BEST OF FRIENDS: Plasma brush technology could one day make dental visits a picnic.
is a typical filling procedure, during which a dentist drills away the infected material from a decayed tooth, preparing the cavity for the polymer-ceramic composite that will fill it. Drilling disturbs microscopic nerve endings at the center of the tooth, called "pulp," Noor explains. Heat from friction, he adds, expands fluid inside "dentinal tubules," pressuring the nerves even more.
Dispensing with those anxiety provocateurs, the plasma brush not only kills bacteria, but also "modifies the surface of the tooth," Li says, improving its ability to bond with the composite. "Most composites are made of polymers and ceramic. They last, on average, 5 to 8 years before they shrink and break," after which bacteria, acids, and enzymes infiltrate and cause more decay. "The plasma brush should greatly improve the bond and eliminate those problems," says Li.
Noor seconds this opinion, noting that the plasma brush won't leave the "smear layer," a normal residue from traditional drilling that also hampers tooth-to-filling adhesion.
Born in Feixian, Shandong Province, on China's eastern coast, Hao Li, now 32, completed both bachelor's and master's degrees in materials science at Xi'an Jiaotong University. He decided to pursue advanced studies in the U.S. because, Li says, "it has the best educational system in the world" and the benefits of advanced dentistry. "There were no dentists in China. No annual cleaning, no floss, and plenty of decay," he says.
A doctoral student at Stevens Institute of Technology in Hoboken, N.J., Li studied biomaterials of every stripe. He says "collaborative conversations" with Yu, the project's 43-year-old principal investigator, and bioengineer Yong Wang inspired his interest in a better way to fill teeth.
Wang, who directs the craniofacial bioengineering program at the University of Missouri-Kansas City, says that the nation's dentists each year spend close to 75 percent of their time restoring failed fillings, procedures that cost patients nearly $70.3 billion in 2002, the last year data were available.
With the plasma brush, Wang says, "dental restorations could be significantly improved."
Though exciting news for the future, don't expect to see a plasma brush at your next dental appointment, cautions prosthodontist Glenn Wolfinger, co-director of the Institute For Facial Esthetics in Fort Washington, Pa.
"While the research is very interesting, a well-controlled multi-center study by respected clinicians will need to be published in a peer reviewed scientific journal," Wolfinger advises. "Many technologies have come along in the past 20 years promising to replace the dental drill and improve composite bonds. But none has yet had a significant impact."
Li is aware that success will involve more than a technological triumph. But rather than focusing on "exact clinical applications," Li says he's perfecting basic processes, like "improving the plasma we are using."