Depireux, Masri win NIH grant for dental drug delivery research

ISR Associate Research Scientist Didier Depireux and Endodontics Department Associate Professor Radi Masri at the University of Maryland School of Dentistry have teamed up on a two-year, $450,000 grant from the National Institute of Dental and Craniofacial Research at the National Institutes of Health for "Magnetic Delivery of Therapeutic Nanoparticles to the Dental Pulp."

Pulpitis, is an inflammation of the dental pulp deep within the tooth, most often experienced as a sharp pain when eating ice cream or having a cold drink. Usually treatment involves the dreaded root canal procedure to remove the damaged pulp. Depireux and Masri’s research could give dental practitioners a much less invasive treatment option. The pair are developing a new, patent-pending technique to deliver medication directly into the center of a tooth.

The research uses strong magnetic fields to move medication-coated, magnetic nanoparticles through the tooth's dentin and into the pulp. Dentin, a solid substance that encases the pulp, is surrounded by a harder-than-bone layer of enamel. "When you have a cavity, usually the enamel has been damaged and the dentin is exposed, so when you eat or drink, it will stimulate the fluid within the dentinal tubules and cause pain," Masri explained.

The researchers are using tubules, the microscopic channels that travel through the dentin into the tooth pulp, as the vehicles to deliver the inflammation-reducing or antibiotic medication. They have designed a system of magnetic arrays effective for upper or lower teeth. By manipulating a series of cube-shaped magnets, they can control the magnetic field so the nanoparticles are pulled through the tubules into the tooth pulp.

Delivering steroid medication using these magnetic nanoparticles could treat inflammation in the pulp. An antibiotic could be delivered to reduce the infection, or a local anesthetic could be utilized to numb a tooth. Even though the nanoparticles are tiny, they are able to deliver a large enough dose for medications to be effective.

Masri and Depireux are currently conducting studies on extracted human teeth to determine the optimal size for the nanoparticles and the most effective, biocompatible coating. By covering the particles with a biocompatible substance, like starch, for example, the body's immune system won't attack the nanoparticles.

"We have been treating pulpal inflammation the same way for decades," Masri says. "This is a contemporary approach to an age-old problem."

--Thanks to Adam Zewe of the University of Maryland School of Dentistry for this story.

Published July 14, 2014