Dave
I had a similar problem a few years ago, before I started diving, and it was indeed a tension thing. I worked for a guy that really wound me up. So much so that I almost couldnt open my jaw wide enough to eat a biscuit. The jaw is suspended on muscles etc and its these that get really tensed up, also there is a piece of cartilidge(sp?) up there near the ear and you sometimes hear it come out of place with an almighty crack. It was suggested by my dentist I get a brace to put in my mouth overnight to reduce the tension. I didnt do this, I soon after moved where I worked and it went away and has never come back. However the last two dives I have done I have had something similar re-appear, I certainly dont feel any more tense than last year but I have changed regs (hence mouthpiece) have you? I'd suggest trying new mouthpieces if you have changed regs/mouthpieces recently. Oddly enough I am now using a small reg than last year so its not been induced by an increase in weight, in fact the opposite.
HTH
Matt
edit - has this only started since you were outed in the Freemans catalogue?
