I had mine removed with a rubber dam in place, over 3 sessions, each a month apart, and detected no extra exposure afterwards.
Be careful with heavy metal detox - it can cause deficiencies in iron and other essential metals. I just used green tea in between meals and fresh cilantro.
I felt much better immediately and saw a gradual improvement of inflammatory problems. Mercury was just one piece in the inflammatory jigsaw puzzle for me.
F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.