Hello twinmom,
Amalgam is a very highly controversial topic. Many claim of its devastating effects of brain and the central nervous system, BUT it is dose specific. Did you know that the Mercury contained in amalgam is nowhere near the amount of Mercury contained in fish? The world wide web is a great source of information, however when you are searching for reliable scientific answers, I recommend using google scholar and reading studies published in reliable scientific journals. Less and less people opt for amalgam fillings because of aesthetic reasons, however amalgam fillings are more durable and long lasting than composite fillings. The reason why amalgam is controversial and many dentists stopped using them is because of environmental waste. The Government monitors closely the amalgam levels in the environment and we, as dentists accumulate a lot of amalgam waste from extra unused amalgams or removed amalgam fillings. This becomes a burden and that is why many practices are going metal free.
-Once again I would like to assure you that there are hundreds of studies on this topic and none have definitely linked amalgam dental fillings with developmental problems in pregnant women. It is also very difficult to scrape off amalgam once it sets and you had them for 10 years. The gray may have been from the polishing/mint tasting volcanic ash used after cleanings to remove stains from teeth. It is great that you are taking care of your oral health while pregnant, since pregnant women are at risk of developing gingivitis if they do not maintain proper oral hygiene.