Amazon.com Review
The Ultrasonex rechargeable toothbrush supercharges your dental hygiene routine, removing far more plaque than even the most manic manual brushing could achieve. Alternating 1.6 MHz ultrasonic and 18,000 SPM carrier waves, the "dual frequency" action purports to reach below the gum line to prevent gingivitis and bleeding. (More likely, it's the 18,000 strokes per minute that does the trick.) It's certainly true that the Ultrasonex leaves teeth as clean as they'll feel short of a trip to the dentist. The charge lasts for up to 4 days, making it easy to bring along on short trips. The ergonomically designed toothbrush feels good in the hand, and it even turns itself off automatically after three minutes--the amount of brushing time recommended by dentists. No cheating by shutting it off manually!
--Mary Park