We use this joint more frequently than most of the other joints in our bodies. Every time we chew, talk, bite down, or swallow we put the TMJ to work. Overuse usually applies to clenchers and grinders - people who tend to clench their jaws tightly together for a variety reasons, primarily stress.
Some people clench and grind their teeth while sleeping and are totally unaware of the behavior.
Gum chewers, who constantly work the joint, tend to be susceptible to TMJ dysfunction . By chewing on only one side of the mouth, undue stress is put on that side's temporomandibular joint. This does not allow for even distribution of force applied to the joint and pain will eventually develop. You can locate the temporomandibular joint by placing your finger on that triangle of skin in the front of your ear and then moving it a teensy bit forward. You should be able to feel a small depression between bones there.