The inability to open or close your jaw all the way may signal what they call "disk displacement without reduction." Usually when you open and close your jaw a small disk stays between your jaw bone and the place where it meets your skull or cranium. When you hear clicking and popping, that usually means the disk is being "displaced" when you chew. When the disk is jammed to the back or front of the disk space and does not move back all the way, it limits how far you can open and close your jaw.

Take a look at www.rad.washington.edu for a discussion of jaw joint anatomy at the University of Washington's site.

Bottom line: If it's not that painful or bothersome, you probably don't need immediate treatment. But you may want to monitor your condition carefully and perhaps be evaluated by a dentist with lots of experience treating TMJ problems. Here's a professional group of dentists who specialize in evaluating and treating TMJ. There's a locator function for finding a specialist in your state:

www.aacfp.org - The American Academy of Craniofacial Pain is an organization of about 500 dentists and other clinicians who treat TMJ.

Good luck!