DentalVibe Tricks Brain to Cut Pain

Dentistry has made huge strides since the 19^th century ads for painless dentists, but fear of pain still keeps many people from getting dental work done. Electronic technology is helping dentists reduce pain by tricking the brain so patients barely notice the injections of anesthetics.

Dentists long ago noticed that if they vibrated the check area around the spot of the injection needle's entrance, nerve signals were interrupted so patients felt less pain. Florida dentist, Dr. Steven G. Goldberg, decided to capitalize on this idea. He first used a vibrating flosser but decided to commercialize a more rugged product, so he linked up with an engineering team to create DentalVibe, a device now being marketed to dentistry offices.

"We provide a vibrating lip retractor that stimulates the region and has a light to illuminate the area," says Dave Schiff, director of engineering at Bresslergroup, the Philadelphia contract design house that designed DentalVibe. The fork on the handheld tool vibrates while the dentist injects anesthetic into the patient gums, pointing the needle between the prongs of the fork.

The engineers use an eccentric cam to vibrate the fork, which is covered with rubber so it's soft enough to be comfortable for patients. Finding the right durometer rubber to permit vibration was a challenge, as was figuring out how to trick the brain so it doesn't adjust for the vibrations and let pain signals go to the brain.

"We run at about 120 Hz with 0.5 mm of amplitude. We found that if it is on for about a second then turns off briefly, it keeps refreshing signals to the brain and continuously masks the pain," Schiff says.

Fitting a powerful motor into the handle was a key design challenge, one that required getting the most vibration from the smallest motor. "One concern was to get the maximum force so we use a dc motor that delivers the most torque on the 1.2V the battery supplies," Schiff says.

Making the unit compact and light were also critical elements in the design. The unit can't take up much space and it can't be bulky. The motor, light source and battery fit in the handle. A light pipe permits illumination at the point of injection while letting designers keep the fork thin so it's not intrusive for patients.

It uses a rechargeable battery that easily lasts the 30 seconds or less that it's activated for injections. Simplicity in design was important to keep costs down and ensure that electronics aren't damaged during the many washdowns endured by dental equipment. "It's a three-part, overmolded assembly that uses a light pipe to shine the light where the dentist will be making the injection," Schiff says.