professional opinions on post and crown issue

About a month and a half ago, my dentist looked at a tooth of mine and suggested a root canal by Dr. O'Connor.  Then he said he would finish by adding a crown for $800.

Well, he looked at the tooth today and said it would now require a post and a crown for $1,119.

I guess I'm thinking:  Could he have been more precise with the diagnosis when he looked at me a month and a half ago?

[toothfairy1215]

Did the Doctor not give you a treatment plan? When you have a root canal the tooth is usually taken out of occlusion to keep you free of pain when biting on it. A post and core build up is needed when there is not enough tooth to hold the crown. I hope this helps.