Is it possible for a dental crown on a molar to be too tight in it's fit?

It is not a good idea to reshape the existing crowns as it is not going to look correct.  You will want to consider doing the front six teeth to get proper symmetry and harmony.

Hi;Very often sensitivity to heat means a dead or dying nerve that requires a root canal.  Please have a root canal specialist check the tooth.Best,Dr. Maddahi

Hi:Due to the temporary crown material and fit, it is very diffcult to be able to chew normally on it.  It's best not to try to chew on the temporary crown until you final crown is cemented.Best,Dr. Maddahi

It appears from the limited info you've given that the depth of the decay in one or both of the treated teeth might have been extensive enough to damage the nerve.  That can often happen. Without and x-ray, its impossible to diagnose. Return to your dentist and bring...

Dear nosc78: It is unfortunate that the provisional broke, but it is not uncommon.  As long as you do not have pain, it is OK.    Make sure that you brush the area very well, right over the remaining temp and do not be afraid to dislodge it.  It is far more important to keep...

From the blurry and limited view of your photo, I agree the metal underside is showing through. They grey hue is the metal.  I have no further info to go on- alt views or x-rays, but I suspect that you have bone loss and tissue (gum) loss in the area which makes the implant...