A couple of years ago I had pain in tooth #12. I visited the dentist and he said I needed a root canal. The pain subsided in the tooth and I did not have RC done. Over the next year and a half it would flare up again and have sensitivity and/or pain, but not consistently. Finally, in the fall of 2008 it became increasingly more sensitive so I made an appointment to have it taken care of. At my visit, the dentist mentions beginning to prepare the tooth for a crown... I ask him... "aren't you going to do a root canal first?" He replied "we don't need to," and proceeds to prepare the tooth for a crown. After the crown the tooth remained a bit sensitive, but no severe pain. Four months after the crown was installed, the tooth absessed. I returned to the dentist and of course he tells me I need a RC. At this visit he tells me he will replace the crown free of charge as he questioned the intregrity of the crown, but wants to charge me $1375 for the RC and $410 for core build-up, plus I have to spend 6 more hours in the dentists chair and a lot of lost time from my job. Since I had had intermitten problems with this tooth over 2+ years and had returned to him because I was having problems again, shouldn't he have done the RC in the first place? Also, if the crown didn't have good intregrity, could it have contributed to the tooth absessing? Are there any expenses I could have avoided if he had done the RC first?

There is not guarantee in dental work. The tooth could have bothered you due to a crack or an abscess. I question why he recommended the RCT the first time you saw him with the symptoms. Did he see an abscess on the x-ray he took at the time?
It does seem odd that he would place a crown on a tooth that he had once recommended a RCT for.
The more times a tooth is worked on increases it's risk of eventually needing a RCT.
Is the crown REALLY an issue? RCTs are often done right through a crown and then the access hole is filled. The crowns can remain for years if well maintained.
What does he mean by the "integrity" of the crown? Perhaps you should seek another opinion before handing over more cash. At least it may put your mind at ease.