Metal still in mouth. Is it safe to chelate?

Dear all,
Here is my situation:
Until relatively recently, my mouth was filled with Amalgam fillings, many of which were placed there during my childhood. After over three decades of this close personal association with Hg, I parted with all lower jaw fillings which were replaced with composites in an UNSAFE way. I felt terrible afterwards and my bottom teeth were hurting for months until the pain slowly dissipated. Of course, I was assured that this experience was normal.

About a couple of years ago the rest of my Amalgam fillings were replaced. This time the procedure was done in a more responsible way (strong suction and a rubber dam on and off).
Finally, during a period of 3 months early in 2016 all my metal crowns (six in total) were replaced with resin-based ones and a piece of a dental tool which was embedded in one of the root canals was removed.
So now I have finally started oral chelation using the AC protocol (4 rounds of DMSA at 12.5 mg so far) assuming that it is safe to do so. BUT IS IT REALLY? Below are a few issues which I am seeking an educated opinion on.
1.
Is it possible to still have some small chunks of Amalgam hiding under a composite filling? After all, the first dentist I hired was careless and convinced that I lost my marbles by requesting an entirely unnecessary procedure. Why would she care to do the job thoroughly if she did not comprehend the danger? A current panoramic photo of my teeth does not reveal anything suspicious or glaringly wrong (no large nuggets of metal showing). However, my present dentist, when pressed for an honest answer, told me that one can not rule out a possibility that a smaller piece of amalgam, something smaller than say a pinhead or a grain of sand is still hiding under a white filling. The only way to be certain would be to re-drill and check.
But maybe my concern is unfounded… Maybe, even if something was left behind, it would not be problematic. Maybe a small chunk of amalgam, once buried under the composite does not pose a risk any more and won’t leach mercury and other metals out during chelation? Would anyone have any thoughts/experiences/observations/educated guesses on this topic?
2.
Unfortunately, I still carry a piece of dental tool in one of my root canals (yes, you heard me: I am talking about piece # 2. As I have already mentioned, piece #1 was removed successfully - partly degraded and in chunks). This piece #2 is one tough thing though, since it is lodged in such a way that an entire tooth would have to be pulled out in order to get rid of it. My current dentist claims that it is safely encased in the cement which fills the root canal and no bodily fluids have access to such places, thus, logically, the chelating agent would not have access to it either. Should I trust this assumption? After all, chunk #1 deteriorated into crumbs even though it was encased exactly the same way.

BTW: I lost count of the number of incorrect assumptions and misguided assurances which were offered by health professionals over the years. My experiences taught me to trust no one with the exception of those who ‘lived it and tried it’ or those who know others who ‘have lived it and tried it’ i.e. people like you guys: the contributors to this and other, similar sites. You are the true trailblazers and heroes. Glad to be able to mingle with this special and awesome crowd.

Joko
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