They only need to be cleaned out once.
The root canals were replaced with a two tooth removable bridge that hooks over the tooth in front and tooth in back.
These people have videos of mercury fillings offgassing, which is a neurotoxin, and more information:
http://www.iaomt.org/index.asp http://mercuryfreedentistga.com/mercury-toxicity http://users.penn.com/~rarearts/mercurypoisoning.htm If Hg was not poisonous, why do they have special hazmat handling protocols when they put it in your mouth, and when they take it out??? And then why do they claim that once it's in your mouth it is safe and inert??? That is not logical.
Nobody should be using Hg in fillings.