Government/Industry to Collaborate to Develop Mercury-Free Dental Material

A mercury-free, direct filling alternative for conventional dental amalgams is being developed at the National Institute of Standards and Technology. The new restorative process uses metallic powders in a form that is easily applied to prepared tooth cavities by dentists using treatment procedures very similar to those in current practice.

The dental material project is a collaborative effort between government and industry. The National Institute of Dental Research is contributing support for the program through the American Dental Association Health Foundation's Center for Excellence. The ADAHF maintains the Paffenbarger Research Center at NIST.

A dental materials manufacturer, Dentsply International, Milford, Del., has a cooperative research and development agreement with NIST to help develop the new mercury-free restorative material.

The new restorative process is based on NIST electrochemical powder technology. The technique was invented by David S. Lashmore, leader of the NIST Electrodeposition Group, and Moshe P. Dariel, guest scientist from the David Ben-Gurion University, Beer-Sheva, Israel.

"The mercury-free dental material project offers us an opportunity to transfer technology developed at NIST to industry and meet a national need," said Lashmore.

He points out that the mercury content of amalgams used in the overwhelming majority of dental restoratives continues to raise concern with regard to their long-term effect on public health and the environment. The new alloy will help reduce the amount of mercury dispersed in the environment by dental waste.

Joyce Reese, NIDR program director for Biomaterials, Pulp Biology and Dental Implants, notes that although there is no scientific evidence linking mercury in amalgam to systemic diseases, the new NIST mercury-free, dental restorative material meets an important objective of the National Institute of Dental Research to find alternative materials for conventional dental amalgams.

Lashmore said that the principal goal of the NIST research has been to develop a high-performance, mercury-free alloy that will consolidate at body temperature in prepared tooth cavities.

The material involves the use of biocompatible metallic powders such as silver-coated tin. These pairs of metals undergo fast diffusion or combine to form an in-situ intermetallic compound at body temperature.

The treatment of tooth cavities is quite simple. The dental practitioner will mix the coated powders with an activating, biocompatible liquid to form a slurry. The mixture is then pressed into a prepared filling with conventional dental instruments. After compaction, the material hardens into a strong, mercury-free dental alloy.

Lashmore explains that even though silver and tin are the principal ingredients, investigations are being conducted with other formulations that may contain copper, gold, or small amounts of other inert materials such as silver, alumina and silicon carbide. He emphasizes that all of the materials under study are free from mercury, indium or gallium, which are commonly used today in dental amalgams.

According to Lashmore, the new direct filling restorative material could be in dental offices within three years. It will be tested both at NIST and by independent dental research laboratories before undergoing review by the Food and Drug Administration.

As a non-regulatory agency of the Commerce Department's Technology Administration, NIST promotes U.S. ecomnomic growth by working with industry to develop and apply technology, measurements and standards.