Louise,

Amalgam fillings always have microscopic or larger cracks in them because for one thing the metal expands and contracts with varying temperatures. Any amalgam filling that is more than a few years old is in this category. I bring this up because bacteria gets in these cracks at a slow but steady rate which can ultimately cause inflammation with the pulp leading to death of the nerves. So you may have a slowly dying tooth there. This is not always evident on a typical dental xray unless decay is visibly seen and/or a pathological area is seen at the root of the tooth. Again, this may or may not be your problem.

I am curious as to why the dentist root planed the premolar....???

I would be that your regular dentist is going to refer you to an endodontist for a root canal. If for no other reason than to stop your complaining about it.... I know that is terrible isn't it??! The last thing you need is another root canal... you've been down that road and look what happened.

Someone else posted on here suggesting the possibility of a fractured root. Again this is commonly seen with molars that have amalgam fillings. From what you have described previously, your dentist did the usual checks for a fracture and they were negative. But that doesn't mean it's not fractured because these things can be hard to diagnose and they are rarely picked up on an xray.... unless the xray is taken at a bisecting angle which sometimes picks up the fracture, but not always.

I'm sorry this is not all that helpful. Just keep your wits about you and remember the pitfalls of root canal therapy. Don't let anyone decide what is in your best interest...hear all of the options and decide for yourself what is best.

Keep us posted...
Bryanna