Stu, the best thing to do is go to a holistic dentist who can send you to a recommended bio-compatibility testing lab which will give you the material that what works best for your body.

Personally I didn't go that route, the dentist I went to recommended a composite that had quartz and 2 other items in it that I can't remember. He said that was the material that seemed to be very benign. I was just so happy to get the mercury out and as long as it wasn't any other metal it wasn't that critical to me.