Regarding mercury and mercury fillings, the book says that if you are having mercury fillings removed, have it done by a holistic dentist who knows how to remove them safely. Then do not conceive until your body has been clear of any mercury, as measured via a urine challenge test and a hair analysis, for at least 4 months. So not 4 months after having the amalgams removed, 4 months after the mercury clears the body. There's stuff in there about how to help clear the body of heavy metals. (btw, the MTHFR gene promotes accumulation of heavy metals). It also says not to conceive at least 4 months after having an x-ray.

On another note, dental checkups are important throughout pregnancy. Peridontal disease has been linked to prematurity, IUGR and other health problems. I'd skip the fluoride treatment though.