[10] Huggins received a series of warnings from the U.S. Food and Drug Administration (FDA) for violating good manufacturing practices and marketing unapproved medical devices.

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.

"[12][13] Huggins's license was subsequently revoked by the Colorado State Board of Dental Examiners for gross negligence and the use of unnecessary and unproven procedures.

[15] In 2002, the National Council Against Health Fraud examined these claims and concluded "there is no scientific evidence that amalgam fillings cause or contribute to the development of these diseases.

"[9] In a paper published in Alternative Medicine Review in 1998, Huggins claimed that changes in cerebrospinal fluid that are typical for multiple sclerosis remitted after the removal of amalgam fillings and root canals.

[20] Huggins claimed that dental care according to his understanding of dentistry has allowed wheelchair-using patients diagnosed with multiple sclerosis to walk unassisted within weeks.

[19] According to a review article on mercury controversy published by Dr. Dodes in the Journal of the American Dental Association, "there are numerous logical and methodological errors in the anti-amalgam literature" and concluded that "the evidence supporting the safety of amalgam restorations is compelling.

"[3] The FDA in 2020 commented "the majority of evidence shows exposure to mercury from dental amalgam does not lead to negative health effects in the general population.