Are the substances in amalgam dental fillings very toxic?

Amalgam was for a long time a subject of controversy in professional dental circles, precisely because of the question of which substances in it are actually harmful and to what extent. The harmful substance is mercury (Hg), or rather its vapours, which are released from the filling. The main part is released when the filling is made or later when it is removed, while a smaller proportion is not limited to these two moments but is continuously present. The matter sounds serious, but it should be stressed that the quantities are extremely small and, compared with the amounts of mercury we receive from food or otherwise from the environment, almost negligible. It would therefore be difficult to say that amalgam fillings are genuinely harmful; the issue is more a matter of principle. We cannot claim that fillings are completely without any harmful effect, but with common sense and the available data we can see that this is not a case of poisoning the body. A greater problem is the ecological issue, since until recently large quantities of waste amalgam ended up in drains, floor pores in dental practices, etc...
Amalgam is still a good material of choice for fillings in the posterior region (from the canines backwards), at least in comparison with white fillings. It is the only material that expands as it sets and thus provides an exceptionally good marginal seal of the filling. In addition, it has high fracture strength and low wear. Its practically only problem is aesthetic.

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