What’s the difference between a sonic and ultrasonic electric toothbrush?
Most of the brushes we review here at Electric Teeth are sonic, such as those from Oral-B and Philips. However, there is another type of brush to consider: the ultrasonic brush. These are rarer to come across, but they are still available from online retailers such as Amazon. In this post we’ll be taking a look at the key differences between the two types of brush, and there’s an infographic further down showing the two side by side.
If you are looking to compare a range of different brushes side by side, you may like to see our full list of electric toothbrush comparisons.
Sonic Electric Toothbrush
To be classified as a sonic toothbrush, the motion or vibration from the brush has to be quick enough to produce a ‘humming’ sound that is within the audible range of the human ear (20 Hz to 20,000 Hz). Sonic brushes typically offer 12,000-24,000 oscillations or 24,000-48,000 movements per minute.
Sonic brushes rely on a sweeping motion alone to clean the teeth, the movement that they provide is often high in amplitude which means they offer larger sweeping brush stroke motions.
It is the bristles on the brush head that move at this speed to essentially brush away food particles and bacteria that sit on the teeth and gumline.
Sonic toothbrushes should not be confused with ultrasonic toothbrushes which operate at a much higher frequency and use ultrasound rather than the motion of the brush head to remove plaque and other bacteria.
Examples of a sonic brush include Oral-B’s range of electric brushes as well as Philips Sonicare range. You can see some of our reviews here.
Ultrasonic Electric Toothbrush
An ultrasonic toothbrush is one that uses a very high frequency of vibration referred to as ultrasound to remove plaque and bacteria from the teeth.
To be classified as such, the brush has to emit a wave of 20,000Hz or 2,400,000 movements per minute, considerably more than the very popular sonic technology.
Within the USA, the Food and Drug Association (FDA) actually specify a minimum of 1.6MHz or 192,000,000 movements per minute.
The high frequency waves, but low in amplitude means the bacterial chains found in the mouth that make up plaque are broken up by the vibration and can work as far as 5mm below the gumline. Essentially speaking the brush can clean the teeth simply by resting the brush on it.
An ultrasonic brush compared to the more commonly seen and used sonic brushes does not need a physical motion to clean the teeth surfaces and gumline.
However many ultrasonic brushes do also provide additional sonic vibration ranging from 9,000 to 40,000 movements per minute, in order to provide additional sweeping motion which removes food particles and bacterial chain remnants.