Health Science Center researchers have discovered a unique way to create a new, invisible component for cavity filling materials that could take the place of amalgam and other composite materials. The innovative dental restorative that was patented in 2004, uses a constituent originally developed for NASA for use in spacecraft.
H. Ralph Rawls, Ph.D., professor in the department of restorative dentistry in the division of biomaterials, and four other departments joined the Southwest Research Institute (SwRI) almost 10 years ago to advance their studies. Together they hold a $5.9 million grant from the National Institute of Dental and Craniofacial Research.
By collaborating with SwRI scientist Steve Wellinghoff, Ph.D., Dr. Rawls and his research team have earned eight patents since 2000 for innovative research on dental restoratives, with another soon to be applied for.
One of the most recently issued patents focuses on two major areas: 1.) developing a durable resin that undergoes low shrinkage and 2.) using nanometer-sized particles made of zirconium oxide to reinforce the resin, since the resin itself is not adequate.
"It’s analogous to the structure of a building," Dr. Rawls said. "A building is not strong enough using concrete alone. Instead, metal rods serve to reinforce the concrete."
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| You would never see this cavity filling without X-ray vision. | |
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Although amalgam, the most widely used material to fill a cavity, is efficient, it has a less appealing appearance and contains mercury. Other composite materials are cosmetically appealing but do not last more than about 10 years. They lack a strong enough resin to withstand chewing and tend to shrink and leave spaces between the filling and tooth, allowing room for further infection.
"We wanted this material to last much longer than current materials, making life easier for dentists and patients," said Benjamin Furman, a senior research associate with Dr. Rawls.
One of the team’s greatest challenges was finding a way to make the dental restorative optically translucent, yet visible on X-ray film.
"If the tooth filling material isn’t visible on an X-ray, dentists cannot see certain features needed to make diagnoses," Dr. Rawls said.
By adapting Dr. Wellinhoff’s methods for creating face shields and spacecraft windows using tantalum oxide, Furman and Dr. Rawls began to investigate the effects this material would have in a dental restorative resin.
"Astronauts experienced blinding flashes while in space because of the cosmic rays," Furman said. "The cosmic rays are not noticeable on Earth because the Earth’s atmosphere blocks them. Dr. Wellinghoff discovered that if you add small enough metal oxide particles to windows on the spacecrafts and face shields, they don’t interact with light but they filter out the cosmic rays."
The research team took Dr. Wellinghoff’s NASA technique and adapted it to their advantage. By using tiny particles made up of zirconium oxide, they created an adequate dental restorative that serves as reinforcement in a low-shrinkage, liquid-crystal monomer. It is strong enough to last about 15 years and shrinks up to 50 percent less than current composite materials, greatly reducing the chance for leakage and decay. Dr. Rawls hopes it will be available for use in the next three to five years.
"We’re pleased to have had so much success through our collaborative effort with Dr. Wellinghoff and the others at SwRI," Dr. Rawls said.
Dr. Rawls’ research team is committed to furthering its studies. The result will be reduced trips to the dentist, lower health costs and better oral hygiene.
