If the choice is between bisphenol-A and mercury, I would choose the former. In a cured epoxy, the amounts of unreacted bisphenol-A are negligible in my view, and pale in comparison to quantities of bispenol-A ubiquitously present in plasticized society.
As for early menarche or precocious puberty in adolescents, each case is different and there is probably no single answer for all. I view phytoestrogens present in soy products as a likely culprit; soybean oil is in the predominance of foods, and the effects of its isoflavones, particularly daidzein and genistein on precocious puberty have been documented. A first person with perfect teeth and no fillings whatsoever may be impacted more relative to early onset of puberty than a second person having ten composites, if the first person consumes substantial isoflavones and the second person consumed few isoflavones.