Other people appear to be down-voting you, so I'll comment instead: The standard defense is that the mercury is locked in place inside the amalgam, and does not migrate. I've never looked at the evidence either way.
> The debate over the safety and efficacy of amalgam has raged since time immemorial. In recent times, it has reached such a feverish pitch that it seems to drown out all sounds of reason. Amalgam has served the dental profession for more than 165 years. Incidents of true allergy to mercury have been rare and attempts to link its usage with diseases like multiple sclerosis and Alzheimer’s disease have not been significantly proven, although there may be some association between amalgam restorations and oral lichenoid lesions.
> Marshall, in his review on dental amalgam, summed it up appropriately: “if some reported values of Hg release are extrapolated to clinical life times, the entire restoration could lose its Hg in short time. For example, a 500 mg amalgam restoration contains approximately 200–250 mg of Hg, and the entire quantity of Hg would be lost in 10,000 days if the Hg was released at the rate of 25 ?g/day. This estimate of release is of the order of magnitude reported in some studies of vapour release”.
In theory. But grinding teeth, chewing, or even brushing can cause flakes to break away. The biggest risk is actually during installation of the amalgam, particularly for dental professionals.
The real crux of the issue is that there are safer effective alternatives. So even if we call the risk "low," it is a needless risk. It only a matter of "when" not "if" these filings are against safety regulations.
I remember in Germany there were lots of studies that showed mercury leaking out. Dentists fought for quite a while but I don't think they are in use anymore. I got my amalgam fillings taken out in the 90s and replaced with plastic and ceramic.
They also observed that we pee pretty much all the mercury we ingest, but that methyl-mercury is the one we absorb, accumulate, and that is highly toxic.
I had one removed about 7 years ago. The dentist fitted a dam to avoid fragments being ingested and to minimise vapor inhalation, and (if I recall correctly) he advised me to breathe as gently as possible during the crucial stage of removal.
The dentists fight it because the science mostly says they’re harmless. Trust me, there’s plenty of money to be made removing the old fillings (which actually is the most dangerous time for mercury contamination) and replacing them with composites. Dentists are incentivized to do so. They just don’t want to cause unneeded hysteria.
As a person who has struggled to afford dental care over other life expenses I would strongly believe that the Mercury only stays in place in optimal conditions. I had a chipped tooth which I didn't treat right away which lead to the tooth decaying. Then it cracked in half. There was a filling that was split in half during this. It was a month later before I could afford work on the tooth. I don't know if that filling had Mercury or not but if it did, my mouth was definitely exposed to it.
That's the defense against removing amalgam that has already been introduced, it's safer locked away than trying to drill it out and risking high level exposure.
In my experience the mercury amalgam fillings tend to crumble and plop out in pieces after a few years. Maybe not the entire filling, but enough to where they'll have to declare a do-over, drill and augment/replace with more mercury amalgam.
Quoting:
> The debate over the safety and efficacy of amalgam has raged since time immemorial. In recent times, it has reached such a feverish pitch that it seems to drown out all sounds of reason. Amalgam has served the dental profession for more than 165 years. Incidents of true allergy to mercury have been rare and attempts to link its usage with diseases like multiple sclerosis and Alzheimer’s disease have not been significantly proven, although there may be some association between amalgam restorations and oral lichenoid lesions.
> Marshall, in his review on dental amalgam, summed it up appropriately: “if some reported values of Hg release are extrapolated to clinical life times, the entire restoration could lose its Hg in short time. For example, a 500 mg amalgam restoration contains approximately 200–250 mg of Hg, and the entire quantity of Hg would be lost in 10,000 days if the Hg was released at the rate of 25 ?g/day. This estimate of release is of the order of magnitude reported in some studies of vapour release”.