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An electric toothbrush truth is a toothbrush that uses electric power supplied usually by a battery to move the brush head rapidly, either oscillating side to side, or rotation-oscillation (where brush heads rotate in one direction and then the other).
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The first successful electric toothbrush, the Broxodent, was conceived in Switzerland in 1954 by Dr. Philippe-Guy Woog. Woog's electric toothbrushes were originally manufactured in Switzerland (later in France) for Broxo S.A. The first clinical study showing its superiority over manual brushing was published by Pr. Arthur Jean Held in Geneva in 1956. Electric toothbrushes were initially created for patients with limited motor skills, as well as orthodontic patients (such as those with braces). Claims have been made that electric toothbrushes are more effective than manual ones as they are less dependent upon patients brushing correctly.
The Broxo Electric Toothbrush was introduced in the USA by E. R. Squibb and Sons Pharmaceuticals at the centennial of the American Dental Association in 1959. After introduction, it was marketed in the USA by Squibb under the names Broxo-Dent or Broxodent. In the 1980s Squibb transferred distribution of the Broxodent line to the Somerset Labs division of Bristol Myers/Squibby
While the Broxodent may have been the first electric toothbrush and a superior product, the electric toothbrush that caught the public's attention in USA was the General Electric Automatic Toothbrush introduced in the early 1960s. Similar to the Broxodent in function, it differed in that it was cordless with rechargeable NiCad batteries, while the Broxodent plugged into a standard wall outlet and run on AC line voltage.
This difference in power source was significant for several reasons. The GE toothbrush, although portable, was rather bulky, about the size of a two-D-cell flashlight handle. NiCad batteries of this period left much to be desired: they suffered from memory and lazy battery effects. The GE Automatic Toothbrush came with a charging stand which held the hand piece upright; most units were kept in the charger which is not the best way to get maximum service life from a NiCad battery. Early NiCad batteries did not hold much energy, and it was not uncommon for the GE Automatic toothbrush to run out of power before brushing was complete, particularly if several people used the same battery-holding handle (with separate brushes) without recharging. Finally, early NiCad batteries tended to have a short lifespan. The batteries were sealed inside the GE device, and the whole unit had to be discarded when the batteries failed. The purchase price of each GE Automatic Toothbrush was lower than a Broxodent. The GE Automatic Toothbrush sold well.
The Broxodent hand piece was slim and remarkably compact, even by today's standards. Since it was powered by AC line voltage, it never ran out of power, although it could grow warm after extended use. Early Broxodent models came with a straight power cord, later units with a coiled cord. All Broxodent cords had a small molded strain relief where the cord entered the hand piece, but this was still the likeliest place for a cord to fail. Since the Broxodent hand pieces were sealed, a cord failure was not repairable and the expensive toothbrush had to be discarded. That said, it was not unusual for a Broxodent toothbrush to last for 20 years or longer; failures were rare.
The use of an AC line voltage appliance in a bathroom environment was problematic. By the early 1990s Underwriter Laboratories (UL) and Canadian Standards Association (CSA) would no longer certify line-voltage appliances for bathroom use. Newer appliances had to use a step-down transformer to operate the actual toothbrush at low voltage (typically 12, 16 or 24 volts). Wiring standards in many countries require that outlets in bath areas must be protected by a RCD/GFCI device (e.g., required in USA since the 1970s on bathroom outlets in new construction).
By the 1990s there were problems with safety certification of Broxo's original design. Further, improved battery-operated toothbrushes were providing formidable competition. Broxo S. A. still produces and markets a low-voltage model, but its public visibility in the USA has been limited in the face of large competitors, such as Philips Sonicare and Braun Oral-B models. Later Broxo models had no major distributor (such as Squibb) in the USA, and only sell online.
The Broxo low-voltage models used several different methods to attach the actual brushes to the hand piece; however, brushes were often not interchangeable between Broxo models. By the 1990s replacement brushes for line-voltage Broxodent models were no longer sold in the USA, so the original Broxodent Electric Toothbrush was no longer suitable for use there although it had started a trend and sold for over 30 years.
Types of electric toothbrushes 
Electric brushes can be classified into two categories according to the type of action that they employ: vibration or rotation-oscillation. When using vibrating toothbrush, a brushing technique similar to that used with a manual toothbrush is recommended, whereas with rotating-oscillating brushes the recommend cleaning technique is to simply move the brush slowly from tooth to tooth.
Ultrasonic toothbrush 
The newest development in this field are the ultrasonic toothbrushes, or simply sonic toothbrushes using ultrasonic waves to clear the teeth. In order for a toothbrush to be considered "ultrasonic", it has to emit a wave at a minimum frequency of 20,000 hertz or 2,400,000 movements per minute. Typically ultrasonic toothbrushes approved by the FDA operate at a frequency of 1.6 MHz, which translates to 192,000,000 movements per minute. Most ultrasonic toothbrushes have an additional sonic vibration ranging from 9,000 to 40,000 movements per minute. Any toothbrush operating at a frequency or vibration less than 2,400,000 movements per minute (20,000 hertz) is a "sonic" toothbrush. It is called sonic because its operating frequency, for example of 31,000 movements per minute, falls into the human hearing range of between roughly 20 hertz to about 20,000 hertz.
Effectiveness of electric toothbrushes 
Independent research finds that although most electric toothbrushes are no more effective than manual brushes—assuming that people using a manual toothbrush will brush effectively—the rotation-oscillation-models have been found to be marginally better than manual ones. The research concludes that the way brushing is done, including the amount of time spent, is more important than the choice of brush. For certain patients with limited manual dexterity or where difficulty exists in reaching rear teeth, however, dentists strongly feel that electric toothbrushes can be especially beneficial.
The effectiveness of an electric toothbrush depends not only on its type of action and on correct use, but also on the condition of the brush head, which loses its effectiveness over time due to bristle breakdown and wear. Most manufacturers, as well as dental professionals, recommend that heads be changed every three to six months at minimum, or as soon as the brush head has visibly deteriorated.
Power source and charging 
Modern electric toothbrushes run on low voltage, 12v or less. A few units use a step-down transformer to power the brush, but most use a battery, usually but not always rechargeable and non-replaceable, fitted inside the handle, which is hermetically sealed to prevent water damage. While early NiCad battery toothbrushes used metal tabs to connect with the charging base, modern toothbrushes use contactless inductive charging: the brush unit and charger stand each contain a coil of wire; when placed in proximity, the powered coil from the stand transfers power by induction to the handle, charging the battery.
Optional features 
Many modern electric toothbrushes have a timer which buzzes or briefly interrupts power, typically after two minutes, and sometimes every 30 seconds. This is associated with a customary recommendation to brush for two minutes, 30 seconds for each of the four quadrants of the mouth.
Some electric toothbrushes have LCD screens which show brushing time and sometimes smiley face icons or other images to encourage optimal brushing. These features could encourage people with lower mental capacity and ability to brush more accurately.
- "Using A Rechargeable Electric Toothbrush" by Oral B
- Robinson PG, Deacon SA, Deery C, Heanue M, Walmsley AD, Worthington HV, Glenny AM, Shaw WC (2009). "Manual versus powered toothbrushing for oral health". Cochrane Database Syst Rev (1): CD002281. doi:10.1002/14651858.CD002281.pub2. PMID 15846633. — Meta-analysis of studies of the effectiveness of electric toothbrushes
- Deery C, Heanue M, Deacon S, Robinson PG, Walmsley AD, Worthington H, Shaw W, Glenny AM (March 2004). "The effectiveness of manual versus powered toothbrushes for dental health: a systematic review". J Dent 32 (3): 197–211. doi:10.1016/j.jdent.2003.11.006. PMID 15001285.
- "Thumbs down for electric toothbrush". BBC News. 21 January 2003.
- Penick C (2004). "Power toothbrushes: a critical review". Int J Dent Hyg 2 (1): 40–4. doi:10.1111/j.1601-5037.2004.00048.x. PMID 16451451.
- A dentist's perspective on the whether patients should be using electric or manual toothbrushes. Commentary — The Smile Team Balwyn North Dentist
-  What Frequency Should you change out your Toothbrush Head?
- Dental and Oral Health (Adults) Don't Let a Disability Keep the Dentist Away — Daniel E. Jolly, Professor of Clinical Dentistry College of Dentistry The Ohio State University.