My current dentist is fabulous, green (no amalgam used in the practice), and very honest. I'm not a fan of radiation exposure, even for a split second -- but at the same time, I'm less of a fan of toxic materials in my mouth all the time. One must choose their battles, and this one was a no-brainer. Not only did he immediately replace the filling, but took an x-ray after the procedure to ensure that all amalgam was removed.
If you haven't had x-rays in a while, it's important to have them just to see what's going on in your mouth. Having them done is really easy, too, as many offices offer digital x-rays --- a small device that's moved easily from area to area in the mouth. It takes just minutes to x-ray your whole mouth, and you can see them immediately on the monitor. Very kewl.
Know yourself, inside and out.
Take control of your health.
Knowledge is power.