What can cause intermittent jaw pain?

In my lower left jaw, the teeth all feel too tight, like there's something between them. Twice in the last two months I've had very severe pain in the area of an old, large filling. But two different dentists (in different states, even) have said the X-rays show no problems. Sometimes an upper tooth, directly above the filling, hurts also. Then the pain goes away for a while. The first time, there was sensitivity to heat and cold. Not the second time, which was less severe than the first. Both dentists are reluctant to remove & replace the old filling; both also do not want to do a root canal. The first time I had a migraine headache, but not the second time. I'm not prone to headaches, as a rule. No chest pain. No clicking as in TMJ problems. I suspect bruxism, but the little clip-on device to prevent tooth grinding hasn't made much difference this past three weeks. Dentist #2, who blames bruxism, would charge $6000 for the root canal. Is this reasonable?

$6000 for a root canal? How much teeth is he doing it on. If it's just one, that sounds too high. My rooth canal didn't cost near that much and my dentist did a good job. I had a similar problem where my filling would hurt and the tooth directly above it. It turns out that it was because I had a wisdom tooth growing in and that caused pressure on some nearby nerves, causing referential pain. I don't think its the same for you though. Sinus infections, heart problems and other conditions can also be a cause of your jaw pain. What I would do is get a third opinion before I agree to getting a $6000 root canal!! Personally, I think that's what it's going to come down to. I had sensitivity to hot and cold and it was excruciating. I used to assume the fetal position everytime it hurt. But when I got a root canal it solved the problem. So, get another opinion before you do anything.

SLAVIA GLANDS COULD BE BLOCKED..
WOW OH WOW CAN THAT HURT,,
FEELS LIKE THE JAW (HINGE) WHEN OPENS AND CLOSES
IS BROKEN LIKE LOCKED JAW..

ANTIBOTICS CLEAR THIS UP--INFECTION... SALVIA GLAND..

Do you have problems with your neck and or shoulders? Have you had any injuries having to do with the same? The pain may be generated from somewhere other than your mouth. Those nerves are tricky and can cause discomfort in unlikely places.

You could still have TMJ even without clicking. You could also be clenching your teeth and not realize it, but there are tons of reason why you could be having this problem.