By Rick Valachovic, DMD, MPH, Clinical Professor and Co-Executive Director of the NYU Dentistry Center for Oral Health Policy and Management

Throughout my career, I’ve tried to look around the corner to see what’s coming around the bend and how it will impact our profession. This year, I caught sight of a new concern that may surprise you: plastics.

What’s the mercury connection? Almost four decades ago, fears about the health effects of dental amalgam obscured its real downside — the need to manage disposal of the mercury contained in amalgam waste. Today  amalgam is used far less often to restore teeth in the United States, but dentistry faces a new environmental challenge: Our clinics, and health care in general, are awash in plastics. These synthetic materials are interwoven in almost every aspect of dental practice — from our personal protective equipment to our office furniture to the materials we use in the mouth.

Take composite resin fillings, which have become the default choice for treating dental caries. Composite looks nicer than amalgam, and its placement allows dentists to preserve more natural tooth, but this material is composed of polymers — the building blocks of plastic.

“We don’t yet know what all the ill effects of this material are,” says Bapanaiah “Penny” Penugonda, BDS, MS, one of NYU Dentistry’s senior mentors/group practice directors. As the first person to receive a master’s in dental materials science at NYU, Dr. Penugonda rates composite fillings “pretty good,” but acknowledges their potential downsides. “When you’re grinding this material, when you’re polishing this material, some of these microplastics are going to come out, and where are they going to go?” he asks.

Plastics and Health

Earlier this year, popular media outlets reported that our brains contain about as much plastic as a typical plastic spoon. The image is almost comical, but the reality demands much more than a passive shrug. Plastics have become ubiquitous in our daily lives, and tiny fragments of various polymers have invaded our bodies. In fact, plastics have been found in human lungs, blood vessels, and placentas, to name just some of the organs studied, and those micro- and nanoparticles are not inert. They release harmful chemicals including endocrine disruptors that have been associated with the global rise in diabetes, declining sperm counts, and certain cancers.

The problem is so vast that in August, delegates from 183 countries met in Geneva to try and finalize a global treaty “to protect the environment and human health from plastic pollution.” This was the fifth meeting held to develop a convention to govern the design, production, and disposal of plastics world-wide. A draft and a revised proposal emerged from the talks, but the delegates adjourned before reaching consensus, leaving observers feeling “deeply disappointed.”

Dentistry’s traditional separation from medicine often places it on the fringes of discussions about human health writ large, but it’s imperative that we tune in to these signals that our environment is imperiling our health. If we are to succeed in adapting to the challenges ahead, our profession must heed these early warnings signs.

A Wake-up Call for Dentistry

Regulation and awareness might reduce the amount of plastic waste humans generate, but it won’t solve the problem of how we restore damaged teeth, correct a malocclusion, or help patients with nighttime bruxism. Since the advent of plastics, the material’s versatility has made it an obvious choice for many dental uses. It can be hard or malleable, clear or opaque, and any color of the rainbow. It’s also long-lasting and typically doesn’t biodegrade. Yet plastics are susceptible to wear, especially when heated, and as they break down, they release tiny particles and known toxins whose impact on human health is now being quantified.

Part of that work is happening here at NYU, where Dr. Penugonda is preparing to conduct research to improve how microplastics are measured in the oral environment. He also plans to investigate whether plastics are leaching into saliva, tooth structure, and soft tissue. I’ve also learned that the American Association of Orthodontists has begun monitoring research into the potential connections between microplastics and dental devices. Clear aligners have many advantages over metal braces, but aligners’ presence in the mouth, their daily wear, and their exposure to friction raise concerns that they may elevate wearers’ risk of microplastic ingestion. They also contribute untold amounts of plastic to the waste stream each year — another reason I’m happy to see orthodontists calling for more research.

In September, the Center for the Investigation of Environmental Hazards (NYU CIEH) at our sister institution NYU Langone hosted its second symposium on plastics and human health. The talks were too wide-ranging to summarize here, but a clarion call emerged that bears repeating. “This is not an us versus them problem. This is an us problem,” said Matthew Campen, PhD, MSPH, a professor in the College of Pharmacy at University of New Mexico. “It is something we all have to figure out and come to terms with.”

The Way Forward

In April, I wrote about ways to make dentistry more environmentally sustainable. Reducing our dependence on single-use plastics, avoiding plastic packaging, and finding less wasteful ways to maintain a sterile environment are effective actions we can start taking now, and more help is on the way. The CIEH symposium showcased a range of novel solutions for replacing commonly used plastics, which are already on the market or in development.

This spirit of innovation is also leading to the creation and adoption of next generation dental materials.

• Silver diamine fluoride (SDF) can be used to prevent and arrest caries, providing dentists with one inexpensive, readily available alternative to conventional “drilling and filling.”
• Here at NYU, researchers have developed zinc-based materials that have been shown in the lab to fight caries and reduce sensitivity without the cosmetic downsides of SDF. The team is now working with industry to develop a commercial product that could be a game-changing non-invasive treatment for tooth decay.
• And if experiments at King’s College London and clinical trials at Kyoto University in Japan play out as hoped, lab-grown teeth and a medicine to facilitate tooth regrowth may revolutionize dentistry in the next ten years.

In the meantime, we have access to one more plastic-free material that is inexpensive, easy to use, and widely available: dental amalgam. Despite its bad rap in the 1990s, there is still no credible scientific evidence linking amalgam fillings to the harms their detractors cite. In fact, a 2018 Canadian government report comparing composite and amalgam concluded: “The best available evidence indicates that, compared with composite resin, amalgam restorations appear to be more clinically efficacious and as safe, while also costing less.” Thanks to an earlier international treaty, the Minamata Convention on Mercury, and subsequent regulations, U.S. dental offices now use amalgam separators to capture mercury waste, reducing dentistry’s contribution to this environmental hazard.

The concerns about mercury underlying these efforts are well founded. Unfortunately, the Minamata Convention signatories went a step further this November, calling for a complete global phase-out of dental amalgam by 2034. This will eliminate one of the most affordable and versatile tools in our restorative toolbox, and it could leave patients in less developed corners of the world with insufficient options for treating dental caries.

In confronting both mercury waste and microplastics, dentistry must remember that human and environmental health are inextricably linked. I believe we can address the global burden of oral disease, practice sustainably, and reduce both the environment’s exposure to mercury and the public’s exposure to microplastics, but will we? Research into the health effects of these particles should be a wake-up call to accelerate our efforts to develop a new paradigm of dental practice. I hope our profession heeds that call. It’s time for all of us to acknowledge the harms inherent in a plastics-filled world and to take concrete steps toward remedying them.