Complex sentence: In the mid- 1980s, the FDA claimed that Huggins's "Amalgameter", a device which claimed to detect "positively or negative charged dental fillings", as a simple battery-powered ammeter being promoted by Huggins with scientifically unsubstantiated claims about dental fillings.
Split into simpler sentences: In the mid- 1980s, Huggins was investigated by the FDA for his marketing of the "Amalgameter", a device which claimed to detect "positively or negative charged dental fillings". The FDA found that the Amalgameter was a simple battery-powered ammeter, but was being promoted with a variety of scientifically unsubstantiated claims about dental fillings.