To better understand how mercury impacts neurons and the brain, checkout this video from the University of Calgary.
Most people don't realize that the mercury in their fillings are making them sick. There has been a great debate about the harmful effects of mercury amalgams. In my opinion, there is no need for mercury to be in our mouths so close to our brains if there is another option.
Biological dentists can be found at the IAOMT website, which is an abundant resource for learning what questions to ask dentists and even has a large database of biological dentists that are close to you.
The International Academy of Oral Medicine & Toxicology organization encourages the safe removal mercury fillings, and can guide you along the way to asking your dentist the appropriate questions,