If your fillings are in good shape I wouldn't bother replacing them - mercury fillings generally last longer than the alternatives, and mercury exposure is likely greater from removing them than leaving them in. Maybe if you have a huge number it's worth doing, but I personally wouldn't be concerned about 3 or 4 (speaking as a toxicologist who's done some work on mercury). If I was getting new fillings I'd go with composite unless it was a really major filling though.
|