Why do you have sensitivity after getting a crown?

I decided to talk about this topic mainly because there have been many times that a patient who needs a crown ends up needing Root canal therapy. In many cases, the patient has no symptoms before the crown preparation and suddenly has throbbing pain or temperature sensitivity after the work is completed. About 30%-40% of teeth with crown preparations end up needing root canal treatment.
Keep in mind that a substantial number of teeth that are prepared for crowns already have significant cumulative physical damage which otherwise would not have needed crowns in the first place. The history of prior injury, whether due to physical trauma or tooth decay, can place the pulps of these teeth at risk. So although the sequence of events suggests that the crown preparation is what caused the pulpal trauma, that really is not the case. The truth is that the crown preparation is the last in a series of insults to the pulp that have contributed to the need of root canal