Fascinating, amalgam was first used over 150 years ago , before randomised clinical trials. There have certainly been many studies since , however compelling evidence has not been produced.
The toxicity of all dental materials has been studied for decades before I studied , which in itself was many years ago. Many dental materials have been discarded because of safety concerns eg endomethasone , whitening with perborates etc.
The largest trial is that of dental staff who not only have amalgams in their own mouths , but also place amalgam, and in terms of mercury exposure more importantly remove amalgams every day. You would expect them to have higher morbidity and mortality rates to the general population. They do not .
All dental materials ,except perhaps gold, have problems. Composite fillings have BIS GMA etc . In the end it’s a risk benefit ratio. Time is running out for amalgam because of environmental, not health concerns and because the alternatives are improving every day.
In terms of health we are becoming aware of more detail of how untreated dental disease , particularly gum disease which around 90% of the UK population have some form of , affects general health from type 2 diabetes to heart disease to dementia.