My dentist told me a story (she had plenty of these but this was the most powerful one) about a girl she knew who was a dental hygienist in a practice using mercury. The girl was trying to get pregnant for a long time with no luck. She also had illnesses which were persistent. My dentist suggested to her that she get away from the place she worked where mercury was used. Eventually the girl decided to do so and the illnesses cleared up and she got pregnant.
Mercury actually off gasses in its normal state, so you don't even have to touch it to be affected.
Use of mercury amalgam goes way back in history to the Chinese. It was resurrected by some dentists in the US in the mid 1800s and the dental association at the time banned it due to it's known issues, so these dentists simply started their own association which is the current American Dental Association because mercury is such an easy and cheap thing to make fillings with.
Mercury was the forerunner of antibiotics. As such it was used to fight infections as it is a bactericide and will kill anything in it's path.
This ADA became the dominant force in the industry presumably because it was in essence the easy way out for the dentists at the time and it still is and once you have told patients this story all your professional life (Mercury is safe) it becomes difficult to back out and say..... "gee I'm sorry I was wrong all those years." Think of all the lawsuits... It would put most dentists out of work and into bankruptcy. Goodbye (the Volvo on) the yellow brick road. Dentists are like the rest of us in that they don't want to lose their jobs.
http://www.iaomt.org/ check out the youtube on the mercury off gassing... and the youtubes on the dentist who explains about his history with mercury and a number of other youtubes on the topic.
This industry generates a lot of money for a lot of people and so the vested interest is extremely high. Why rock the boat? The current ADA is very adamant that mercury is safe despite the science in other countries and the outright banning in some countries and the government in one country that banned it and is paying dentists to remove it from patients. There is a lotta moolah and egos involved and so the apologies that would have to happen in the US to change this mess are too much so dentists just duke it out in court and hope they can use their considerable financial clout to fund the dirtiest lawyers they can find. Also they duke it out with the dentists who are breaking the bad news about amalgam. This is where the dirtiest stuff is going on both in Canada and the US.
Fortunately with the internet it is difficult for people to lie in public. It is too easy for people to check out the story and decide for themselves.
There are some interesting court cases on the subject in the US and the ADA has had to back off on some it's claims. I haven't kept up on the developments as we got rid of the crap in our mouths. The mercury wall is crumbling.