to open and close your mouth. It is like most other joints in your body in that there is cartilage, fluid, bones, and muscles involved. And just like any other joint in the body any piece to this puzzle can deteriorate, get misplaced, damaged, or have any other number of problems.
If any sort of damage does occur then pain may result. If you are having pain there a number of different treatments available to help resolve the problem. One of those ways is to have the patient where a TMJ mouth guard. This appliance will help stabilize a joint that may be damaged or inflamed and gives the dentist valuable information as to what may be causing the problem.