Dr. Scott's 'electric' toothbrush
In the late 1800s in the USA, a man named Dr. George A. Scott claimed to invent an "electric" toothbrush. However, unlike actual electronically-powered bristle brushes, Dr. Scott's brush merely sent a strong electrical current through the brush to whoever was using it at the time. The shock was apparently (according to lore of the time) supposed to "promote good health".
Evolution of the modern toothbrush
Although a true electric toothbrush was first conceived in 1880 and reliably sold in 1939 (in Switzerland), it took almost 30 years for the invention to be produced in the USA; the Broxodent, was a rotating electric toothbrush introduced by Squibb Pharmaceutical at the centennial of the American Dental Association in 1960. These were initially created for patients with limited motor skills, as well orthodontic patients (such as those with braces). Claims have been made that these are more effective than manual toothbrushes, as it leaves less room for patients to brush incorrectly.
The electronic compartments in most of the electronic toothbrushes are completely sealed to prevent water damage. There are no metal contacts. These toothbrushes charge using a technique called inductive charging. In the brush unit is one half of a transformer, and in the charge-unit is the other part of the transformer. When brought together, a varying magnetic field in one coil induces a current in the other coil, thereby allowing for the charging of a battery.
Other electric toothbrushes use replaceable batteries, disposable or rechargeable, storing them in the bottom, generally thicker than a normal toothbrush.
Independent research finds that most electric toothbrushes are no more effective than the manual variety. . The exception is the "rotation-oscillation"-models, including many of the electrical brushes in Braun's Oral B-series, but even this brush performs only marginally better than a regular manual brush. The research done indicates that the way the brushing is performed is of a higher importance than the choice of brush.
- American Artifacts - Dr. Scott's Quack Electric Devices
- Academy of General Dentistry - Dental advances
-  Robinson PG, Deacon SA, Deery C, Heanue M, Walmsley AD, Worthington HV, Glenny AM, and Shaw WC. Manual versus powered toothbrushing for oral health. Cochrane Database of Systematic Reviews 2007 Issue 4
-  Deery C, Heanue M, Deacon S, Robinson PG, Walmsley AD, Worthington H, Shaw W, Glenny AM. The effectiveness of manual versus powered toothbrushes for dental health: a systematic review. Journal of Dentistry. Volume 32, Issue 3, March 2004, Pages 197-211
- Thumbs down for electric toothbrush - BBC News
-  Penick, Catherine (2004) Power toothbrushes: a critical review - International Journal of Dental Hygiene 2 (1), 40-44. doi: 10.1111/j.1601-5037.2004.00048.x
- Manual versus powered tooth brushing for oral health. Commentary