I recently had a cavity removed from a molar. Because it was quite deep, the dentist filled it with a sedative filling and we waited two weeks to see if I experienced any sensitivity. During that time I did not have any sensitivity to cold or hot and the tooth felt fine. Originally, I was told that the remaining tooth structure was about 2 to 3 mm away from the root and that if it did not become sensitive, the tooth would be restored with an onlay. However, upon arriving to the appointment, he decided to do a crown. When I asked why a crown instead of an onlay, I was told a crown would provide a longer lifetime to the restoration so I agreed. If it helps to know the cavity was only affecting the MO surfaces. My dilemma is that after more of the tooth structure was removed to prep for the crown, my tooth began to feel sensitive to the air device my dentist was using, when before it wasn't. After the procedure was done I was feeling pain in my cheek (where the anesthesia was injected) and sensitivity in my tooth. I had trouble sleeping due to the pain. Today the tooth is no longer sensitive but I am paying close attention to it. My question is, was there really a need to crown the tooth instead of using an onlay? Not sure if I chose wisely, since it seems the extra drilling might have caused root sensitivity. If the tooth eventually needs a root canal, will I have to obtain a new crown? I guess I'm concerned about having a crown, then a root canal, and no metal-post to strengthen the tooth.