#31 tooth needs gumline cavity filled. Dentist suggested amalgam to get better seal due to location. I'm concerned w/ amalgam regardless FDA cleared.

Amalgams. have been around for 100 years & there is no valid scientific research to prove otherwise. They are routinely taught & used in dental schools. They are present in my own mouth & I could have all of them replaced with composite for free but choose not to. No one can stop you from being concerned other than yourself. Gumline cavities can be restored with composite fillings if retraction\isolated.
Use glass ionomer. I would choose a glass ionomer restoration if possible. The restoration releases fluoride and it would be beneficial to the area, if you can get proper isolation. If you can not get proper isolation, crown lengthening procedure may be indicated for long term success. Amalgam is an acceptable restoration.
Amalgam Controversy. Also note that the American Dental Association long ago approved its use, and that it has been used without incident since the 1800's. Concern is good, irrational fear is not. In any event cervical lesions can be restored with composite with the proper preparation and isolation. The choice is yours.
Amalgam is safe. The amalgam is a safe and durable choice. Most research finds no relationship between fillings and symptoms of mercury poisoning or other side effects. Advances in modern dental technology allow to place tooth colored composite fillings instead of amalgam fillings to restore the natural appearance of the tooth.