Originally posted by Christopher:
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.
A lot of my fillings (and I have a lot, sigh) are on the grinding surfaces. The resin composites of a few years ago simply weren't up to the job - 5 years maximum, as opposed to typically at least 10 and anything up to 20 years for metal. They were much too soft to resist the amount of wear.
I had a long, if slightly one-sided, conversation with my dentist about it several years ago, because I'd gone in for filling work a couple of days after the BBC's shock horror expose programme had claimed that dentists were killing their patients with mercury poisoning. He'd already seen the start of the rush to get those nasty mercury fillings replaced with lovely safe plastic, and was happy to be able to rant on the subject to someone who was very determined to have metal, thank you very much. Being a materials scientist, I had a somewhat more informed layman's view than Joe Public, because the ongoing improvement in dental materials is one of those things that gets occasional coverage in the general materials science press.