I don't think taking Iodine makes you leach more mercury from your fillings. What Iodine does is release the mercury from your tissues. You need some kind of "catcher". The best catcher is glutathione. The body makes this. Glutathione will release the mercury into the liver, which dumps it into the gallbladder, which dumps it into the colon.
There is a problem with this last step when you have mercury in your body: mercury prevents magnesium from doing it's work. This makes the little tube that runs from the gallbladder to colon cramp. In turn this prevents the gallbladder from emtpying. This then is dagerous to the liver.
Take a lot of extra magnesium to offset this effect.
Once the mercury is in the colon you want to snatch it up before it is reabsorbed. Take chlorella for that.
Take extra NAC and selenium so your body can make glutathione. You will need extra selenium anyway, because mercury will bind to it, making it unavailable to the rest of the body.
A lot of vitamins and minerals and also enzymes and chemical reactions are rendered inefficient by mercury. Take a good multi vitamin and mineral to try to keep the damage limited.
Mercury makes you retain copper.
NAC binds zinc and copper, so take care that you get enough zinc. Since mercury makes you retain copper, ou probably have enough copper.
Get rid of the amalgams! My husband (finally) got his out about 3/4 of a year ago and he is improving fast. He had a mouth full of them. It took four long sessions at the dentist (take plenty of chlorella afterwards) to replace them. Before he had them taken out he was already using Iodine and it helped even though he still had amalgams. But it was only after he had his Amalgams removed that the improvement was so obvious.