@Shiroyasha @karolat Sadly this is true, however I would be quite surprised if it applied here. Which isn't to claim it's outside the realm of logical possibility but it's a risk estimate thing.

Generally that happens with pharmaceuticals and food additives and such. Things that you consume regularly and that interact with your biochemistry. The other notable one is scenarios such as building materials where there's an absolutely massive quantity of something that can dissipate gradually into an enclosed space that has a fairly low rate of ventilation overall.

With tooth filling there are two obvious factors. One is that it's a single application of an exceedingly small quantity. There just isn't very much of whatever it is to begin with, it's not like you keep going back to the dentist to get some more of it on a weekly basis or whatever.

The other is the chemistry. It's inert by design (once properly cured ofc). It isn't supposed to interact with your biochemistry because more broadly it isn't supposed to interact with *anything*. It needs to stay in place in order to do its job so if it was leaching out over time it would be dissolving away gradually and a tooth filling that up and disappears on you isn't fit for purpose I would think.

For a back of the envelope, figure its mass when it goes in versus 20 years later. The difference in mass spread out over that time period is the maximum dosage of whatever it is you might be worried about.