Solana Beach, CA--Evidence that highly infectious diseases--such as HIV--can potentially be transmitted by dental instruments led an engineer to design and patent what he says is the first fully sealed, sterilizable power module for dental handpieces. Called the MIYAD Electric System, the hand-held drive is, interestingly, composed of many off-the-shelf components that keep down costs and make it maintenance-free.
For patients, the unit's best feature might be that it's comparatively quiet. The high-pitched whine of air-powered dental drills is notorious for its ability to instill fear in the bravest souls. The secret is that the MIYAD unit is powered by a 12V, 22-mm diameter coreless dc electric motor.
Donald Hogan, developer of the power module and president of MIYAD (Solana Beach, CA), chose an electric motor not for its sound characteristics, but because it could be sealed. "It's sterilizable, immersible, and will eliminate cross-contamination of diseases such as HIV and hepatitis by the dental handpiece," he says. "Nothing is going to blow in your mouth. Nothing."
Hogan's concern for material being blown in a patient's mouth isn't just paranoia. Reuters news service reported in September 1995 of the possibility that the lubricants in unsealed dental instruments could potentially harbor viruses.
"Air-operated devices must vent the air they use," says Hogan. "There is a chance that a virus can get into the lubrication and then be blown into the next patient." To prevent this, the MIYAD unit is sealed with O-rings, enabling it to be fully immersed for sterilization.
The dc motor turns at 25,000 to 35,000 rpm from 9 to 18V, depending on model. It's claimed that the MIYAD's 5 to 6 oz-inches of torque is roughly 20% more than a comparable air motor. Motor life is spec'd at 2,000 hours, and the motor is replaceable.
Ten years ago the situation was reversed, with electric motors lagging the performance of a comparable-size air motor, says Hogan. But advancements and rare-earth magnets have pushed dc motors ahead.
For low-torque polishing tasks, air-powered handpieces can run up to 500,000 rpm. Hogan gives the MIYAD high-speed capability via a standard 1:4 gearbox, which steps output up to 140,000 rpm. The unit accepts standard dental handpieces, which attach to the end, just like any air motor.
An off-the-shelf power supply and variable-speed foot controller completes the package and helps hold down costs. For use in remote locations, a battery pack is available.
Hogan has also incorporated the core technology into surgical instruments and manicurist tools.