Upper molar crowned, root canalled(same tooth), 3 roots done by x-ray shown, still mild tooth pain always, does this mean 4th? canal?

Quite likely.: Quite likely. The first upper molars often have a fourth canal commonly called the mb 2. (mesial buccal). Many endodontic specialists use high powered microscopes to detect these very small canals. My suggestion would be to have an evaluation by an endodontist that uses this technology.

Perhaps..: Most upper molars only have 3 canals, but...A 4th is possible. Sometimes a tooth with a root canal needs time to calm down. I don't know what your time frames are but give it a little more time. Then go back and see the dentist that did your root canal. It might need a retreat or apicoectomy, or maybe just another round of antibiotics. Either way...I commend you...Good call.

Several causes: That is just one of several possibilities. It could be an unresolved infection, a root or internal fracture, a bite problem, especially if you clench or grind your tooth. Go back to your dentist, discuss your symptoms and have him\her evaluate the tooth and suggest an appropriate course of action.

Possibly: Post endodontic pain can occur for a variety of reasons. One common one is a missed canal. For the best evaluation try to seek the advise of a root canal specialist (endodontist). Their training and equipment will provide you with the most likely cause for the persistent symptoms. 3d imaging called cbct is currently used to identify missing canals. Ask your endodontist. Good luck.

Perhaps: Perhaps. See the endodontist for assessment of extra canal. Cone beam CT may be needed.