Why do I have blue gums under an old root canal? (Photo)

I think your best option would be to have that crown replaced. It shouldn’t be possible to remove it as you describe. If there is a crack there, it can and probably will decay. The metal in the crown will make it difficult to see decay on an x-ray. The first symptom will likely be pain, but at t...

It is certainly possible to put a crown on a wisdom tooth. If there is enough solid tooth structure and the tooth is in an appropriate position, it shouldn’t be a problem.

It is possible that the crown was not properly cemented or may have an air bubble. My recommendation is to go see a dentist before the situation gets worst or you end up losing the crown. 

Based on my experience, darkening around a porcelain crown is  more likely to be present whenever metal is used as a substructure for the crown ( PFM or porcelain fused to metal / gold crowns).   PFM crowns have an opaque “non-precious metal” , “semi-precious metal” or “high n...

Do not use glue. This is never a good idea.    Find a dentist to consult with and recement.   Good luck.  

Your tooth might be hitting high and need to be adjusted, or you may have a nerve problem in the tooth which would mean a root canal.  Find a dentist to confirm.