I've read many times that it can be perplexing trying to determine if we are having dental issues or MS issues. I've been told a lot of root canals have been performed and the issue is MS. I've been warned to be careful of expensive dental treatments because it could be MS.

Soooooo......how do you know?
I had right sided pain in my teeth. Dentist sees nothing wrong in the xrays (taken 3 times). Then it goes away......hmmmmmm.
I have a very old crown back there.....PERHAPS I would see some relief with replacing it....
Dentist says my molar roots are really close to my sinuses.......
I have a polyp the size of a quarter in that sinus..........sinus can cause tooth pain.
I also get an "ache" in my jaw (I always thought it was a strange kind of spasticity in the muscle there) Went to eye doctors for years thinking I was straining my face or something because I was not seeing well (barely nearsighted but refused to wear glasses half the time).

My approach to the subject is this:
Do like doctors do.....rule out everything else. If there is a chance it can be dental...then get the appropriate dental work done. If it still persists, then its MS. AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHhh!!!
Its just the nature of the beast.