In 1845 the American Society of Dental Surgeons banned the use of mercury fillings because of health concerns.*
Do these health concerns persist today? Check out these videos: Video 1 — Mercury FIllings Video 2 — Neuron Degeneration
(*) Source: Ring ME (2005). “Founders of a profession: the original subscribers to the first dental journal in the world”. The Journal
of the American College of Dentists 72 (2): 20–5.