How Often Are Root Canals Needed Right After Putting in a Dental Crown?

Thank you for your question. On occasion there are cases, which are a border line in nature. For example, when cavity is very close to the nerve. Some schools recommend to remove a nerve and perform a root canal therapy right there and then. Others say why create additional expence for the patient and devitilize the tooth, when there is no need because there are no symptoms at this time. One school has more conservative philosophy then the other. Work with a dentist you are more comfiortable with.Another possible reason might  be grinding of the teeth. Most dental work is done while patient is numb.That means patient can not feel the bite the same way in comparison to being not numb. Being a grinder myself and having experience of uncomfortable " high bite" after a dental treatment , the best advise I can give you is to see your dentist within 3 days of treatment. It will help to check and make sure your bite is perfect and it just might prevent a root canal therapy.In case a root canal is needed after a crown placement, it can be done through the top of the crown and sealed afterwords with a filling matching crown's color. 

When a tooth is prepared for a crown by a dentist, the tooth structure encompessing the nerve can be thick and stable or thin and weak. Most of the time, a dentist can get a good enough feel for the need of a root canal while preparing the tooth and will warn the patient...or not. If the patient is sensitive after the crown was started, It may even be indicated to wear the temporary for an extended period until symptoms subside. A final crown could also be placed with temporary cement for a few months just in case so that the crown doesnt have to be damaged when doing the root canal. 

A root canal specialist will drill through a permenatley placed crown-regardless if it is new or old. I personally believe a new crown should be made-regardless.