I heard many years ago that mercury fillings could prove to be a health risk, I had some and had them all removed, I don't recall them causing me any problems that I am aware of , but didn't risk keeping them in there either. I had mine removed way before dx with MS, but who's to say, remnants of that stuff could linger for a very long time or maybe even permanently, there's just no telling.

My dentist removed my metal fillings almost immediately when I became his patient. He performed this free of charge, just wanting to remove any possible bad issue metal fillings might have with MS. No idea what a biological dentist is or why it would matter what kind of dentist needed to remove fillings, no matter the type.

I considered having all my mercury fillings replaced with amalgam a while back but came to the conclusion there was no evidence of medical benefits as a result.
It's easy to do things like this out of desperation, unless it's a proven treatment with measurable benefit, you're simply lining someone else's pockets.
Save your money for the future, you never know what might happen in the field of a cure, massive steps are being achieved in the world of auto immune diseases ATM, whilst it's not going to happen next week, it MAY happen sooner than later.

I had all of my mercury fillings removed about 15 years ago and not by a specialist. But whatever works for you.

Also, absolutely wear a rubber DENTAL DAM if they remove mercury at a regular dentist!! You don't want the particles going down your throat at all.