Electric toothbrush is a toothbrush that makes rapid automatic bristle motions, either back-and-forth oscillation or rotation-oscillation, in order to clean teeth.
Motions at sonic speeds or below are made by a motor. In the case of ultrasonic toothbrushes, ultrasonic motions are produced by a piezoelectric crystal.
A modern electric toothbrush is usually powered by a rechargeable battery charged through inductive charging when the brush sits in the charging base between uses.
Electric toothbrushes can be classified according to the frequency (speed) of their movements as power, sonic or ultrasonic toothbrushes, depending on whether they make movements that are below, in or above the audible range (20–20,000 Hz or 2400–2,400,000 movements per minute), respectively.
The first electric toothbrush was invented 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 device plugged into a standard wall outlet and ran on line voltage. Electric toothbrushes were initially created for patients with limited motor skills and for orthodontic patients.
When using vibrating toothbrush, a brushing technique similar to that used with a manual toothbrush is recommended, whereas with rotating-oscillating brushes the recommended cleaning technique is to simply move the brush slowly from tooth to tooth.
Electric toothbrushes can also be classified according to the speed of their movements as standard power toothbrushes, sonic toothbrushes or ultrasonic toothbrushes.
If the motion of the toothbrush is sufficiently rapid to produce a hum in the audible frequency of human range (20 Hz to 20,000 Hz), it can be classified as a sonic toothbrush.
Any electric toothbrush with movement faster than (20 Hz to 20,000 Hz) can be classified as an ultrasonic toothbrush. Certain ultrasonic toothbrushes.
Sonic toothbrushes are a subset of electric toothbrushes with movement that is fast enough to produce vibration in the audible range.
Most modern rechargeable electric toothbrushes from brands such as Sonicare, FOREO, and Oral-B fall into this category and typically have a frequencies that range from 200 to 400 Hz, that is 12,000–24,000 oscillations or 24,000–48,000 movements per minute.
Because sonic toothbrushes rely on sweeping motion alone to clean the teeth, the movement that they provide is often high in amplitude, meaning that the length of the sweeping movements that they make is large.
The newest developments in this field are ultrasonic toothbrushes, which use ultrasonic waves to clean the teeth.
In order for a toothbrush to be considered "ultrasonic" it has to emit a wave at a minimum frequency of 20,000 Hz or 2,400,000 movements per minute.
Typically, ultrasonic toothbrushes approved by the U.S. Food and Drug Administration (FDA) operate at a frequency of 1.6 MHz, which translates to 192,000,000 movements per minute.
Ultrasonic toothbrushes emit vibrations that are very high in frequency but low in amplitude. These vibrations break up bacterial chains that make up dental plaque and remove their methods of attachment to the tooth surface up to 5 mm below the gum line.
Claims have been made that electric toothbrushes are more effective than manual ones as they are less dependent upon a user's personal brushing technique.
Some dentists also claim that they help children with overcoming their fear of the dentist. Independent research finds that most electric toothbrushes are no more effective than manual brushes—assuming that people use a manual toothbrush 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 patients with limited manual dexterity or where difficulty exists in reaching rear teeth, however, dentists regard electric toothbrushes as being especially beneficial.
A 2014 Cochrane review suggested the effectiveness of electric toothbrushes over manual ones: plaque build-up and gingival inflammation was reduced by 11% and 6% respectively after one to three months of use and after three months of use, the reduction observed was greater – 21% reduction in plaque and 11% reduction in gingival inflammation.
In addition, ultrasound from a commercially available ultrasonic toothbrush has been shown to break up dental plaque composed of chains of cariogenic Streptococcus mutans bacteria, destroying their cell walls and removing their methods of attachment to the enamel surface, at a distance of 5mm from the plaque.
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. Most manufacturers recommend that heads be changed every three to six months at minimum, or as soon as the brush head has visibly deteriorated.