Sometimes when i open my mouth wide enough, my jaw locks itself (but it's rare). does this mean i have tmj?

Yes: If your jaw locks open, it is because the articular disc has move from its normal position to prevent jaw closure. For this to occur, the structures holding the disc firmly in place have stretched. So, physical changes to the joint imply a disease process has occurred. Only you can decide if you would like to keep things from worsening before you develop full TMJ symptoms.

NO: When a jaw locks open, it usually means that the part of the lower jaw that meets the scull has travelled beyond the bounderies of the socket. This is often associated with hyperactivity of muscles that move the jaw. You should talk to a dentist who has advanced training in TMJ disorders.

Questionable: Tmj refers to the physical joint space of the lower jaw. The appropriate term is tmd or temporo mandibular dysfunction. There are many symptoms that can be associated with this. Yours may be simply a loose joint that dislocstes itself upon excessive opening. I would discuss this issue with your dentist and have him/her evaluate.

Yes, but: Yes, your intermitten open locking is one of the TMj diorders. But if it is rare, no treatment indicated and prognosis good. Just avoid situation where you open wide enough to lock, or the condition could progress to something more serious.

TMJ DISEASE/SYNDROME: Yes & no. The causes for TMJD vary in severity and determine treatment plans. Talk to your dentist or PCP. X-Ray studies may help to characterize your issue and determine if you have inflammatory vs. osteoarthritis. If you have bruxism (teeth grinding) that will contribute to pain/popping/locking. It is best to get treatment earlier than later. TMJD can also cause debilitating headaches.

No, dislocation: TMJ becomes dislocated when the condyle moves too far and gets stuck in front of a bony eminence. TMJ dislocation is due to either trauma or more often the excessive opening of the lower jaw.

No: This is called subluxation. Anatomically, your condyle (the part of your lower jaw in front of your ear) slides past the bump in your upper jaw (the arcuate eminence) - back from your cheekbone- and gets stuck. Some patient's get stuck here and have to be seen ASAP for repositioning. I would avoid this as much as possible, as it is an extended range movement . Good Luck.