The Pros and Cons of a Proposed Dental Filling Material

Adam S. Harwood, DMD
OHSU/Kristyna Wentz-Graff


OHSU/Kristyna Wentz-Graff

Dental fillings have been successfully employed since the 1800s as an expedient method for repairing the damage done by tooth decay. In fact, according to the National Institute of Dental and Craniofacial Research, 92% of adults ages 20 to 64 have at least one cavity in their permanent teeth. Also, the average American adult has roughly seven permanent teeth with fillings. There’s no question that amalgam fillings have proved themselves a dental mainstay, which is why researchers who have developed a new filling material are creating quite a buzz in the dental and medical community. 

In the face of the increasing demand for aesthetic dental restorations, the search is on for improved resin composites that will provide a better bonding interface between the tooth and the restoration material. This year, researchers from Oregon Health & Science University School of Dentistry have developed such a new filling material for cavities. Since their announcement, industry professionals have been debating whether this compound is a breakthrough or a potential safety hazard. The controversial substance creating the stir is called thiourethane, which makes up a part of the new filling’s chemical compound.

What’s the issue? Proponents cite a new study by the researchers in the journal Scientific Reports on the new filling substance, which uses thiourethane, saying it will be twice as resistant to breakage than standard fillings. Opponents point to the material, which is used as a protective coating for car bumpers and wood decks, as a major health safety concern and a tough sell for dental consumers not keen on questionable additives. 

In addition to claiming that the filling material is twice as resistant to cracking and breakage than standard fillings, the OHSU researchers have formulated an adhesive that provides a 30% stronger seal than current filling adhesives.

There’s a lot to be excited about here. Dentists have used amalgam fillings for years. But recently patients have expressed increasing concerns over the use of mercury in amalgam fillings. Critics are pointing to the small amounts of mercury that are released from amalgam fillings over time and potentially pass into the body’s blood and organs, including the brain. 

Plus, it’s well documented that fillings don’t stay adhered to the tooth forever, with the average filling needing replacement with 8 years. Today’s dental composites also still employ the original methacrylate monomer, known as Bis-GMA. When polymerized, this monomer has the potential to work with certain microorganisms in the mouth to cause a recurrence of decay in the filled tooth. 

Alternatives to amalgam have included metal onlays or inlays, composite “tooth colored” filling material that is bonded to the tooth, and different types of dental crowns.  

And just as patients have looked for alternatives to traditional amalgam fillings due to the short nature of their effectiveness and health concerns over mercury exposure, researchers are still trying to evaluate this new dental filling material’s safety and if potential exposure to thiourethane is dangerous in the long term.  

As we learn more about the new dental filling material, it’s important to understand the overall toll it can take on patients’ overall health. Until we can address these concerns, the best defense is prevention.

Dr. Harwood is a graduate of the Tufts University School of Dental Medicine with an advanced degree in endodontics. He was the first endodontist in New York to use a surgical operating microscope. Also, he is a member of the ADA and a specialist member of the American Association of Endodontists. He has taught endodontics at the Tufts University School of Dental Medicine, New York University School of Dentistry, and the Metropolitan Hospital Center. He can be reached at

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