Thanks for answering.
Sounds like they've done their research. Sometimes you can see fractures during endodontic treatment, especially with those microscopes that most endodontists use. But sometimes you can't unfortunately.
They can try using some light to see if they can shine the tooth to see if they might spot the crack.
Hmm.. as for opening up a flap, that means that they want to flap down the gums to visually see the root/bone and make a diagnosis that way.
I can't think of any other diagnostic tests that they can run at this point. If I do think of something, I'll be sure to post.
In response to your questions, pressure tests were done several times and it is definitely the #19 tooth. The pain happens when biting down on something hard (piece of bone or a corn kernel), but doesn’t hurt upon release. Numerous x-rays over the last two months have not revealed a fracture. Endodontist and periodontist have said it could be “something” microscopic or a vertical crack in the root (wouldn’t that have been detected during root canal?). The tooth does not move or wiggle. Pain was relieved with topical or injected anesthesia. I now have a temporary crown while we wait for the tooth to “calm down” before my next periodontist visit. I keep hearing the term “open up the flap” as the next diagnostic procedure. What other diagnostic tools would you recommend to determine microscopic fracture or cracked root or anything other problems?
Here's a couple of websites that may help explain a cracked/fractured tooth in more detail
http://www.ada.org/prof/resources/pubs/jada/patient/patient_25.pdf
http://www.aae.org/patients/patientinfo/faqs/cracksum.htm
Hmm.. seems like you've gone through the whole spectrum. I agree with your assessment, it doesn't sound like a neuralgia of any sort.
When doing their assessment, did they apply pressure to all your teeth to see which one triggered the pain. It is important to note that the pain you feel when you bite down (or get percussed on) is the same pain. I have had patients report to me that they feel some pain but its not the same that they are concerned about. With anesthesia, did it relieve the pain. If it didn't, it would imply that the pain is not localized to the tooth. How mobile is the tooth, does it seem that it can wiggle a little or is it pretty solid?
I'm sure that they've already looked for this, but its possible that the tooth may have a fracture. Generally with fractures, you have pain when chewing down on the tooth. Generally the pain is more intense when letting go than when you bite down initially. Fractures are hard to see visibily and also on radiographs. They can be rather small. It is a little bit more rare for a fracture to occur on a tooth with a crown though. Also, when fractures occur, they do result in pocketing after awhile as the bone is resorbed.
If it wasn't discussed as a possibility, I would ask your dentist about ruling that out.
Hope that helps!