Thursday, August 6, 2009

Electric toothbrush

Electric toothbrush, made by Braun.

An electric toothbrush is a toothbrush that uses electric power to move the brush head, normally in an oscillating pattern, though electric toothbrushes are sometimes called 'rotary' toothbrushes.


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 did not move on its own, and was not actually electrical at all. Like Dr. Scott's other "electric brush" products, the device merely contained a magnet in the handle. The magnetic field was claimed to provide health benefits.

Evolution of the modern toothbrush

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 these are more effective than manual toothbrushes, as it leaves less room for patients to brush incorrectly.

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/Squibb.

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 one major aspect: the cordless hand piece relied on rechargeable NiCad batteries for power, while the Broxodent hand piece was designed to plug into a standard wall outlet and run on AC line voltage. Broxodent USA models were designed for 110v 60Hz AC power; other models were available for European power standards.

This difference in power source was significant for several reasons. In the case of the GE unit, the hand piece was portable but it was also 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 spent their life sitting 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 power (not as much power as a comparable alkaline batteries, for example) and it was not uncommon for the GE Automatic toothbrush to run out of power before tooth brushing was complete - particularly if several members of the family used the same hand piece within a short time space. Finally, early NiCad batteries tended to have a short lifespan. The batteries were sealed inside the GE hand piece and the whole unit was frequently discarded when the batteries failed. The GE Automatic Toothbrush was less expensive than the Broxodent which may have contributed to its disposable characteristic. Despite the shortcomings of the GE Automatic Toothbrush, the public was hooked on electric toothbrushing.

In contrast, the Broxodent hand piece was slim and remarkably compact - even by today's standards. Since it was powered by AC line voltage, it never grew tired or slowed down, 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 likely place for a cord to fail. Since the Broxodent hand pieces were sealed, a cord failure was not repairable and the expensive hand piece had to be discarded. That said, it was not unusual for a Broxodent hand piece to last for 20 years or longer and 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 at the wall to transmit lower voltage to the hand-held unit (typically 12, 16 or 24 volts) - modern hair blowers frequently use this approach. Many such appliances also include a Ground Fault Circuit Interrupter in the step-down transformer for added protection against electrical shock. Wiring standards in many countries now require that outlets in bath areas must be protected by a GFCI device (required in USA since 1970's on bathroom outlets in new construction).

By the decade of the 1990s, Broxo's original design was still functional, but problems with safety certification could not be ignored. Further, improved low-voltage design 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 have only been selling online.

The Broxo low-voltage models used one of several different methods to attach brushes to the hand piece. However, the brushes for low-voltage models would not fit the original line-voltage Broxodent. Brushes were not even interchangeable among various Broxo low-voltage models. By the 1990s, replacement brushes for line-voltage Broxodent models were no longer being sold in the USA (they were available in Europe) so the original Broxodent Electric Toothbrush was rapidly approaching the end of its product life. But this innovative product started a trend and enjoyed 30+ years of product leadership.


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. 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 . Of course, built into any conclusion in this area is the assumption that persons using a manual toothbrush will, in fact, brush their teeth in an approved manner and for a suitably long period.

Key Functions

Type of motion

Three main mechanics in how the toothbrush head works in electric toothbrushes are vibrating, oscillating, and sonic. Most studies have focused upon the vibrating and oscillating heads, but not the sonic type.

Power source and charging

Modern electric toothbrushes run on low voltage - typically 12v or less. A few units still use a step-down transformer to power the handpiece, but most use power from a rechargeable battery in the hand piece. The electronic compartments in most of the electric toothbrushes are completely sealed to prevent water damage. While early NiCad battery toothbrushes used metal tabs to connect with the charging base, modern 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. There are no exposed contacts and the handpiece can be completely sealed.

Other electric toothbrushes use replaceable batteries, disposable or rechargeable, storing them in the bottom, generally thicker than a normal toothbrush.

Timer function

Many modern electric toothbrushes have a timer for two minutes - the user is alerted via extra buzzing, noise or a brief power interruption. Quality models may have an incremental timer that buzzes four times or every thirty seconds up to two minutes. Dentists consider the incremental timer to be a key function. The benefit of the timer function is to encourage brushing to last two minutes - the incremental timer alerts the user to brush each quarter of the mouth for a consistent clean in all areas of the mouth. The timer function is also important because brushing too quickly is a significant cause of inadequate oral hygiene. A new release in 2008 was the Smart Guide by Braun Oral-B which provides individuals with a guide to proper brushing via a wireless display.

Visual Stimuli

Some electric toothbrushes use LCD screens, which, in addition to showing how many minutes you've brushed (or the optimal amount of time, usually 2 minutes or more) show smiley faces or other images to encourage optimal brushing. There is minimal evidence to suggest such features add any value. Likewise, there is little evidence to support that such features only serve as gimmicks for the purpose of selling better.

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