To take the official stance of the American Dental Association, Amalgam is not dangerous. When it is set, the Mercury in the restoration is completely bound and inert. Dramatized claims of amalgam removals from a patient's mouth and a sudden cure of any and all disease processes they may have no scientific merit/explanation for them, just anecdotal claims.
What I tell my patients when they ask me is that the greatest risk for mercury problems with amalgam restorations is for myself and my assistant who are around the unbound, unset amalgam with great frequency. I also will open my mouth and let my patients see that I have a couple of amalgam restorations in my mouth, and I tell them that they have been there since 1985. I end this discussion with telling them that part of my job involves keeping current with all the latest research on these topics, and that if I thought there was any health issues related to amalgam restorations, why would I have them in my own mouth?? :wink:
Frankly, the literature that tries to make amalgam out to be the pending doom of civilization as we know it today, is junk science if you evaluate it critically. Look, the legislature in California just denied a bill that would eliminate the placement if amalgam restoration by 2006, because the scientific proof behind the anti amalgamists claims was determined to be junk science. <img border="0" title="" alt="[Eek!]" src="eek.gif" />
The major issue with amalgam in dentistry may end up being more with waste water disposal levels of mercury than with amalgam placement issues. Many communities are imposing/finally enforcing water mercury concentration limits. This could really dramtically effect how we dispose of this waste water when amalgam removal is done, since the purifiers to eliminate the amalgam down to the allowable levels can have price tags/maintenance fees rapidly appproaching 6 figures, and the potential fines for non-compliance could be much greater than that!
Amalgam though is still a great restorative material! For those in school now/residency now that believe that all you need is some bonding agent and composite, just wait until your composite restorations placed with sub gingival margins, mandibular posterior lingual surfaces, the disto-buccals of maxillary 2nd molars, many squirming, fidgety pedo patients, have been i the mouth for a couple of years, and you see the recurrent decay on the bite-wings(this will happen commonly even with rubber dam isolation in those questionable circumstances). The flip side of this is as long as its been atleast 2 years since you placed the original composite, the patient's insurance company will pay for its replacement(at the amalgam reimbursement fees of course!), this way, after a few years you'll be giving yourself a future supply of restorative work, and potentially some endo and crown and bridge too!

Don't get me wrong, I love composite, you just need to be very carefull in selecting appropriate places to place them(atleast until they come up with an composite that can be placed in less than a dry field, and perform as well long term as amalgam does)