My dentist calls the white filling a "composite" -- which is no more helpful a word than "amalgam". ("A composite of what?" I asked. "Resins," I was told.) The composite material by itself is less strong than amalgam; but since it bonds to the tooth and amalgam doesn't, the tooth itself is stronger with composite fillings. And less sensitive to heat and cold. I haven't had a bit of trouble with the two I have.
Before the dentist put in the first one, he surprised me by saying "You're not an alcoholic, are you?" He said the daily, heavy ingestion of alcohol can cause the composite to erode.