Quoted from YeOldPinPlayer:That's a logical fallacy - an argument from ignorance. As such it's an invalid way to prove your point. Even if your premise was correct it doesn't mean B follows A.
Nothing means anything.
My dentist teaches dentistry at the big university's medical school.
If she says that it's the currently accepted practice to remove mercury from a patient's mouth whenever they are already numbed up for a procedure, then I trust her knowledge more than somebody from the internet.
If your 70 year old dentist says you should continue to have mercury installed in your mouth, you can take his word for it, or find a younger dentist.