I'm sorry for your father.

I do believe that most official medicine today is complete crap.
I do believe that it sould be not trusted.
I do believe that there are much, much more effective and safe methods.
But I also believe that most dentists are stupid and misinformed, not that they are criminals that try to poison the world. After all they suffer from mercury too.

The problem is that medicine is very dogmatic. Once it assumes something it's very hard to change her mind. Especially since it implies that they were wrong.

Another problem is that man often gets into stuff without knowing the consequences (also because they are hard to calculate).

Now mercury has been used quite a lot in the history of medicine. I can believe that mercury is used because its cheap and effective, despite being deadly, because they really dont care much about peoples health. But I doubt they use it for the precise reason of harming people.

Oh well, after all this is a minor detail. The result is that they harm people, on purpose or by stupidity, we will never know.