I feel sensation on root canal tooth on touching?!

I feel sensation on root canal tooth on touching?

I had a root canal done on upper left molar tooth more than 3 months earlier. It now has a temporary crown on it. I get a sensation feeling when I touch this tooth but there is no pain. There is no hot and cold sensation also. Before temporary crown I used to get mild pain on this tooth also, which is not there now. Dentist says there is no infection.
Will it require a re-root canal. What is the cause? Should I visit another dentist?

Without seeing this it's hard to figure out what is going on. Why did you have the RC in the first place? Was it due to cavities? Was it due to pain starting up? If the latter, then the tooth may have had a fracture line going down the root and entering the nerve. All a root canal does is remove the tissues inside of the crown and root of the tooth. There are still gobs of nerves attached to the outside of the root and these are probably the ones that are being stimulated when you touch the tooth. If your doc says you are ok having the temp. on this long [even that could be causing the sensation as they don't fit that great and could be irritating the gum] then maybe you should wait a while longer to see what develops. I think you should discuss this with your doc but if it was me I'd leave it up to you as to whether I wanted to spend more $$ on it.....however, if it was my tooth, I'd go ahead with the crown.