The U.S. Food and Drug Administration (FDA) recently hosted a public meeting of the Immunology Devices Panel of the Medical Devices Advisory Committee to discuss metal-containing implants and dental amalgam.
In September 2019, the FDA announced a paper on biological responses to metal implants. The paper focuses on how metal materials are impacted by a physiological environment, expected and potential toxicologic and immune system responses to the metal associated with an implant, as well as subsequent clinical manifestations. The paper identifies where gaps and opportunities for further research exist in the current scientific evidence related to immunological responses to metal-containing implants.
Metals and metal alloys are commonly used in implanted medical devices and in inserts like amalgam dental fillings, and these materials are sometimes in contact with parts of the body for extended periods of time. Part of the FDA's evaluation to determine whether a medical device is safe and effective involves reviewing information about metals and other materials used in the device.
The FDA has heard concerns raised by patients and other device users, and has received adverse event reports that note biological responses to certain metals used in medical devices. Based on their evaluation, they believe the current evidence, although limited, suggests some individuals may be predisposed to develop a local or systemic immune or inflammatory reaction when exposed to certain metals contained in select implantable devices.
The symptoms some people have noted may be limited to the region where the device is implanted or may be more generalized. Reported systemic symptoms include fatigue, rash, joint and muscle pain, and weakness. Although uncommon and varied, these symptoms can sometimes mimic more well-established inflammatory conditions, such as systemic lupus erythematosus.
The most common metals and alloys used in implants include stainless steel, cobalt-chrome alloy, titanium, and nickel-titanium alloy (nitinol). Other metals, such as gold, platinum, silver, iridium, tantalum, and tungsten, are also common in many medical devices.
Building on prior work and steps outlined in the Medical Device Safety Action Plan announced in 2018, the FDA conducted a comprehensive review of metals used in medical devices, due to concerns raised by patients and reported adverse events potentially related to biological responses to certain types of materials in medical devices. This is part of a broader review of the use of select materials in implantable devices.
Dental amalgam is a dental restorative material used to fill teeth damaged by tooth decay. Dental amalgam is a metallic compound consisting of liquid elemental mercury and a powdered alloy composed of silver, tin, copper, and other metals.
Engineering testing is routinely done to evaluate the potential for metal wear and corrosion of a specific device through different possible mechanisms.
