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Biomedical Engineering
Fixing Fillings — The Natural Way
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The sound of it is enough to send chills down your spine. It’s the dentist’s drill — and the 90 percent of us who get cavities will have a run-in with it at one time or another.
Dentists usually repair cavities by drilling out the decayed part of a tooth and filling it with a synthetic material like amalgam or tooth-colored composites. But fillings are far from perfect.
"Composites are soft and moldable materials that are photo-cured to become hard and permanent after a dentist fills a cavity," said H. Ralph Rawls, Ph.D., professor of biomaterials in the department of restorative dentistry. "The composite material shrinks, which eventually causes a gap to form, allowing bacteria to leak into the pulp of the tooth. It can cause a painful infection."
While Dr. Rawls continues to develop filling materials that won’t shrink, the human body may have its own perfect solution. It’s called tertiary dentin.
"Tertiary dentin is the tooth’s own natural defense mechanism," Dr. Rawls said. "Over time, the tooth will naturally produce tertiary dentin, which forms a barrier against bacteria leaking into the pulp."
Unfortunately, our teeth don’t make tertiary dentin fast enough to fend off a painful toothache. And the dentist’s drill doesn’t help.
"Teeth have a limited ability to self-heal, but when a patient gets a cavity filled, the high speed hand drills that are used inhibit this activity," said Mary MacDougall, Ph.D., associate dean for research and professor of pediatric dentistry.
Dr. MacDougall has identified specialized protein "cytokines" that stimulate dentin-forming cells (odontoblasts). She and Dr. Rawls have developed a liquid "carrier" system to deliver the cytokines to the site of a cavity. "The carrier is a liquid solution that helps preserve the cytokines and stimulates dentin formation," Dr. Rawls said. "Stimulating this natural repair mechanism is the first step toward being able to replace part of the tooth with its own natural material," Dr. Rawls said.
And it is bioengineering at its best. "This is the body’s own natural process," Dr. MacDougall said. "We are just enhancing it."
The National Institute of Dental and Cranial Research recently awarded Dr. Rawls and his team a five-year, $5.6 million grant to continue this research. The Health Science Center is collaborating with the Southwest Research Institute to develop an advanced dental restorative system.
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