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The research team working to bring the plasma dental brush into commercial use includes, left to right, Meng Chen, chief scientist with Nanova, Inc.; Hao Li, associate professor of mechanical engineering; Qing Hong, mechanical engineering doctoral candidate; Qingsong Yu, associate professor of mechanical engineering; Andrew Ritts, senior research scientist with Nanova, Inc.; Adam Blumhagen, mechanical engineering doctoral candidate; and Xiaoqing Dong, postdoctoral fellow.

Clinical trials are expected to begin early this summer on a technology that aims to make visits to the dentist easier and less frequent.

Mechanical engineering Associate Professor Qingsong Yu said the plasma dental “brush” he and Hao Li, also an associate professor of mechanical engineering at the University of Missouri College of Engineering, have developed and filed a patent application for should be ready for clinical testing in June. Nanova, Inc., the researchers’ small business, has licensed the technology from the university and is working with the University of Tennessee Health Science Center (UTHSC) College of Dentistry in Memphis to produce multiple, portable machines that would transport between dentists’ chairs with ease.

The researchers’ plasma brush creates a stronger bond between a tooth and the dental composite resin used to fill cavities, resulting in fewer dental visits.

Andrew Ritts, senior research scientist with Nanova, Inc., demonstrates how non-invasive the plasma “brush” can be. While the dental restoration procedure remains the same, adding a step that includes the plasma brush may help create a stronger bond between teeth and restorative material. Researchers have designed the plasma brush’s “cool flame” to be quick and fairly non-invasive.

Yu said much of the dental filling process remains the same when using the plasma brush. What’s different is an added step that uses the brush to help create a stronger bond between tooth dentin — calcified tissue just below tooth enamel — and the dental adhesive used to bond the dental composite.

“The problem is the adhesive/dentin interface. The adhesive is organic, but the tooth is mainly inorganic, so the interface is very weak and is not compatible with each other,” Yu said.

Current dental restoration methods involve tooth preparation, which includes removal of decayed material and enamel that would otherwise be unsupported after removal of decayed dentin. After preparation, adhesive is applied and cured, followed by layers of dental composite.

The plasma brush is used to modify the surface properties of the dentin, making it more compatible with the dental adhesive. This results in a stronger bond between the dental adhesive and the tooth. Research data has shown that the bond between tooth dentin and dental adhesive after using the plasma brush to modify the chemical properties of the dentin is about 60 percent stronger than a bond created without the plasma brush, Yu said.

“Plasma modifies the surface properties of the dentin,” Yu said. “Then we have a better match with the adhesive.”

Over time, the adhesive that keeps the composite in the tooth wears down. Yu said the average dental filling, especially those using dental amalgam — metal dental restoration material — lasts up to about 15 or 20 years. Fillings fall out or separate from the tooth after the adhesive is no longer effective. Plasma treatments could lead to less need for dental restoration work on existing fillings — and fewer trips to the dentist.

The plasma’s blue flame creates a brush-like appearance only a few millimeters long. Machines that feature multiple functions, such as the output and duration of the plasma flame, are on their way to the University of Tennessee Health Science Center (UTHSC) College of Dentistry in Memphis to begin clinical trials.

Yu also stressed that while the portion of the dental restoration procedure utilizing the plasma brush can be minimally invasive, the rest of the procedure is primarily the same.

“We don’t change anything the dentist will do,” he said. “By adding one step, we hope to get a better interface bonding, and we’re hoping it will last longer.”

There are no actual bristles on this plasma brush, which uses a “cool flame” that also kills bacteria in the areas it is applied, making it useful for cleaning the affected area during tooth preparation.

“We’ve used this technology for material processing,” Yu said.

While its use in dentistry is relatively new, the use of plasma technology to create stronger bonds can be found in other industries. It has been used commercially in the automotive industry, Yu said. Some automakers in Europe use plasma to treat bumper moldings prior to applying car paint. The plasma affects the bumper material similarly to the way it affects dentin: it modifies the surface properties allowing a better bond between the molding material and car paint.

Research on the plasma brush began about six years ago with a research grant from the National Science Foundation. Application of the plasma brush to dental research is a collaborative effort from Yu, Li, Meng Chen, chief scientist with Nanova, Inc., Professor Yong Wang, from the University of Missouri-Kansas City School of Dentistry, and Associate Professor Liang Hong, from UTHSC.

Once clinical trials begin, researchers will gain better insight into the effects of the plasma brush on dental restoration. Yu said it is too early to predict how long dental fillings made using the plasma treatment will last, but their durability should be significantly improved.