Hmmm. Lexapro is what I was first put on when it started to happen. Had the same problem with citalopram -- only worse(!) The clenched jaw was all the time. The mis-alignmet was not constant, but quite frequent.
Though it's been years since being on either one of them, I still do occasionally get jaw mis-alignment, where it won't close. Ironically enough, it happened today! So weird.
Have had Wellbutrin as an add-on AD for a couple of years now. It's certainly possible there's a connection, but I take the Wellbutrin every day and the jaw thing only happens from time to time. Doesn't really matter, as it's minor and intermittent.

Let us know how it goes with your Pdoc, ok? Do you have an appointment soon?