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Volpe Research Center postdocs pursuing improved dental composites

March 11, 2016

By David Burger

Drs. Huyang (left) and Yang
Gaithersburg, Md. — Two postdoctoral researchers with strong international research backgrounds are working with the team at the ADA Foundation Dr. Anthony Volpe Research Center on cutting-edge explorations that may bring new materials and tools into dental practice in the near future.

George Huyang, Ph.D., and Yin Yang, Ph.D., work as part of a VRC team that is researching longer-lasting dental composites, with interesting new findings arising regularly. "We see each other almost every day," said Dr. Yang of her colleague. "It is always fun to share our new discoveries and research progress or setbacks with each other. We are good colleagues and friends."

Drs. Huyang and Yang are a part of the research team overseen by Jirun Sun, Ph.D. This team is investigating novel ways to improve the service length of composites, originally invented in 1962 by Dr. Ray Bowen. The research includes the integration of self-healing properties and new resin systems into these next-generation composites. In 2013, the National Institute of Dental and Craniofacial Research awarded the VRC a five-year grant to support Dr. Sun and his team on this project.

Dr. Huyang grew up in Sydney, Australia, and graduated from the University of Sydney in 2007 and received his doctorate in 2012 from the same university. He has been at the VRC since 2014.

Dr. Huyang's research focuses primarily on the concept and application of a self-healing dental composite. He synthesizes components of this composite, molds the composite into specific-sized specimens and tests their mechanical properties, healing ability and durability.

"The service lifetime of existing dental composites has been short, and it is difficult to repair them once they've been implanted into a patient's mouth," said Dr. Huyang. "Therefore, it is best if we could incorporate self-healing characteristics into the material to improve its service life. There have been many challenges we have encountered throughout this research, such as the lack of standard methods to measure the healing efficiency. But through composition modifications and method development, we have successfully made dental composites that can heal the cracks autonomously and also designed and evaluated new tools to determine the effectiveness of the healing."  

Dr. Yang grew up in Changsha, the capital of Hunan province in China, an area that she says is "famous for its spicy food and television industry." After earning her bachelor's degree from East China University of Science and Technology in Shanghai, she was awarded a doctorate in chemistry at Dartmouth College in New Hampshire. She arrived at the VRC in 2015.

Dr. Yang's research includes developing polymerizable molecules and studying the kinetics of their polymerization process — basically the rate and degree of the polymerization and the composition of the polymer obtained.

"Dental resins using BisGMA-TEGDMA, a key chemical component in dental composites as the polymer backbone, were introduced by Dr. Ray Bowen back in the 1960s," Dr. Yang said. "However, their susceptibility to hydrolytic and enzymatic degradations in oral environments has limited their average service life to about eight years. As a result, longer-lasting dental composites are needed. One possible solution is to replace the hydrolyzable ester groups with ether groups. Our recent study has shown that such modification indeed drastically improves the stability of the resin."

Dr. Bowen joined the ADA research center staff in 1956 after his first published research paper and presentation at an International Association for Dental Research meeting led to an encounter with Dr. Robert Nelson of the ADA Research Unit. That unit evolved to become first the ADA Foundation Paffenbarger Research Center (PRC), and later the ADA Foundation Dr. Anthony Volpe Research Center. After years of very productive research for the ADA, including development of many other dental materials, Dr. Bowen became director of the PRC in 1983 and was director until 1994. He became the ADA's first distinguished scientist in 1994.

Both Dr. Huyang and Dr. Yang are committed to continuing their career in scientific research.

"I hope that in five years, I would have a successful career in the field of science, whether it be in industry or academia," Dr. Huyang said. "In 20 years? I feel it is really hard to say, and that too many things can change. Maybe that is a question I can answer in five years."

"In the next five years, I would like to continue using basic science and research to make something that could be applied, something that is useful in our daily life or practical in advanced technologies," said Dr. Yang. "Chemistry is interesting because it's a field where you can create things that do not exist otherwise. As for my next 20 years, I am not sure yet. I want to keep my options open. But definitely a career related to chemistry and material science."

For the time being, the two are focused on their goals of developing pioneering dental composites.

Dr. Huyang said, "For self-healing dental composites, there is the big overall goal of improving dental material to improve their lifespan, and each individual step has its own goals along the way, like confirming the healing or developing a standard method for measuring healing. Smaller goals like these will keep us move forward as research progresses."

"I want to understand dental resins as much as possible," said Dr. Yang. "I want to solve current problems and create better resins to be applied to dentistry. The most satisfying moment for me as a young researcher is when I tackle a problem and come up with a solution after overcoming a series of difficulties."

For more information on the ADA Foundation Dr. Anthony Volpe Research Center, go to  To support the scientific research being done by the VRC or other ADA Foundation programs, visit