insurance for amalgam removal

Hi! My husband needs to have his Amalgams removed, but he does not currently have dental insurance. Do most insurance companies cover Amalgam removal? If he gets insurance, and then shortly thereafter has this work done, will they still cover the cost, or do they have some sort of rule that a certain amount of time (and payments) has to go by before they will cover it? Can anyone recommed a good dental insurance co.?
Any suggestions are greatly appreciated!
Thanks,
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