Here is the hard part, the sedative filling material is weak and will not last, requiring a more permanent restoration. From the description it sounds like a crown would be best (trust me, in my mouth, I would take a lab made restoration like a crown, inlay, onlay, etc over a large filling EVERY TIME!!!). This further work will further inflame the nerve. A healthy nerve would be able to handle any necessary fillings or crowns, but an unhealthy nerve will not survive the inflammation that will occur from the necessary work to fix the tooth. I would expect the root canal on this tooth.

This is the most important part. LACK OF PAIN DOES NOT MEAN LACK OF PROBLEM. It is like heart disease, some experience no problems until they have a heart attack. Does this mean that there was not a problem? NO, it was there for quite some time.

The tooth could be dying and this would initially diminish the pain and cause abnormal sensitivity to cold. Eventually the pain to cold will be lost then followed by a latent period. After that, a radiating, unprovoked pain in the angle of the jaw. It may swell as a result of an infection or cause a blister that drains the infection.