A new toothbrush from Ultreo, Inc., a University of Washington spin-off, features technology that was first stumbled upon at the university’s Applied Physics Lab. Here’s what makes this brush different than anything else you ever had in your mouth:
It all began in 2003, when the UW’s Pierre Mourad met local entrepreneur Jack Gallagher for a steak lunch. Mourad, a research scientist in APL’s Center for Industrial and Medical Ultrasound and research associate professor in the UW’s Department of Neurological Surgery, was using high-frequency pulses to deliver drugs to brain tissue and to diagnose pain. Mourad sought an investor for a medical company. Gallagher, who helped launch the Sonicare toothbrush, had another idea: He wanted to build a better toothbrush.
Mourad began tinkering in the lab. He knew that ultrasound, already used in high-pressure professional dental cleanings, could clean teeth. The technique works because ultrasound is the right frequency to vibrate bubbles. As the bubbles vibrate more than 20,000 times per second, they move the surrounding fluid, creating thin layers of water that sweep off the plaque.
Previous attempts to create a consumer-grade ultrasonic toothbrush had failed. Ultrasound travels much better in water than in air, and directing the pulses was a challenge. Mourad believed he could do better.
“It helped that I had a lab filled with gizmos,” he said. “We can build anything at APL.” The lab’s engineers inserted a transducer, a machine that turns electric pulses into mechanical pulses, into the head of the toothbrush. Then they built a rubber waveguide to direct those pulses to the edge of the bristles. The prototype was a toothbrush connected to a rack holding about 100 pounds of equipment, including a 150-Watt amplifier.
Everyone left the room before Mourad tried brushing for the first time. He survived, and a toothbrush was born.
After the physicists had settled on a basic design, the project moved to the School of Dentistry.
“There have been toothbrushes that tried to use ultrasound,” said Frank Roberts, an associate professor of periodontics. “But they haven’t been very effective. It took people that knew a lot about ultrasound to do it well.”
Dental researchers studied what frequency and intensity of ultrasound would be best to remove plaque and preserve gum health. In the lab, they coated artificial teeth with brightly colored plaque to compare results using different settings. Ultreo directs ultrasonic energy toward the bristle tips, which also vibrate but at slower, sonic frequencies. Lab tests showed that adding ultrasound cleared plaque from grooved surfaces better than using a traditional power brush.
“The addition of the ultrasonic to the power toothbrush was able to remove more plaque from places the bristles didn’t reach,” Roberts said. “I’ve been impressed with it.”
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