is removal of mercury a danger as well? where is there a good dentist in MI or MA

Does anyone know of a dentist in either michigan or massachusetts that removes mercury from fillings. Also had two root canals. Dangers with what they filled roots with? What should they fill the tooth with that is safe. I went to my dentist and asked if fillings were mercury. He said yes but then said it is not necessary to take it out unless there is some form of a crack leaking the mercury into my body. Also, said that when you remove mercury that is actually more dangerous than leaving them in because of the spillage while taking them out...? true?