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Researcher Uses Microscopic Particles to Deliver Drugs into Teeth

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Written by Adam Zewe

Ouch! You've just taken a drink from an ice-cold glass of lemonade and felt a sharp pain in one of your teeth. If that pain is caused by pulpitis, or an inflammation of the dental pulp deep within the tooth, treatment could require a root canal procedure to remove the damaged pulp. But research being conducted at the University of Maryland School of Dentistry (UMSOD) could provide dental practitioners with a much less invasive treatment for pulpitis. Radi Masri, DDS, MS, PhD, associate professor in the Department of Endodontics, Prosthodontics and Operative Dentistry, is developing a new, patent-pending technique to deliver medication directly into the center of a tooth.

Dr. Masri and his collaborator, Didier Depireux, PhD, associate research scientist at the A. James Clark School of Engineering at the University of Maryland, College Park, recently received a two-year, $450,000 grant from the National Institute of Dental and Craniofacial Research for their project, "Magnetic Delivery of Therapeutic Nanoparticles to the Dental Pulp." The study uses strong magnetic fields to move microscopic particles 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 explains.

Masri is using the tubules, the microscopic channels that travel through the dentin into the tooth pulp, as a vehicle to deliver medication that could reduce inflammation or treat infection. Researchers attach medication to microscopic balls known as nanoparticles. By creating the nanoparticles out of a magnetic substance, like iron, the researchers can use a magnetic field to push those particles, and the attached medication, through the tubules and into the pulp.

Masri and Depireux have designed a system of magnetic arrays that are 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. Masri's research has shown that, even though the nanoparticles are tiny, they are able to deliver a large enough dose for medications to be effective.

He is 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, Masri explains. He is hopeful that this grant will allow him to conduct enough preliminary studies so that he can eventually move the project into human trials. Testing in live patients will allow Masri to determine if this procedure actually reduces pain.

Masri is excited for the implications this project holds for the future of dental care. "We have been treating pulpal inflammation the same way for decades. This is a contemporary approach to an age-old problem," he concludes.

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