Is pulsating pain under a newly installed crown on a molar mean infection or is the crown defective?!

I've done thousands of root canals on teeth exactly like what you describe. Here's what happens. You probably had an old filling in the tooth. That means the dental pulp was already stressed. Any time you have a tooth worked on the pulp gets inflamed. Sometimes the inflammation is mild and the pulp (tooth nerve) can recover and return to its normal and healthy condition. Other times the inflammation is too severe and causes tooth pain. In your case the process of preparing the tooth for the crown and the crown cementation process produced a pulp that is so inflamed that a root canal will be necessary to relieve your pain. The pain is so intense because the pulp is trapped within the hard tooth structure and can't swell to alleviate the pressure on the inside of your tooth.
Hope this helps,
Dr.THealth Question & Answer

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It sounds like you need a root canal. Placing a crown on a tooth would not cause pain. However, the prepping of the tooth for the crown may have exacerbated a condition that was already going on. You needed a crown for a reason, most of the time it is because of decay. A dentist will try to preserve the tooth by cleaning out the decay but often the decay goes to the root and that's what causes pain.

There are many possibilities so call your dentist, it may also be that your crown is ill fitting.Health Question & Answer

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