When you get Amalgam fillings out, you need to get them replaced with other fillings which do not contain amalgam.
Before the dentist takes the old filling out and puts the new one in, he/she will give you an injection so you don't feel any pain. The injection may hurt. The new filling should not hurt, but be like previous fillings you have had.
You need to find a dentist who will replace Amalgam fillings. Some dentists will not do it.